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Levy RM, Mekhail NA, Kapural L, Gilmore CA, Petersen EA, Goree JH, Pope JE, Costandi SJ, Kallewaard JW, Thomson S, Gilligan C, AlFarra T, Broachwala MY, Chopra H, Hunter CW, Rosen SM, Amirdelfan K, Falowski SM, Li S, Scowcroft J, Lad SP, Sayed D, Antony A, Deer TR, Hayek SM, Guirguis MN, Boeding RB, Calodney AK, Bruel B, Buchanan P, Soliday N, Duarte RV, Leitner A, Staats PS. Maximal Analgesic Effect Attained by the Use of Objective Neurophysiological Measurements With Closed-Loop Spinal Cord Stimulation. Neuromodulation 2024:S1094-7159(24)00655-X. [PMID: 39254621 DOI: 10.1016/j.neurom.2024.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/26/2024] [Accepted: 07/16/2024] [Indexed: 09/11/2024]
Abstract
OBJECTIVES Spinal cord stimulation (SCS) has been challenged by the lack of neurophysiologic data to guide therapy optimization. Current SCS programming by trial-and-error results in suboptimal and variable therapeutic effects. A novel system with a physiologic closed-loop feedback mechanism using evoked-compound action potentials enables the optimization of physiologic neural dose by consistently and accurately activating spinal cord fibers. We aimed to identify neurophysiologic dose metrics and their ranges that resulted in clinically meaningful treatment responses. MATERIALS AND METHODS Subjects from 3 clinical studies (n = 180) with baseline back and leg pain ≥60 mm visual analog scale and physical function in the severe to crippled category were included. Maximal analgesic effect (MAE) was operationally defined as the greatest percent reduction in pain intensity or as the greatest cumulative responder score (minimal clinically important differences [MCIDs]) obtained within the first 3 months of SCS implant. The physiologic metrics that produced the MAE were analyzed. RESULTS We showed that a neural dose regimen with a high neural dose accuracy of 2.8μV and dose ratio of 1.4 resulted in a profound clinical benefit to chronic pain patients (MAE of 79 ± 1% for pain reduction and 12.5 ± 0.4 MCIDs). No differences were observed for MAE or neurophysiological dose metrics between the trial phase and post-implant MAE visit. CONCLUSION For the first time, an evidence-based neural dose regimen is available for a neurostimulation intervention as a starting point to enable optimization of clinical benefit, monitoring of adherence, and management of the therapy.
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Affiliation(s)
- Robert M Levy
- Neurosurgical Services, Clinical Research, Anesthesia Pain Care Consultants, Tamarac, FL, USA.
| | - Nagy A Mekhail
- Evidence-Based Pain Management Research, Neurologic Institute, Cleveland Clinic, Cleveland Ohio, OH, USA
| | - Leonardo Kapural
- Center for Clinical Research, Carolinas Pain Institute, Winston-Salem, NC, USA
| | | | - Erika A Petersen
- Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Johnathan H Goree
- Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | | | - Shrif J Costandi
- Evidence-Based Pain Management Research, Neurologic Institute, Cleveland Clinic, Cleveland Ohio, OH, USA
| | - Jan Willem Kallewaard
- Department of Anaesthesiology and Pain Management, Rijnstate Hospital, Elst, The Netherlands; Department of Anesthesiology and Pain Medicine, Amsterdam University Medical Centre, Amsterdam, The Netherlands
| | - Simon Thomson
- Pain Medicine and Neuromodulation, Mid & South Essex University Hospitals, Essex, UK
| | | | - Tariq AlFarra
- Department of Physical Medicine & Rehabilitation, Mount Sinai Hospital, New York, NY, USA
| | - Mustafa Y Broachwala
- Department of Physical Medicine & Rehabilitation, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Harman Chopra
- Department of Physical Medicine & Rehabilitation, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Corey W Hunter
- Ainsworth Institute of Pain Management, New York, NY, USA
| | - Steven M Rosen
- Delaware Valley Pain and Spine Institute, Trevose, PA, USA
| | | | | | - Sean Li
- National Spine and Pain Centers, Shrewsbury, NJ, USA
| | | | - Shivanand P Lad
- Department of Neurosurgery, Duke University Medical Center, Durham, NC, USA
| | - Dawood Sayed
- Department of Anesthesiology, University of Kansas School of Medicine, Kansas City, KS, USA
| | - Ajay Antony
- The Orthopaedic Institute, Gainesville, FL, USA
| | - Timothy R Deer
- The Spine and Nerve Center of the Virginias, Charleston, WV, USA
| | - Salim M Hayek
- Division of Pain Medicine, University Hospitals, Cleveland Medical Center, Cleveland, OH, USA
| | | | | | | | - Brian Bruel
- Department of Physical Medicine and Rehabilitation, McGovern Medical School and Cy Pain and Spine PLLC, Houston, TX, USA
| | - Patrick Buchanan
- Spanish Hills Interventional Pain Specialists, Camarillo, CA, USA
| | - Nicole Soliday
- Saluda Medical Pty Ltd, Macquarie Park, New South Wales, Australia
| | - Rui V Duarte
- Saluda Medical Pty Ltd, Macquarie Park, New South Wales, Australia; Department of Health Data Science, University of Liverpool, Liverpool, UK
| | - Angela Leitner
- Saluda Medical Pty Ltd, Macquarie Park, New South Wales, Australia
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Ho JS, Poon C, North R, Grubb W, Lempka S, Bikson M. A Visual and Narrative Timeline Review of Spinal Cord Stimulation Technology and US Food and Drug Administration Milestones. Neuromodulation 2024; 27:1020-1025. [PMID: 38970616 DOI: 10.1016/j.neurom.2024.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/03/2024] [Accepted: 05/13/2024] [Indexed: 07/08/2024]
Abstract
OBJECTIVES The aim of this study was to present key technologic and regulatory milestones in spinal cord stimulation (SCS) for managing chronic pain on a narrative timeline with visual representation, relying on original sources to the extent possible. MATERIALS AND METHODS We identified technical advances in SCS that facilitated and enhanced treatment on the basis of scientific publications and approvals from the United States (US) Food and Drug Administration (FDA). We presented milestones limited to first use in key indications and in the context of new technology validation. We focused primarily on pain management, but other indications (eg, motor disorder in multiple sclerosis) were included when they affected technology development. RESULTS We developed a comprehensive visual and narrative timeline of SCS technology and US FDA milestones. Since its conception in the 1960s, the science and technology of SCS neuromodulation have continuously evolved. Advances span lead design (from paddle-type to percutaneous, and increased electrode contacts) and stimulator technology (from wireless power to internally powered and rechargeable, with miniaturized components, and programmable multichannel devices), with expanding stimulation program flexibility (such as burst and kilohertz stimulation frequencies), as well as usage features (such as remote programming and magnetic resonance imaging conditional compatibility). CONCLUSIONS This timeline represents the evolution of SCS technology alongside expanding FDA-approved indications for use.
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Affiliation(s)
- Johnson S Ho
- Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
| | - Cynthia Poon
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Richard North
- The Neuromodulation Foundation, Inc, Baltimore, MD, USA; Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - William Grubb
- Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - Scott Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA; Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Marom Bikson
- Department of Biomedical Engineering, The City College of New York, New York, NY, USA
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Will A, Fishman M, Schultz D, Danko M, Verill D, Davies C, Retterath P, Miller N, Tonder L, Johanek L, Dinsmoor D, Tan Y, Franke A, Soghomonyan S. Improvements in Therapy Experience with Evoked Compound Action Potential Controlled, Closed-Loop Spinal Cord Stimulation - Primary Outcome of the ECHO-MAC Randomized Clinical Trial. THE JOURNAL OF PAIN 2024:104646. [PMID: 39094810 DOI: 10.1016/j.jpain.2024.104646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 07/17/2024] [Accepted: 07/26/2024] [Indexed: 08/04/2024]
Abstract
Spinal cord stimulation (SCS) is a well-established treatment for chronic neuropathic pain. However, over- or under-delivery of the SCS may occur because the spacing between the stimulating electrodes and the spinal cord is not fixed; spacing changes with motion and postural shifts may result in variable delivery of the SCS dose, and in turn a sub-optimal therapy experience for the patient. The evoked compound action potential (ECAP)-a measure of neural activation - may be used as a control signal to adapt SCS parameters in real-time to compensate for this variability. In this prospective, multicenter, randomized, single-blind, crossover trial, reduction in overstimulation intensity was used as a perceptual measure to evaluate a novel ECAP-controlled, closed-loop (CL) SCS algorithm relative to traditional open-loop (OL) SCS. The primary outcome used a Likert scale to assess sensation during activities of daily living with CL versus OL SCS. Of the 42 subjects in the Intent-to-Treat Analysis set, 97.6% had a reduction in sensation with CL versus OL SCS. The primary objective was met as the lower confidence limit (87.4%) exceeded the performance goal of 50% (p < 0.001). A total of 88.1% (37/42) of subjects preferred CL and 11.9% (5/42) preferred OL SCS. SCS dose consistency during CL SCS was demonstrated by the reduced variability in ECAP amplitude with CL SCS (SD: 8.72 µV) relative to OL SCS (SD: 19.95 µV). Together, these results demonstrate that the ECAP-controlled, CL algorithm reduces or eliminates unwanted sensation, and thereby provides a more preferred and consistent SCS experience. PERSPECTIVE: Patients with chronic pain need durable and dependable options for pain relief. SCS is an important therapy option, and new technology advancements could improve long-term therapy use. Closed-loop SCS offers a preferred and more consistent therapy experience for patients that could lead to increased therapy utilization and reliable therapy outcomes.
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Affiliation(s)
- Andrew Will
- Twin Cities Pain Clinic, 7235 Ohms Ln, Edina, MN 55439.
| | - Michael Fishman
- Center for Pain Control, 1235 Penn Avenue, Wyomissing, PA 19610.
| | - David Schultz
- Nura Pain Clinics, 7400 France Ave S, Edina, MN 55435.
| | - Michael Danko
- Premier Pain Treatment Institute, 111 Vandament Way, Mt Orab, OH 45154.
| | - Daniel Verill
- Kettering Medical Center, 3700 Southern Blvd Suite 300, Kettering, OH 45429.
| | | | | | - Nathan Miller
- Coastal Research Institute, 6221 Metropolitan St, Carlsbad, CA, 92009.
| | - Lisa Tonder
- Medtronic Neuromodulation - Pain Therapies, 7000 Central Ave NE, Minneapolis, MN 55432.
| | - Lisa Johanek
- Medtronic Neuromodulation - Pain Therapies, 7000 Central Ave NE, Minneapolis, MN 55432.
| | - David Dinsmoor
- Medtronic Neuromodulation - Pain Therapies, 7000 Central Ave NE, Minneapolis, MN 55432.
| | - Ye Tan
- Medtronic Neuromodulation - Pain Therapies, 7000 Central Ave NE, Minneapolis, MN 55432.
| | - Abi Franke
- Medtronic Neuromodulation - Pain Therapies, 7000 Central Ave NE, Minneapolis, MN 55432.
| | - Suren Soghomonyan
- The Ohio State University Wexner Medical Center, N411 Doan Hall, 410 West 10th Avenue, Columbus, OH 43210.
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Lam DV, Chin J, Brucker-Hahn MK, Settell M, Romanauski B, Verma N, Upadhye A, Deshmukh A, Skubal A, Nishiyama Y, Hao J, Lujan JL, Zhang S, Knudsen B, Blanz S, Lempka SF, Ludwig KA, Shoffstall AJ, Park HJ, Ellison ER, Zhang M, Lavrov I. The role of spinal cord neuroanatomy and the variances of epidurally evoked spinal responses. Bioelectron Med 2024; 10:17. [PMID: 39020366 PMCID: PMC11253499 DOI: 10.1186/s42234-024-00149-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 05/28/2024] [Indexed: 07/19/2024] Open
Abstract
BACKGROUND Spinal cord stimulation (SCS) has demonstrated multiple benefits in treating chronic pain and other clinical disorders related to sensorimotor dysfunctions. However, the underlying mechanisms are still not fully understood, including how electrode placement in relation to the spinal cord neuroanatomy influences epidural spinal recordings (ESRs). To characterize this relationship, this study utilized stimulation applied at various anatomical sections of the spinal column, including at levels of the intervertebral disc and regions correlating to the dorsal root entry zone. METHOD Two electrode arrays were surgically implanted into the dorsal epidural space of the swine. The stimulation leads were positioned such that the caudal-most electrode contact was at the level of a thoracic intervertebral segment. Intraoperative cone beam computed tomography (CBCT) images were utilized to precisely determine the location of the epidural leads relative to the spinal column. High-resolution microCT imaging and 3D-model reconstructions of the explanted spinal cord illustrated precise positioning and dimensions of the epidural leads in relation to the surrounding neuroanatomy, including the spinal rootlets of the dorsal and ventral columns of the spinal cord. In a separate swine cohort, implanted epidural leads were used for SCS and recording evoked ESRs. RESULTS Reconstructed 3D-models of the swine spinal cord with epidural lead implants demonstrated considerable distinctions in the dimensions of a single electrode contact on a standard industry epidural stimulation lead compared to dorsal rootlets at the dorsal root entry zone (DREZ). At the intervertebral segment, it was observed that a single electrode contact may cover 20-25% of the DREZ if positioned laterally. Electrode contacts were estimated to be ~0.75 mm from the margins of the DREZ when placed at the midline. Furthermore, ventral rootlets were observed to travel in proximity and parallel to dorsal rootlets at this level prior to separation into their respective sides of the spinal cord. Cathodic stimulation at the level of the intervertebral disc, compared to an 'off-disc' stimulation (7 mm rostral), demonstrated considerable variations in the features of recorded ESRs, such as amplitude and shape, and evoked unintended motor activation at lower stimulation thresholds. This substantial change may be due to the influence of nearby ventral roots. To further illustrate the influence of rootlet activation vs. dorsal column activation, the stimulation lead was displaced laterally at ~2.88 mm from the midline, resulting in variances in both evoked compound action potential (ECAP) components and electromyography (EMG) components in ESRs at lower stimulation thresholds. CONCLUSION The results of this study suggest that the ECAP and EMG components of recorded ESRs can vary depending on small differences in the location of the stimulating electrodes within the spinal anatomy, such as at the level of the intervertebral segment. Furthermore, the effects of sub-centimeter lateral displacement of the stimulation lead from the midline, leading to significant changes in electrophysiological metrics. The results of this pilot study reveal the importance of the small displacement of the electrodes that can cause significant changes to evoked responses SCS. These results may provide further valuable insights into the underlying mechanisms and assist in optimizing future SCS-related applications.
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Affiliation(s)
- Danny V Lam
- Neural Lab, Abbott Neuromodulation, Plano, TX, USA
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Veterans Affairs Medical Center, Advanced Platform Technology Center, Louis Stokes Cleveland, Cleveland, OH, USA
| | - Justin Chin
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Meagan K Brucker-Hahn
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Megan Settell
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
- Department of Neurosurgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Ben Romanauski
- Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA
| | | | - Aniruddha Upadhye
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Ashlesha Deshmukh
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
| | - Aaron Skubal
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
| | | | - Jian Hao
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - J Luis Lujan
- Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Simeng Zhang
- Neural Lab, Abbott Neuromodulation, Plano, TX, USA
| | - Bruce Knudsen
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
| | - Stephan Blanz
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
- University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
| | - Kip A Ludwig
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
- Department of Neurosurgery, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrew J Shoffstall
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Veterans Affairs Medical Center, Advanced Platform Technology Center, Louis Stokes Cleveland, Cleveland, OH, USA
| | | | | | | | - Igor Lavrov
- Department of Neurology, Mayo Clinic, Rochester, MN, USA.
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA.
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Nijhuis H, Kallewaard JW, van de Minkelis J, Hofsté WJ, Elzinga L, Armstrong P, Gültuna I, Almac E, Baranidharan G, Nikolic S, Gulve A, Vesper J, Dietz BE, Mugan D, Huygen FJPM. Durability of Evoked Compound Action Potential (ECAP)-Controlled, Closed-Loop Spinal Cord Stimulation (SCS) in a Real-World European Chronic Pain Population. Pain Ther 2024:10.1007/s40122-024-00628-z. [PMID: 38954217 DOI: 10.1007/s40122-024-00628-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 06/06/2024] [Indexed: 07/04/2024] Open
Abstract
INTRODUCTION Closed-loop spinal cord stimulation (CL-SCS) is a recently introduced system that records evoked compound action potentials (ECAPs) from the spinal cord elicited by each stimulation pulse and uses this information to automatically adjust the stimulation strength in real time, known as ECAP-controlled SCS. This innovative system compensates for fluctuations in the distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a predetermined target level. This data collection study was designed to assess the performance of the first CL-SCS system in a real-world setting under normal conditions of use in multiple European centers. The study analyzes and presents clinical outcomes and electrophysiological and device data and compares these findings with those reported in earlier pre-market studies of the same system. METHODS This prospective, multicenter, observational study was conducted in 13 European centers and aimed to gather electrophysiological and device data. The study focused on the real-world application of this system in treating chronic pain affecting the trunk and/or limbs, adhering to standard conditions of use. In addition to collecting and analyzing basic demographic information, the study presents data from the inaugural patient cohort permanently implanted at multiple European centers. RESULTS A significant decrease in pain intensity was observed for overall back or leg pain scores (verbal numerical rating score [VNRS]) between baseline (mean ± standard error of the mean [SEM]; n = 135; 8.2 ± 0.1), 3 months (n = 93; 2.3 ± 0.2), 6 months (n = 82; 2.5 ± 0.3), and 12 months (n = 76; 2.5 ± 0.3). Comparison of overall pain relief (%) to the AVALON and EVOKE studies showed no significant differences at 3 and 12 months between the real-world data release (RWE; 71.3%; 69.6%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies. Further investigation was undertaken to objectively characterize the physiological parameters of SCS therapy in this cohort using the metrics of percent time above ECAP threshold (%), dose ratio, and dose accuracy (µV), according to previously described methods. Results showed that a median of 90% (40.7-99.2) of stimuli were above the ECAP threshold, with a dose ratio of 1.3 (1.1-1.4) and dose accuracy of 4.4 µV (0.0-7.1), based on data from 236, 230, and 254 patients, respectively. Thus, across all three metrics, the majority of patients had objective therapy metrics corresponding to the highest levels of pain relief in previously reported studies (usage over threshold > 80%, dose ratio > 1.2, and error < 10 µV). CONCLUSIONS In conclusion, this study provides valuable insights into the real-world application of the ECAP-controlled CL-SCS system, highlighting its potential for maintaining effective pain relief and objective neurophysiological therapy metrics at levels seen in randomized control trials, and potential for quantifying patient burden associated with SCS system use via patient-device interaction metrics. CLINICAL TRIAL REGISTRATION In the Netherlands, the study is duly registered on the International Clinical Trials Registry Platform (Trial NL7889). In Germany, the study is duly registered as NCT05272137 and in the United Kingdom as ISCRTN27710516 and has been reviewed by the ethics committee in both countries.
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Affiliation(s)
- Harold Nijhuis
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM, Nieuwegein, Netherlands.
| | - Jan-Willem Kallewaard
- Rijnstate Hospital, Velp, Netherlands
- Erasmus University Medical Center, Rotterdam, Netherlands
| | | | - Willem-Jan Hofsté
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM, Nieuwegein, Netherlands
| | | | | | | | - Emre Almac
- Alrijne Hospital, Leiderdorp, Netherlands
| | | | | | - Ashish Gulve
- James Cook University Hospital, Middlesbrough, UK
| | - Jan Vesper
- Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | | | - Dave Mugan
- Saluda Medical Europe Ltd, Harrogate, UK
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Rogers ER, Capogrosso M, Lempka SF. Biophysics of Frequency-Dependent Variation in Paresthesia and Pain Relief during Spinal Cord Stimulation. J Neurosci 2024; 44:e2199232024. [PMID: 38744531 PMCID: PMC11211721 DOI: 10.1523/jneurosci.2199-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 05/05/2024] [Accepted: 05/08/2024] [Indexed: 05/16/2024] Open
Abstract
The neurophysiological effects of spinal cord stimulation (SCS) for chronic pain are poorly understood, resulting in inefficient failure-prone programming protocols and inadequate pain relief. Nonetheless, novel stimulation patterns are regularly introduced and adopted clinically. Traditionally, paresthetic sensation is considered necessary for pain relief, although novel paradigms provide analgesia without paresthesia. However, like pain relief, the neurophysiological underpinnings of SCS-induced paresthesia are unknown. Here, we paired biophysical modeling with clinical paresthesia thresholds (of both sexes) to investigate how stimulation frequency affects the neural response to SCS relevant to paresthesia and analgesia. Specifically, we modeled the dorsal column (DC) axonal response, dorsal column nucleus (DCN) synaptic transmission, conduction failure within DC fiber collaterals, and dorsal horn network output. Importantly, we found that high-frequency stimulation reduces DC fiber activation thresholds, which in turn accurately predicts clinical paresthesia perception thresholds. Furthermore, we show that high-frequency SCS produces asynchronous DC fiber spiking and ultimately asynchronous DCN output, offering a plausible biophysical basis for why high-frequency SCS is less comfortable and produces qualitatively different sensation than low-frequency stimulation. Finally, we demonstrate that the model dorsal horn network output is sensitive to SCS-inherent variations in spike timing, which could contribute to heterogeneous pain relief across patients. Importantly, we show that model DC fiber collaterals cannot reliably follow high-frequency stimulation, strongly affecting the network output and typically producing antinociceptive effects at high frequencies. Altogether, these findings clarify how SCS affects the nervous system and provide insight into the biophysics of paresthesia generation and pain relief.
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Affiliation(s)
- Evan R Rogers
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109
| | - Marco Capogrosso
- Department of Neurological Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
- Rehab and Neural Engineering Labs, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan 48109
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da Cunha PHM, de Andrade DC. The deep and the deeper: Spinal cord and deep brain stimulation for neuropathic pain. Presse Med 2024; 53:104231. [PMID: 38636785 DOI: 10.1016/j.lpm.2024.104231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 04/04/2024] [Indexed: 04/20/2024] Open
Abstract
Neuropathic pain occurs in people experiencing lesion or disease affecting the somatosensorial system. It is present in 7 % of the general population and may not fully respond to first- and second-line treatments in up to 40 % of cases. Neuromodulation approaches are often proposed for those not tolerating or not responding to usual pharmacological management. These approaches can be delivered surgically (invasively) or non-invasively. Invasive neuromodulation techniques were the first to be employed in neuropathic pain. Among them is spinal cord stimulation (SCS), which consists of the implantation of epidural electrodes over the spinal cord. It is recommended in some guidelines for peripheral neuropathic pain. While recent studies have called into question its efficacy, others have provided promising data, driven by advances in techniques, battery capabilities, programming algorithms and software developments. Deep brain stimulation (DBS) is another well-stablished neuromodulation therapy routinely used for movement disorders; however, its role in pain management remains limited to specific research centers. This is not only due to variable results in the literature contesting its efficacy, but also because several different brain targets have been explored in small trials, compromising comparisons between these studies. Structures such as the periaqueductal grey, posterior thalamus, anterior cingulate cortex, ventral striatum/anterior limb of the internal capsule and the insula are the main targets described to date in literature. SCS and DBS present diverse rationales for use, mechanistic backgrounds, and varying levels of support from experimental studies. The present review aims to present their methodological details, main mechanisms of action for analgesia and their place in the current body of evidence in the management of patients with neuropathic pain, as well their particularities, effectiveness, safety and limitations.
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Affiliation(s)
| | - Daniel Ciampi de Andrade
- Center for Neuroplasticity and Pain, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
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Patil AS, Levasseur B, Gupta M. Neuromodulation and Habituation: A Literature Review and Conceptional Analysis of Sustaining Therapeutic Efficacy and Mitigating Habituation. Biomedicines 2024; 12:930. [PMID: 38790891 PMCID: PMC11118194 DOI: 10.3390/biomedicines12050930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 04/14/2024] [Accepted: 04/18/2024] [Indexed: 05/26/2024] Open
Abstract
Spinal cord stimulation (SCS) is a therapeutic modality for the treatment of various chronic pain conditions that has rapidly evolved over the past 50 years. Unfortunately, over time, patients implanted with SCS undergo a habituation phenomenon leading to decreased pain relief. Consequently, the discovery of new stimulation waveforms and SCS applications has been shown to prolong efficacy and reduce explantation rates. This article explores various SCS waveforms, their applications, and proposes a graded approach to habituation mitigation. We suspect the neural habituation phenomenon parallels that seen in pharmacology. Consequently, we urge further exploration of the early introduction of these stimulation strategies to abate spinal cord stimulation habituation.
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Affiliation(s)
- Anand S. Patil
- St. Luke’s Rehabilitation Medical Center, Spokane, WA 99202, USA
| | | | - Mayank Gupta
- Neuroscience Research Center, LLC, Overland Park, KS 66215, USA
- Kansas Pain Management, Overland Park, KS 66210, USA
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Mekhail NA, Levy RM, Deer TR, Kapural L, Li S, Amirdelfan K, Hunter CW, Rosen SM, Costandi SJ, Falowski SM, Burgher AH, Pope JE, Gilmore CA, Qureshi FA, Staats PS, Scowcroft J, McJunkin T, Kim CK, Yang MI, Stauss T, Rauck R, Duarte RV, Soliday N, Leitner A, Hanson E, Ouyang Z, Mugan D, Poree L. Neurophysiological outcomes that sustained clinically significant improvements over 3 years of physiologic ECAP-controlled closed-loop spinal cord stimulation for the treatment of chronic pain. Reg Anesth Pain Med 2024:rapm-2024-105370. [PMID: 38490687 DOI: 10.1136/rapm-2024-105370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 03/17/2024]
Abstract
INTRODUCTION A novel, spinal cord stimulation (SCS) system with a physiologic closed-loop (CL) feedback mechanism controlled by evoked compound action potentials (ECAPs) enables the optimization of physiologic neural dose and the accuracy of the stimulation, not possible with any other commercially available SCS systems. The report of objective spinal cord measurements is essential to increase the transparency and reproducibility of SCS therapy. Here, we report a cohort of the EVOKE double-blind randomized controlled trial treated with CL-SCS for 36 months to evaluate the ECAP dose and accuracy that sustained the durability of clinical improvements. METHODS 41 patients randomized to CL-SCS remained in their treatment allocation and were followed up through 36 months. Objective neurophysiological data, including measures of spinal cord activation, were analyzed. Pain relief was assessed by determining the proportion of patients with ≥50% and ≥80% reduction in overall back and leg pain. RESULTS The performance of the feedback loop resulted in high-dose accuracy by keeping the elicited ECAP within 4µV of the target ECAP set on the system across all timepoints. Percent time stimulating above the ECAP threshold was >98%, and the ECAP dose was ≥19.3µV. Most patients obtained ≥50% reduction (83%) and ≥80% reduction (59%) in overall back and leg pain with a sustained response observed in the rates between 3-month and 36-month follow-up (p=0.083 and p=0.405, respectively). CONCLUSION The results suggest that a physiological adherence to supra-ECAP threshold therapy that generates pain inhibition provided by ECAP-controlled CL-SCS leads to durable improvements in pain intensity with no evidence of loss of therapeutic effect through 36-month follow-up.
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Affiliation(s)
- Nagy A Mekhail
- Evidence-Based Pain Management Research, Cleveland Clinic, Cleveland, Ohio, USA
| | - Robert M Levy
- Anesthesia Pain Care Consultants, Boca Raton, Florida, USA
| | - Timothy R Deer
- Spine and Nerve Center of the Virginias, Charleston, West Virginia, USA
| | | | - Sean Li
- National Spine and Pain Centers, Shrewsbury, New Jersey, USA
| | - Kasra Amirdelfan
- Integrated Pain Management Medical Group Inc, Walnut Creek, California, USA
| | - Corey W Hunter
- Ainsworth Institute of Pain Management, New York, New York, USA
| | - Steven M Rosen
- Delaware Valley Pain and Spine Institute, Trevose, Pennsylvania, USA
| | - Shrif J Costandi
- Evidence-Based Pain Management Research, Cleveland Clinic, Cleveland, Ohio, USA
| | - Steven M Falowski
- Argires-Marotti Neurosurgical Associates of Lancaster, Lancaster, Pennsylvania, USA
| | | | - Jason E Pope
- Evolve Restorative Center, Santa Rosa, California, USA
| | | | | | - Peter S Staats
- National Spine and Pain Centers, Shrewsbury, New Jersey, USA
| | | | | | - Christopher K Kim
- Spine and Nerve Center of the Virginias, Charleston, West Virginia, USA
| | | | - Thomas Stauss
- Pain Physicians of Wisconsin, Milwaukee, Wisconsin, USA
| | - Richard Rauck
- Carolinas Pain Institute, Winston-Salem, North Carolina, USA
| | - Rui V Duarte
- Department of Health Data Science, University of Liverpool, Liverpool, UK
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Nicole Soliday
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Angela Leitner
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Erin Hanson
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Zhonghua Ouyang
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Dave Mugan
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Lawrence Poree
- University of California San Francisco, San Francisco, California, USA
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Sagalajev B, Zhang T, Abdollahi N, Yousefpour N, Medlock L, Al-Basha D, Ribeiro-da-Silva A, Esteller R, Ratté S, Prescott SA. Absence of paresthesia during high-rate spinal cord stimulation reveals importance of synchrony for sensations evoked by electrical stimulation. Neuron 2024; 112:404-420.e6. [PMID: 37972595 DOI: 10.1016/j.neuron.2023.10.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/24/2023] [Accepted: 10/18/2023] [Indexed: 11/19/2023]
Abstract
Electrically activating mechanoreceptive afferents inhibits pain. However, paresthesia evoked by spinal cord stimulation (SCS) at 40-60 Hz becomes uncomfortable at high pulse amplitudes, limiting SCS "dosage." Kilohertz-frequency SCS produces analgesia without paresthesia and is thought, therefore, not to activate afferent axons. We show that paresthesia is absent not because axons do not spike but because they spike asynchronously. In a pain patient, selectively increasing SCS frequency abolished paresthesia and epidurally recorded evoked compound action potentials (ECAPs). Dependence of ECAP amplitude on SCS frequency was reproduced in pigs, rats, and computer simulations and is explained by overdrive desynchronization: spikes desychronize when axons are stimulated faster than their refractory period. Unlike synchronous spikes, asynchronous spikes fail to produce paresthesia because their transmission to somatosensory cortex is blocked by feedforward inhibition. Our results demonstrate how stimulation frequency impacts synchrony based on axon properties and how synchrony impacts sensation based on circuit properties.
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Affiliation(s)
- Boriss Sagalajev
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Tianhe Zhang
- Boston Scientific Neuromodulation, Valencia, CA 25155, USA
| | - Nooshin Abdollahi
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Noosha Yousefpour
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Laura Medlock
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Dhekra Al-Basha
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | | | - Stéphanie Ratté
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Steven A Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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11
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Goudelocke C, Jungbauer Nikolas LM, Bittner KC, Offutt SJ, Miller AE, Slopsema JP. Sensing in Sacral Neuromodulation: A Feasibility Study in Subjects With Urinary Incontinence and Retention. Neuromodulation 2024; 27:392-398. [PMID: 37589643 DOI: 10.1016/j.neurom.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/27/2023] [Accepted: 07/06/2023] [Indexed: 08/18/2023]
Abstract
OBJECTIVES Sacral neuromodulation (SNM) therapy standard of care relies on visual-motor responses and patient-reported sensory responses in deciding optimized lead placement and programming. Automatic detection of stimulation responses could offer a simple, consistent indicator for optimizing SNM. The purpose of this study was to measure and characterize sacral evoked responses (SERs) resulting from sacral nerve stimulation using a commercial, tined SNM lead. MATERIALS AND METHODS A custom external research system with stimulation and sensing hardware was connected to the percutaneous extension of an implanted lead during a staged (tined lead) evaluation for SNM. The system collected SER recordings across a range of prespecified stimulation settings (electrode configuration combinations for bipolar stimulation and bipolar sensing) during intraoperative and postoperative sessions in 21 subjects with overactive bladder (OAB) and nonobstructive urinary retention (NOUR). Motor and sensory thresholds were collected during the same sessions. RESULTS SERs were detected in all 21 subjects. SER morphology (number of peaks, magnitude, and timing) varied across electrode configurations within and across subjects. Among subjects and electrode configurations tested, recordings contained SERs at motor threshold and/or sensory threshold in 75% to 80% of subjects. CONCLUSIONS This study confirmed that implanted SNM leads can be used to directly record SERs elicited by stimulation in subjects with OAB and NOUR. SERs were readily detectable at typical SNM stimulation settings and procedural time points. Using these SERs as possible objective measures of SNM response has the capability to automate patient-specific SNM therapy, potentially providing consistent lead placement, programming, and/or closed-loop therapy.
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Affiliation(s)
- Colin Goudelocke
- Department of Urology, Ochsner Medical Center, New Orleans, LA, USA
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12
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Versantvoort EM, Dietz BE, Mugan D, Vuong QC, Luli S, Obara I. Evoked compound action potential (ECAP)-controlled closed-loop spinal cord stimulation in an experimental model of neuropathic pain in rats. Bioelectron Med 2024; 10:2. [PMID: 38195618 PMCID: PMC10777641 DOI: 10.1186/s42234-023-00134-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/29/2023] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Preclinical models of spinal cord stimulation (SCS) are lacking objective measurements to inform translationally applicable SCS parameters. The evoked compound action potential (ECAP) represents a measure of dorsal column fiber activation. This measure approximates the onset of SCS-induced sensations in humans and provides effective analgesia when used with ECAP-controlled closed-loop (CL)-SCS systems. Therefore, ECAPs may provide an objective surrogate for SCS dose in preclinical models that may support better understanding of SCS mechanisms and further translations to the clinics. This study assessed, for the first time, the feasibility of recording ECAPs and applying ECAP-controlled CL-SCS in freely behaving rats subjected to an experimental model of neuropathic pain. METHODS Adult male Sprague-Dawley rats (200-300 g) were subjected to spared nerve injury (SNI). A custom-made six-contact lead was implanted epidurally covering T11-L3, as confirmed by computed tomography or X-ray. A specially designed multi-channel system was used to record ECAPs and to apply ECAP-controlled CL-SCS for 30 min at 50 Hz 200 µs. The responses of dorsal column fibers to SCS were characterized and sensitivity towards mechanical and cold stimuli were assessed to determine analgesic effects from ECAP-controlled CL-SCS. Comparisons between SNI rats and their controls as well as between stimulation parameters were made using omnibus analysis of variance (ANOVA) tests and t-tests. RESULTS The recorded ECAPs showed the characteristic triphasic morphology and the ECAP amplitude (mV) increased as higher currents (mA) were applied in both SNI animals and controls (SNI SCS-ON and sham SCS-ON). Importantly, the use of ECAP-based SCS dose, implemented in ECAP-controlled CL-SCS, significantly reduced mechanical and cold hypersensitivity in SNI SCS-ON animals through the constant and controlled activation of dorsal column fibers. An analysis of conduction velocities of the evoked signals confirmed the involvement of large, myelinated fibers. CONCLUSIONS The use of ECAP-based SCS dose implemented in ECAP-controlled CL-SCS produced analgesia in animals subjected to an experimental model of neuropathic pain. This approach may offer a better method for translating SCS parameters between species that will improve understanding of the mechanisms of SCS action to further advance future clinical applications.
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Affiliation(s)
- Eline M Versantvoort
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
| | - Birte E Dietz
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Saluda Medical Europe Ltd, Harrogate, HG2 8NB, UK
| | - Dave Mugan
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
- Saluda Medical Europe Ltd, Harrogate, HG2 8NB, UK
| | - Quoc C Vuong
- Bioscience Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK
| | - Saimir Luli
- Preclinical In Vivo Imaging, Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE2 4HH, UK
| | - Ilona Obara
- School of Pharmacy, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK.
- Translational and Clinical Research Institute, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK.
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13
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North RB, Sung JH, Matthews LA, Zander HJ, Lempka SF. Postural Changes in Spinal Cord Stimulation Thresholds: Current and Voltage Sources. Neuromodulation 2024; 27:178-182. [PMID: 37804279 DOI: 10.1016/j.neurom.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 07/27/2023] [Accepted: 08/04/2023] [Indexed: 10/09/2023]
Abstract
OBJECTIVE Spinal cord stimulation (SCS) thresholds are known to change with body position; however, these changes have not been fully characterized for both "constant-voltage" and "constant-current" pulse generators. This study aimed to evaluate and quantify changes in psychophysical thresholds resulting from postural changes that may affect both conventional paresthesia-based SCS and novel paresthesia-free SCS technologies. MATERIALS AND METHODS We measured perceptual, usage, and discomfort thresholds in four body positions (prone, supine, sitting, standing) in 149 consecutive patients, with temporary lower thoracic percutaneous epidural electrodes placed for treating persistent low back and leg pain. We trialed 119 patients with constant-voltage stimulators and 30 patients with constant-current stimulators. RESULTS Moving from supine to the sitting, standing, or prone positions caused all three thresholds (perceptual, usage, and discomfort) to increase by 22% to 34% for constant-voltage stimulators and by 44% to 82% for constant-current stimulators. Changing from a seated to a supine position caused stimulation to exceed discomfort threshold significantly more often for constant-current (87%) than for constant-voltage (63%) stimulators (p = 0.01). CONCLUSIONS Posture-induced changes in SCS thresholds occurred consistently as patients moved from lying (supine or prone) to upright (standing or sitting) positions. These changes were more pronounced for constant-current than for constant-voltage pulse generators and more often led to stimulation-evoked discomfort. These observations are consistent with postural changes in spinal cord position measured in imaging studies, and with computer model predictions of neural recruitment for these different spinal cord positions. These observations have implications for the design, implantation, and clinical application of spinal cord stimulators, not only for conventional paresthesia-based SCS but also for paresthesia-free SCS.
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Affiliation(s)
- Richard B North
- Neuromodulation Foundation, Inc, Baltimore, MD; Departments of Neurosurgery, Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD.
| | - Jung H Sung
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Liam A Matthews
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI; Biointerfaces Institute, University of Michigan, Ann Arbor, MI
| | - Hans J Zander
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI; Biointerfaces Institute, University of Michigan, Ann Arbor, MI
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI; Biointerfaces Institute, University of Michigan, Ann Arbor, MI; Department of Anesthesiology, University of Michigan, Ann Arbor, MI
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14
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Taccola G, Kissane R, Culaclii S, Apicella R, Liu W, Gad P, Ichiyama RM, Chakrabarty S, Edgerton VR. Dynamic electrical stimulation enhances the recruitment of spinal interneurons by corticospinal input. Exp Neurol 2024; 371:114589. [PMID: 37907125 DOI: 10.1016/j.expneurol.2023.114589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/12/2023] [Accepted: 10/25/2023] [Indexed: 11/02/2023]
Abstract
Highly varying patterns of electrostimulation (Dynamic Stimulation, DS) delivered to the dorsal cord through an epidural array with 18 independent electrodes transiently facilitate corticospinal motor responses, even after spinal injury. To partly unravel how corticospinal input are affected by DS, we introduced a corticospinal platform that allows selective cortical stimulation during the multisite acquisition of cord dorsum potentials (CDPs) and the simultaneous supply of DS. Firstly, the epidural interface was validated by the acquisition of the classical multisite distribution of CDPs and their input-output profile elicited by pulses delivered to peripheral nerves. Apart from increased EMGs, DS selectively increased excitability of the spinal interneurons that first process corticospinal input, without changing the magnitude of commands descending from the motor cortex, suggesting a novel correlation between muscle recruitment and components of cortically-evoked CDPs. Finally, DS increases excitability of post-synaptic spinal interneurons at the stimulation site and their responsiveness to any residual supraspinal control, thus supporting the use of electrical neuromodulation whenever the motor output is jeopardized by a weak volitional input, due to a partial disconnection from supraspinal structures and/or neuronal brain dysfunctions.
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Affiliation(s)
- Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Roger Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Department of Musculoskeletal & Ageing Science, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA; UCLA California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Parag Gad
- SpineX Inc, Los Angeles, CA 90064, USA
| | - Ronaldo M Ichiyama
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Samit Chakrabarty
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - V Reggie Edgerton
- Rancho Research Institute, Los Amigos National Rehabilitation Center, Downey, CA 90242, USA; University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, Badalona 08916, Spain
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15
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Várkuti B, Halász L, Hagh Gooie S, Miklós G, Smits Serena R, van Elswijk G, McIntyre CC, Lempka SF, Lozano AM, Erōss L. Conversion of a medical implant into a versatile computer-brain interface. Brain Stimul 2024; 17:39-48. [PMID: 38145752 DOI: 10.1016/j.brs.2023.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 12/27/2023] Open
Abstract
BACKGROUND Information transmission into the human nervous system is the basis for a variety of prosthetic applications. Spinal cord stimulation (SCS) systems are widely available, have a well documented safety record, can be implanted minimally invasively, and are known to stimulate afferent pathways. Nonetheless, SCS devices are not yet used for computer-brain-interfacing applications. OBJECTIVE Here we aimed to establish computer-to-brain communication via medical SCS implants in a group of 20 individuals who had been operated for the treatment of chronic neuropathic pain. METHODS In the initial phase, we conducted interface calibration with the aim of determining personalized stimulation settings that yielded distinct and reproducible sensations. These settings were subsequently utilized to generate inputs for a range of behavioral tasks. We evaluated the required calibration time, task training duration, and the subsequent performance in each task. RESULTS We could establish a stable spinal computer-brain interface in 18 of the 20 participants. Each of the 18 then performed one or more of the following tasks: A rhythm-discrimination task (n = 13), a Morse-decoding task (n = 3), and/or two different balance/body-posture tasks (n = 18; n = 5). The median calibration time was 79 min. The median training time for learning to use the interface in a subsequent task was 1:40 min. In each task, every participant demonstrated successful performance, surpassing chance levels. CONCLUSION The results constitute the first proof-of-concept of a general purpose computer-brain interface paradigm that could be deployed on present-day medical SCS platforms.
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Affiliation(s)
| | - László Halász
- Albert-Szentgyörgyi Medical School, Doctoral School of Clinical Medicine, Clinical and Experimental Research for Reconstructive and Organ-Sparing Surgery, University of Szeged, Szeged, Hungary
| | | | - Gabriella Miklós
- CereGate GmbH, München, Germany; National Institute of Mental Health, Neurology, and Neurosurgery, Budapest, Hungary; János Szentágothai Doctoral School of Neurosciences, Semmelweis University, Budapest, Hungary
| | - Ricardo Smits Serena
- CereGate GmbH, München, Germany; Department of Orthopaedics and Sports Orthopaedics, Klinikum Rechts der Isar, Technical University of Munich, München, Germany
| | | | - Cameron C McIntyre
- Department of Biomedical Engineering and Department of Neurosurgery, Duke University, Durham, NC, USA
| | - Scott F Lempka
- Department of Biomedical Engineering, Department of Anesthesiology and the Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Andres M Lozano
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Loránd Erōss
- National Institute of Mental Health, Neurology, and Neurosurgery, Budapest, Hungary
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Su PYP, Arle J, Poree L. Closing the loop and raising the bar: Automated control systems in neuromodulation. Pain Pract 2024; 24:177-185. [PMID: 37638532 DOI: 10.1111/papr.13290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 08/04/2023] [Indexed: 08/29/2023]
Abstract
INTRODUCTION Neuromodulation has emerged as a promising therapy for the management of chronic pain, movement disorders, and other neurological conditions. Spinal cord stimulation (SCS) is a widely used form of neuromodulation that involves the delivery of electrical impulses to the spinal cord to modulate the transmission of pain signals to the brain. In recent years, there has been increasing interest in the use of automation systems to improve the efficacy and safety of SCS. This narrative review summarizes the status of Food and Drug Administration-approved autonomous neuromodulation devices including closed loop, feedforward, and feedback systems. The review discusses the advantages and disadvantages of each system and focuses specifically on the use of these systems for SCS. It is important for clinicians to understand the expanding role of automation in neuromodulation in order to select appropriate therapies founded on automation systems to the specific needs of the patient and the underlying condition. CONCLUSION The review also provides insights into the current state of the art in neuromodulation automation systems and discusses potential future directions for research in this field.
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Affiliation(s)
- Po-Yi Paul Su
- Department of Anesthesia, University of California San Francisco, San Francisco, California, USA
| | | | - Lawrence Poree
- Department of Anesthesia, University of California San Francisco, San Francisco, California, USA
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17
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Gmel GE, Santos Escapa R, Benkohen TE, Mugan D, Parker JL, Palmisani S. Postsynaptic dorsal column pathway activation during spinal cord stimulation in patients with chronic pain. Front Neurosci 2023; 17:1297814. [PMID: 38188030 PMCID: PMC10771283 DOI: 10.3389/fnins.2023.1297814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/08/2023] [Indexed: 01/09/2024] Open
Abstract
Spinal cord stimulation (SCS) treatment for chronic pain relies on the activation of primary sensory fibres ascending to the brain in the dorsal columns. While the efficacy of SCS has been demonstrated, the precise mechanism of action and nature of the fibres activated by stimulation remain largely unexplored. Our investigation in humans with chronic neuropathic pain undergoing SCS therapy, found that post-synaptic dorsal column (PSDC) fibres can be activated synaptically by the primary afferents recruited by stimulation, and axonically by the stimulation pulses directly. Synaptic activation occurred in 9 of the 14 patients analysed and depended on the vertebral level of stimulation. A clear difference in conduction velocities between the primary afferents and the PSDC fibres were observed. Identification of PSDC fibre activation in humans emphasises the need for further investigation into the role they play in pain relief and the sensory response sensation (paraesthesia) experienced by patients undergoing SCS.
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Affiliation(s)
| | | | | | - Dave Mugan
- Saluda Medical, Macquarie Park, NSW, Australia
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18
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Chen J, Sprigg J, Castle N, Matson C, Hedjoudje A, Dai C. A Virtual Inner Ear Model Selects Ramped Pulse Shapes for Vestibular Afferent Stimulation. Bioengineering (Basel) 2023; 10:1436. [PMID: 38136027 PMCID: PMC10740892 DOI: 10.3390/bioengineering10121436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/03/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Bilateral vestibular deficiency (BVD) results in chronic dizziness, blurry vision when moving the head, and postural instability. Vestibular prostheses (VPs) show promise as a treatment, but the VP-restored vestibulo-ocular reflex (VOR) gain in human trials falls short of expectations. We hypothesize that the slope of the rising ramp in stimulation pulses plays an important role in the recruitment of vestibular afferent units. To test this hypothesis, we utilized customized programming to generate ramped pulses with different slopes, testing their efficacy in inducing electrically evoked compound action potentials (eCAPs) and current spread via bench tests and simulations in a virtual inner model created in this study. The results confirmed that the slope of the ramping pulses influenced the recruitment of vestibular afferent units. Subsequently, an optimized stimulation pulse train was identified using model simulations, exhibiting improved modulation of vestibular afferent activity. This optimized slope not only reduced the excitation spread within the semicircular canals (SCCs) but also expanded the neural dynamic range. While the model simulations exhibited promising results, in vitro and in vivo experiments are warranted to validate the findings of this study in future investigations.
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Affiliation(s)
- Joseph Chen
- Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA
- School of Medicine and Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA
| | - Jayden Sprigg
- Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA
| | - Nicholas Castle
- Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA
| | - Cayman Matson
- School of Medicine and Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA
| | | | - Chenkai Dai
- Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA
- School of Medicine and Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA
- Biomedical Engineering Department, Johns Hopkins University, Baltimore, MD 21218, USA
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Single PS, Scott JB, Mugan D. Measures of Dosage for Spinal-Cord Electrical Stimulation: Review and Proposal. IEEE Trans Neural Syst Rehabil Eng 2023; 31:4653-4660. [PMID: 37983153 DOI: 10.1109/tnsre.2023.3335100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
This manuscript proposes an electrical definition of therapeutic dose for spinal-cord systems used for the treatment of chronic pain, analogous to the pharmacological definition. Dose-response relationships are fundamental to pharmacology, radio-therapy, and other treatments, but have never been properly established for neuromodulation. This manuscript offers a robust measure of dose, pre-requisite to establishing a reliable and repeatable dose-response relationship. The new definition, enabled by the system transresistance obtained from measurement of evoked action potentials, recognizes the mechanism of action of spinal cord stimulation (SCS), and should improve acceptance of the therapy as compared to pharmacological treatments which are currently used more frequently for the treatment of chronic pain. The new definition suggests methods for personalization and standardization of the dose in SCS, and is potentially generalizable to all neuromodulation therapies in which nervous tissue is excited including sacral nerve stimulation (SNS), vagal nerve stimulation (VNS) and deep-brain stimulation (DBS). Formulas are provided, and applied using patient data. Powerful conclusions are drawn from application of the new measure.
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Shlobin NA, Wu C. Current Neurostimulation Therapies for Chronic Pain Conditions. Curr Pain Headache Rep 2023; 27:719-728. [PMID: 37728863 DOI: 10.1007/s11916-023-01168-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2023] [Indexed: 09/21/2023]
Abstract
PURPOSE OF REVIEW Neurostimulation treatment options have become more commonly used for chronic pain conditions refractory to these options. In this review, we characterize current neurostimulation therapies for chronic pain conditions and provide an analysis of their effectiveness and clinical adoption. This manuscript will inform clinicians of treatment options for chronic pain. RECENT FINDINGS Non-invasive neurostimulation includes transcranial direct current stimulation and repetitive transcranial magnetic stimulation, while more invasive options include spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), dorsal root ganglion stimulation, motor cortex stimulation, and deep brain stimulation. Developments in transcranial direct current stimulation, repetitive transcranial magnetic stimulation, spinal cord stimulation, and peripheral nerve stimulation render these modalities most promising for the alleviating chronic pain. Neurostimulation for chronic pain involves non-invasive and invasive modalities with varying efficacy. Well-designed randomized controlled trials are required to delineate the outcomes of neurostimulatory modalities more precisely.
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Affiliation(s)
- Nathan A Shlobin
- Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Chengyuan Wu
- Department of Neurological Surgery, Thomas Jefferson University Hospitals, 909 Walnut Street, Floor 2, Philadelphia, PA, 19107, USA.
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Nijhuis HJA, Hofsté WJ, Krabbenbos IP, Dietz BE, Mugan D, Huygen F. First Report on Real-World Outcomes with Evoked Compound Action Potential (ECAP)-Controlled Closed-Loop Spinal Cord Stimulation for Treatment of Chronic Pain. Pain Ther 2023; 12:1221-1233. [PMID: 37481774 PMCID: PMC10444915 DOI: 10.1007/s40122-023-00540-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 06/30/2023] [Indexed: 07/25/2023] Open
Abstract
INTRODUCTION A novel closed-loop spinal cord stimulation (SCS) system has recently been approved for use which records evoked compound action potentials (ECAPs) from the spinal cord and utilizes these recordings to automatically adjust the stimulation strength in real time. It automatically compensates for fluctuations in distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a determined target level. This data collection was principally designed to evaluate the performance of this first closed-loop SCS system in a 'real-world' setting under normal conditions of use in a single European center. METHODS In this prospective, single-center observational data collection, 22 patients were recruited at the outpatient pain clinic of the St. Antonius Hospital. All candidates were suffering from chronic pain in the trunk and/or limbs due to PSPS type 2 (persistent spinal pain syndrome). As standard of care, follow-up visits were completed at 3 months, 6 months, and 12 months post-device activation. Patient-reported outcome data (pain intensity, patient satisfaction) and electrophysiological and device data (ECAP amplitude, conduction velocity, current output, pulse width, frequency, usage), and patient interaction with their controller were collected at baseline and during standard of care follow-up visits. RESULTS Significant decreases in pain intensity for overall back or leg pain scores (verbal numerical rating score = VNRS) were observed between baseline [mean ± SEM (standard error of the mean); n = 22; 8.4 ± 0.2)], 3 months (n = 12; 1.9 ± 0.5), 6 months (n = 16; 2.6 ± 0.5), and 12 months (n = 20; 2.0 ± 0.5), with 85.0% of the patients being satisfied at 12 months. Additionally, no significant differences in average pain relief at 3 months and 12 months between the real-world data (77.2%; 76.8%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies were observed. CONCLUSIONS These initial 'real-world' data on ECAP-controlled, closed-loop SCS in a real-world clinical setting appear to be promising, as they provide novel insights of the beneficial effect of ECAP-controlled, closed-loop SCS in a real-world setting. The presented results demonstrate a noteworthy maintenance of pain relief over 12 months and corroborate the outcomes observed in the AVALON prospective, multicenter, single-arm study and the EVOKE double-blind, multicenter, randomized controlled trial. TRIAL REGISTRATION The data collection is registered on the International Clinical Trials Registry Platform (Trial NL7889).
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Affiliation(s)
- Harold J. A. Nijhuis
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
- Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Willem-Jan Hofsté
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
| | - Imre P. Krabbenbos
- St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands
| | | | - Dave Mugan
- Saluda Medical Europe Ltd, Harrogate, United Kingdom
| | - Frank Huygen
- Erasmus University Medical Center, Rotterdam, The Netherlands
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Leitner A, Hanson E, Soliday N, Staats P, Levy R, Pope J, Kallewaard JW, Doleys D, Li S, Weisbein J, Amirdelfan K, Poree L. Real World Clinical Utility of Neurophysiological Measurement Utilizing Closed-Loop Spinal Cord Stimulation in a Chronic Pain Population: The ECAP Study Protocol. J Pain Res 2023; 16:2497-2507. [PMID: 37497371 PMCID: PMC10368120 DOI: 10.2147/jpr.s411927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023] Open
Abstract
Background Spinal cord stimulation (SCS) is an established chronic pain treatment, but the effectiveness of traditional, open-loop paradigms has been plagued by variable sustainability in a real-world setting. A new approach, utilizing evoked compound action potential (ECAP) controlled closed-loop (CL) SCS, continuously monitors spinal cord activation and automatically adjusts the stimulation amplitude of every pulse, maintaining stimulation at the prescribed ECAP level through this continual feedback mechanism. Recent studies demonstrated the long-term safety and efficacy of ECAP-controlled CL-SCS. Here, we report the design of a prospective, multicenter, single-arm feasibility study to characterize clinical outcomes in a real-world chronic pain population utilizing ECAP-controlled CL-SCS. Objective neurophysiological measurements such as device performance and patient therapy compliance, will be analyzed against baseline biopsychosocial assessments, to explore the clinical utility of these objective physiologic biomarkers in patient phenotyping. Methods This study will enroll up to 300 subjects with chronic, intractable trunk and/or limb pain in up to 25 United States investigation sites. Subjects meeting eligibility criteria will undergo a trial procedure and a permanent implant following a successful trial. Neurophysiological measurements (measured in-clinic and continuously during home use) and clinical outcomes including pain, quality-of-life, psychological, emotional, and functional assessments will be collected at baseline, trial end, and up to 24-months post-implantation. Discussion Associations between objective neurophysiological data, clinical evaluation and patient-reported outcomes may have important clinical and scientific implications. They may provide novel insights about the chronic pain pathophysiology, its modulation during CL-SCS, and identification of pain phenotypes and/or mechanisms associated with treatment response during SCS trials and long-term therapy. Data from the ECAP study could lead to improvements in diagnosis, assessment, patient identification and management of chronic pain. It could also provide the foundation for development of a new SCS treatment approach customized by the patient's pain phenotype, unique neurophysiology, and disease severity.
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Affiliation(s)
- Angela Leitner
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Erin Hanson
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Nicole Soliday
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia
| | - Peter Staats
- National Spine and Pain Centers, Shrewsbury, NJ, USA
| | - Robert Levy
- Departments of Neurosurgery and Clinical Research, Anesthesia Pain Care Consultants, Tamarac, FL, USA
| | - Jason Pope
- Evolve Restorative Center, Santa Rosa, CA, USA
| | - Jan W Kallewaard
- Department of Anaesthesiology and Pain Management, Rijnstate Hospital, Arnhem, the Netherlands
- Department of Anesthesiology and Pain Medicine, Amsterdam University Medical Centre, Amsterdam, the Netherlands
| | - Daniel Doleys
- Pain and Rehabilitation Institute, Birmingham, AL, USA
| | - Sean Li
- National Spine and Pain Centers, Shrewsbury, NJ, USA
| | | | | | - Lawrence Poree
- Department of Anesthesia and Perioperative Care, University of California at San Francisco, San Francisco, CA, USA
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Taccola G, Kissane R, Culaclii S, Apicella R, Liu W, Gad P, Ichiyama RM, Chakrabarty S, Edgerton VR. Spinal facilitation of descending motor input. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.30.547229. [PMID: 37461548 PMCID: PMC10349979 DOI: 10.1101/2023.06.30.547229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/25/2023]
Abstract
Highly varying patterns of electrostimulation (Dynamic Stimulation, DS) delivered to the dorsal cord through an epidural array with 18 independent electrodes transiently facilitate corticospinal motor responses, even after spinal injury. To partly unravel how corticospinal input are affected by DS, we introduced a corticospinal platform that allows selective cortical stimulation during the multisite acquisition of cord dorsum potentials (CDPs) and the simultaneous supply of DS. Firstly, the epidural interface was validated by the acquisition of the classical multisite distribution of CDPs on the dorsal cord and their input-output profile elicited by pulses delivered to peripheral nerves. Apart from increased EMGs, DS selectively increased excitability of the spinal interneurons that first process corticospinal input, without changing the magnitude of commands descending from the motor cortex, suggesting a novel correlation between muscle recruitment and components of cortically-evoked CDPs. Finally, DS increases excitability of post-synaptic spinal interneurons at the stimulation site and their responsiveness to any residual supraspinal control, thus supporting the use of electrical neuromodulation whenever the motor output is jeopardized by a weak volitional input, due to a partial disconnection from supraspinal structures and/or neuronal brain dysfunctions.
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Affiliation(s)
- Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Roger Kissane
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
- Department of Musculoskeletal & Ageing Science, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Rosamaria Apicella
- Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
- UCLA California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Parag Gad
- Rancho Research Institute, Downy, CA 90242, USA; Los Amigos National Rehabilitation Center
- University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA
| | - Ronaldo M. Ichiyama
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Samit Chakrabarty
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - V. Reggie Edgerton
- Rancho Research Institute, Downy, CA 90242, USA; Los Amigos National Rehabilitation Center
- University of Southern California Neurorestoration Center, Keck School of Medicine, Los Angeles, CA 90033; USA
- Institut Guttmann. Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain
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24
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Levy RM, Mekhail N, Abd-Elsayed A, Abejón D, Anitescu M, Deer TR, Eldabe S, Goudman L, Kallewaard JW, Moens M, Petersen EA, Pilitsis JG, Pope JE, Poree L, Raslan AM, Russo M, Sayed D, Staats PS, Taylor RS, Thomson S, Verrills P, Duarte RV. Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation. Neuromodulation 2023; 26:1015-1022. [PMID: 36604242 DOI: 10.1016/j.neurom.2022.11.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 01/05/2023]
Abstract
BACKGROUND Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity. AIM The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response". DISCUSSION Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.
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Affiliation(s)
- Robert M Levy
- Neurosurgical Services, Clinical Research, Anesthesia Pain Care Consultants, Tamarac, FL, USA
| | - Nagy Mekhail
- Department of Pain Management, Cleveland Clinic, Cleveland, OH, USA
| | - Alaa Abd-Elsayed
- Department of Anesthesiology and Pain Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - David Abejón
- Multidisciplinary Pain Management Unit, Hospital Universitario Quirónsalud, Madrid, Spain
| | | | - Timothy R Deer
- The Spine and Nerve Center of the Virginias, Charleston, WV, USA
| | - Sam Eldabe
- Department of Pain Medicine, The James Cook University Hospital, Middlesbrough, UK
| | - Lisa Goudman
- Department of Neurosurgery, Universitair Ziekenhuis Brussel, Brussels, Belgium; Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, Belgium; STIMULUS research group, Vrije Universiteit Brussel, Brussels, Belgium; Research Foundation-Flanders, Brussels, Belgium
| | - Jan W Kallewaard
- Department of Anaesthesiology and Pain Management, Rijnstate Hospital, Velp, the Netherlands; Department of Anesthesiology and Pain Medicine, Amsterdam University Medical Centre, Amsterdam, the Netherlands
| | - Maarten Moens
- Department of Neurosurgery, Universitair Ziekenhuis Brussel, Brussels, Belgium; Center for Neurosciences (C4N), Vrije Universiteit Brussel, Brussels, Belgium; STIMULUS research group, Vrije Universiteit Brussel, Brussels, Belgium; Department of Radiology, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Erika A Petersen
- Department of Neurosurgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Julie G Pilitsis
- Department of Clinical Neurosciences, Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | | | - Lawrence Poree
- Department of Anesthesia and Perioperative Care, University of California at San Francisco, San Francisco, CA, USA
| | - Ahmed M Raslan
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Marc Russo
- Hunter Pain Specialists, Broadmeadow, New South Wales, Australia
| | - Dawood Sayed
- The University of Kansas Medical Center, Kansas City, KS, USA
| | | | - Rod S Taylor
- College of Medicine and Health, University of Exeter, Exeter, UK; MRC/CSO Social and Public Health Sciences Unit & Robertson Centre for Biostatistics, Institute of Health and Well Being, University of Glasgow, Glasgow, UK
| | - Simon Thomson
- Department of Pain Medicine and Neuromodulation, Mid & South Essex University Hospitals, Essex, UK
| | - Paul Verrills
- Metro Pain Group, Melbourne, New South Wales, Australia
| | - Rui V Duarte
- Saluda Medical Pty Ltd, Artarmon, New South Wales, Australia; Liverpool Reviews and Implementation Group, Department of Health Data Science, University of Liverpool, Liverpool, UK.
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Sharma M, Bhaskar V, Yang L, FallahRad M, Gebodh N, Zhang T, Esteller R, Martin J, Bikson M. Novel Evoked Synaptic Activity Potentials (ESAPs) Elicited by Spinal Cord Stimulation. eNeuro 2023; 10:ENEURO.0429-22.2023. [PMID: 37130780 PMCID: PMC10198607 DOI: 10.1523/eneuro.0429-22.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/05/2023] [Accepted: 04/11/2023] [Indexed: 05/04/2023] Open
Abstract
Spinal cord stimulation (SCS) evokes fast epidural evoked compound action potential (ECAP) that represent activity of dorsal column axons, but not necessarily a spinal circuit response. Using a multimodal approach, we identified and characterized a delayed and slower potential evoked by SCS that reflects synaptic activity within the spinal cord. Anesthetized female Sprague Dawley rats were implanted with an epidural SCS lead, epidural motor cortex stimulation electrodes, an epidural spinal cord recording lead, an intraspinal penetrating recording electrode array, and intramuscular electromyography (EMG) electrodes in the hindlimb and trunk. We stimulated the motor cortex or the epidural spinal cord and recorded epidural, intraspinal, and EMG responses. SCS pulses produced characteristic propagating ECAPs (composed of P1, N1, and P2 waves with latencies <2 ms) and an additional wave ("S1") starting after the N2. We verified the S1-wave was not a stimulation artifact and was not a reflection of hindlimb/trunk EMG. The S1-wave has a distinct stimulation-intensity dose response and spatial profile compared with ECAPs. 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX; a selective competitive antagonist of AMPA receptors (AMPARs)] significantly diminished the S1-wave, but not ECAPs. Furthermore, cortical stimulation, which did not evoke ECAPs, produced epidurally detectable and CNQX-sensitive responses at the same spinal sites, confirming epidural recording of an evoked synaptic response. Finally, applying 50-Hz SCS resulted in dampening of S1-wave but not ECAPs. Therefore, we hypothesize that the S1-wave is synaptic in origin, and we term the S1-wave type responses: evoked synaptic activity potentials (ESAPs). The identification and characterization of epidurally recorded ESAPs from the dorsal horn may elucidate SCS mechanisms.
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Affiliation(s)
- Mahima Sharma
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Vividha Bhaskar
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Lillian Yang
- Department of Molecular, Cellular and Biomedical Sciences, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Mohamad FallahRad
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Nigel Gebodh
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Tianhe Zhang
- Boston Scientific Neuromodulation Research and Advanced Concepts, Valencia, CA 91355
| | - Rosana Esteller
- Boston Scientific Neuromodulation Research and Advanced Concepts, Valencia, CA 91355
| | - John Martin
- Department of Molecular, Cellular and Biomedical Sciences, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
| | - Marom Bikson
- Neural Engineering Laboratory, Department of Biomedical Engineering, The City College of the City University of New York, City College Center for Discovery and Innovation, New York, NY 10031
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Lam CM, Latif U, Sack A, Govindan S, Sanderson M, Vu DT, Smith G, Sayed D, Khan T. Advances in Spinal Cord Stimulation. Bioengineering (Basel) 2023; 10:185. [PMID: 36829678 PMCID: PMC9951889 DOI: 10.3390/bioengineering10020185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/17/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Neuromodulation, specifically spinal cord stimulation (SCS), has become a staple of chronic pain management for various conditions including failed back syndrome, chronic regional pain syndrome, refractory radiculopathy, and chronic post operative pain. Since its conceptualization, it has undergone several advances to increase safety and convenience for patients and implanting physicians. Current research and efforts are aimed towards novel programming modalities and modifications of existing hardware. Here we review the recent advances and future directions in spinal cord stimulation including a brief review of the history of SCS, SCS waveforms, new materials for SCS electrodes (including artificial skins, new materials, and injectable electrodes), closed loop systems, and neurorestorative devices.
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Affiliation(s)
- Christopher M. Lam
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Usman Latif
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Andrew Sack
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Susheel Govindan
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Miles Sanderson
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Dan T. Vu
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Gabriella Smith
- School of Medicine, University of Kansas, Kansas City, KS 66160, USA
| | - Dawood Sayed
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
| | - Talal Khan
- Department of Anesthesiology and Pain Medicine, University of Kansas Health System, Kansas City, KS 66160, USA
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27
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Cedeño DL, Vallejo R, Kelley CA, Platt DC, Litvak LM, Straka M, Dinsmoor DA. Spinal Evoked Compound Action Potentials in Rats With Clinically Relevant Stimulation Modalities. Neuromodulation 2023; 26:68-77. [PMID: 35961888 DOI: 10.1016/j.neurom.2022.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 06/07/2022] [Accepted: 06/29/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVES Rats are commonly used for translational pain and spinal cord stimulation (SCS) research. Although many SCS parameters are configured identically between rats and humans, stimulation amplitudes in rats are often programmed relative to visual motor threshold (vMT). Alternatively, amplitudes may be programmed relative to evoked compound action potential (ECAP) thresholds (ECAPTs), a sensed measure of neural activation. The objective of this study was to characterize ECAPTs, evoked compound muscle action potential thresholds (ECMAPTs), and vMTs with clinically relevant SCS modalities. MATERIALS AND METHODS We implanted ten anesthetized rats with two quadripolar epidural SCS leads: one for stimulating in the lumbar spine, and another for sensing ECAPs in the thoracic spine. We then delivered two SCS paradigms to the rats. The first used 50-Hz SCS with 50-, 100-, 150-, and 200-μs pulse widths (PWs), whereas the second used a 50-Hz, 150-μs PW low-rate program (LRP) multiplexed to a 1200-Hz, 50-μs PW high-rate program (HRP). We increased SCS amplitudes up to the vMT in the first paradigm, and in the second, we increased HRP amplitudes up to the HRP ECAPT with a fixed amplitude (70% of the vMT) LRP. For each test case, we captured ECAPTs, ECMAPTs, and vMTs from each rat. RESULTS vMTs were 3.0 ± 0.7 times greater than ECAPTs, with vMTs marginally (3.0 ± 3.6%) greater than ECMAPTs (mean ± SD) across all PWs with the first paradigm. With the second paradigm, we noted a negligible increase (3.6 ± 6.2%) on the LRP ECAP as HRP amplitudes were increased. CONCLUSIONS Our results demonstrate reasonable levels of neural activation in anesthetized rats with SCS amplitudes appropriately programmed relative to vMT or ECMAPT when using clinically relevant SCS modalities. Furthermore, we demonstrate the feasibility of ECAP recording in rats with multiplexed HRP SCS.
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28
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Ramadan A, König SD, Zhang M, Ross EK, Herman A, Netoff TI, Darrow DP. Methods and system for recording human physiological signals from implantable leads during spinal cord stimulation. FRONTIERS IN PAIN RESEARCH 2023; 4:1072786. [PMID: 36937564 PMCID: PMC10020336 DOI: 10.3389/fpain.2023.1072786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/23/2023] [Indexed: 03/06/2023] Open
Abstract
Objectives This article presents a method-including hardware configuration, sampling rate, filtering settings, and other data analysis techniques-to measure evoked compound action potentials (ECAPs) during spinal cord stimulation (SCS) in humans with externalized percutaneous electrodes. The goal is to provide a robust and standardized protocol for measuring ECAPs on the non-stimulation contacts and to demonstrate how measured signals depend on hardware and processing decisions. Methods Two participants were implanted with percutaneous leads for the treatment of chronic pain with externalized leads during a trial period for stimulation and recording. The leads were connected to a Neuralynx ATLAS system allowing us to simultaneously stimulate and record through selected electrodes. We examined different hardware settings, such as online filters and sampling rate, as well as processing techniques, such as stimulation artifact removal and offline filters, and measured the effects on the ECAPs metrics: the first negative peak (N1) time and peak-valley amplitude. Results For accurate measurements of ECAPs, the hardware sampling rate should be least at 8 kHz and should use a high pass filter with a low cutoff frequency, such as 0.1 Hz, to eliminate baseline drift and saturation (railing). Stimulation artifact removal can use a double exponential or a second-order polynomial. The polynomial fit is 6.4 times faster on average in computation time than the double exponential, while the resulting ECAPs' N1 time and peak-valley amplitude are similar between the two. If the baseline raw measurement drifts with stimulation, a median filter with a 100-ms window or a high pass filter with an 80-Hz cutoff frequency preserves the ECAPs. Conclusions This work is the first comprehensive analysis of hardware and processing variations on the observed ECAPs from SCS leads. It sets recommendations to properly record and process ECAPs from the non-stimulation contacts on the implantable leads.
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Affiliation(s)
- Ahmed Ramadan
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Seth D. König
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States
- Department of Psychiatry and Behavioral Sciences, University of Minnesota, Minneapolis, MN, United States
| | - Mingming Zhang
- Clinical and Applied Research, Abbott Neuromodulation, Plano, TX, United States
- Correspondence: David P. Darrow Mingming Zhang
| | - Erika K. Ross
- Clinical and Applied Research, Abbott Neuromodulation, Plano, TX, United States
| | - Alexander Herman
- Department of Psychiatry and Behavioral Sciences, University of Minnesota, Minneapolis, MN, United States
| | - Theoden I. Netoff
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - David P. Darrow
- Department of Neurosurgery, University of Minnesota, Minneapolis, MN, United States
- Correspondence: David P. Darrow Mingming Zhang
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Falowski SM, Kim CH, Obradovic M, Parker JL. A Prospective Multicenter Case Series Utilizing Intraoperative Neuromonitoring With Evoked Compound Action Potentials to Confirm Spinal Cord Stimulation Lead Placement. Neuromodulation 2022; 25:724-730. [DOI: 10.1016/j.neurom.2021.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 10/18/2021] [Accepted: 11/08/2021] [Indexed: 11/25/2022]
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Closed-Loop Systems in Neuromodulation. Neurosurg Clin N Am 2022; 33:297-303. [DOI: 10.1016/j.nec.2022.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Calvert JS, Darie R, Parker SR, Shaaya E, Syed S, McLaughlin BL, Fridley JS, Borton DA. Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation. Neuromodulation 2022:S1094-7159(22)00644-4. [PMID: 35551869 PMCID: PMC9643656 DOI: 10.1016/j.neurom.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/07/2022] [Accepted: 03/23/2022] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Recent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation. MATERIALS AND METHODS In each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles. RESULTS We observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array. CONCLUSIONS These results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.
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Affiliation(s)
- Jonathan S Calvert
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Radu Darie
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Samuel R Parker
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA
| | - Elias Shaaya
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | - Sohail Syed
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | | | - Jared S Fridley
- Department of Neurosurgery, Brown University and Rhode Island Hospital, Providence, RI, USA
| | - David A Borton
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, USA; Department of Veterans Affairs, Center for Neurorestoration and Neurotechnology, Providence, RI, USA; Carney Institute for Brain Science, Brown University, Providence, RI, USA.
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Kiang L, Woodington B, Carnicer-Lombarte A, Malliaras G, Barone DG. Spinal cord bioelectronic interfaces: opportunities in neural recording and clinical challenges. J Neural Eng 2022; 19. [PMID: 35320780 DOI: 10.1088/1741-2552/ac605f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/23/2022] [Indexed: 11/11/2022]
Abstract
Bioelectronic stimulation of the spinal cord has demonstrated significant progress in restoration of motor function in spinal cord injury (SCI). The proximal, uninjured spinal cord presents a viable target for the recording and generation of control signals to drive targeted stimulation. Signals have been directly recorded from the spinal cord in behaving animals and correlated with limb kinematics. Advances in flexible materials, electrode impedance and signal analysis will allow SCR to be used in next-generation neuroprosthetics. In this review, we summarize the technological advances enabling progress in SCR and describe systematically the clinical challenges facing spinal cord bioelectronic interfaces and potential solutions, from device manufacture, surgical implantation to chronic effects of foreign body reaction and stress-strain mismatches between electrodes and neural tissue. Finally, we establish our vision of bi-directional closed-loop spinal cord bioelectronic bypass interfaces that enable the communication of disrupted sensory signals and restoration of motor function in SCI.
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Affiliation(s)
- Lei Kiang
- Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, Singapore, 169608, SINGAPORE
| | - Ben Woodington
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Alejandro Carnicer-Lombarte
- Clinical Neurosciences, University of Cambridge, Bioelectronics Laboratory, Cambridge, CB2 0PY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - George Malliaras
- University of Cambridge, University of Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Damiano G Barone
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, Cambridgeshire, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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Sheldon BL, Bao J, Khazen O, Pilitsis JG. Spinal Cord Stimulation as Treatment for Cancer and Chemotherapy-Induced Pain. FRONTIERS IN PAIN RESEARCH 2022; 2:699993. [PMID: 35295456 PMCID: PMC8915692 DOI: 10.3389/fpain.2021.699993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 07/23/2021] [Indexed: 01/17/2023] Open
Abstract
Neuropathic pain is a rampant disease exacting a significant toll on patients, providers, and health care systems around the globe. Neuromodulation has been successfully employed to treat many indications including failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), phantom limb pain (PLP), radiculopathies, and intractable pelvic pain, among many others. Recent studies have also demonstrated efficacy for cancer-related pain and chemotherapy induced neuropathy with these techniques. Spinal cord stimulation (SCS) is the most commonly employed technique and involves implantation of percutaneous or paddle leads targeting the dorsal columns of the spinal cord with the goal of disrupting the pain signals traveling to the brain. Tonic, high frequency, and burst waveforms have all been shown to reduce pain and disability in chronic pain patients. Closed-loop SCS systems that automatically adjust stimulation parameters based on feedback (such as evoked compound action potentials) are becoming increasingly used to help ease the burden placed on patients to adjust their programming to their pain and position. Additionally, dorsal root ganglion stimulation (DRGS) is a newer technique that allows for dermatomal coverage especially in patients with pain in up to two dermatomes. Regardless of the technique chosen, neuromodulation has been shown to be cost-effective and efficacious and should be given full consideration in patients with chronic pain conditions.
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Affiliation(s)
- Breanna L Sheldon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Jonathan Bao
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Olga Khazen
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Julie G Pilitsis
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States.,Department of Neurosurgery, Albany Medical Center, Albany, NY, United States
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Mekhail N, Levy RM, Deer TR, Kapural L, Li S, Amirdelfan K, Hunter CW, Rosen SM, Costandi SJ, Falowski SM, Burgher AH, Pope JE, Gilmore CA, Qureshi FA, Staats PS, Scowcroft J, McJunkin T, Carlson J, Kim CK, Yang MI, Stauss T, Pilitsis J, Poree L, Brounstein D, Gilbert S, Gmel GE, Gorman R, Gould I, Hanson E, Karantonis DM, Khurram A, Leitner A, Mugan D, Obradovic M, Ouyang Z, Parker J, Single P, Soliday N. Durability of Clinical and Quality-of-Life Outcomes of Closed-Loop Spinal Cord Stimulation for Chronic Back and Leg Pain: A Secondary Analysis of the Evoke Randomized Clinical Trial. JAMA Neurol 2022; 79:251-260. [PMID: 34998276 PMCID: PMC8742908 DOI: 10.1001/jamaneurol.2021.4998] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Importance Chronic pain is debilitating and profoundly affects health-related quality of life. Spinal cord stimulation (SCS) is a well-established therapy for chronic pain; however, SCS has been limited by the inability to directly measure the elicited neural response, precluding confirmation of neural activation and continuous therapy. A novel SCS system measures the evoked compound action potentials (ECAPs) to produce a real-time physiological closed-loop control system. Objective To determine whether ECAP-controlled, closed-loop SCS is associated with better outcomes compared with fixed-output, open-loop SCS at 24 months following implant. Design, Setting, and Participants The Evoke study was a double-blind, randomized, controlled, parallel arm clinical trial with 36 months of follow-up. Participants were enrolled from February 2017 to 2018, and the study was conducted at 13 US investigation sites. SCS candidates with chronic, intractable back and leg pain refractory to conservative therapy, who consented, were screened. Key eligibility criteria included overall, back, and leg pain visual analog scale score of 60 mm or more; Oswestry Disability Index score of 41 to 80; stable pain medications; and no previous SCS. Analysis took place from October 2020 to April 2021. Interventions ECAP-controlled, closed-loop SCS was compared with fixed-output, open-loop SCS. Main Outcomes and Measures Reported here are the 24-month outcomes of the trial, which include all randomized patients in the primary and safety analyses. The primary outcome was a reduction of 50% or more in overall back and leg pain assessed at 3 and 12 months (previously published). Results Of 134 randomized patients, 65 (48.5%) were female and the mean (SD) age was 55.2 (10.6) years. At 24 months, significantly more closed-loop than open-loop patients were responders (≥50% reduction) in overall pain (53 of 67 [79.1%] in the closed-loop group; 36 of 67 [53.7%] in the open-loop group; difference, 25.4% [95% CI, 10.0%-40.8%]; P = .001). There was no difference in safety profiles between groups (difference in rate of study-related adverse events: 6.0 [95% CI, -7.8 to 19.7]). Improvements were also observed in health-related quality of life, physical and emotional functioning, and sleep, in parallel with opioid reduction or elimination. Objective neurophysiological measurements substantiated the clinical outcomes and provided evidence of activation of inhibitory pain mechanisms. Conclusions and Relevance ECAP-controlled, closed-loop SCS, which elicited a more consistent neural response, was associated with sustained superior pain relief at 24 months, consistent with the 3- and 12-month outcomes.
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Affiliation(s)
| | - Robert M. Levy
- International Neuromodulation Society, Neuromodulation: Technology at the Neural Interface, San Francisco, California
| | - Timothy R. Deer
- The Spine and Nerve Center of The Virginias, Charleston, West Virginia
| | - Leonardo Kapural
- Carolinas Pain Institute, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Sean Li
- Premier Pain Centers, Shrewsbury, New Jersey
| | | | | | - Steven M. Rosen
- Delaware Valley Pain and Spine Institute, Trevose, Pennsylvania
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Lawrence Poree
- University of California at San Francisco, San Francisco
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Chakravarthy K, FitzGerald J, Will A, Trutnau K, Corey R, Dinsmoor D, Litvak L. A Clinical Feasibility Study of Spinal Evoked Compound Action Potential Estimation Methods. Neuromodulation 2022; 25:75-84. [PMID: 35041590 DOI: 10.1111/ner.13510] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/18/2021] [Accepted: 07/06/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Spinal cord stimulation (SCS) is a treatment for chronic neuropathic pain. Recently, SCS has been enhanced further with evoked compound action potential (ECAP) sensing. Characteristics of the ECAP, if appropriately isolated from concurrent stimulation artifact (SA), may be used to control, and aid in the programming of, SCS systems. Here, we characterize the sensitivity of the ECAP growth curve slope (S) to both neural response (|Sresp|) and SA contamination (|Sart|) for four spinal ECAP estimation methods with a novel performance measure (|Sresp/Sart|). MATERIALS AND METHODS We collected a library of 112 ECAP and associated artifact recordings with swept stimulation amplitudes from 14 human subjects. We processed the signals to reduce SA from these recordings by applying one of three schemes: a simple high-pass (HP) filter, subtracting an artifact model (AM) consisting of decaying exponential and linear components, or applying a template correlation method consisting of a triangularly weighted sinusoid. We compared these against each other and to P2-N1, a standard method of measuring ECAP amplitude. We then fit the ECAP estimates from each method with a function representing the growth curve and calculated the Sresp and Sart parameters following the fit. RESULTS Any SA reduction scheme selected may result in under- or overestimation of neural activation or misclassification of SA as ECAP. In these experiments, the ratio of neural signal preservation to SA misclassification (|Sresp/Sart|) on the ECAP estimate was superior (p < 0.05) with the HP and AM schemes relative to the others. CONCLUSIONS This work represents the first comprehensive assessment of spinal ECAP estimation schemes. Understanding the clinically relevant sensitivities of these schemes is increasingly important, particularly with closed-loop SCS systems using ECAP as a feedback control variable where misclassification of artifact as neural signal may lead to suboptimal therapy adjustments.
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Affiliation(s)
| | - James FitzGerald
- Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, UK
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Mekhail N, Poree L. Response to: A Clinical Feasibility Study of Spinal Evoked Compound Action Potential Estimation Methods. Neuromodulation 2022; 25:155-156. [DOI: 10.1016/j.neurom.2021.10.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/30/2021] [Indexed: 11/26/2022]
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Vallejo R, Chakravarthy K, Will A, Trutnau K, Dinsmoor D. A New Direction for Closed-Loop Spinal Cord Stimulation: Combining Contemporary Therapy Paradigms with Evoked Compound Action Potential Sensing. J Pain Res 2021; 14:3909-3918. [PMID: 35002310 PMCID: PMC8721159 DOI: 10.2147/jpr.s344568] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/21/2021] [Indexed: 01/01/2023] Open
Abstract
Spinal cord stimulation (SCS) utilizes the delivery of mild electrical pulses via epidural electrodes placed on the dorsal side of the spinal cord, typically to treat chronic pain. The first clinical use of SCS involved the delivery of paresthesia inducing, low-frequency waveforms to the neural targets corresponding to the painful areas. Contemporary SCS therapies now leverage novel therapeutic pathways to limit paresthesia and deliver superior clinical outcomes. Historically, SCS has largely been delivered with fixed stimulation parameters. This approach, referred to as open-loop (OL) SCS, does not account for the fluctuations in spacing-driven by postural changes and activity-between the electrodes and the cord. These fluctuations result in variability in the delivered dose and the volume of tissue activation (VTA) that manifests with each stimulation pulse. Inconsistent dosing may lead to suboptimal therapeutic efficacy and durability. To address this clinical need, closed-loop (CL) SCS systems have been developed to automatically adjust stimulation parameters to compensate for this variability. The evoked compound action potential (ECAP), a biopotential generated by the synchronous activation of dorsal column fibers, is indicative of the VTA resulting from the stimulation pulse. The ECAP may be utilized as a control signal in CL SCS systems to adjust stimulation parameters to reduce variability in the ECAP, and in turn, variability in the VTA. While investigational CL SCS systems with ECAP sensing have so far focused solely on managing paresthesia-based SCS, such systems must also incorporate the stimulation approaches that now define the contemporary clinical practice of SCS. Accordingly, we describe here a flexible, next-generation framework for neural responsive SCS that blends science-based methodologies for pain management with real-time CL control for biophysical variation. We conclude with a clinical example of such a system and the associated performance characteristics.
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Affiliation(s)
| | - Krishnan Chakravarthy
- Anesthesiology and Pain Management, University of California San Diego, San Diego, CA, USA
| | | | | | - David Dinsmoor
- Neuromodulation Research & Technology, Medtronic plc, Minneapolis, MN, USA
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Wendt K, Denison T, Foster G, Krinke L, Thomson A, Wilson S, Widge AS. Physiologically informed neuromodulation. J Neurol Sci 2021; 434:120121. [PMID: 34998239 PMCID: PMC8976285 DOI: 10.1016/j.jns.2021.120121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/19/2021] [Accepted: 12/21/2021] [Indexed: 01/09/2023]
Abstract
The rapid evolution of neuromodulation techniques includes an increasing amount of research into stimulation paradigms that are guided by patients' neurophysiology, to increase efficacy and responder rates. Treatment personalisation and target engagement have shown to be effective in fields such as Parkinson's disease, and closed-loop paradigms have been successfully implemented in cardiac defibrillators. Promising avenues are being explored for physiologically informed neuromodulation in psychiatry. Matching the stimulation frequency to individual brain rhythms has shown some promise in transcranial magnetic stimulation (TMS). Matching the phase of those rhythms may further enhance neuroplasticity, for instance when combining TMS with electroencephalographic (EEG) recordings. Resting-state EEG and event-related potentials may be useful to demonstrate connectivity between stimulation sites and connected areas. These techniques are available today to the psychiatrist to diagnose underlying sleep disorders, epilepsy, or lesions as contributing factors to the cause of depression. These technologies may also be useful in assessing the patient's brain network status prior to deciding on treatment options. Ongoing research using invasive recordings may allow for future identification of mood biomarkers and network structure. A core limitation is that biomarker research may currently be limited by the internal heterogeneity of psychiatric disorders according to the current DSM-based classifications. New approaches are being developed and may soon be validated. Finally, care must be taken when incorporating closed-loop capabilities into neuromodulation systems, by ensuring the safe operation of the system and understanding the physiological dynamics. Neurophysiological tools are rapidly evolving and will likely define the next generation of neuromodulation therapies.
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Affiliation(s)
- Karen Wendt
- Department of Engineering Science and MRC Brain Network Dynamics Unit, University of Oxford, Oxford, UK.
| | - Timothy Denison
- Department of Engineering Science and MRC Brain Network Dynamics Unit, University of Oxford, Oxford, UK
| | - Gaynor Foster
- Welcony Inc., Plymouth, MN, United States of America
| | - Lothar Krinke
- Welcony Inc., Plymouth, MN, United States of America; Department of Neuroscience, School of Medicine, West Virginia University, Morgantown, WV, United States of America
| | - Alix Thomson
- Welcony Inc., Plymouth, MN, United States of America
| | - Saydra Wilson
- Department of Psychiatry and Behavioral Sciences, University of Minnesota-Twin Cities, Minneapolis, MN, United States of America
| | - Alik S Widge
- Department of Psychiatry and Behavioral Sciences, University of Minnesota-Twin Cities, Minneapolis, MN, United States of America; Medical Discovery Team on Additions, University of Minnesota, Minneapolis, MN, United States of America
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Gmel GE, Vollebregt PF, Thijssen MEG, Santos Escapa R, McAlees E, Mugan D, Parker JL, Knowles CH. Electrophysiological Responses in the Human S3 Nerve During Sacral Neuromodulation for Fecal Incontinence. Front Neurosci 2021; 15:712168. [PMID: 34707473 PMCID: PMC8545143 DOI: 10.3389/fnins.2021.712168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/20/2021] [Indexed: 11/26/2022] Open
Abstract
Intra-operative electrode placement for sacral neuromodulation (SNM) relies on visual observation of motor contractions alone, lacking complete information on neural activation from stimulation. This study aimed to determine whether electrophysiological responses can be recorded directly from the S3 sacral nerve during therapeutic SNM in patients with fecal incontinence, and to characterize such responses in order to better understand the mechanism of action (MOA) and whether stimulation is subject to changes in posture. Eleven patients undergoing SNM were prospectively recruited. A bespoke stimulating and recording system was connected (both intraoperatively and postoperatively) to externalized SNM leads, and electrophysiological responses to monopolar current sweeps on each electrode were recorded and analyzed. The nature and thresholds of muscle contractions (intraoperatively) and patient-reported stimulation perception were recorded. We identified both neural responses (evoked compound action potentials) as well as myoelectric responses (far-field potentials from muscle activation). We identified large myelinated fibers (conduction velocity: 36–60 m/s) in 5/11 patients, correlating with patient-reported stimulation perception, and smaller myelinated fibers (conduction velocity <15 m/s) in 4/11 patients (not associated with any sensation). Myoelectric responses (observed in 7/11 patients) were attributed to pelvic floor and/or anal sphincter contraction. Responses varied with changes in posture. We present the first direct electrophysiological responses recorded from the S3 nerve during ongoing SNM in humans, showing both neural and myoelectric responses. These recordings highlight heterogeneity of neural and myoelectric responses (relevant to understanding MOA of SNM) and confirm that electrode lead position can change with posture.
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Affiliation(s)
| | - Paul F Vollebregt
- National Bowel Research Centre, Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | | | | | - Eleanor McAlees
- National Bowel Research Centre, Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Dave Mugan
- Saluda Medical Pty Ltd, Artarmon, NSW, Australia
| | | | - Charles H Knowles
- National Bowel Research Centre, Centre for Neuroscience, Surgery and Trauma, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Chakravarthy K, Reddy R, Al-Kaisy A, Yearwood T, Grider J. A Call to Action Toward Optimizing the Electrical Dose Received by Neural Targets in Spinal Cord Stimulation Therapy for Neuropathic Pain. J Pain Res 2021; 14:2767-2776. [PMID: 34522135 PMCID: PMC8434932 DOI: 10.2147/jpr.s323372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/16/2021] [Indexed: 12/20/2022] Open
Abstract
Spinal cord stimulation has seen unprecedented growth in new technology in the 50 years since the first subdural implant. As we continue to grow our understanding of spinal cord stimulation and relevant mechanisms of action, novel questions arise as to electrical dosing optimization. Programming adjustment — dose titration — is often a process of trial and error that can be time-consuming and frustrating for both patient and clinician. In this report, we review the current preclinical and clinical knowledge base in order to provide insights that may be helpful in developing more rational approaches to spinal cord stimulation dosing. We also provide key conclusions that may help in directing future research into electrical dosing, given the advent of newer waveforms outside traditional programming parameters.
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Affiliation(s)
- Krishnan Chakravarthy
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, San Diego, CA, USA.,VA San Diego Healthcare System, San Diego, Ca, USA
| | - Rajiv Reddy
- Department of Anesthesiology and Pain Medicine, University of California San Diego Health Sciences, San Diego, CA, USA
| | - Adnan Al-Kaisy
- Pain Management and Neuromodulation Centre at Guy's and St. Thomas' NHS Trust, London, UK
| | - Thomas Yearwood
- Pain Management and Neuromodulation Centre at Guy's and St. Thomas' NHS Trust, London, UK
| | - Jay Grider
- Division of Pain Medicine, Department of Anesthesiology, University of Kentucky College of Medicine, Lexington, KY, 40536, USA
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Pilitsis JG, Chakravarthy KV, Will AJ, Trutnau KC, Hageman KN, Dinsmoor DA, Litvak LM. The Evoked Compound Action Potential as a Predictor for Perception in Chronic Pain Patients: Tools for Automatic Spinal Cord Stimulator Programming and Control. Front Neurosci 2021; 15:673998. [PMID: 34335157 PMCID: PMC8320888 DOI: 10.3389/fnins.2021.673998] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
Objectives Spinal cord stimulation (SCS) is a drug free treatment for chronic pain. Recent technological advances have enabled sensing of the evoked compound action potential (ECAP), a biopotential that represents neural activity elicited from SCS. The amplitudes of many SCS paradigms – both sub- and supra-threshold – are programmed relative to the patient’s perception of SCS. The objective of this study, then, is to elucidate relationships between the ECAP and perception thresholds across posture and SCS pulse width. These relationships may be used for the automatic control and perceptually referenced programming of SCS systems. Methods ECAPs were acquired from 14 subjects across a range of postures and pulse widths with swept amplitude stimulation. Perception (PT) and discomfort (DT) thresholds were recorded. A stimulation artifact reduction scheme was employed, and growth curves were constructed from the sweeps. An estimate of the ECAP threshold (ET), was calculated from the growth curves using a novel approach. Relationships between ET, PT, and DT were assessed. Results ETs were estimated from 112 separate growth curves. For the postures and pulse widths assessed, the ET tightly correlated with both PT (r = 0.93; p < 0.0001) and DT (r = 0.93; p < 0.0001). The median accuracy of ET as a predictor for PT across both posture and pulse width was 0.5 dB. Intra-subject, ECAP amplitudes at DT varied up to threefold across posture. Conclusion We provide evidence that the ET varies across both different positions and varying pulse widths and suggest that this variance may be the result of postural dependence of the recording electrode-tissue spacing. ET-informed SCS holds promise as a tool for SCS parameter configuration and may offer more accuracy over alternative approaches for neural and perceptual control in closed loop SCS systems.
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Affiliation(s)
- Julie G Pilitsis
- Department of Neurosurgery, Albany Medical Center, Albany, NY, United States
| | - Krishnan V Chakravarthy
- Department of Anesthesiology, University of California, San Diego, La Jolla, CA, United States
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Spinal cord stimulation in chronic neuropathic pain: mechanisms of action, new locations, new paradigms. Pain 2021; 161 Suppl 1:S104-S113. [PMID: 33090743 PMCID: PMC7434213 DOI: 10.1097/j.pain.0000000000001854] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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44
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Boakye M, Ugiliweneza B, Madrigal F, Mesbah S, Ovechkin A, Angeli C, Bloom O, Wecht JW, Ditterline B, Harel NY, Kirshblum S, Forrest G, Wu S, Harkema S, Guest J. Clinical Trial Designs for Neuromodulation in Chronic Spinal Cord Injury Using Epidural Stimulation. Neuromodulation 2021; 24:405-415. [PMID: 33794042 DOI: 10.1111/ner.13381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/11/2021] [Accepted: 02/09/2021] [Indexed: 12/17/2022]
Abstract
STUDY DESIGN This is a narrative review focused on specific challenges related to adequate controls that arise in neuromodulation clinical trials involving perceptible stimulation and physiological effects of stimulation activation. OBJECTIVES 1) To present the strengths and limitations of available clinical trial research designs for the testing of epidural stimulation to improve recovery after spinal cord injury. 2) To describe how studies can control for the placebo effects that arise due to surgical implantation, the physical presence of the battery, generator, control interfaces, and rehabilitative activity aimed to promote use-dependent plasticity. 3) To mitigate Hawthorne effects that may occur in clinical trials with intensive supervised participation, including rehabilitation. MATERIALS AND METHODS Focused literature review of neuromodulation clinical trials with integration to the specific context of epidural stimulation for persons with chronic spinal cord injury. CONCLUSIONS Standard of care control groups fail to control for the multiple effects of knowledge of having undergone surgical procedures, having implanted stimulation systems, and being observed in a clinical trial. The irreducible effects that have been identified as "placebo" require sham controls or comparison groups in which both are implanted with potentially active devices and undergo similar rehabilitative training.
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Affiliation(s)
- Maxwell Boakye
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Beatrice Ugiliweneza
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Health Management and Systems Sciences, University of Louisville, Louisville, KY, USA
| | - Fabian Madrigal
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA
| | - Samineh Mesbah
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Alexander Ovechkin
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Claudia Angeli
- Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Department of Bioengineering, University of Louisville, Louisville, KY, USA.,Frazier Rehabilitation Institute, University of Louisville Health, Louisville, KY, USA
| | - Ona Bloom
- Feinstein Institute for Medical Research, Manhasset, NY, USA.,Department of Molecular Medicine, Zucker School of Medicine at Hofstra Northwell, Manhasset, NY, USA.,Department of Physical Medicine and Rehabilitation, Zucker School of Medicine at Hofstra Northwell, Manhasset, NY, USA.,James J Peters VA Medical Center, Bronx, NY, USA
| | - Jill W Wecht
- James J Peters VA Medical Center, Bronx, NY, USA.,The Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Bonnie Ditterline
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA
| | - Noam Y Harel
- James J Peters VA Medical Center, Bronx, NY, USA.,The Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steven Kirshblum
- Kessler Institute for Rehabilitation, Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NY, USA.,Human Performance and Engineering Research, Kessler Foundation, West Orange, NJ, USA
| | - Gail Forrest
- Human Performance and Engineering Research, Kessler Foundation, West Orange, NJ, USA.,Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Samuel Wu
- Department of Biostatistics, CTSI Data Coordinating Center, University of Florida, Gainesville, FL, USA
| | - Susan Harkema
- Department of Neurological Surgery, University of Louisville, Louisville, KY, USA.,Kentucky Spinal Cord Injury Research Center, University of Louisville, Louisville, KY, USA.,Frazier Rehabilitation Institute, University of Louisville Health, Louisville, KY, USA
| | - James Guest
- Neurological Surgery, and the Miami Project to Cure Paralysis, Miller School of Medicine, Miami, FL, USA
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Deer TR, Eldabe S, Falowski SM, Huntoon MA, Staats PS, Cassar IR, Crosby ND, Boggs JW. Peripherally Induced Reconditioning of the Central Nervous System: A Proposed Mechanistic Theory for Sustained Relief of Chronic Pain with Percutaneous Peripheral Nerve Stimulation. J Pain Res 2021; 14:721-736. [PMID: 33737830 PMCID: PMC7966353 DOI: 10.2147/jpr.s297091] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/26/2021] [Indexed: 12/23/2022] Open
Abstract
Peripheral nerve stimulation (PNS) is an effective tool for the treatment of chronic pain, although its efficacy and utilization have previously been significantly limited by technology. In recent years, purpose-built percutaneous PNS devices have been developed to overcome the limitations of conventional permanently implanted neurostimulation devices. Recent clinical evidence suggests clinically significant and sustained reductions in pain can persist well beyond the PNS treatment period, outcomes that have not previously been observed with conventional permanently implanted neurostimulation devices. This narrative review summarizes mechanistic processes that contribute to chronic pain, and the potential mechanisms by which selective large diameter afferent fiber activation may reverse these changes to induce a prolonged reduction in pain. The interplay of these mechanisms, supported by data in chronic pain states that have been effectively treated with percutaneous PNS, will also be discussed in support of a new theory of pain management in neuromodulation: Peripherally Induced Reconditioning of the Central Nervous System (CNS).
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Affiliation(s)
- Timothy R Deer
- The Spine and Nerve Center of the Virginias, Charleston, WV, USA
| | - Sam Eldabe
- Department of Pain Medicine, The James Cook University Hospital, Middlesbrough, UK
| | - Steven M Falowski
- Department of Neurosurgery, Neurosurgical Associates of Lancaster, Lancaster, PA, USA
| | - Marc A Huntoon
- Anesthesiology, Virginia Commonwealth University Medical Center, Richmond, VA, USA
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Russo M, Brooker C, Cousins MJ, Taylor N, Boesel T, Sullivan R, Holford L, Hanson E, Gmel GE, Shariati NH, Poree L, Parker J. Sustained Long-Term Outcomes With Closed-Loop Spinal Cord Stimulation: 12-Month Results of the Prospective, Multicenter, Open-Label Avalon Study. Neurosurgery 2021; 87:E485-E495. [PMID: 32023344 PMCID: PMC8184296 DOI: 10.1093/neuros/nyaa003] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 11/22/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Spinal cord stimulation (SCS) activates the dorsal column fibers using electrical stimuli. Current SCS systems function in fixed-output mode, delivering the same stimulus regardless of spinal cord (SC) activation. OBJECTIVE To present long-term outcomes of a novel closed-loop SCS system that aims to maintain the SC activation near a set target level and within a therapeutic window for each patient. SC activation is measured through the evoked compound action potential (ECAP) generated by each stimulus pulse. METHODS Fifty patients with lower back and/or leg pain who were successfully trialed received a permanent system (Evoke; Saluda Medical, Sydney, Australia). Ratings of pain (visual analog scale), quality of life, function, sleep, and medication use were collected at baseline and at each visit. SC activation levels were reported in summary statistics. The therapeutic window for each individual patient was defined as the range of ECAP amplitudes between sensation threshold and uncomfortably strong stimulation. RESULTS At 12 mo, the proportion of patients with ≥50% relief was 76.9% (back), 79.3% (leg), and 81.4% (overall), and the proportion with ≥80% pain relief was 56.4% (back), 58.6% (leg), and 53.5% (overall). Patients spent a median of 84.9% of their time with stimulation in their therapeutic window, and 68.8% (22/32) eliminated or reduced their opioid intake. Statistically significant improvements in secondary outcomes were observed. CONCLUSION The majority of patients experienced more than 80% pain relief with stable SC activation, as measured by ECAP amplitude at 12 mo, providing evidence for the long-term effectiveness of the Evoke closed-loop SCS system.
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Affiliation(s)
- Marc Russo
- Hunter Pain Clinic, Broadmeadow, Australia
| | - Charles Brooker
- MJC Pain Management and Research Centre, St. Leonards, Australia.,Northern Pain Centre, St. Leonards, Australia
| | - Michael J Cousins
- MJC Pain Management and Research Centre, St. Leonards, Australia.,Northern Pain Centre, St. Leonards, Australia
| | - Nathan Taylor
- MJC Pain Management and Research Centre, St. Leonards, Australia.,Northern Pain Centre, St. Leonards, Australia
| | | | | | - Lewis Holford
- MJC Pain Management and Research Centre, St. Leonards, Australia.,Northern Pain Centre, St. Leonards, Australia
| | | | | | | | | | - John Parker
- Saluda Medical Pty Ltd, Artarmon, Australia.,Graduate School of Biomedical Engineering, University of New South Wales, Kensington, Australia
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Gmel GE, Santos Escapa R, Parker JL, Mugan D, Al-Kaisy A, Palmisani S. The Effect of Spinal Cord Stimulation Frequency on the Neural Response and Perceived Sensation in Patients With Chronic Pain. Front Neurosci 2021; 15:625835. [PMID: 33551738 PMCID: PMC7859107 DOI: 10.3389/fnins.2021.625835] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/05/2021] [Indexed: 11/30/2022] Open
Abstract
Background The effect of spinal cord stimulation (SCS) amplitude on the activation of dorsal column fibres has been widely studied through the recording of Evoked Compound Action Potentials (ECAPs), the sum of all action potentials elicited by an electrical stimulus applied to the fibres. ECAP amplitude grows linearly with stimulus current after a threshold, and a larger ECAP results in a stronger stimulus sensation for patients. This study investigates the effect of stimulus frequency on both the ECAP amplitude as well as the perceived stimulus sensation in patients undergoing SCS therapy for chronic back and/or leg pain. Methods Patients suffering with chronic neuropathic lower-back and/or lower-limb pain undergoing an epidural SCS trial were recruited. Patients were implanted according to standard practice, having two 8-contact leads (8 mm inter-electrode spacing) which overlapped 2–4 contacts around the T9/T10 interspace. Both lead together thus spanning about three vertebral levels. Neurophysiological recordings were taken during the patient’s trial phase at two routine follow-ups using a custom external stimulator capable of recording ECAPs in real-time from all non-stimulating contacts. Stimulation was performed at various vertebral levels, varying the frequency (ranging from 2 to 455 Hz) while all other stimulating variables were kept constant. During the experiments subjects were asked to rate the stimulation-induced sensation (paraesthesia) on a scale from 0 to 10. Results Frequency response curves showed an inverse relationship between stimulation sensation strength and ECAP amplitude, with higher frequencies generating smaller ECAPs but stronger stimulation-induced paraesthesia (at constant stimulation amplitude). Both relationships followed logarithmic trends against stimulus frequency meaning that the effects on ECAP amplitude and sensation are larger for smaller frequencies. Conclusion This work supports the hypothesis that SCS-induced paraesthesia is conveyed through both frequency coding and population coding, fitting known psychophysics of tactile sensory information processing. The inverse relationship between ECAP amplitude and sensation for increasing frequencies at fixed stimulus amplitude questions common assumptions of monotonic relationships between ECAP amplitude and sensation strength.
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Affiliation(s)
| | | | | | - Dave Mugan
- Saluda Medical Pty Ltd., Artarmon, NSW, Australia
| | - Adnan Al-Kaisy
- Guy's & St. Thomas' NHS Foundation Trust, London, United Kingdom
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Chakravarthy K, Bink H, Dinsmoor D. Sensing Evoked Compound Action Potentials from the Spinal Cord: Novel Preclinical and Clinical Considerations for the Pain Management Researcher and Clinician. J Pain Res 2020; 13:3269-3279. [PMID: 33328760 PMCID: PMC7733896 DOI: 10.2147/jpr.s289098] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 11/25/2020] [Indexed: 01/16/2023] Open
Abstract
Purpose Spinal cord stimulation (SCS) is a drug-free treatment for chronic neuropathic pain. Recent SCS technology can record evoked compound action potentials (ECAPs) in the spinal cord during therapy and utilize features of the sensed ECAP to optimize the SCS. The purpose of this work is to characterize the relevant parameters that govern the integrity and morphology of acquired ECAPs, and the implications for pain management clinicians and researchers working with ECAPs. Materials and Methods Eight-contact percutaneous SCS leads were implanted into sheep, and a prototype ECAP-sensing system was used to record spinal cord activity across a range of electrode configurations, pulse widths, and stimulus amplitudes. Similar iterative testing was then completed in human subjects who were undergoing trials of commercial SCS systems. Results Longer pulse width stimulation results in a progressive increase in ECAP latency, a neurophysiologic effect that enables ECAP sensing with longer pulses despite more encroachment by stimulation artifact. ECAPs may manifest a polyphasic morphology—an effect not seen in all subjects studied—with longer pulse width stimulation; these later phases may be used to assess ECAP amplitude when earlier features are effaced by artifact. Triphasic stimulation limits artifact from spinal cord ECAPs at the expense of potentially higher activation thresholds. If applied, alternating polarity stimulation must account for the ECAP latency differences resulting from alternating sites of neural activation. Conclusion Together, this information can allow the ECAP to be readily distinguished from the stimulation artifact, although movement may continue to be a confounder; caution is inculcated for ECAP signal processing techniques that rely on the stability of the artifact to avoid clinically misleading results. The promise of closed-loop, ECAP-servoed neuromodulation relies on accurate and proper sensing of the ECAP, while clearly elucidating the clinically relevant trade-offs and design choices made to enable these novel features.
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Affiliation(s)
- Krishnan Chakravarthy
- Anesthesiology and Pain Management, University of California San Diego, San Diego, CA, USA
| | - Hank Bink
- Neuromodulation, Medtronic Plc, Minneapolis, MN, USA
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49
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Kim EK, Lee CS, Yoo Y, Park JW, Kim JS, Kim Y, Moon JY, Kim YC. The Long-term Effectiveness of the Automatic Position-Adaptive System in Spinal Cord Stimulation: A Retrospective Comparative Study with a Two-Year Follow-up. PAIN MEDICINE 2020; 21:2288-2297. [PMID: 32443142 DOI: 10.1093/pm/pnaa121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To compare the nonadaptive manual system with the position-adaptive system in subjects with permanent spinal cord stimulator (SCS) implantation over a two-year follow-up period. DESIGN Retrospective study. SETTING Tertiary university-based national hospital. SUBJECTS Patients who underwent permanent SCS implantation procedures. METHODS Patients were divided into an adaptive group and a nonadaptive group according to the type of implanted SCS device. The primary outcome was the change (%) in pain intensity from baseline between the adaptive and nonadaptive groups at 24 months after SCS implantation. The secondary outcomes were comparisons of detailed clinical variables such as the scores of patient pain and satisfaction during the two-year follow-up after SCS therapy. Further, the number of subjects with SCS removal or revision within two years after SCS implantation was investigated. RESULTS Of 187 patients with permanent SCS implantation, 85 in the nonadaptive group and 64 in the position-adaptive group were finally analyzed. The reduction in pain intensity at 24 months was higher in the adaptive group (-38.6%) than in the nonadaptive group (-30.8%, P = 0.05). Similarly, patient satisfaction with the SCS treatment at 24 months was superior in the adaptive group than in the nonadaptive group (85.7% vs 67.5% were satisfied in each group, respectively, P = 0.024). During the two years, 5.3% of patients (N = 10) underwent SCS removal and 7.0% (N = 13) underwent revision procedures. CONCLUSIONS There was a trend of a sustained reduction in pain intensity as well as improvement in patient satisfaction at two-year follow-up in the position-adaptive system, suggesting long-term benefit over the nonadaptive manual system during SCS treatment.
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Affiliation(s)
- Eun Kyoung Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chang-Soon Lee
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea.,Department of Integrated Cancer Care Center, Seoul National University Cancer Hospital, Seoul, Republic of Korea
| | - Yongjae Yoo
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea.,Department of Integrated Cancer Care Center, Seoul National University Cancer Hospital, Seoul, Republic of Korea
| | - Jin-Woo Park
- Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - Jung Soo Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Youngwon Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jee Youn Moon
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea.,Department of Integrated Cancer Care Center, Seoul National University Cancer Hospital, Seoul, Republic of Korea
| | - Yong-Chul Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.,Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Republic of Korea
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Duarte RV, Soliday N, Leitner A, Taylor RS. Health-Related Quality of Life Associated With Pain Health States in Spinal Cord Stimulation for Chronic Neuropathic Pain. Neuromodulation 2020; 24:142-149. [PMID: 32940398 DOI: 10.1111/ner.13267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/04/2020] [Accepted: 08/10/2020] [Indexed: 12/18/2022]
Abstract
OBJECTIVES A substantial proportion of patients have recently reported pain reduction levels of ≥80% following treatment with Evoked Compound Action Potential (ECAP) spinal cord stimulation (SCS). The additional health-related quality of life (HRQoL) utility gain that can be achieved in this patient group is unclear. The aim of this study is to quantify the HRQoL utility values seen in a remission health state (defined as ≥80% pain reduction) and contrast with more traditional health states of <50% and ≥50% pain relief. MATERIALS AND METHODS Pain intensity assessed using a 100 mm visual analogue scale (VAS) and EQ-5D-5L questionnaires were collected from 204 patients treated with ECAP SCS for chronic back and leg pain and followed up to 12 months. Utility values were derived using EQ-5D-5L responses crosswalked to EQ-5D-3L. Linear regression models adjusted for baseline utility values and patient demographics were used to compare differences in utility values across health states. RESULTS Patients in the remission health state (i.e., ≥80% pain reduction) consistently reported statistically significant greater utility values (+0.09 to +0.15, all p < 0.003) compared to patients reporting ≥50% pain relief at 3- and 12-month follow-up for overall, back, and leg VAS pain. The gain in utility values per percent unit of pain reduction was statistically significant at 3- and 12-month follow-up with a mean increase in HRQoL utility score between 0.003 and 0.005 observed for each percent of pain reduction. CONCLUSION Our analyses show that patients in a remission health state report statistically and clinically significant better HRQoL than patients experiencing lesser pain relief.
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Affiliation(s)
- Rui V Duarte
- Liverpool Reviews and Implementation Group, University of Liverpool, Liverpool, UK
| | | | | | - Rod S Taylor
- Institute of Health and Well Being, University of Glasgow, Glasgow, UK.,College of Medicine and Health, University of Exeter, Exeter, UK
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