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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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2
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Corna A, Cojocaru AE, Bui MT, Werginz P, Zeck G. Avoidance of axonal stimulation with sinusoidal epiretinal stimulation. J Neural Eng 2024; 21:026036. [PMID: 38547529 DOI: 10.1088/1741-2552/ad38de] [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: 09/28/2023] [Accepted: 03/28/2024] [Indexed: 04/11/2024]
Abstract
Objective.Neuromodulation, particularly electrical stimulation, necessitates high spatial resolution to achieve artificial vision with high acuity. In epiretinal implants, this is hindered by the undesired activation of distal axons. Here, we investigate focal and axonal activation of retinal ganglion cells (RGCs) in epiretinal configuration for different sinusoidal stimulation frequencies.Approach.RGC responses to epiretinal sinusoidal stimulation at frequencies between 40 and 100 Hz were tested inex-vivophotoreceptor degenerated (rd10) isolated retinae. Experiments were conducted using a high-density CMOS-based microelectrode array, which allows to localize RGC cell bodies and axons at high spatial resolution.Main results.We report current and charge density thresholds for focal and distal axon activation at stimulation frequencies of 40, 60, 80, and 100 Hz for an electrode size with an effective area of 0.01 mm2. Activation of distal axons is avoided up to a stimulation amplitude of 0.23µA (corresponding to 17.3µC cm-2) at 40 Hz and up to a stimulation amplitude of 0.28µA (14.8µC cm-2) at 60 Hz. The threshold ratio between focal and axonal activation increases from 1.1 for 100 Hz up to 1.6 for 60 Hz, while at 40 Hz stimulation frequency, almost no axonal responses were detected in the tested intensity range. With the use of synaptic blockers, we demonstrate the underlying direct activation mechanism of the ganglion cells. Finally, using high-resolution electrical imaging and label-free electrophysiological axon tracking, we demonstrate the extent of activation in axon bundles.Significance.Our results can be exploited to define a spatially selective stimulation strategy avoiding axonal activation in future retinal implants, thereby solving one of the major limitations of artificial vision. The results may be extended to other fields of neuroprosthetics to achieve selective focal electrical stimulation.
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Affiliation(s)
- Andrea Corna
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | | | - Mai Thu Bui
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Paul Werginz
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Günther Zeck
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
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3
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Rigoard P, Billot M, Bougeard R, Llopis JE, Raoul S, Matis G, Vesper J, Belaïd H. Improved Outcomes and Therapy Longevity after Salvage Using a Novel Spinal Cord Stimulation System for Chronic Pain: Multicenter, Observational, European Case Series. J Clin Med 2024; 13:1079. [PMID: 38398392 PMCID: PMC10889739 DOI: 10.3390/jcm13041079] [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: 11/27/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/25/2024] Open
Abstract
Spinal cord stimulation (SCS) is proven to effectively relieve chronic neuropathic pain. However, some implanted patients may face loss of efficacy (LoE) over time, and conversion to more recent devices may rescue SCS therapy. Recent SCS systems offer novel stimulation capabilities, such as temporal modulation and spatial neural targeting, and can be used to replace previous neurostimulators without changing existing leads. Our multicenter, observational, consecutive case series investigated real-world clinical outcomes in previously implanted SCS patients who were converted to a new implantable pulse generator. Data from 58 patients in seven European centers were analyzed (total follow-up 7.0 years, including 1.4 years after conversion). In the Rescue (LoE) subgroup (n = 51), the responder rate was 58.5% at the last follow-up, and overall pain scores (numerical rating scale) had decreased from 7.3 ± 1.7 with the previous SCS system to 3.5 ± 2.5 (p < 0.0001). Patients who converted for improved battery longevity (n = 7) had their pain scores sustained below 3/10 with their new neurostimulator. Waveform preferences were diverse and patient dependent (34.4% standard rate; 44.8% sub-perception modalities; 20.7% combination therapy). Our results suggest that patients who experience LoE over time may benefit from upgrading to a more versatile SCS system.
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Affiliation(s)
- Philippe Rigoard
- PRISMATICS Lab, Poitiers University Hospital, 86021 Poitiers, France;
| | - Maxime Billot
- PRISMATICS Lab, Poitiers University Hospital, 86021 Poitiers, France;
| | | | | | - Sylvie Raoul
- CHU de Nantes-Hopital Laennec, 44800 Saint-Herblain, France;
| | | | - Jan Vesper
- Universitaetsklinikum Dusseldorf, 40225 Dusseldorf, Germany;
| | - Hayat Belaïd
- Fondation Adolphe de Rothschild, 75019 Paris, France;
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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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Wahezi SE, Caparo MA, Malhotra R, Sundaram L, Batti K, Ejindu P, Veeramachaneni R, Anitescu M, Hunter CW, Naeimi T, Farah F, Kohan L. Current Waveforms in Spinal Cord Stimulation and Their Impact on the Future of Neuromodulation: A Scoping Review. Neuromodulation 2024; 27:47-58. [PMID: 38184341 DOI: 10.1016/j.neurom.2023.11.002] [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: 09/10/2023] [Revised: 10/16/2023] [Accepted: 11/13/2023] [Indexed: 01/08/2024]
Abstract
BACKGROUND Neuromodulation is a standard and well-accepted treatment for chronic refractory neuropathic pain. There has been progressive innovation in the field over the last decade, particularly in areas of spinal cord stimulation (SCS) and dorsal root ganglion stimulation. Improved outcomes using proprietary waveforms have become customary in the field, leading to an unprecedented expansion of these products and a plethora of options for the management of pain. Although advances in waveform technology have improved our fundamental understanding of neuromodulation, a scoping review describing new energy platforms and their associated clinical effects and outcomes is needed. The authors submit that understanding electrophysiological neuromodulation may be important for clinical decision-making and programming selection for personalized patient care. OBJECTIVE This review aims to characterize ways differences in mechanism of action and clinical outcomes of current spinal neuromodulation products may affect contemporary clinical decision-making while outlining a possible path for the future SCS. STUDY DESIGN The study is a scoping review of the literature about newer generation SCS waveforms. MATERIALS AND METHODS A literature report was performed on PubMed and chapters to include articles on spine neuromodulation mechanism of action and efficacy. RESULTS A total of 8469 studies were identified, 75 of which were included for the scoping review after keywords defining recent waveform technology were added. CONCLUSIONS Clinical data suggest that neuromodulation remains a promising tool in the treatment of chronic pain. The evidence for SCS for treating chronic pain seems compelling; however, more long-term and comparative data are needed for a comparison of waveforms when it comes to the etiology of pain. In addition, an exploration into combination waveform therapy and waveform cycling may be paramount for future clinical studies and the development of new technologies.
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Affiliation(s)
- Sayed E Wahezi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA.
| | - Moorice A Caparo
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Ria Malhotra
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lakshman Sundaram
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Kevin Batti
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Prince Ejindu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | | | - Magdalena Anitescu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Corey W Hunter
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Tahereh Naeimi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Fadi Farah
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lynn Kohan
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
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6
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Heijmans L, Zhang TC, Esteller R, Joosten EA. Ninety-Hz Spinal Cord Stimulation-Induced Analgesia Is Dependent on Active Charge Balance and Is Nonlinearly Related to Amplitude: A Sham-Controlled Behavioral Study in a Rodent Model of Chronic Neuropathic Pain. Neuromodulation 2024; 27:95-107. [PMID: 37978974 DOI: 10.1016/j.neurom.2023.09.005] [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: 06/06/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 11/19/2023]
Abstract
BACKGROUND Ninety-Hz active-recharge spinal cord stimulation (SCS) applied at below sensory-threshold intensity, as used with fast-acting subperception therapy spinal cord stimulation, has been shown clinically to produce significant analgesia, but additional characterization is required to better understand the therapy. This preclinical study investigates the behavioral effect of multiple 90-Hz SCS variants in a rodent model of neuropathic pain, focusing on charge balance and the relationship between 90-Hz efficacy and stimulation intensity. MATERIALS AND METHODS Rats (n = 24) received a unilateral partial sciatic nerve ligation to induce neuropathic pain and were implanted with a quadripolar lead at T13. Mechanical hypersensitivity was assessed before, during, and after 60 minutes of SCS. After a prescreen with 50-Hz SCS 67% motor threshold ([MT], the positive control), rats underwent a randomized-crossover study including sham SCS and several 90-Hz SCS paradigms (at 40% MT or 60% MT, either using active or pseudopassive recharge) (experiment 1, n = 16). A second, identical experiment (experiment 2) was performed to supplement data with 90-Hz SCS at 20% and 80% MT (experiment 2, n = 8). RESULTS Experiment 1: At 40% MT, 90-Hz active-recharge SCS produced a significantly larger recovery to baseline than did 90-Hz pseudopassive SCS at both tested intensities and sham SCS. Experiment 2: Only the 90-Hz SCS active recharge at 40% MT and 50-Hz SCS positive control caused mean recovery to baseline that was statistically better than that of sham SCS. CONCLUSIONS The degree to which 90-Hz SCS reduced mechanical hypersensitivity during stimulation depended on the nature of charge balance, with 90-Hz active-recharge SCS generating better responses than did 90-Hz pseudopassive recharge SCS. In addition, our findings suggest that the amplitude of 90-Hz active-recharge SCS must be carefully configured for efficacy.
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Affiliation(s)
- Lonne Heijmans
- Department of Anesthesiology and Pain Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.
| | - Tianhe C Zhang
- Boston Scientific: Neuromodulation, Research and Advanced Concepts Team, Valencia, CA, USA
| | - Rosana Esteller
- Boston Scientific: Neuromodulation, Research and Advanced Concepts Team, Valencia, CA, USA
| | - Elbert A Joosten
- Department of Anesthesiology and Pain Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
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7
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Rigoard P, Ounajim A, Moens M, Goudman L, Roulaud M, Lorgeoux B, Baron S, Nivole K, Many M, Lampert L, David R, Billot M. Should we Oppose or Combine Waveforms for Spinal Cord Stimulation in PSPS-T2 Patients? A Prospective Randomized Crossover Trial (MULTIWAVE Study). THE JOURNAL OF PAIN 2023; 24:2319-2339. [PMID: 37473903 DOI: 10.1016/j.jpain.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/16/2023] [Accepted: 07/12/2023] [Indexed: 07/22/2023]
Abstract
Refractory persistent spinal pain syndrome after surgery (PSPS-T2) can be successfully addressed by spinal cord stimulation (SCS). While conventional stimulation generates paresthesia, recent systems enable the delivery of paresthesia-free stimulation. Studies have claimed non-inferiority/superiority of selected paresthesia-free stimulation compared with paresthesia-based stimulation, but the comparative efficacy between different waveforms still needs to be determined in a given patient. We designed a randomized controlled 3-month crossover trial to compare pain relief of paresthesia-based stimulation versus high frequency versus burst in 28 PSPS-T2 patients implanted with multiwave SCS systems. Our secondary objectives were to determine the efficacy of these 3 waveforms on pain surface, quality of life, functional capacity, psychological distress, and validated composite multidimensional clinical response index to provide holistic comparisons at 3-, 6-, 9-, and 15-month post-randomization. The preferred stimulation modality was documented during the follow-up periods. No difference between the waveforms was observed in this study (P = .08). SCS led to significant pain relief, quality of life improvement, improvement of multidimensional clinical response index, and of all other clinical outcomes at all follow-up visits. Forty-four percent of the patients chose to keep the paresthesia-based stimulation modality after the 15-month follow-up period. By giving the possibility to switch and/or to combine several waveforms, the overall rate of SCS responders further increased with 25%. In this study, high frequency or burst do not appear superior to paresthesia-based stimulation, wherefore paresthesia-based stimulation should still be considered as a valid option. However, combining paresthesia-based stimulation with paresthesia-free stimulation, through personalized multiwave therapy, might significantly improve SCS responses. PERSPECTIVE: This article assesses clinical SCS efficacy on pain relief, by comparing paresthesia-based stimulation and paresthesia-free stimulation (including high frequency and burst) modalities in patient presenting with PSPS-T2. Switching and/or combining waveforms contribute to increasing the global SCS responders rate.
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Affiliation(s)
- Philippe Rigoard
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France; Department of Neuro-Spine & Neuromodulation, Poitiers University Hospital, Poitiers, France; Pprime Institute UPR 3346, CNRS, ISAE-ENSMA, University of Poitiers, Chasseneuil-du-Poitou, France
| | - Amine Ounajim
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Maarten Moens
- Department of Neurosurgery, Universitair Ziekenhuis Brussel, Brussels, Belgium; STIMULUS research group, Vrije Universiteit Brussel, Brussels, Belgium; Department of Radiology, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Lisa Goudman
- Department of Neurosurgery, Universitair Ziekenhuis Brussel, Brussels, Belgium; STIMULUS research group, Vrije Universiteit Brussel, Brussels, Belgium; Research Foundation-Flanders (FWO), Brussels, Belgium
| | - Manuel Roulaud
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Bertille Lorgeoux
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Sandrine Baron
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Kévin Nivole
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Mathilde Many
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Lucie Lampert
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
| | - Romain David
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France; Department of Physical and Rehabilitation Medicine Unit, Poitiers University Hospital, University of Poitiers, Poitiers, France
| | - Maxime Billot
- PRISMATICS Lab (Predictive Research in Spine/Neuromodulation Management and Thoracic Innovation/Cardiac Surgery), Poitiers University Hospital, Poitiers, France
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Rogers ER, Mirzakhalili E, Lempka SF. Model-based analysis of subthreshold mechanisms of spinal cord stimulation for pain. J Neural Eng 2023; 20:066003. [PMID: 37906966 PMCID: PMC10632558 DOI: 10.1088/1741-2552/ad0858] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/11/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
Objective.Spinal cord stimulation (SCS) is a common treatment for chronic pain. For decades, SCS maximized overlap between stimulation-induced paresthesias and the patient's painful areas. Recently developed SCS paradigms relieve pain at sub-perceptible amplitudes, yet little is known about the neural response to these new waveforms or their analgesic mechanisms of action. Therefore, in this study, we investigated the neural response to multiple forms of paresthesia-free SCS.Approach.We used computational modeling to investigate the neurophysiological effects and the plausibility of commonly proposed mechanisms of three paresthesia-free SCS paradigms: burst, 1 kHz, and 10 kHz SCS. Specifically, in C- and Aβ-fibers, we investigated the effects of different SCS waveforms on spike timing and activation thresholds, as well as how stochastic ion channel gating affects the response of dorsal column axons. Finally, we characterized membrane polarization of superficial dorsal horn neurons.Main results.We found that none of the SCS waveforms activate nor modulate spike timing in C-fibers. Spike timing was modulated in Aβ-fibers only at suprathreshold amplitudes. Ion channel stochasticity had little effect on Aβ-fiber activation thresholds but produced heterogeneous spike timings at suprathreshold amplitudes. Finally, local cells were preferentially polarized in their axon terminals, and the magnitude of this polarization was dependent on cellular morphology and position relative to the stimulation electrodes.Significance.Overall, the mechanisms of action of subparesthetic SCS remain unclear. Our results suggest that no SCS waveforms directly activate C-fibers, and modulation of spike timing is unlikely at subthreshold amplitudes. We conclude that potential subthreshold neuromodulatory effects of SCS on local cells are likely to be presynaptic in nature, as axons are preferentially depolarized during SCS.
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Affiliation(s)
- Evan R Rogers
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Ehsan Mirzakhalili
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, United States of America
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9
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Brucker-Hahn MK, Zander HJ, Will AJ, Vallabh JC, Wolff JS, Dinsmoor DA, Lempka SF. Evoked compound action potentials during spinal cord stimulation: effects of posture and pulse width on signal features and neural activation within the spinal cord. J Neural Eng 2023; 20:046028. [PMID: 37531954 DOI: 10.1088/1741-2552/aceca4] [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: 03/22/2023] [Accepted: 08/01/2023] [Indexed: 08/04/2023]
Abstract
Objective.Evoked compound action potential (ECAP) recordings have emerged as a quantitative measure of the neural response during spinal cord stimulation (SCS) to treat pain. However, utilization of ECAP recordings to optimize stimulation efficacy requires an understanding of the factors influencing these recordings and their relationship to the underlying neural activation.Approach.We acquired a library of ECAP recordings from 56 patients over a wide assortment of postures and stimulation parameters, and then processed these signals to quantify several aspects of these recordings (e.g., ECAP threshold (ET), amplitude, latency, growth rate). We compared our experimental findings against a computational model that examined the effect of variable distances between the spinal cord and the SCS electrodes.Main results.Postural shifts strongly influenced the experimental ECAP recordings, with a 65.7% lower ET and 178.5% higher growth rate when supine versus seated. The computational model exhibited similar trends, with a 71.9% lower ET and 231.5% higher growth rate for a 2.0 mm cerebrospinal fluid (CSF) layer (representing a supine posture) versus a 4.4 mm CSF layer (representing a prone posture). Furthermore, the computational model demonstrated that constant ECAP amplitudes may not equate to a constant degree of neural activation.Significance.These results demonstrate large variability across all ECAP metrics and the inability of a constant ECAP amplitude to provide constant neural activation. These results are critical to improve the delivery, efficacy, and robustness of clinical SCS technologies utilizing these ECAP recordings to provide closed-loop stimulation.
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Affiliation(s)
- Meagan K Brucker-Hahn
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Hans J Zander
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Andrew J Will
- Twin Cities Pain Clinic, Edina, MN, United States of America
| | - Jayesh C Vallabh
- Ohio State Wexner Medical Center, Columbus, OH, United States of America
| | - Jason S Wolff
- iSpine Clinics, Maple Grove, MN, United States of America
| | | | - Scott F Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, United States of America
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10
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Kuo SW, Zhang T, Esteller R, Grill WM. In Vivo Measurements reveal that both low- and high-frequency spinal cord stimulation heterogeneously modulate superficial dorsal horn neurons. Neuroscience 2023; 520:119-131. [PMID: 37085007 DOI: 10.1016/j.neuroscience.2023.04.010] [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: 07/20/2022] [Revised: 03/01/2023] [Accepted: 04/08/2023] [Indexed: 04/23/2023]
Abstract
Current sub-perception spinal cord stimulation (SCS) is characterized by the use of high-frequency pulses to achieve paresthesia-free analgesic effects. High-frequency SCS demonstrates distinctive properties from paresthesia-based SCS, such as a longer time course to response, implying the existence of alternative mechanism(s) of action beyond gate control theory. We quantified the responses to SCS of single neurons within the superficial dorsal horn (SDH), a structure in close proximity to SCS electrodes, to investigate the mechanisms underlying high-frequency SCS in 62 urethane-anesthetized male rats. Sciatic nerve stimulation was delivered to isolate lumbar SDH neurons with evoked C-fiber activity. The evoked C-fiber activity before and after the application of SCS was compared to quantify the effects of SCS across stimulation intensity and stimulation duration at three different stimulation frequencies. We observed heterogeneous responses of SDH neurons which depended primarily on the type of unit. Low-threshold units with spontaneous activity, putatively inhibitory interneurons, tended to be facilitated by SCS while the other unit types were suppressed. The effects of SCS were more prominent with increased stimulation duration from 30 s to 30 m across frequencies. Our results highlight the importance of inhibitory interneurons in modulating local circuits of the SDH and the importance of local circuit contributions to the analgesic mechanisms of SCS.
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Affiliation(s)
- Su-Wei Kuo
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Tianhe Zhang
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Rosana Esteller
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC; Departments of Electrical and Computer Engineering, Neurobiology, and Neurosurgery, Duke University, Durham, NC.
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Verma N, Romanauski B, Lam D, Lujan L, Blanz S, Ludwig K, Lempka S, Shoffstall A, Knudson B, Nishiyama Y, Hao J, Park HJ, Ross E, Lavrov I, Zhang M. Characterization and applications of evoked responses during epidural electrical stimulation. Bioelectron Med 2023; 9:5. [PMID: 36855060 PMCID: PMC9976490 DOI: 10.1186/s42234-023-00106-5] [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: 01/23/2023] [Accepted: 02/08/2023] [Indexed: 03/02/2023] Open
Abstract
BACKGROUND Epidural electrical stimulation (EES) of the spinal cord has been FDA approved and used therapeutically for decades. However, there is still not a clear understanding of the local neural substrates and consequently the mechanism of action responsible for the therapeutic effects. METHOD Epidural spinal recordings (ESR) are collected from the electrodes placed in the epidural space. ESR contains multi-modality signal components such as the evoked neural response (due to tonic or BurstDR™ waveforms), evoked muscle response, stimulation artifact, and cardiac response. The tonic stimulation evoked compound action potential (ECAP) is one of the components in ESR and has been proposed recently to measure the accumulative local potentials from large populations of neuronal fibers during EES. RESULT Here, we first review and investigate the referencing strategies, as they apply to ECAP component in ESR in the domestic swine animal model. We then examine how ECAP component can be used to sense lead migration, an adverse outcome following lead placement that can reduce therapeutic efficacy. Lastly, we show and isolate concurrent activation of local back and leg muscles during EES, demonstrating that the ESR obtained from the recording contacts contain both ECAP and EMG components. CONCLUSION These findings may further guide the implementation of recording and reference contacts in an implantable EES system and provide preliminary evidence for the utility of ECAP component in ESR to detect lead migration. We expect these results to facilitate future development of EES methodology and implementation of use of different components in ESR to improve EES therapy.
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Affiliation(s)
- Nishant Verma
- Abbott Neuromodulation, 6901 Preston Rd, Plano, TX, 75024, USA
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
| | - Ben Romanauski
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Danny Lam
- Abbott Neuromodulation, 6901 Preston Rd, Plano, TX, 75024, USA
| | - Luis Lujan
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 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
| | - Kip 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
| | - Scott Lempka
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- APT Center, Louis Stokes Cleveland VA Medical Center, OH, Cleveland, USA
- Department of Biomedical Engineering, Department of Anesthesiology, Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA
| | - Andrew Shoffstall
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- APT Center, Louis Stokes Cleveland VA Medical Center, OH, Cleveland, USA
| | - Bruce Knudson
- Department of Biomedical Engineering, University of Wisconsin Madison, Madison, USA
- Wisconsin Institute for Translational Neuroengineering (WITNe), Madison, WI, USA
| | - Yuichiro Nishiyama
- Department of Neurology, Department of Physiology and Biomedical Engineering, Mayo Clinic, 500 First Street SW, Rochester, MN, 55905, USA
| | - Jian Hao
- Department of Neurology, Department of Physiology and Biomedical Engineering, Mayo Clinic, 500 First Street SW, Rochester, MN, 55905, USA
| | - Hyun-Joo Park
- Abbott Neuromodulation, 6901 Preston Rd, Plano, TX, 75024, USA
| | - Erika Ross
- Abbott Neuromodulation, 6901 Preston Rd, Plano, TX, 75024, USA
| | - Igor Lavrov
- Department of Neurology, Department of Physiology and Biomedical Engineering, Mayo Clinic, 500 First Street SW, Rochester, MN, 55905, USA.
| | - Mingming Zhang
- Abbott Neuromodulation, 6901 Preston Rd, Plano, TX, 75024, USA.
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