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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.
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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.
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2
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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.
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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
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3
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Lee G, Ray E, Yoon HJ, Genovese S, Choi YS, Lee MK, Şahin S, Yan Y, Ahn HY, Bandodkar AJ, Kim J, Park M, Ryu H, Kwak SS, Jung YH, Odabas A, Khandpur U, Ray WZ, MacEwan MR, Rogers JA. A bioresorbable peripheral nerve stimulator for electronic pain block. SCIENCE ADVANCES 2022; 8:eabp9169. [PMID: 36197971 PMCID: PMC9534494 DOI: 10.1126/sciadv.abp9169] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 08/18/2022] [Indexed: 05/31/2023]
Abstract
Local electrical stimulation of peripheral nerves can block the propagation of action potentials, as an attractive alternative to pharmacological agents for the treatment of acute pain. Traditional hardware for such purposes, however, involves interfaces that can damage nerve tissue and, when used for temporary pain relief, that impose costs and risks due to requirements for surgical extraction after a period of need. Here, we introduce a bioresorbable nerve stimulator that enables electrical nerve block and associated pain mitigation without these drawbacks. This platform combines a collection of bioresorbable materials in architectures that support stable blocking with minimal adverse mechanical, electrical, or biochemical effects. Optimized designs ensure that the device disappears harmlessly in the body after a desired period of use. Studies in live animal models illustrate capabilities for complete nerve block and other key features of the technology. In certain clinically relevant scenarios, such approaches may reduce or eliminate the need for use of highly addictive drugs such as opioids.
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Affiliation(s)
- Geumbee Lee
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Precision Biology Research Center, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Emily Ray
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Hong-Joon Yoon
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Sabrina Genovese
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Yeon Sik Choi
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Min-Kyu Lee
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Samet Şahin
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Department of Bioengineering, Bilecik Şeyh Edebali University, 11230 Bilecik, Merkez/Bilecik, Turkey
| | - Ying Yan
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Hak-Young Ahn
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Amay J. Bandodkar
- Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC 27606, USA
- Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST), North Carolina State University, Raleigh, NC 27606, USA
| | - Joohee Kim
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Minsu Park
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
| | - Hanjun Ryu
- Department of Advanced Materials Engineering, Chung-Ang University, Anseong 17546, Republic of Korea
| | - Sung Soo Kwak
- Center for Bionics, Biomedical Research Division, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Yei Hwan Jung
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Arman Odabas
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
- Department of Internal Medicine, Stanford University Medical Center, Stanford, CA 94305, USA
| | - Umang Khandpur
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Wilson Z. Ray
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Matthew R. MacEwan
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
- Department of Neurological Surgery, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - John A. Rogers
- Querrey Simpson Institute for Bioelectronics, Northwestern University, Evanston, IL 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Coolen RL, Emmer KM, Spantidea PI, van Asselt E, Scheepe JR, Serdijn WA, Blok BFM. Kilohertz alternating current neuromodulation of the pudendal nerves: effects on the anal canal and anal sphincter in rats. J Appl Biomed 2022; 20:56-69. [PMID: 35727123 DOI: 10.32725/jab.2022.009] [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: 11/16/2021] [Accepted: 06/21/2022] [Indexed: 11/05/2022] Open
Abstract
The first two objectives were to establish which stimulation parameters of kilohertz frequency alternating current (KHFAC) neuromodulation influence the effectiveness of pudendal nerve block and its safety. The third aim was to determine whether KHFAC neuromodulation of the pudendal nerve can relax the pelvic musculature, including the anal sphincter. Simulation experiments were conducted to establish which parameters can be adjusted to improve the effectiveness and safety of the nerve block. The outcome measures were block threshold (measure of effectiveness) and block threshold charge per phase (measure of safety). In vivo, the pudendal nerves in 11 male and 2 female anesthetized Sprague Dawley rats were stimulated in the range of 10 Hz to 40 kHz, and the effect on anal pressure was measured. The simulations showed that block threshold and block threshold charge per phase depend on waveform, interphase delay, electrode-to-axon distance, interpolar distance, and electrode array orientation. In vivo, the average anal pressure during unilateral KHFAC stimulation was significantly lower than the average peak anal pressure during low-frequency stimulation (p < 0.001). Stimulation with 20 kHz and 40 kHz (square wave, 10 V amplitude, 50% duty cycle, no interphase delay) induced the largest anal pressure decrease during both unilateral and bilateral stimulation. However, no statistically significant differences were detected between the different frequencies. This study showed that waveform, interphase delay and the alignment of the electrode along the nerve affect the effectiveness and safety of KHFAC stimulation. Additionally, we showed that KHFAC neuromodulation of the pudendal nerves with an electrode array effectively reduces anal pressure in rats.
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Affiliation(s)
- Rosa L Coolen
- Erasmus Medical Center, Department of Urology, Rotterdam, Zuid-Holland, Netherlands
| | - Koen M Emmer
- Delft University of Technology, Section Bioelectronics, Delft, Zuid-Holland, Netherlands
| | | | - Els van Asselt
- Erasmus Medical Center, Department of Urology, Rotterdam, Zuid-Holland, Netherlands
| | - Jeroen R Scheepe
- Erasmus Medical Center, Department of Urology, Rotterdam, Zuid-Holland, Netherlands
| | - Wouter A Serdijn
- Delft University of Technology, Section Bioelectronics, Delft, Zuid-Holland, Netherlands
| | - Bertil F M Blok
- Erasmus Medical Center, Department of Urology, Rotterdam, Zuid-Holland, Netherlands
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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.
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Zhang J, Mao G, Feng Y, Zhang B, Liu B, Lu X, Wang Z. Inhibiting Spasticity by Blocking Nerve Signal Conduction in Rats With Spinal Cord Transection. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2355-2364. [PMID: 34723805 DOI: 10.1109/tnsre.2021.3124530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Spasticity is a common motor disorder following a variety of upper motor neuron lesions that seriously affects the quality of patient's life. We aimed to evaluate whether muscle spasms can be suppressed by blocking nerve signal conduction. A rat model of lower limb spasm was prepared and the conduction of pathological nerve signals were blocked to study the inhibitory effect of nerve signal block on muscle spasm. The experimental results showed that 4 weeks after the 9th segment of the rat's thoracic spinal cord was completely transacted, the H/M -ratio of the lower limbs increased, and rate-dependent depression was weakened. When the rat model was stimulated by external forces, the electromyography (EMG) signals of the spastic gastrocnemius muscles continued to erupt. After blocking the conduction of nerve signals in the rat sciatic nerve, the spastic EMG signal of the gastrocnemius muscle disappeared. The effective blocking time and blocking efficiency increased with increasing blocking signal amplitude, and the maximum blocking efficiency reached 73%. The experimental results of this study proved the feasibility of inhibiting lower limb spasticity by blocking nerve signal conduction.
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Neudorfer C, Chow CT, Boutet A, Loh A, Germann J, Elias GJ, Hutchison WD, Lozano AM. Kilohertz-frequency stimulation of the nervous system: A review of underlying mechanisms. Brain Stimul 2021; 14:513-530. [PMID: 33757930 DOI: 10.1016/j.brs.2021.03.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 03/08/2021] [Accepted: 03/11/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Electrical stimulation in the kilohertz-frequency range has gained interest in the field of neuroscience. The mechanisms underlying stimulation in this frequency range, however, are poorly characterized to date. OBJECTIVE/HYPOTHESIS To summarize the manifold biological effects elicited by kilohertz-frequency stimulation in the context of the currently existing literature and provide a mechanistic framework for the neural responses observed in this frequency range. METHODS A comprehensive search of the peer-reviewed literature was conducted across electronic databases. Relevant computational, clinical, and mechanistic studies were selected for review. RESULTS The effects of kilohertz-frequency stimulation on neural tissue are diverse and yield effects that are distinct from conventional stimulation. Broadly, these can be divided into 1) subthreshold, 2) suprathreshold, 3) synaptic and 4) thermal effects. While facilitation is the dominating mechanism at the subthreshold level, desynchronization, spike-rate adaptation, conduction block, and non-monotonic activation can be observed during suprathreshold kilohertz-frequency stimulation. At the synaptic level, kilohertz-frequency stimulation has been associated with the transient depletion of the available neurotransmitter pool - also known as synaptic fatigue. Finally, thermal effects associated with extrinsic (environmental) and intrinsic (associated with kilohertz-frequency stimulation) temperature changes have been suggested to alter the neural response to stimulation paradigms. CONCLUSION The diverse spectrum of neural responses to stimulation in the kilohertz-frequency range is distinct from that associated with conventional stimulation. This offers the potential for new therapeutic avenues across stimulation modalities. However, stimulation in the kilohertz-frequency range is associated with distinct challenges and caveats that need to be considered in experimental paradigms.
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Affiliation(s)
- Clemens Neudorfer
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - Clement T Chow
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - Alexandre Boutet
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - Aaron Loh
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - Jürgen Germann
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - Gavin Jb Elias
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada
| | - William D Hutchison
- Krembil Research Institute, University of Toronto, Ontario, Canada; Department of Physiology, Toronto Western Hospital and University of Toronto, Ontario, Canada
| | - Andres M Lozano
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University of Toronto, Canada; Krembil Research Institute, University of Toronto, Ontario, Canada.
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Ray S, Javeed S, Khalifeh JM, Chandra N, Birenbaum N, Felder JM, Moran D, Ray WZ, MacEwan MR. High-Frequency Alternating Current Block Using Macro-Sieve Electrodes: A Pilot Study. Cureus 2021; 13:e13728. [PMID: 33842107 PMCID: PMC8020727 DOI: 10.7759/cureus.13728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background and objective High-frequency alternating current (HFAC) can yield a rapid-acting and reversible nerve conduction block. The present study aimed to demonstrate the successful implementation of HFAC block delivery via regenerative macro-sieve electrodes (MSEs). Methods Dual-electrode assemblies in two configurations [dual macro-sieve electrode-1 (DMSE-I), DMSE-II] were fabricated from pairs of MSEs and implanted in the transected and subsequently repaired sciatic nerves of two male Lewis rats. After four months of postoperative nerve regeneration through the MSEs' transit zones, the efficacy of acute HFAC block was tested for both configurations. Frequencies ranging from 10 kHz to 42 kHz, and stimulus amplitudes with peak-to-peak voltages ranging from 2 V to 20 V were tested. Evoked muscle force measurement was used to quantify the nerve conduction block. Results HFAC stimulation delivered via DMSE assemblies obtained a complete block at frequencies of 14 to 26 kHz and stimulus amplitudes of 12 to 20 V p-p. The threshold voltage for the complete block showed an approximately linear dependence on frequency. The threshold voltage for the partial conduction block was also approximately linear. For those frequencies that displayed both partial and complete block, the partial block thresholds were consistently lower. Conclusion This study provides a proof of concept that regenerative MSEs can achieve complete and reversible conduction block via HFAC stimulation of regenerated nerve tissue. A chronically interfaced DMSE assembly may thereby facilitate the inactivation of targeted nerves in cases wherein pathologic neuronal hyperactivity is involved.
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Affiliation(s)
- Soumyajit Ray
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, USA
| | - Saad Javeed
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, USA
| | - Jawad M Khalifeh
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, USA
| | - Nikhil Chandra
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, USA
| | - Nathan Birenbaum
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, USA
| | - John M Felder
- Department of Plastic Surgery, Washington University School of Medicine, St. Louis, USA
| | - Daniel Moran
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, USA
| | - Wilson Z Ray
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, USA
| | - Matthew R MacEwan
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, USA.,Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, USA
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Peña E, Pelot NA, Grill WM. Quantitative comparisons of block thresholds and onset responses for charge-balanced kilohertz frequency waveforms. J Neural Eng 2020; 17:046048. [PMID: 32777778 DOI: 10.1088/1741-2552/abadb5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE There is growing interest in delivering kilohertz frequency (KHF) electrical signals to block conduction in peripheral nerves for treatment of various diseases. Previous studies used different KHF waveforms to achieve block, and it remains unclear how waveform affects nerve block parameters. APPROACH We quantified the effects of waveform on KHF block of the rat tibial nerve in vivo and in computational models. We compared block thresholds and onset responses across current-controlled sinusoids and charge-balanced rectangular waveforms with different asymmetries and duty cycles. MAIN RESULTS Sine waves had higher block thresholds than square waves, but used less power at block threshold. Block threshold had an inverse relationship with duty cycle of rectangular waveforms irrespective of waveform asymmetry. Computational model results were consistent with relationships measured in vivo, although the models underestimated the effect of duty cycle on increasing thresholds. The axonal membrane substantially filtered waveforms, the filter transfer function was strikingly similar across waveforms, and filtering resulted in post-filtered rms block thresholds that were approximately constant across waveforms in silico and in vivo. Onset response was not consistently affected by waveform shape, but onset response was smaller at amplitudes well above block threshold. Therefore, waveforms with lower block thresholds (e.g. sine waves or square waves) could be more readily increased to higher amplitudes relative to block threshold to reduce onset response. We also observed a reduction in onset responses across consecutive trials after initial application of supra-block threshold amplitudes. SIGNIFICANCE Waveform had substantial effects on block thresholds, and the amplitude relative to block threshold had substantial effects on onset response. These data inform choice of waveform in subsequent studies and clinical applications, enhance effective use of block in therapeutic applications, and facilitate the design of parameters that achieve block with minimal onset responses.
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Affiliation(s)
- Edgar Peña
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, United States of America
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Kilohertz waveforms optimized to produce closed-state Na+ channel inactivation eliminate onset response in nerve conduction block. PLoS Comput Biol 2020; 16:e1007766. [PMID: 32542050 PMCID: PMC7316353 DOI: 10.1371/journal.pcbi.1007766] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 06/25/2020] [Accepted: 03/02/2020] [Indexed: 02/01/2023] Open
Abstract
The delivery of kilohertz frequency alternating current (KHFAC) generates rapid, controlled, and reversible conduction block in motor, sensory, and autonomic nerves, but causes transient activation of action potentials at the onset of the blocking current. We implemented a novel engineering optimization approach to design blocking waveforms that eliminated the onset response by moving voltage-gated Na+ channels (VGSCs) to closed-state inactivation (CSI) without first opening. We used computational models and particle swarm optimization (PSO) to design a charge-balanced 10 kHz biphasic current waveform that produced conduction block without onset firing in peripheral axons at specific locations and with specific diameters. The results indicate that it is possible to achieve onset-free KHFAC nerve block by causing CSI of VGSCs. Our novel approach for designing blocking waveforms and the resulting waveform may have utility in clinical applications of conduction block of peripheral nerve hyperactivity, for example in pain and spasticity. Many neurological disorders, including pain and spasticity, are characterized by undesirable increases in sensory, motor, or autonomic nerve activity. Local application of kilohertz frequency alternating currents (KHFAC) can effectively and completely block the conduction of undesired hyperactivity through peripheral nerves and could be a therapeutic approach for alleviating disease symptoms. However, KHFAC nerve block produces an undesirable initial burst of action potentials prior to achieving block. This onset firing may result in muscle contraction and pain and is a significant impediment to potential clinical applications of KHFAC nerve block. We present a novel engineering optimization approach for designing a blocking waveform that completely eliminated the onset firing in peripheral axons by moving voltage-gated Na+ channels to closed-state inactivation. Our results suggest that the resulting KHFAC waveform can generate electric nerve block without an onset response. Our approach for optimizing blocking waveforms represents a novel engineering design methodology with myriad potential applications and has relevance for the conduction block of peripheral nerve hyperactivity.
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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.
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Ling D, Luo J, Wang M, Cao X, Chen X, Fang K, Yu B. Kilohertz high-frequency alternating current blocks nerve conduction without causing nerve damage in rats. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:661. [PMID: 31930062 DOI: 10.21037/atm.2019.10.36] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background In recent years, 2-50 kHz high-frequency alternating current has been shown to block nerve conduction mostly based on simulation models or experiments in vitro. This study aimed to assess the nerve block effects and related parameters of kilohertz alternating current in a rat model. Methods High-frequency biphasic rectangular stimulus pulse was applied to rat's sciatic nerve in vivo, and its blockade frequency and intensity was studied by recording the changes of compound muscle action potential (CMAP) amplitude and muscle states before and after stimulation. Secondly, diameter and circumference of sciatic nerve was measured at stimulating point by ultrasound. The correlation between stimulus' frequency and the nerve's diameter and circumference was studied. Lastly, we assessed nerve damage causing by high-frequency electrical stimulation by measuring CMAP and nerve conduction velocity (NCV) in the following day and sciatic nerve hematoxylin-eosin staining, both blocked side and contralateral side. Results When the current intensity was fixed, the blockade only occurred in a specific frequency range, above or below might have partial block effect. Preliminary statistical results showed that the blocking frequency of high-frequency alternating current was negatively linearly correlated with the circumference of sciatic nerve (P<0.05); HE staining of the sciatic nerve showed no axon and myelin sheath damage on blocked or opposite side, and the CMAP and NCV of the sciatic nerve remeasured in the next day were normal, indicating high-frequency electrical stimulation produced no nerve injury. Conclusions High-frequency alternating current stimulation can block nerve conduction without causing nerve damage, and the complete block frequency is negatively linearly correlated with the circumference of sciatic nerve.
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Affiliation(s)
- Dandan Ling
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Junjie Luo
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Mengying Wang
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Xiaodan Cao
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Xiaorui Chen
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Kexin Fang
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
| | - Bin Yu
- Department of Anesthesiology, Tongji Hospital Affiliated to Tongji University, Tongji University School of Medicine, Shanghai 200065, China
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Vrabec TL, Eggers TE, Foldes EL, Ackermann DM, Kilgore KL, Bhadra N. Reduction of the onset response in kilohertz frequency alternating current nerve block with amplitude ramps from non-zero amplitudes. J Neuroeng Rehabil 2019; 16:80. [PMID: 31253152 PMCID: PMC6599251 DOI: 10.1186/s12984-019-0554-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/19/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Kilohertz frequency alternating current (KHFAC) waveforms reversibly block conduction in mammalian peripheral nerves. The initiation of the KHFAC produces nerve activation, called the onset response, before complete block occurs. An amplitude ramp, starting from zero amplitude, is ineffective in eliminating this onset activity. We postulated that initiating the ramp from a non-zero amplitude would produce a different effect on the onset. METHODS Experiments were conducted in an in vivo rat model. KHFAC was applied at supra block threshold amplitudes and then reduced to a lower sub block amplitude (25, 50, 75 and 90% of the block threshold amplitude). The amplitude was then increased again to the original supra block threshold amplitude with an amplitude ramp. This ramp time was varied for each of the amplitude levels tested. RESULTS The amplitude ramp was successful in eliminating a second onset. This was always possible for the ramps up from 75 and 90% block threshold amplitude, usually from 50% but never from 25% of the block threshold amplitude. CONCLUSIONS This maneuver can potentially be used to initiate complete nerve block, transition to partial block and then resume complete block without producing further onset responses.
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Affiliation(s)
- T L Vrabec
- MetroHealth Medical Center, Cleveland, OH, USA
| | - T E Eggers
- Dept of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.
| | - E L Foldes
- College of Health Solutions, Arizona State University, Tempe, AZ, USA
| | | | - K L Kilgore
- MetroHealth Medical Center, Cleveland, OH, USA.,Dept of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.,Louis Stokes Cleveland Department, Veterans Affairs Medical Center, Cleveland, OH, USA
| | - N Bhadra
- MetroHealth Medical Center, Cleveland, OH, USA
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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
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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.
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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.
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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
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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
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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]
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Patel YA, Butera RJ. Challenges associated with nerve conduction block using kilohertz electrical stimulation. J Neural Eng 2018; 15:031002. [DOI: 10.1088/1741-2552/aaadc0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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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]
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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]
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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]
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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.
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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
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Energy efficient neural stimulation: coupling circuit design and membrane biophysics. PLoS One 2012; 7:e51901. [PMID: 23272188 PMCID: PMC3521743 DOI: 10.1371/journal.pone.0051901] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 11/13/2012] [Indexed: 11/19/2022] Open
Abstract
The delivery of therapeutic levels of electrical current to neural tissue is a well-established treatment for numerous indications such as Parkinson's disease and chronic pain. While the neuromodulation medical device industry has experienced steady clinical growth over the last two decades, much of the core technology underlying implanted pulse generators remain unchanged. In this study we propose some new methods for achieving increased energy-efficiency during neural stimulation. The first method exploits the biophysical features of excitable tissue through the use of a centered-triangular stimulation waveform. Neural activation with this waveform is achieved with a statistically significant reduction in energy compared to traditional rectangular waveforms. The second method demonstrates energy savings that could be achieved by advanced circuitry design. We show that the traditional practice of using a fixed compliance voltage for constant-current stimulation results in substantial energy loss. A portion of this energy can be recuperated by adjusting the compliance voltage to real-time requirements. Lastly, we demonstrate the potential impact of axon fiber diameter on defining the energy-optimal pulse-width for stimulation. When designing implantable pulse generators for energy efficiency, we propose that the future combination of a variable compliance system, a centered-triangular stimulus waveform, and an axon diameter specific stimulation pulse-width has great potential to reduce energy consumption and prolong battery life in neuromodulation devices.
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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.
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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
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Ackermann DM, Bhadra N, Foldes EL, Kilgore KL. Separated interface nerve electrode prevents direct current induced nerve damage. J Neurosci Methods 2011; 201:173-6. [PMID: 21276819 PMCID: PMC3099145 DOI: 10.1016/j.jneumeth.2011.01.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/31/2010] [Accepted: 01/13/2011] [Indexed: 11/22/2022]
Abstract
Direct current, DC, can be used to quickly and reversibly block activity in excitable tissue, or to quickly and reversibly increase or decrease the natural excitability of a neuronal population. However, the practical use of DC to control neuronal activity has been extremely limited due to the rapid tissue damage caused by its use. We show that a separated interface nerve electrode, SINE, is a much safer method to deliver DC to excitable tissue and may be valuable as a laboratory research tool or potentially for clinical treatment of disease.
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26
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Joseph L, Butera RJ. High-frequency stimulation selectively blocks different types of fibers in frog sciatic nerve. IEEE Trans Neural Syst Rehabil Eng 2011; 19:550-7. [PMID: 21859632 DOI: 10.1109/tnsre.2011.2163082] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Conduction block using high-frequency alternating current (HFAC) stimulation has been shown to reversibly block conduction through various nerves. However, unlike simulations and experiments on myelinated fibers, prior experimental work in our lab on the sea-slug, Aplysia, found a nonmonotonic relationship between frequency and blocking thresholds in the unmyelinated fibers. To resolve this discrepancy, we investigated the effect of HFAC waveforms on the compound action potential of the sciatic nerve of frogs. Maximal stimulation of the nerve produces a compound action potential consisting of the A-fiber and C-fiber components corresponding to the myelinated and unmyelinated fibers' response. In our study, HFAC waveforms were found to induce reversible block in the A-fibers and C-fibers for frequencies in the range of 5-50 kHz and for amplitudes from 0.1-1 mA. Although the A-fibers demonstrated the monotonically increasing threshold behavior observed in published literature, the C-fibers displayed a nonmonotonic relationship, analogous to that observed in the unmyelinated fibers of Aplysia. This differential blocking behavior observed in myelinated and unmyelinated fibers during application of HFAC waveforms has diverse implications for the fields of selective stimulation and pain management.
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Affiliation(s)
- Laveeta Joseph
- Laboratory for Neuroengineering, The Wallace H Coulter Department of Biomedical Engineering, Georgia Tech/Emory University, The Interdisciplinary Bioengineering Graduate Program, Atlanta, GA 30332, USA
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Ackermann DM, Ethier C, Foldes EL, Oby ER, Tyler D, Bauman M, Bhadra N, Miller L, Kilgore KL. Electrical conduction block in large nerves: high-frequency current delivery in the nonhuman primate. Muscle Nerve 2011; 43:897-9. [PMID: 21607972 PMCID: PMC3101373 DOI: 10.1002/mus.22037] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent studies have made significant progress toward the clinical implementation of high-frequency conduction block (HFB) of peripheral nerves. However, these studies were performed in small nerves, and questions remain regarding the nature of HFB in large-diameter nerves. This study in nonhuman primates shows reliable conduction block in large-diameter nerves (up to 4.1 mm) with relatively low-threshold current amplitude and only moderate nerve discharge prior to the onset of block.
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Affiliation(s)
- D Michael Ackermann
- Cleveland FES Center, Hamman 601, 2500 MetroHealth Drive, Cleveland, Ohio 44109, USA.
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Design, fabrication and evaluation of a conforming circumpolar peripheral nerve cuff electrode for acute experimental use. J Neurosci Methods 2010; 196:31-7. [PMID: 21187115 DOI: 10.1016/j.jneumeth.2010.12.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 12/10/2010] [Accepted: 12/15/2010] [Indexed: 11/22/2022]
Abstract
Nerve cuff electrodes are a principle tool of basic and applied electro-neurophysiology studies and are championed for their ability to achieve good nerve recruitment with low thresholds. We describe the design and method of fabrication for a novel circumpolar peripheral nerve electrode for acute experimental use. This cylindrical cuff-style electrode provides approximately 270° of radial electrode contact with a nerve for each of an arbitrary number of contacts, has a profile that allows for simple placement and removal in an acute nerve preparation, and is designed for adjustment of the cylindrical diameter to ensure a close fit on the nerve. For each electrode, the electrical contacts were cut from 25 μm platinum foil as an array so as to maintain their positions relative to each other within the cuff. Lead wires were welded to each intended contact. The structure was then molded in silicone elastomer, after which the individual contacts were electrically isolated. The final electrode was curved into a cylindrical shape with an inner diameter corresponding to that of the intended target nerve. The positions of these contacts were well maintained during the molding and shaping process and failure rates during fabrication due to contact displacements were very low. Established electrochemical measurements were made on one electrode to confirm expected behavior for a platinum electrode and to measure the electrode impedance to applied voltages at different frequencies. These electrodes have been successfully used for nerve stimulation, recording, and conduction block in a number of different acute animal experiments by several investigators.
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Ackermann DM, Bhadra N, Foldes EL, Wang XF, Kilgore KL. Effect of nerve cuff electrode geometry on onset response firing in high-frequency nerve conduction block. IEEE Trans Neural Syst Rehabil Eng 2010; 18:658-65. [PMID: 20813650 PMCID: PMC3467702 DOI: 10.1109/tnsre.2010.2071882] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The delivery of high-frequency alternating currents has been shown to produce a focal and reversible conduction block in whole nerve and is a potential therapeutic option for various diseases and disorders involving pathological or undesired neurological activity. However, delivery of high-frequency alternating current to a nerve produces a finite burst of neuronal firing, called the onset response, before the nerve is blocked. Reduction or elimination of the onset response is very important to moving this type of nerve block into clinical applications since the onset response is likely to result in undesired muscle contraction and pain. This paper describes a study of the effect of nerve cuff electrode geometry (specifically, bipolar contact separation distance), and waveform amplitude on the magnitude and duration of the onset response. Electrode geometry and waveform amplitude were both found to affect these measures. The magnitude and duration of the onset response showed a monotonic relationship with bipolar separation distance and amplitude. The duration of the onset response varied by as much as 820% on average for combinations of different electrode geometries and waveform amplitudes. Bipolar electrodes with a contact separation distance of 0.5 mm resulted in the briefest onset response on average. Furthermore, the data presented in this study provide some insight into a biophysical explanation for the onset response. These data suggest that the onset response consists of two different phases: one phase which is responsive to experimental variables such as electrode geometry and waveform amplitude, and one which is not and appears to be inherent to the transition to the blocked state. This study has implications for nerve block electrode and stimulation parameter selection for clinical therapy systems and basic neurophysiology studies.
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Affiliation(s)
- D Michael Ackermann
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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Gerges M, Foldes EL, Ackermann DM, Bhadra N, Bhadra N, Kilgore KL. Frequency- and amplitude-transitioned waveforms mitigate the onset response in high-frequency nerve block. J Neural Eng 2010; 7:066003. [PMID: 20966536 DOI: 10.1088/1741-2560/7/6/066003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
High-frequency alternating currents (HFAC) have proven to be a reversible and rapid method of blocking peripheral nerve conduction, holding promise for treatment of disorders associated with undesirable neuronal activity. The delivery of HFAC is characterized by a transient period of neural firing at its inception, termed the 'onset response'. The onset response is minimized for higher frequencies and higher amplitudes, but requires larger currents. However, the complete block can be maintained at lower frequencies and amplitudes, using lower currents. In this in vivo study on whole mammalian peripheral nerves, we demonstrate a method to minimize the onset response by initiating the block using a stimulation paradigm with a high frequency and large amplitude, and then transitioning to a low-frequency and low-amplitude waveform, reducing the currents required to maintain the conduction block. In five of six animals, it was possible to transition from a 30 kHz to a 10 kHz waveform without inducing any transient neural firing. The minimum transition time was 0.03 s. Transition activity was minimized or eliminated with longer transition times. The results of this study show that this method is feasible for achieving a nerve block with minimal onset responses and current amplitude requirements.
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Conduction block of whole nerve without onset firing using combined high frequency and direct current. Med Biol Eng Comput 2010; 49:241-51. [PMID: 20890673 DOI: 10.1007/s11517-010-0679-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 09/11/2010] [Indexed: 10/19/2022]
Abstract
This study investigates a novel technique for blocking a nerve using a combination of direct and high frequency alternating currents (HFAC). HFAC can produce a fast acting and reversible conduction block, but cause intense firing at the onset of current delivery. We hypothesized that a direct current (DC) block could be used for a very brief period in combination with HFAC to block the onset firing, and thus establish a nerve conduction block which does not transmit onset response firing to an end organ. Experiments were performed in rats to evaluate (1) nerve response to anodic and cathodic DC of various amplitudes, (2) degree of nerve activation to ramped DC, (3) a method of blocking onset firing generated by high frequency block with DC, and (4) prolonged non-electrical conduction failure caused by DC delivery. The results showed that cathodic currents produced complete block of the sciatic nerve with a mean block threshold amplitude of 1.73 mA. Ramped DC waveforms allowed for conduction block without nerve activation; however, down ramps were more reliable than up ramps. The degree of nerve activity was found to have a non-monotonic relationship with up ramp time. Block of the onset response resulting from 40 kHz current using DC was achieved in each of the six animals in which it was attempted; however, DC was found to produce a prolonged conduction failure that likely resulted from nerve damage.
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Dowden BR, Wark HA, Normann RA. Muscle-selective block using intrafascicular high-frequency alternating current. Muscle Nerve 2010; 42:339-47. [DOI: 10.1002/mus.21678] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ackermann DM, Foldes EL, Bhadra N, Kilgore KL. Nerve conduction block using combined thermoelectric cooling and high frequency electrical stimulation. J Neurosci Methods 2010; 193:72-6. [PMID: 20705099 DOI: 10.1016/j.jneumeth.2010.07.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Revised: 07/30/2010] [Accepted: 07/31/2010] [Indexed: 10/19/2022]
Abstract
Conduction block of peripheral nerves is an important technique for many basic and applied neurophysiology studies. To date, there has not been a technique which provides a quickly initiated and reversible "on-demand" conduction block which is both sustainable for long periods of time and does not generate activity in the nerve at the onset of the conduction block. In this study we evaluated the feasibility of a combined method of nerve block which utilizes two well established nerve blocking techniques in a rat and cat model: nerve cooling and electrical block using high frequency alternating currents (HFAC). This combined method effectively makes use of the contrasting features of both nerve cooling and electrical block using HFAC. The conduction block was initiated using nerve cooling, a technique which does not produce nerve "onset response" firing, a prohibitive drawback of HFAC electrical block. The conduction block was then readily transitioned into an electrical block. A long-term electrical block is likely preferential to a long-term nerve cooling block because nerve cooling block generates large amounts of exhaust heat, does not allow for fiber diameter selectivity and is known to be unsafe for prolonged delivery.
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