1
|
Dewberry LS, Porche K, Koenig T, Allen KD, Otto KJ. High frequency alternating current neurostimulation decreases nocifensive behavior in a disc herniation model of lumbar radiculopathy. Bioelectron Med 2023; 9:15. [PMID: 37434246 DOI: 10.1186/s42234-023-00119-0] [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: 04/29/2023] [Accepted: 06/19/2023] [Indexed: 07/13/2023] Open
Abstract
BACKGROUND The purpose of this study was to evaluate if kilohertz frequency alternating current (KHFAC) stimulation of peripheral nerve could serve as a treatment for lumbar radiculopathy. Prior work shows that KHFAC stimulation can treat sciatica resulting from chronic sciatic nerve constriction. Here, we evaluate if KHFAC stimulation is also beneficial in a more physiologic model of low back pain which mimics nucleus pulposus (NP) impingement of a lumbar dorsal root ganglion (DRG). METHODS To mimic a lumbar radiculopathy, autologous tail NP was harvested and placed upon the right L5 nerve root and DRG. During the same surgery, a cuff electrode was implanted around the sciatic nerve with wires routed to a headcap for delivery of KHFAC stimulation. Male Lewis rats (3 mo., n = 18) were separated into 3 groups: NP injury + KHFAC stimulation (n = 7), NP injury + sham cuff (n = 6), and sham injury + sham cuff (n = 5). Prior to surgery and for 2 weeks following surgery, animal tactile sensitivity, gait, and static weight bearing were evaluated. RESULTS KHFAC stimulation of the sciatic nerve decreased behavioral evidence of pain and disability. Without KHFAC stimulation, injured animals had heightened tactile sensitivity compared to baseline (p < 0.05), with tactile allodynia reversed during KHFAC stimulation (p < 0.01). Midfoot flexion during locomotion was decreased after injury but improved with KHFAC stimulation (p < 0.05). Animals also placed more weight on their injured limb when KHFAC stimulation was applied (p < 0.05). Electrophysiology measurements at end point showed decreased, but not blocked, compound nerve action potentials with KHFAC stimulation (p < 0.05). CONCLUSIONS KHFAC stimulation decreases hypersensitivity but does not cause additional gait compensations. This supports the idea that KHFAC stimulation applied to a peripheral nerve may be able to treat chronic pain resulting from sciatic nerve root inflammation.
Collapse
Affiliation(s)
- Lauren Savannah Dewberry
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Dr. JG56, P.O. Box 116131, Gainesville, FL, 32611, USA
| | - Ken Porche
- Lillian S Wells Department of Neurosurgery at the University of Florida, College of Medicine, 1505 SW Archer Road Gainesville, FL, 32608, Gainesville, USA
| | - Travis Koenig
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Dr. JG56, P.O. Box 116131, Gainesville, FL, 32611, USA
| | - Kyle D Allen
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Dr. JG56, P.O. Box 116131, Gainesville, FL, 32611, USA
- Pain Research & Intervention Center of Excellence, University of Florida, CTSI 2004 Mowry Road, Gainesville, FL, USA
- Department of Orthopedics and Sports Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Kevin J Otto
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Dr. JG56, P.O. Box 116131, Gainesville, FL, 32611, USA.
- Department of Neuroscience, University of Florida, 1149 Newell Dr. L1-100, P.O. Box 100244, Gainesville, FL, USA.
- Department of Electrical and Computer Engineering, University of Florida, 968 Center Dr, Gainesville, FL, 32611, USA.
- Department of Chemical Engineering, University of Florida, 1030 Center Drive, P.O. Box 116005, Gainesville, FL, 32611, USA.
- Department of Materials Science and Engineering, University of Florida, 549 Gale Lemerand Dr, P.O. Box 116400, Gainesville, FL, 32611, USA.
- Department of Neurology, 1149 Newell Dr, P.O. Box 100236, Gainesville, FL, L3-10032610, USA.
- Nanoscience Institute for Medical and Engineering Technology (NIMET), University of Florida, 1041 Center Drive, Gainesville, FL, 32611, USA.
| |
Collapse
|
2
|
Peña E, Pelot NA, Grill WM. Spatiotemporal parameters for energy efficient kilohertz-frequency nerve block with low onset response. J Neuroeng Rehabil 2023; 20:72. [PMID: 37271812 PMCID: PMC10240787 DOI: 10.1186/s12984-023-01195-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 05/23/2023] [Indexed: 06/06/2023] Open
Abstract
BACKGROUND Electrical nerve conduction block has great potential for treatment of disease through reversible and local inactivation of somatic and autonomic nerves. However, the relatively high energy requirements and the presence of undesired excitation at the onset of the kilohertz-frequency (KHF) signals used for block pose obstacles to effective translation. Frequency, electrode geometry, and waveform shape are known to influence block threshold and onset response, but available data provide a limited understanding of how to select these parameters to optimize nerve block. METHODS We evaluated KHF nerve block in rat tibial nerve across frequencies (5-60 kHz), electrode geometries (monopolar, bipolar, and tripolar), and waveform shapes. We present a novel Fourier-based method for constructing composite signals that systematically sample the KHF waveform design space. RESULTS The lowest frequencies capable of blocking (5-16 kHz) were not the most energy-efficient among the tested frequencies. Further, bipolar cuffs required the largest current and power to block, monopolar cuffs required the lowest current, and both tripolar and monopolar cuffs required the lowest power. Tripolar cuffs produced the smallest onset response across frequencies. Composite signals comprised of a first harmonic sinusoid at fundamental frequency (f0) superposed on a second harmonic sinusoid at 2f0 could block at lower threshold and lower onset response compared to the constituent sinusoids alone. This effect was strongly dependent on the phase of the second harmonic and on the relative amplitudes of the first and second harmonics. This effect was also dependent on electrode geometry: monopolar and tripolar cuffs showed clear composite signal effects in most experiments; bipolar cuffs showed no clear effects in most experiments. CONCLUSIONS Our data provide novel information about block threshold and onset response at the boundary of frequencies that can block. Our results also show an interaction between spatial (cuff geometry) and temporal (frequency and waveform shape) parameters. Finally, while previous studies suggested that temporal parameters could reduce onset response only in exchange for increased block threshold (or vice versa), our results show that waveform shape influences KHF response in ways that can be exploited to reduce both energy and onset responses.
Collapse
Affiliation(s)
- Edgar Peña
- Department of Biomedical Engineering, Duke University, Room 1427, Fitzpatrick CIEMAS, 101 Science Drive Campus Box 90281, Durham, NC, 27708, USA
| | - Nicole A Pelot
- Department of Biomedical Engineering, Duke University, Room 1427, Fitzpatrick CIEMAS, 101 Science Drive Campus Box 90281, Durham, NC, 27708, USA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Room 1427, Fitzpatrick CIEMAS, 101 Science Drive Campus Box 90281, Durham, NC, 27708, USA.
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA.
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA.
- Department of Neurosurgery, Duke University School of Medicine, Durham, NC, USA.
| |
Collapse
|
3
|
Kim Y, Cohen E. Combining transcutaneous interferential-current for nerve inhibition with a robotic assistant device for increasing ankle dorsiflexion in walking. Gait Posture 2023; 102:205-209. [PMID: 37043990 DOI: 10.1016/j.gaitpost.2023.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 03/27/2023] [Accepted: 04/05/2023] [Indexed: 04/14/2023]
Abstract
BACKGROUND A kilohertz-frequency alternating current transcutaneously applied was introduced as a novel neuromodulation technology for nerve inhibition innervating antagonist muscles. Combining this electrical nerve inhibition with a robotic assistance device has been proposed but not investigated. RESEARCH QUESTION This study aimed to demonstrate the effect of combining electrical nerve inhibition with a wearable robotic device on increasing ankle dorsiflexion during walking. We hypothesized that the wearable robotic device would elicit a greater ankle dorsiflexion angle with the same force in walking by applying the transcutaneous interferential-current nerve inhibition (TINI) technique to the tibial nerve. METHODS Eleven healthy young adults performed three experimental conditions. The ankle assistance (AA) condition was walking while wearing an ankle device with operating dorsiflexion assistance during pre-swing and swing phases. For the ankle assistance with electrical stimulation (AE) condition, TINI on the tibial nerve was additionally applied from the AA condition. In the ankle non-assistance (AN) condition, participants wore the device, but assistance was not provided. The joint angles during walking were measured and digitized through a motion analysis system. RESULTS During a gait cycle, immediate changes in ankle joint motions were observed in the sagittal plane. In the pre-swing phase, ankle dorsiflexion angle was significantly greater in AE condition than AA and AN. There was no significant difference in joint angle between AA and AN. SIGNIFICANCE This study demonstrates the effectiveness of combining TINI with a wearable robotic ankle device in increasing dorsiflexion angle during the pre-swing phase. This finding provides the feasibility of using TINI as a neuromodulation technique for assisting functional movement in human walking.
Collapse
Affiliation(s)
- Yushin Kim
- Department of Sports Rehabilitation, Cheongju University, Cheongju, South Korea.
| | - Ezra Cohen
- Division of Pediatric Rheumatology, Boston University; Division of Immunology, Boston Children's Hospital, Boston, MA, United States
| |
Collapse
|
4
|
Álvarez DMC, Serrano-Muñoz D, Fernández-Pérez JJ, Gómez-Soriano J, Avendaño-Coy J. Effect of percutaneous electrical stimulation with high-frequency alternating currents at 30 kHz on the sensory-motor system. Front Neurosci 2023; 17:1048986. [PMID: 36845426 PMCID: PMC9947497 DOI: 10.3389/fnins.2023.1048986] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/24/2023] [Indexed: 02/11/2023] Open
Abstract
Background Unmodulated high-frequency alternating currents (HFAC) are employed for producing peripheral nerves block. HFAC have been applied in humans with frequencies up to 20 kHz, whether transcutaneously, percutaneously, or via surgically-implanted electrodes. The aim of this study was to assess the effect of percutaneous HFAC, applied with ultrasound-guided needles at 30 kHz, on the sensory-motor nerve conduction of healthy volunteers. Methods A parallel, double-blind, randomized clinical trial with a placebo control was conducted. Percutaneous HFAC at 30 kHz or sham stimulation was applied via ultrasound-guided needles in 48 healthy volunteers (n = 24 in each group) for 20 min. The assessed outcome variables were pressure pain threshold (PPT), mechanical detection threshold (MDT), maximal finger flexion strength (MFFS), antidromic sensory nerve action potential (SNAP), hand temperature, and subjective sensations by the participants. The measurements were recorded pre-intervention, during the stimulation (at 15 min), immediately post-intervention (at 20 min), and 15 min after the end of treatment. Results The PPT increased in the active group compared with sham stimulation, both during the intervention [14.7%; 95% confidence interval (CI): 4.4-25.0], immediately post-intervention (16.9%; 95% CI: -7.2-26.5), and 15 min after the end of the stimulation (14.3%; 95% CI: 4.4-24.3) (p < 0.01). The proportion of participants who reported feelings of numbness and heaviness was significantly higher in the active group (46 and 50%, respectively) than in the sham group (8 and 18%, respectively) (p < 0.05). No intergroup differences were observed in the remaining outcome variables. No unexpected adverse effects derived from the electrical stimulation were reported. Conclusion Percutaneous stimulation with HFAC at 30 kHz applied to the median nerve increased the PPT and subjective perception of numbness and heaviness. Future research should evaluate its potential therapeutic effect in people with pain. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT04884932, identifier NCT04884932.
Collapse
Affiliation(s)
- David Martín-Caro Álvarez
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, Toledo, Spain
| | | | - Juan José Fernández-Pérez
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Julio Gómez-Soriano
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Juan Avendaño-Coy
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursing of Toledo, Universidad de Castilla-La Mancha, Toledo, Spain
| |
Collapse
|
5
|
Bender SA, Green DB, Daniels RJ, Ganocy SP, Bhadra N, Vrabec TL. Effects on heart rate from direct current block of the stimulated rat vagus nerve. J Neural Eng 2023; 20:10.1088/1741-2552/acacc9. [PMID: 36535037 PMCID: PMC9972895 DOI: 10.1088/1741-2552/acacc9] [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: 08/24/2022] [Accepted: 12/19/2022] [Indexed: 12/23/2022]
Abstract
Objective.Although electrical vagus nerve stimulation has been shown to augment parasympathetic control of the heart, the effects of electrical conduction block have been less rigorously characterized. Previous experiments have demonstrated that direct current (DC) nerve block can be applied safely and effectively in the autonomic system, but additional information about the system dynamics need to be characterized to successfully deploy DC nerve block to clinical practice.Approach.The dynamics of the heart rate (HR) from DC nerve block of the vagus nerve were measured by stimulating the vagus nerve to lower the HR, and then applying DC block to restore normal rate. DC block achieved rapid, complete block, as well as partial block at lower amplitudes.Main Results. Complete block was also achieved using lower amplitudes, but with a slower induction time. The time for DC to induce complete block was significantly predicted by the amplitude; specifically, the amplitude expressed as a percentage of the current required for a rapid, 60 s induction time. Recovery times after the cessation of DC block could occur both instantly, and after a significant delay. Both blocking duration and injected charge were significant in predicting the delay in recovery to normal conduction.Significance. While these data show that broad features such as induction and recovery can be described well by the DC parameters, more precise features of the HR, such as the exact path of the induction and recoveries, are still undefined. These findings show promise for control of the cardiac autonomic nervous system, with potential to expand to the sympathetic inputs as well.
Collapse
Affiliation(s)
- Shane A. Bender
- Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA
| | - David B. Green
- Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA
| | - Robert J. Daniels
- Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA
| | - Stephen P. Ganocy
- Department of Psychiatry, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Niloy Bhadra
- Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA
| | - Tina L. Vrabec
- Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.,Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH, USA
| |
Collapse
|
6
|
Neuromodulation as a Potential Disease-Modifying Therapy for Osteoarthritis. Curr Rheumatol Rep 2023; 25:1-11. [PMID: 36435890 DOI: 10.1007/s11926-022-01094-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2022] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW The following review discusses the therapeutic potential of targeting the autonomic nervous system (ANS) for osteoarthritis (OA) treatment and encourages the field to consider the candidacy of bioelectronic medicine as a novel OA treatment strategy. RECENT FINDINGS The study of OA pathogenesis has focused on changes occurring at the joint level. As such, treatments for OA have been aimed at the local joint environment, intending to resolve local inflammation and decrease pain. However, OA pathogenesis has shown to be more than joint wear and tear. Specifically, OA-related peripheral and central sensitization can prompt neuroplastic changes in the nervous system beyond the articular joint. These neuroplastic changes may alter physiologic systems, like the neuroimmune axis. In this way, OA and related comorbidities may share roots in the form of altered neuroimmune communication and autonomic dysfunction. ANS modulation may be able to modify OA pathogenesis or reduce the impact of OA comorbidities. Moreover, blocking chronic nociceptive drive from the joint may help to prevent maladaptive nervous system plasticity in OA.
Collapse
|
7
|
Green DB, Kilgore JA, Bender SA, Daniels RJ, Gunzler DD, Vrabec TL, Bhadra N. Effects of waveform shape and electrode material on KiloHertz frequency alternating current block of mammalian peripheral nerve. Bioelectron Med 2022; 8:11. [PMID: 35883133 PMCID: PMC9327420 DOI: 10.1186/s42234-022-00093-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/30/2022] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES KiloHertz frequency alternating current waveforms produce conduction block in peripheral nerves. It is not clearly known how the waveform shape affects block outcomes, and if waveform effects are frequency dependent. We determined the effects of waveform shape using two types of electrodes. MATERIALS AND METHODS Acute in-vivo experiments were performed on 12 rats. Bipolar electrodes were used to electrically block motor nerve impulses in the sciatic nerve, as measured using force output from the gastrocnemius muscle. Three blocking waveforms were delivered (sinusoidal, square and triangular) at 6 frequencies (10-60 kHz). Bare platinum electrodes were compared with carbon black coated electrodes. We determined the minimum amplitude that could completely block motor nerve conduction (block threshold), and measured properties of the onset response, which is a transient period of nerve activation at the start of block. In-vivo results were compared with computational modeling conducted using the NEURON simulation environment using a nerve membrane model modified for stimulation in the kilohertz frequency range. RESULTS For the majority of parameters, in-vivo testing and simulations showed similar results: Block thresholds increased linearly with frequency for all three waveforms. Block thresholds were significantly different between waveforms; lowest for the square waveform and highest for triangular waveform. When converted to charge per cycle, square waveforms required the maximum charge per phase, and triangular waveforms the least. Onset parameters were affected by blocking frequency but not by waveform shape. Electrode comparisons were performed only in-vivo. Electrodes with carbon black coatings gave significantly lower block thresholds and reduced onset responses across all blocking frequencies. For 10 and 20 kHz, carbon black coating significantly reduced the charge required for nerve block. CONCLUSIONS We conclude that both sinusoidal and square waveforms at frequencies of 20 kHz or higher would be optimal. Future investigation of carbon black or other high charge capacity electrodes may be useful in achieving block with lower BTs and onsets. These findings will be of importance for designing clinical nerve block systems.
Collapse
Affiliation(s)
- David B. Green
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA
| | - Joseph A. Kilgore
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH USA
| | - Shane A. Bender
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH USA
| | - Robert J. Daniels
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH USA
| | - Douglas D. Gunzler
- grid.411931.f0000 0001 0035 4528Department of Medicine, Population Health Research Institute, Center for Healthcare Research & Policy, MetroHealth Medical Center, Cleveland, OH USA
| | - Tina L. Vrabec
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH USA
| | - Niloy Bhadra
- grid.411931.f0000 0001 0035 4528Department of Physical Medicine and Rehabilitation, MetroHealth Medical Center, Cleveland, OH USA ,grid.67105.350000 0001 2164 3847Department of Physical Medicine and Rehabilitation, School of Medicine, Case Western Reserve University, Cleveland, OH USA
| |
Collapse
|
8
|
Álvarez DMC, Serrano-Muñoz D, Fernández-Pérez JJ, Gómez-Soriano J, Avendaño-Coy J. Effect of Percutaneous Electric Stimulation with High-Frequency Alternating Currents on the Sensory-Motor System of Healthy Volunteers: A Double-Blind Randomized Controlled Study. J Clin Med 2022; 11:jcm11071832. [PMID: 35407438 PMCID: PMC8999650 DOI: 10.3390/jcm11071832] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 02/05/2023] Open
Abstract
Former studies investigated the application of high-frequency alternating currents (HFAC) in humans for blocking the peripheral nervous system. The present trial aims to assess the effect of HFAC on the motor response, somatosensory thresholds, and peripheral nerve conduction when applied percutaneously using frequencies of 10 kHz and 20 kHz in healthy volunteers. A parallel, placebo-controlled, double-blind, randomized clinical trial was conducted. Ultrasound-guided HFAC at 10 kHz and 20 kHz and sham stimulation were delivered to the median nerve of 60 healthy volunteers for 20 min. The main assessed variables were the maximum isometric flexion strength (MFFS) of the index finger, myotonometry, pressure pain threshold (PPT), mechanical detection threshold (MDT), and sensory nerve action potential (SNAP). A decrease in the MFFS is observed immediately postintervention compared to baseline, both in the 10 kHz group (−8.5%; 95% CI −14.9 to −2.1) and the 20 kHz group (−12.0%; 95% CI −18.3 to −5.6). The between-group comparison of changes in MFFS show a greater reduction of −10.8% (95% CI −19.8 to −1.8) immediately postintervention in the 20 kHz compared to the sham stimulation group. The percutaneous stimulation applying 20 kHz HFAC to the median nerve produces a reversible postintervention reduction in strength with no adverse effects.
Collapse
|
9
|
Muzquiz MI, Mintch L, Horn MR, Alhawwash A, Bashirullah R, Carr M, Schild JH, Yoshida K. A Reversible Low Frequency Alternating Current Nerve Conduction Block Applied to Mammalian Autonomic Nerves. SENSORS 2021; 21:s21134521. [PMID: 34282758 PMCID: PMC8271881 DOI: 10.3390/s21134521] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 11/30/2022]
Abstract
Electrical stimulation can be used to modulate activity within the nervous system in one of two modes: (1) Activation, where activity is added to the neural signalling pathways, or (2) Block, where activity in the nerve is reduced or eliminated. In principle, electrical nerve conduction block has many attractive properties compared to pharmaceutical or surgical interventions. These include reversibility, localization, and tunability for nerve caliber and type. However, methods to effect electrical nerve block are relatively new. Some methods can have associated drawbacks, such as the need for large currents, the production of irreversible chemical byproducts, and onset responses. These can lead to irreversible nerve damage or undesirable neural responses. In the present study we describe a novel low frequency alternating current blocking waveform (LFACb) and measure its efficacy to reversibly block the bradycardic effect elicited by vagal stimulation in anaesthetised rat model. The waveform is a sinusoidal, zero mean(charge balanced), current waveform presented at 1 Hz to bipolar electrodes. Standard pulse stimulation was delivered through Pt-Black coated PtIr bipolar hook electrodes to evoke bradycardia. The conditioning LFAC waveform was presented either through a set of CorTec® bipolar cuff electrodes with Amplicoat® coated Pt contacts, or a second set of Pt Black coated PtIr hook electrodes. The conditioning electrodes were placed caudal to the pulse stimulation hook electrodes. Block of bradycardic effect was assessed by quantifying changes in heart rate during the stimulation stages of LFAC alone, LFAC-and-vagal, and vagal alone. The LFAC achieved 86.2±11.1% and 84.3±4.6% block using hook (N = 7) and cuff (N = 5) electrodes, respectively, at current levels less than 110 µAp (current to peak). The potential across the LFAC delivering electrodes were continuously monitored to verify that the blocking effect was immediately reversed upon discontinuing the LFAC. Thus, LFACb produced a high degree of nerve block at current levels comparable to pulse stimulation amplitudes to activate nerves, resulting in a measurable functional change of a biomarker in the mammalian nervous system.
Collapse
Affiliation(s)
- M. Ivette Muzquiz
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (M.I.M.); (M.R.H.); (J.H.S.)
| | | | - M. Ryne Horn
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (M.I.M.); (M.R.H.); (J.H.S.)
| | - Awadh Alhawwash
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA;
- Biomedical Technology Department, King Saud University, Riyadh 11362, Saudi Arabia
| | - Rizwan Bashirullah
- Galvani Bioelectronics Inc., Collegeville, PA 19426, USA; (R.B.); (M.C.)
| | - Michael Carr
- Galvani Bioelectronics Inc., Collegeville, PA 19426, USA; (R.B.); (M.C.)
| | - John H. Schild
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (M.I.M.); (M.R.H.); (J.H.S.)
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA;
| | - Ken Yoshida
- Department of Biomedical Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; (M.I.M.); (M.R.H.); (J.H.S.)
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA;
- Correspondence:
| |
Collapse
|
10
|
Dewberry LS, Dru A, Gravenstine M, Nguyen B, Anderson J, Vaziri S, Hoh D, Allen K, Otto KJ. Partial high frequency nerve block decreases neuropathic signaling following chronic sciatic nerve constriction injury. J Neural Eng 2020; 18. [PMID: 33027782 DOI: 10.1088/1741-2552/abbf03] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 10/07/2020] [Indexed: 11/11/2022]
Abstract
OBJECTIVE High frequency (HF) block can quickly and reversibly stop nerve conduction. We hypothesized HF block at the sciatic nerve would minimize nociception by preventing neuropathic signals from reaching the central nervous system. APPROACH Lewis rats were implanted with a constriction cuff and a distal cuff electrode around their right sciatic nerve. Tactile sensitivity was evaluated using the 50% paw withdrawal threshold determined using Chaplan's method for von Frey monofilaments. Over the course of 49 days, the 50% paw withdrawal threshold was measured 1) before HF block, 2) during HF block (50 kHz, 3 Vpp), and 3) after HF block. Gait was observed and scored before and during block. At end point, HF block efficacy was directly evaluated using additional cuff electrodes to elicit and record compound neural action potentials across the HF blocking cuff. MAIN RESULTS At days 7 and 14 days post-operation, tactile sensitivity was significantly lower during HF block compared to before and after block (p < 0.005). Additionally, an increase in gait disability was not visually observed during HF block. SIGNIFICANCE HF block can reduce tactile sensitivity in a limb with a neuropthic injury in a rapidly reversible fashion.
Collapse
Affiliation(s)
- Lauren Savannah Dewberry
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Biomedical Sciences Building JG56, Gainesville, FL 32611-6131, Gainesville, Florida, 32611-7011, UNITED STATES
| | - Alexander Dru
- Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, Florida, UNITED STATES
| | - Maxwell Gravenstine
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, UNITED STATES
| | - Brian Nguyen
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, UNITED STATES
| | - James Anderson
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, UNITED STATES
| | - Sasha Vaziri
- Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, Florida, UNITED STATES
| | - Daniel Hoh
- Lillian S. Wells Department of Neurosurgery, University of Florida, Gainesville, Florida, UNITED STATES
| | - Kyle Allen
- Department of Biomedical Engineering, University of Florida, P.O. Box 116131, USA, Gainesville, Florida, 32611-6131, UNITED STATES
| | - Kevin J Otto
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, 32611-7011, UNITED STATES
| |
Collapse
|
11
|
Counted cycles method to measure the block inception time of kiloHertz frequency mammalian motor nerve block. J Neurosci Methods 2020; 333:108561. [PMID: 31883742 DOI: 10.1016/j.jneumeth.2019.108561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 11/26/2019] [Accepted: 12/16/2019] [Indexed: 11/21/2022]
Abstract
BACKGROUND Kilohertz frequency alternating currents (KHFAC) produce rapid nerve conduction block of mammalian peripheral nerves and have potential clinical applications in reducing nerve hyperactivity. However, there are no experimental measurements of the block inception time (BIT) for the complete block of mammalian motor axons, i.e. the time from the start of delivery of the KHFAC to the axons reaching a fully blocked state. NEW METHOD A "counted cycles" method (CCM) was designed to exploit characteristics of the onset response, which is typical of KHFAC block, to measure the BIT with a millisecond time resolution. Randomized and repeated experiments were conducted in an in-vivo rodent model, using trains of KHFAC over a range of complete cycle counts at three frequencies (10, 20, and 40 kHz). RESULTS Complete motor nerve conduction block was obtained in the rat sciatic nerve (N = 4) with an average BIT range of 5 ms-10 ms. The fastest BIT measured was 2.5 ms-5 ms. There was no statistical difference between the block inception times for the three frequencies tested. COMPARISON WITH EXISTING METHODS There are no comparable methods to measure the KHFAC BIT. CONCLUSION The KHFAC BIT is faster than previously estimated. KHFAC motor nerve block is established in milliseconds. These results may assist in the design of methods to eliminate the onset response produced by KHFAC nerve block.
Collapse
|
12
|
Serrano-Muñoz D, Avendaño-Coy J, Simón-Martínez C, Taylor J, Gómez-Soriano J. 20-kHz alternating current stimulation: effects on motor and somatosensory thresholds. J Neuroeng Rehabil 2020; 17:22. [PMID: 32075666 PMCID: PMC7031925 DOI: 10.1186/s12984-020-00661-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 02/13/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND High frequency alternating current (HFAC) stimulation have been shown to produce a peripheral nerve conduction block. Currently, all the studies applying HFAC stimulation in clinical studies, have employed frequencies below 10 kHz. The main aim of this work was to investigate the neuromodulatory effect of transcutaneous 20 kHz stimulation on somatosensory and pain thresholds, and maximal handgrip strength. METHODS A randomized, crossover, single-blinded, placebo-controlled trial was conducted following recruitment of fourteen healthy volunteers. Transcutaneous stimulation at 20 kHz and sham stimulation were applied over the ulnar and median nerves of fourteen healthy volunteers for 20 min. Maximal handgrip strength (MHS), mechanical detection threshold (MDT) and pressure pain threshold (PPT) were registered prior to, during (15 min), immediately after the end (20 min), and 10 min following stimulation. RESULTS The 20 kHz stimulation showed a lower MHS during the stimulation at the 15 min (30.1 kgs SE 2.8) and at 20 min (31.8 kgs, SE 2.8) when compared to sham stimulation (35.1 kgs, SE 3.4; p < 0.001 and 34.2 kgs, SE 3.4; p = 0.03, respectively). The 20 kHz stimulation resulted in a slight increase in MDT at 15 min (0.25 mN; 0.25-2.00) when compared to the sham stimulation (0.25 mN; 0.25-0.25; p = 0.02), and no effects were showed for PPT. CONCLUSIONS High-frequency stimulation at 20 kHz suggests a partial block of nerve activity. Studies in subjects with neurological disorders characterized by nerve hyperactivity are needed to confirm the clinical impact of this non-invasive electrical stimulation technique. TRIAL REGISTRATION NCT, NCT02837458. Registered on 12 April 2017.
Collapse
Affiliation(s)
- Diego Serrano-Muñoz
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, 45071, Toledo, Spain.,Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursery, Castilla La Mancha University, 45071, Toledo, Spain
| | - Juan Avendaño-Coy
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursery, Castilla La Mancha University, 45071, Toledo, Spain.
| | - Cristina Simón-Martínez
- Department of Rehabilitation Sciences, KU Leuven - University of Leuven, 3000, Leuven, Belgium
| | - Julian Taylor
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, 45071, Toledo, Spain
| | - Julio Gómez-Soriano
- Toledo Physiotherapy Research Group (GIFTO), Faculty of Physiotherapy and Nursery, Castilla La Mancha University, 45071, Toledo, Spain
| |
Collapse
|
13
|
Kim Y, Bulea TC, Park HS. Transcutaneous high-frequency alternating current for rapid reversible muscle force reduction below pain threshold. J Neural Eng 2019; 16:066013. [PMID: 31344687 DOI: 10.1088/1741-2552/ab35ce] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE The development of non-invasive, quickly reversible techniques for controlling undesired muscle force production (e.g. spasticity) could expand rehabilitation approaches in those with pathology by increasing the type and intensity of exercises that can be performed. High-frequency alternating current (HFAC) has been previously established as a viable method for blocking neural conduction in peripheral nerves. However, clinical application of HFAC for nerve conduction block is limited due to the invasiveness of surgical procedures and the painful onset response. This study aimed to examine the use of transcutaneous HFAC (tHFAC) at various stimulation frequencies to address these shortfalls. APPROACH Ten individuals participated in the study. Surface electrodes were utilized to apply tHFAC (0.5-12 kHz) to the median and ulnar nerves. Individual pain threshold was determined by gradual increase of stimulation amplitude. Subjects then performed a force-matching task by producing grip forces up to the maximal voluntary contraction level with and without application of tHFAC below the pain threshold. MAIN RESULTS Pain threshold current amplitude increased linearly with stimulation frequency. Statistical analysis showed that both stimulation frequency and charge injected per phase had significant effects (p < 0.05) on grip force reduction. At the group level, application of tHFAC below pain threshold reduced grip force by a maximum of 40.7% ± 8.1%. Baseline grip force trials interspersed between tHFAC trials showed consistent grip force, indicating that fatigue was not a factor in force reduction. SIGNIFICANCE Our results demonstrate the effectiveness of tHFAC at reducing muscle force when applied below the pain threshold, suggesting its potential clinical viability. Future studies are necessary to further elucidate the mechanism of force reduction before clinical application.
Collapse
Affiliation(s)
- Yushin Kim
- Major of Sports Health Rehabilitation, Cheongju University, Cheongju, Republic of Korea
| | | | | |
Collapse
|
14
|
Serrano-Muñoz D, Gómez-Soriano J, Bravo-Esteban E, Ávila-Martín G, Galán-Arriero I, Taylor J, Avendaño-Coy J. Soleus H-reflex modulation following transcutaneous high- and low-frequency spinal stimulation in healthy volunteers. J Electromyogr Kinesiol 2019; 46:1-7. [DOI: 10.1016/j.jelekin.2019.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 12/22/2022] Open
|
15
|
Toward the Bionic Face: A Novel Neuroprosthetic Device Paradigm for Facial Reanimation Consisting of Neural Blockade and Functional Electrical Stimulation. Plast Reconstr Surg 2019; 143:62e-76e. [PMID: 30589784 DOI: 10.1097/prs.0000000000005164] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Facial palsy is a devastating condition potentially amenable to rehabilitation by functional electrical stimulation. Herein, a novel paradigm for unilateral facial reanimation using an implantable neuroprosthetic device is proposed and its feasibility demonstrated in a live rodent model. The paradigm comprises use of healthy-side electromyographic activity as control inputs to a system whose outputs are neural stimuli to effect symmetric facial displacements. The vexing issue of suppressing undesirable activity resulting from aberrant neural regeneration (synkinesis) or nerve transfer procedures is addressed using proximal neural blockade. METHODS Epimysial and nerve cuff electrode arrays were implanted in the faces of Wistar rats. Stimuli were delivered to evoke blinks and whisks of various durations and amplitudes. The dynamic relation between electromyographic signals and facial displacements was modeled, and model predictions were compared against measured displacements. Optimal parameters to achieve facial nerve blockade by means of high-frequency alternating current were determined, and the safety of continuous delivery was assessed. RESULTS Electrode implantation was well tolerated. Blinks and whisks of tunable amplitudes and durations were evoked by controlled variation of neural stimuli parameters. Facial displacements predicted from electromyographic input modelling matched those observed with a variance-accounted-for exceeding 96 percent. Effective and reversible facial nerve blockade in awake behaving animals was achieved, without detrimental effect noted from long-term continual use. CONCLUSIONS Proof-of-principle of rehabilitation of hemifacial palsy by means of a neuroprosthetic device has been demonstrated. The use of proximal neural blockade coupled with distal functional electrical stimulation may have relevance to rehabilitation of other peripheral motor nerve deficits.
Collapse
|
16
|
Roldan LM, Eggers TE, Kilgore KL, Bhadra N, Vrabec T, Bhadra N. Measurement of block thresholds in kiloHertz frequency alternating current peripheral nerve block. J Neurosci Methods 2019; 315:48-54. [PMID: 30641091 PMCID: PMC6380354 DOI: 10.1016/j.jneumeth.2019.01.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/21/2018] [Accepted: 01/10/2019] [Indexed: 01/09/2023]
Abstract
BACKGROUND Kilohertz frequency alternating currents (KHFAC) produce rapid nerve conduction block of mammalian peripheral nerve and have potential clinical applications in reducing peripheral nerve hyperactivity. The experimental investigation of KHFAC nerve block requires a robust output measure and this has proven to be the block threshold (BT), the lowest current or voltage at which the axons of interest are completely blocked. All significant literature in KHFAC nerve block, both simulations and experimental, were reviewed to determine the block threshold method that was used. The two common methods used are the High-Low method experimentally and the Binary search method for simulations. NEW METHOD Four methods to measure the block threshold (High-Low, High-Low-High, Binary and Random) at three frequencies (10, 20 and 30 kHz) were compared through randomized repeated experiments in the in-vivo rodent sciatic nerve-gastrocnemius model. RESULTS The literature review showed that more than 50% of publications did not measure the block threshold. The experimental results showed no statistical difference in the BT value between the four methods. COMPARISON WITH EXISTING METHOD(S) However, there were differences in the number of significant onset responses, depending on the method. The run time for the BT determination was the shortest for the High-Low method. CONCLUSIONS It is recommended that all research in electrical nerve block, including KHFAC, should include measurement of the BT. The High-Low method is recommended for most experimental situations but the Binary method could also be a viable option, especially where onset responses are minimal.
Collapse
Affiliation(s)
- Leah Marie Roldan
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Thomas E Eggers
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Kevin L Kilgore
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, 44109, USA; Louis Stokes VA Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
| | - Narendra Bhadra
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Tina Vrabec
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Niloy Bhadra
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA; MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, 44109, USA.
| |
Collapse
|
17
|
Serrano-Muñoz D, Avendaño-Coy J, Simón-Martínez C, Taylor J, Gómez-Soriano J. Effect of high-frequency alternating current transcutaneous stimulation over muscle strength: a controlled pilot study. J Neuroeng Rehabil 2018; 15:103. [PMID: 30419966 PMCID: PMC6233282 DOI: 10.1186/s12984-018-0443-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 10/18/2018] [Indexed: 11/18/2022] Open
Abstract
Background High-frequency alternating currents of greater than 1 kHz applied on peripheral nerves has been used in animal studies to produce a motor nerve block. It has been evidenced that frequencies higher than 5 kHz are necessary to produce a complete peripheral nerve block in primates, whose nerve thickness is more similar to humans. The aim of the study was to determine the effect on muscle strength after the application of a high-frequency stimulation at 5 and 10 kHz compared to sham stimulation in healthy volunteers. Findings Transcutaneous stimulation at 5 kHz, 10 kHz and sham stimulation were applied to eleven healthy volunteers over the ulnar and median nerves for 20 min. Maximal handgrip strength was measured before, during, immediately after the intervention, and 10 min after the end of intervention. The 10 kHz stimulation showed a lower handgrip strength during the intervention (28.1 N, SEM 3.9) when compared to 5 kHz (31.1 N, SEM 3.6; p < 0.001) and to sham stimulation (33.7 N, SEM 3.9; p < 0.001). Furthermore, only stimulation at 10 kHz decreased handgrip strength when compared to baseline. Conclusions These findings suggest high-frequency stimulation has an inhibitory effect over muscle strength. Future studies are required in patients that are characterized by motor hyperactive such as spasticity or tremors. Clinical trial registration NCT, NCT03169049. Registered on 30 May 2017
Collapse
Affiliation(s)
- Diego Serrano-Muñoz
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, 45071, Toledo, Spain
| | - Juan Avendaño-Coy
- Toledo Physiotherapy Research Group (GIFTO), Nursing and Physiotherapy School, Castilla La Mancha University, 45071, Toledo, Spain.
| | - Cristina Simón-Martínez
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, 45071, Toledo, Spain.,Department of Rehabilitation Sciences, KU Leuven - University of Leuven, 3000, Leuven, Belgium
| | - Julian Taylor
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, 45071, Toledo, Spain
| | - Julio Gómez-Soriano
- Toledo Physiotherapy Research Group (GIFTO), Nursing and Physiotherapy School, Castilla La Mancha University, 45071, Toledo, Spain
| |
Collapse
|
18
|
Kim Y, Cho HJ, Park HS. Technical development of transcutaneous electrical nerve inhibition using medium-frequency alternating current. J Neuroeng Rehabil 2018; 15:80. [PMID: 30126438 PMCID: PMC6102860 DOI: 10.1186/s12984-018-0421-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 08/06/2018] [Indexed: 11/22/2022] Open
Abstract
Background Innovative technical approaches to controlling undesired sensory and motor activity, such as hyperalgesia or spasticity, may contribute to rehabilitation techniques for improving neural plasticity in patients with neurologic disorders. To date, transcutaneous electrical stimulation has used low frequency pulsed currents for sensory inhibition and muscle activation. Yet, few studies have attempted to achieve motor nerve inhibition using transcutaneous electrical stimulation. This study aimed to develop a technique for transcutaneous electrical nerve inhibition (TENI) using medium-frequency alternating current (MFAC) to suppress both sensory and motor nerve activity in humans. Methods Surface electrodes were affixed to the skin of eight young adults to stimulate the median nerve. Stimulation intensity was increased up to 50% and 100% of the pain threshold. To identify changes in sensory perception by transcutaneous MFAC (tMFAC) stimulation, we examined tactile and pressure pain thresholds in the index and middle fingers before and after stimulation at 10 kHz. To demonstrate the effect of tMFAC stimulation on motor inhibition, stimulation was applied while participants produced flexion forces with the index and middle fingers at target forces (50% and 90% of MVC, maximum voluntary contraction). Results tMFAC stimulation intensity significantly increased tactile and pressure pain thresholds, indicating decreased sensory perception. During the force production task, tMFAC stimulation with the maximum intensity immediately reduced finger forces by ~ 40%. Finger forces recovered immediately after stimulation cessation. The effect on motor inhibition was greater with the higher target force (90% MVC) than with the lower target (50% MVC). Also, higher tMFAC stimulation intensity provided a greater inhibition effect on both sensory and motor nerve activity. Conclusion We found that tMFAC stimulation immediately inhibits sensory and motor activity. This pre-clinical study demonstrates a novel technique for TENI using MFAC stimulation and showed that it can effectively inhibit both sensory perception and motor activity. The proposed technique can be combined with existing rehabilitation devices (e.g., a robotic exoskeleton) to inhibit undesired sensorimotor activities and to accelerate recovery after neurologic injury.
Collapse
Affiliation(s)
- Yushin Kim
- Major in Sport, Health & Rehabilitation, Department of Health Administration and Healthcare, Cheongju University, Cheongju, 28503, Republic of Korea.,Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hang-Jun Cho
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Hyung-Soon Park
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
| |
Collapse
|
19
|
Avendano-Coy J, Serrano-Munoz D, Taylor J, Goicoechea-Garcia C, Gomez-Soriano J. Peripheral Nerve Conduction Block by High-Frequency Alternating Currents: A Systematic Review. IEEE Trans Neural Syst Rehabil Eng 2018; 26:1131-1140. [DOI: 10.1109/tnsre.2018.2833141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
20
|
Bhadra N, Foldes E, Vrabec T, Kilgore K, Bhadra N. Temporary persistence of conduction block after prolonged kilohertz frequency alternating current on rat sciatic nerve. J Neural Eng 2018; 15:016012. [PMID: 29309274 PMCID: PMC6035886 DOI: 10.1088/1741-2552/aa89a4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECTIVE Application of kilohertz frequency alternating current (KHFAC) waveforms can result in nerve conduction block that is induced in less than a second. Conduction recovers within seconds when KHFAC is applied for about 5-10 min. This study investigated the effect of repeated and prolonged application of KHFAC on rat sciatic nerve with bipolar platinum electrodes. APPROACH Varying durations of KHFAC at signal amplitudes for conduction block with intervals of no stimulus were studied. Nerve conduction was monitored by recording peak Gastrocnemius muscle force utilizing stimulation electrodes proximal (PS) and distal (DS) to a blocking electrode. The PS signal traveled through the block zone on the nerve, while the DS went directly to the motor end-plate junction. The PS/DS force ratio provided a measure of conduction patency of the nerve in the block zone. MAIN RESULTS Conduction recovery times were found to be significantly affected by the cumulative duration of KHFAC application. Peak stimulated muscle force returned to pre-block levels immediately after cessation of KHFAC delivery when it was applied for less than about 15 min. They fell significantly but recovered to near pre-block levels for cumulative stimulus of 50 ± 20 min, for the tested On/Off times and frequencies. Conduction recovered in two phases, an initial fast one (60-80% recovery), followed by a slower phase. No permanent conduction block was seen at the end of the observation period during any experiment. SIGNIFICANCE This carry-over block effect may be exploited to provide continuous conduction block in peripheral nerves without continuous application of KHFAC.
Collapse
Affiliation(s)
- Narendra Bhadra
- Case Western Reserve University, Cleveland, OH, USA
- Metro Health Medical Center, Cleveland, OH, USA
- Functional Electrical Stimulation Center, Cleveland, OH, USA
| | - Emily Foldes
- Case Western Reserve University, Cleveland, OH, USA
- College of Health Solutions, Arizona State University Phoenix, AZ
| | - Tina Vrabec
- Case Western Reserve University, Cleveland, OH, USA
- Metro Health Medical Center, Cleveland, OH, USA
- Functional Electrical Stimulation Center, Cleveland, OH, USA
| | - Kevin Kilgore
- Case Western Reserve University, Cleveland, OH, USA
- Metro Health Medical Center, Cleveland, OH, USA
- Louis Stokes VA Medical Center, Cleveland, OH, USA
- Functional Electrical Stimulation Center, Cleveland, OH, USA
| | - Niloy Bhadra
- Case Western Reserve University, Cleveland, OH, USA
- Metro Health Medical Center, Cleveland, OH, USA
- Functional Electrical Stimulation Center, Cleveland, OH, USA
| |
Collapse
|
21
|
Bhadra N, Kilgore KL. Fundamentals of Kilohertz Frequency Alternating Current Nerve Conduction Block of the Peripheral Nervous System. Neuromodulation 2018. [DOI: 10.1016/b978-0-12-805353-9.00010-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
22
|
Patel YA, Kim BS, Rountree WS, Butera RJ. Kilohertz Electrical Stimulation Nerve Conduction Block: Effects of Electrode Surface Area. IEEE Trans Neural Syst Rehabil Eng 2017; 25:1906-1916. [DOI: 10.1109/tnsre.2017.2684161] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
23
|
Effect of Unmodulated 5-kHz Alternating Currents Versus Transcutaneous Electrical Nerve Stimulation on Mechanical and Thermal Pain, Tactile Threshold, and Peripheral Nerve Conduction: A Double-Blind, Placebo-Controlled Crossover Trial. Arch Phys Med Rehabil 2017; 98:888-895. [DOI: 10.1016/j.apmr.2016.11.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/14/2016] [Accepted: 11/17/2016] [Indexed: 11/21/2022]
|
24
|
North JM, Hong KSJ, Cho PY. Clinical Outcomes of 1 kHz Subperception Spinal Cord Stimulation in Implanted Patients With Failed Paresthesia-Based Stimulation: Results of a Prospective Randomized Controlled Trial. Neuromodulation 2016; 19:731-737. [PMID: 27186822 DOI: 10.1111/ner.12441] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/25/2016] [Accepted: 03/16/2016] [Indexed: 12/01/2022]
Abstract
BACKGROUND Pain relief via spinal cord stimulation (SCS) has historically revolved around producing paresthesia to replace pain, with success measured by the extent of paresthesia-pain overlap. In a recent murine study, by Shechter et al., showed the superior efficacy of high frequency SCS (1 kHz and 10 kHz) at inhibiting the effects of mechanical hypersensitivity compared to sham or 50 Hz stimulation. In the same study, authors report there were no differences in efficacy between 1 kHz and 10 kHz delivered at subperception stimulation strength (80% of motor threshold). Therefore, we designed a randomized, 2 × 2 crossover study of low frequency supra-perception SCS vs. subperception SCS at 1 kHz frequency in order to test whether subperception stimulation at 1 kHz was sufficient to provide effective pain relief in human subjects. METHODS Twenty-two subjects with SCS, and inadequate pain relief based on numeric pain rating scale (NPRS) scores (>5) were enrolled, and observed for total of seven weeks (three weeks of treatment, one week wash off, and another three weeks of treatment). Subjects were asked to rate their pain on NPRS as a primary efficacy variable, and complete the Oswestry Disability Index (ODI) and Patient's Global Impression of Change (PGIC) as secondary outcome measures. RESULTS Out of 22 subjects that completed the study, 21 subjects (95%) reported improvements in average, best, and worst pain NPRS scores. All NPRS scores were significantly lower with subperception stimulation compared to paresthesia-based stimulation (p < 0.01, p < 0.05, and p < 0.05, respectively). As with NPRS scores, the treatment effect of subperception stimulation was significantly greater than that of paresthesia based stimulation on ODI scores (p = 3.9737 × 10-5 ) and PGIC scores (p = 3.0396 × 10-5 ).
Collapse
Affiliation(s)
- James M North
- The Center for Clinical Research, Carolinas Pain Institute, Winston-Salem, NC, USA
| | - Kyung-Soo Jason Hong
- The Center for Clinical Research, Carolinas Pain Institute, Winston-Salem, NC, USA.
| | - Philip Young Cho
- Mathematical Sciences, United States Air Force Academy, Colorado Springs, CO, USA
| |
Collapse
|
25
|
Miller JP, Eldabe S, Buchser E, Johanek LM, Guan Y, Linderoth B. Parameters of Spinal Cord Stimulation and Their Role in Electrical Charge Delivery: A Review. Neuromodulation 2016; 19:373-84. [DOI: 10.1111/ner.12438] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 03/07/2016] [Indexed: 12/16/2022]
Affiliation(s)
- Jonathan P. Miller
- Functional and Restorative Neurosurgery Center and Department of Neurological Surgery, Case Western Reserve University School of Medicine, University Hospitals Case Medical Center; Cleveland OH USA
| | - Sam Eldabe
- The James Cook University Hospital; Middlesbrough UK
| | - Eric Buchser
- Anaesthesia and Pain Management Services at the Neuromodulation Centre; Hospital de Morges, Morges; Switzerland
| | - Lisa M. Johanek
- Department of Medical Affairs, Medtronic, PLC; Minneapolis MN USA
| | - Yun Guan
- Department of Anesthesiology/Critical Care Medicine; The Johns Hopkins University School of Medicine; Baltimore MD USA
| | - Bengt Linderoth
- Functional Neurosurgery, Department of Clinical Neuroscience, Karolinska Institutet; Stockholm Sweden
| |
Collapse
|
26
|
Kinfe TM, Pintea B, Link C, Roeske S, Güresir E, Güresir Á, Vatter H. High Frequency (10 kHz) or Burst Spinal Cord Stimulation in Failed Back Surgery Syndrome Patients With Predominant Back Pain: Preliminary Data From a Prospective Observational Study. Neuromodulation 2016; 19:268-75. [DOI: 10.1111/ner.12379] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 09/28/2015] [Accepted: 10/23/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Thomas M. Kinfe
- Department of Neurosurgery, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
- Department of Neurosurgery, Division of Functional Neurosurgery and Neuromodulation, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Bogdan Pintea
- Department of Neurosurgery, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Carolina Link
- Department of Anesthesiology, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Sandra Roeske
- DZNE, German Center for Neurodegenerative Diseases; Bonn Germany
- Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Erdem Güresir
- Department of Neurosurgery, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Ági Güresir
- Department of Neurosurgery, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| | - Hartmut Vatter
- Department of Neurosurgery, Rheinische Friedrich Wilhelms University Hospital; Bonn Germany
| |
Collapse
|
27
|
|
28
|
Patel YA, Butera RJ. Differential fiber-specific block of nerve conduction in mammalian peripheral nerves using kilohertz electrical stimulation. J Neurophysiol 2015; 113:3923-9. [PMID: 25878155 DOI: 10.1152/jn.00529.2014] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 04/13/2015] [Indexed: 11/22/2022] Open
Abstract
Kilohertz electrical stimulation (KES) has been shown to induce repeatable and reversible nerve conduction block in animal models. In this study, we characterized the ability of KES stimuli to selectively block specific components of stimulated nerve activity using in vivo preparations of the rat sciatic and vagus nerves. KES stimuli in the frequency range of 5-70 kHz and amplitudes of 0.1-3.0 mA were applied. Compound action potentials were evoked using either electrical or sensory stimulation, and block of components was assessed through direct nerve recordings and muscle force measurements. Distinct observable components of the compound action potential had unique conduction block thresholds as a function of frequency of KES. The fast component, which includes motor activity, had a monotonically increasing block threshold as a function of the KES frequency. The slow component, which includes sensory activity, showed a nonmonotonic block threshold relationship with increasing KES frequency. The distinct trends with frequency of the two components enabled selective block of one component with an appropriate choice of frequency and amplitude. These trends in threshold of the two components were similar when studying electrical stimulation and responses of the sciatic nerve, electrical stimulation and responses of the vagus nerve, and sensorimotor stimulation and responses of the sciatic nerve. This differential blocking effect of KES on specific fibers can extend the applications of KES conduction block to selective block and stimulation of neural signals for neuromodulation as well as selective control of neural circuits underlying sensorimotor function.
Collapse
Affiliation(s)
- Yogi A Patel
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, Georgia; and
| | - Robert J Butera
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia
| |
Collapse
|
29
|
Soin A, Syed Shah N, Fang ZP. High-Frequency Electrical Nerve Block for Postamputation Pain: A Pilot Study. Neuromodulation 2015; 18:197-205; discussion 205-6. [DOI: 10.1111/ner.12266] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/07/2014] [Accepted: 12/04/2014] [Indexed: 11/30/2022]
|
30
|
Fisher KM, Jillani NE, Oluoch GO, Baker SN. Blocking central pathways in the primate motor system using high-frequency sinusoidal current. J Neurophysiol 2014; 113:1670-80. [PMID: 25475345 PMCID: PMC4346720 DOI: 10.1152/jn.00347.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrical stimulation with high-frequency (2-10 kHz) sinusoidal currents has previously been shown to produce a transient and complete nerve block in the peripheral nervous system. Modeling and in vitro studies suggest that this is due to a prolonged local depolarization across a broad section of membrane underlying the blocking electrode. Previous work has used cuff electrodes wrapped around the peripheral nerve to deliver the blocking stimulus. We extended this technique to central motor pathways, using a single metal microelectrode to deliver focal sinusoidal currents to the corticospinal tract at the cervical spinal cord in anesthetized adult baboons. The extent of conduction block was assessed by stimulating a second electrode caudal to the blocking site and recording the antidromic field potential over contralateral primary motor cortex. The maximal block achieved was 99.6%, similar to findings of previous work in peripheral fibers, and the optimal frequency for blocking was 2 kHz. Block had a rapid onset, being complete as soon as the transient activation associated with the start of the sinusoidal current was over. High-frequency block was also successfully applied to the pyramidal tract at the medulla, ascending sensory pathways in the dorsal columns, and the descending systems of the medial longitudinal fasciculus. High-frequency sinusoidal stimulation produces transient, reversible lesions in specific target locations and therefore could be a useful alternative to permanent tissue transection in some experimental paradigms. It also could help to control or prevent some of the hyperactivity associated with chronic neurological disorders.
Collapse
Affiliation(s)
- Karen M Fisher
- Institute of Neuroscience, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom; and
| | - Ngalla E Jillani
- Institute of Primate Research, National Museums of Kenya, Karen, Nairobi, Kenya
| | - George O Oluoch
- Institute of Primate Research, National Museums of Kenya, Karen, Nairobi, Kenya
| | - Stuart N Baker
- Institute of Neuroscience, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom; and
| |
Collapse
|
31
|
Kilgore KL, Bhadra N. Reversible nerve conduction block using kilohertz frequency alternating current. Neuromodulation 2013; 17:242-54; discussion 254-5. [PMID: 23924075 DOI: 10.1111/ner.12100] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 06/04/2013] [Accepted: 06/21/2013] [Indexed: 01/25/2023]
Abstract
OBJECTIVES The features and clinical applications of balanced-charge kilohertz frequency alternating currents (KHFAC) are reviewed. Preclinical studies of KHFAC block have demonstrated that it can produce an extremely rapid and reversible block of nerve conduction. Recent systematic analysis and experimentation utilizing KHFAC block have resulted in a significant increase in interest in KHFAC block, both scientifically and clinically. MATERIALS AND METHODS We review the history and characteristics of KHFAC block, the methods used to investigate this type of block, the experimental evaluation of block, and the electrical parameters and electrode designs needed to achieve successful block. We then analyze the existing clinical applications of high-frequency currents, comparing the early results with the known features of KHFAC block. RESULTS Although many features of KHFAC block have been characterized, there is still much that is unknown regarding the response of neural structures to rapidly fluctuating electrical fields. The clinical reports to date do not provide sufficient information to properly evaluate the mechanisms that result in successful or unsuccessful treatment. CONCLUSIONS KHFAC nerve block has significant potential as a means of controlling nerve activity for the purpose of treating disease. However, early clinical studies in the use of high-frequency currents for the treatment of pain have not been designed to elucidate mechanisms or allow direct comparisons to preclinical data. We strongly encourage the careful reporting of the parameters utilized in these clinical studies, as well as the development of outcome measures that could illuminate the mechanisms of this modality.
Collapse
Affiliation(s)
- Kevin L Kilgore
- Department of Orthopaedics, MetroHealth Medical Center, Cleveland, OH, USA; Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | | |
Collapse
|
32
|
Cuellar JM, Alataris K, Walker A, Yeomans DC, Antognini JF. Effect of high-frequency alternating current on spinal afferent nociceptive transmission. Neuromodulation 2012; 16:318-27; discussion 327. [PMID: 23252766 DOI: 10.1111/ner.12015] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/24/2012] [Accepted: 11/06/2012] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The study was performed to test the hypothesis that high-frequency alternating current (HFAC) ranging from 2 to 100 kHz delivered to the spinal dorsal roots reduces activity of spinal wide dynamic range (WDR) dorsal horn neurons (DHNs) during noxious peripheral stimulation. MATERIALS AND METHODS This hypothesis was tested in both small and large animal in vivo preparations. Single-unit extracellular spinal DHN recordings were performed in seven adult rats and four adult goats while testing various parameters of HFAC delivered to the nerve roots or dorsal root entry zone using various electrode types. Frequencies tested ranged from 2 to 100 kHz but focused on the 3 to 50 kHz range. This study investigated the ability of HFAC to inhibit WDR neuronal activity evoked by noxious mechanical (pinch), and electrical stimuli was tested but was primarily focused on electrical stimulation. RESULTS Rat Study: Effects of HFAC were successfully tested on 11 WDR neurons. Suppression or complete blockade of evoked activity was observed in all 11 of these neurons. Complete data sets for neurons systematically tested with 15 baseline and post-HFAC stimulus sweeps were obtained in five neurons, the nociceptive activity of which was suppressed by an average of 69 ± 9.7% (p < 0.0001). Goat Study: HFAC was successfully tested on 15 WDR neurons. Conclusive suppression or complete nociceptive blockade was observed for 12/15 and complete data sets with at least 20 baseline and post-HFAC stimulus sweeps were obtained from eight DHNs. For these neurons the mean activity suppression was 70 ± 10% (p < 0.005). CONCLUSIONS Delivery of HFAC to the region of epidural nerve root or nerve root entry inhibited afferent nociceptive input and therefore may have potential to serve as an alternative to traditional spinal cord stimulation without sensory paresthesia as neuronal activation cannot occur at frequencies in this range.
Collapse
Affiliation(s)
- Jason M Cuellar
- Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, New York, NY, USA
| | | | | | | | | |
Collapse
|
33
|
Ackermann DM, Bhadra N, Gerges M, Thomas PJ. Dynamics and sensitivity analysis of high-frequency conduction block. J Neural Eng 2011; 8:065007. [PMID: 22056338 PMCID: PMC3417344 DOI: 10.1088/1741-2560/8/6/065007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The local delivery of extracellular high-frequency stimulation (HFS) has been shown to be a fast acting and quickly reversible method of blocking neural conduction and is currently being pursued for several clinical indications. However, the mechanism for this type of nerve block remains unclear. In this study, we investigate two hypotheses: (1) depolarizing currents promote conduction block via inactivation of sodium channels and (2) the gating dynamics of the fast sodium channel are the primary determinate of minimal blocking frequency. Hypothesis 1 was investigated using a combined modeling and experimental study to investigate the effect of depolarizing and hyperpolarizing currents on high-frequency block. The results of the modeling study show that both depolarizing and hyperpolarizing currents play an important role in conduction block and that the conductance to each of three ionic currents increases relative to resting values during HFS. However, depolarizing currents were found to promote the blocking effect, and hyperpolarizing currents were found to diminish the blocking effect. Inward sodium currents were larger than the sum of the outward currents, resulting in a net depolarization of the nodal membrane. Our experimental results support these findings and closely match results from the equivalent modeling scenario: intra-peritoneal administration of the persistent sodium channel blocker ranolazine resulted in an increase in the amplitude of HFS required to produce conduction block in rats, confirming that depolarizing currents promote the conduction block phenomenon. Hypothesis 2 was investigated using a spectral analysis of the channel gating variables in a single-fiber axon model. The results of this study suggested a relationship between the dynamical properties of specific ion channel gating elements and the contributions of corresponding conductances to block onset. Specifically, we show that the dynamics of the fast sodium inactivation gate are too slow to track the high-frequency changes in membrane potential during HFS, and that the behavior of the fast sodium current was dominated by the low-frequency depolarization of the membrane. As a result, in the blocked state, only 5.4% of nodal sodium channels were found to be in the activatable state in the node closest to the blocking electrode, resulting in conduction block. Moreover, we find that the corner frequency for the persistent sodium channel activation gate corresponds to the frequency below which high-frequency stimuli of arbitrary amplitude are incapable of inducing conduction block.
Collapse
Affiliation(s)
| | - Niloy Bhadra
- Dept. of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- MetroHealth Medical Center, Cleveland, OH, USA
| | | | - Peter J. Thomas
- Depts. of Mathematics, Biology and Cognitive Science, Case Western Reserve University, Cleveland, OH, USA
- Dept. of Neuroscience, Oberlin College, Oberlin, OH, USA
| |
Collapse
|