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Caldas-Martinez S, Goswami C, Forssell M, Cao J, Barth AL, Grover P. Cell-specific effects of temporal interference stimulation on cortical function. Commun Biol 2024; 7:1076. [PMID: 39223260 DOI: 10.1038/s42003-024-06728-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 08/13/2024] [Indexed: 09/04/2024] Open
Abstract
Temporal interference (TI) stimulation is a popular non-invasive neurostimulation technique that utilizes the following salient neural behavior: pure sinusoid (generated in off-target brain regions) appears to cause no stimulation, whereas modulated sinusoid (generated in target brain regions) does. To understand its effects and mechanisms, we examine responses of different cell types, excitatory pyramidal (Pyr) and inhibitory parvalbumin-expressing (PV) neurons, to pure and modulated sinusoids, in intact network as well as in isolation. In intact network, we present data showing that PV neurons are much less likely than Pyr neurons to exhibit TI stimulation. Remarkably, in isolation, our data shows that almost all Pyr neurons stop exhibiting TI stimulation. We conclude that TI stimulation is largely a network phenomenon. Indeed, PV neurons actively inhibit Pyr neurons in the off-target regions due to pure sinusoids (in off-target regions) generating much higher PV firing rates than modulated sinusoids in the target regions. Additionally, we use computational studies to support and extend our experimental observations.
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Affiliation(s)
| | - Chaitanya Goswami
- Electrical & Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Mats Forssell
- Electrical & Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Jiaming Cao
- School of Computer Science, University of Birmingham, Birmingham, UK
| | - Alison L Barth
- Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Pulkit Grover
- Electrical & Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
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2
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Waataja JJ, Honda CN, Asp AJ, Nihilani RK, Farajidavar A. The Duration and Intensity of High Frequency Alternating Current Influences the Degree and Recovery of Nerve Conduction Block. IEEE Trans Biomed Eng 2024; 71:2170-2179. [PMID: 38335073 DOI: 10.1109/tbme.2024.3364350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
OBJECTIVE The purpose of this paper is to investigate the persistence of nerve blockade beyond the duration of applying high frequency alternating current (HFAC) to thinly myelinated and non-myelinated fibers, also termed a "carry-over effect". METHODS In this study, we used electrically-evoked compound action potentials from isolated rat vagus nerves to assess the influence of 5 kHz HFAC amplitude and duration on the degree of the carry-over effect. Current amplitudes from 1-10 mA and 5 kHz durations from 10-120 seconds were tested. RESULTS By testing 20 different combinations of 5 kHz amplitude and duration, we found a significant interaction between 5 kHz amplitude and duration on influencing the carry-over effect. CONCLUSION The degree of carry-over effect was dependent on 5 kHz amplitude, as well as duration. SIGNIFICANCE Utilizing the carry-over effect may be useful in designing energy efficient nerve blocking algorithms for the treatment of diseases influenced by nerve activity.
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3
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Lee JI, Werginz P, Kameneva T, Im M, Fried SI. Membrane depolarization mediates both the inhibition of neural activity and cell-type-differences in response to high-frequency stimulation. Commun Biol 2024; 7:734. [PMID: 38890481 PMCID: PMC11189419 DOI: 10.1038/s42003-024-06359-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/20/2024] [Indexed: 06/20/2024] Open
Abstract
Neuromodulation using high frequency (>1 kHz) electric stimulation (HFS) enables preferential activation or inhibition of individual neural types, offering the possibility of more effective treatments across a broad spectrum of neurological diseases. To improve effectiveness, it is important to better understand the mechanisms governing activation and inhibition with HFS so that selectivity can be optimized. In this study, we measure the membrane potential (Vm) and spiking responses of ON and OFF α-sustained retinal ganglion cells (RGCs) to a wide range of stimulus frequencies (100-2500 Hz) and amplitudes (10-100 µA). Our findings indicate that HFS induces shifts in Vm, with both the strength and polarity of the shifts dependent on the stimulus conditions. Spiking responses in each cell directly correlate with the shifts in Vm, where strong depolarization leads to spiking suppression. Comparisons between the two cell types reveal that ON cells are more depolarized by a given amplitude of HFS than OFF cells-this sensitivity difference enables the selective targeting. Computational modeling indicates that ion-channel dynamics largely account for the shifts in Vm, suggesting that a better understanding of the differences in ion-channel properties across cell types may improve the selectivity and ultimately, enhance HFS-based neurostimulation strategies.
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Affiliation(s)
- Jae-Ik Lee
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Paul Werginz
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Tatiana Kameneva
- School of Science, Computing, and Engineering Technologies, Swinburne University of Technology, Hawthorn, VIC, Australia
- Department of Biomedical Engineering, University of Melbourne, Parkville, VIC, Australia
| | - Maesoon Im
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
- KHU-KIST Department of Converging Science and Technology, Kyung Hee University, Seoul, Republic of Korea
| | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Boston VA Healthcare System, Rehabilitation, Research and Development, Boston, MA, USA
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4
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Conde SV, Sacramento JF, Zinno C, Mazzoni A, Micera S, Guarino MP. Bioelectronic modulation of carotid sinus nerve to treat type 2 diabetes: current knowledge and future perspectives. Front Neurosci 2024; 18:1378473. [PMID: 38646610 PMCID: PMC11026613 DOI: 10.3389/fnins.2024.1378473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 03/26/2024] [Indexed: 04/23/2024] Open
Abstract
Bioelectronic medicine are an emerging class of treatments aiming to modulate body nervous activity to correct pathological conditions and restore health. Recently, it was shown that the high frequency electrical neuromodulation of the carotid sinus nerve (CSN), a small branch of the glossopharyngeal nerve that connects the carotid body (CB) to the brain, restores metabolic function in type 2 diabetes (T2D) animal models highlighting its potential as a new therapeutic modality to treat metabolic diseases in humans. In this manuscript, we review the current knowledge supporting the use of neuromodulation of the CSN to treat T2D and discuss the future perspectives for its clinical application. Firstly, we review in a concise manner the role of CB chemoreceptors and of CSN in the pathogenesis of metabolic diseases. Secondly, we describe the findings supporting the potential therapeutic use of the neuromodulation of CSN to treat T2D, as well as the feasibility and reversibility of this approach. A third section is devoted to point up the advances in the neural decoding of CSN activity, in particular in metabolic disease states, that will allow the development of closed-loop approaches to deliver personalized and adjustable treatments with minimal side effects. And finally, we discuss the findings supporting the assessment of CB activity in metabolic disease patients to screen the individuals that will benefit therapeutically from this bioelectronic approach in the future.
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Affiliation(s)
- Silvia V. Conde
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Joana F. Sacramento
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Ciro Zinno
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Alberto Mazzoni
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Silvestro Micera
- The BioRobotics Institute Scuola Superiore Sant’Anna, Pontedera, Italy
| | - Maria P. Guarino
- ciTechCare, School of Health Sciences Polytechnic of Leiria, Leiria, Portugal
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5
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Ye H, Dima M, Hall V, Hendee J. Cellular mechanisms underlying carry-over effects after magnetic stimulation. Sci Rep 2024; 14:5167. [PMID: 38431662 PMCID: PMC10908793 DOI: 10.1038/s41598-024-55915-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 02/28/2024] [Indexed: 03/05/2024] Open
Abstract
Magnetic fields are widely used for neuromodulation in clinical settings. The intended effect of magnetic stimulation is that neural activity resumes its pre-stimulation state right after stimulation. Many theoretical and experimental works have focused on the cellular and molecular basis of the acute neural response to magnetic field. However, effects of magnetic stimulation can still last after the termination of the magnetic stimulation (named "carry-over effects"), which could generate profound effects to the outcome of the stimulation. However, the cellular and molecular mechanisms of carry-over effects are largely unknown, which renders the neural modulation practice using magnetic stimulation unpredictable. Here, we investigated carry-over effects at the cellular level, using the combination of micro-magnetic stimulation (µMS), electrophysiology, and computation modeling. We found that high frequency magnetic stimulation could lead to immediate neural inhibition in ganglion neurons from Aplysia californica, as well as persistent, carry-over inhibition after withdrawing the magnetic stimulus. Carry-over effects were found in the neurons that fired action potentials under a variety of conditions. The carry-over effects were also observed in the neurons when the magnetic field was applied across the ganglion sheath. The state of the neuron, specifically synaptic input and membrane potential fluctuation, plays a significant role in generating the carry-over effects after magnetic stimulation. To elucidate the cellular mechanisms of such carry-over effects under magnetic stimulation, we simulated a single neuron under magnetic stimulation with multi-compartment modeling. The model successfully replicated the carry-over effects in the neuron, and revealed that the carry-over effect was due to the dysfunction of the ion channel dynamics that were responsible for the initiation and sustaining of membrane excitability. A virtual voltage-clamp experiment revealed a compromised Na conductance and enhanced K conductance post magnetic stimulation, rendering the neurons incapable of generating action potentials and, therefore, leading to the carry over effects. Finally, both simulation and experimental results demonstrated that the carry-over effects could be controlled by disturbing the membrane potential during the post-stimulus inhibition period. Delineating the cellular and ion channel mechanisms underlying carry-over effects could provide insights to the clinical outcomes in brain stimulation using TMS and other modalities. This research incentivizes the development of novel neural engineering or pharmacological approaches to better control the carry-over effects for optimized clinical outcomes.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA.
| | - Maria Dima
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
| | - Vincent Hall
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
| | - Jenna Hendee
- Department of Biology, Loyola University Chicago, Quinlan Life Sciences Education and Research Center, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA
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6
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Park D, Kim Y. Kilohertz-frequency interferential current induces hypoalgesic effects more comfortably than TENS. Sci Rep 2023; 13:8644. [PMID: 37244893 DOI: 10.1038/s41598-023-35489-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 05/18/2023] [Indexed: 05/29/2023] Open
Abstract
Recent research on transcutaneous electrical stimulation has shown that inhibiting nerve conduction with a kilohertz frequency is both effective and safe. This study primarily aims to demonstrate the hypoalgesic effect on the tibial nerve using transcutaneous interferential-current nerve inhibition (TINI), which injects the kilohertz frequency produced by the interferential currents. Additionally, the secondary objective was to compare the analgesic effect and comfort of TINI and transcutaneous electrical nerve stimulation (TENS). Thirty-one healthy adults participated in this cross-over repeated measures study. The washout period was set to 24 h or more. Stimulus intensity was set just below the pain threshold level. TINI and TENS were applied for 20 min each. The ankle passive dorsiflexion range of motion, pressure pain threshold (PPT), and tactile threshold were measured at the baseline, pre-test, test (immediately before ceasing intervention), and post-test (30 min after ceasing intervention) sessions. After the interventions, the participants evaluated the level of discomfort for TINI and TENS on a 10 cm visual analog scale (VAS). As the results, PPT significantly increased compared to baseline in test and posttest sessions of TINI, but not in those of TENS. Also, participants reported that TENS was 36% more discomfort than TINI. The hypoalgesic effect was not significantly different between TINI and TENS. In conclusion, we found that TINI inhibited mechanical pain sensitivity and that the inhibitory effect persisted long after electrical stimulation ceased. Our study also shows that TINI provides the hypoalgesic effect more comfortably than TENS.
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Affiliation(s)
- Dahoon Park
- Department of Sports Rehabilitation, Cheongju University, Cheongju, South Korea
| | - Yushin Kim
- Department of Sports Rehabilitation, Cheongju University, Cheongju, South Korea.
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7
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Zhong Y, Wang J, Beckel J, de Groat WC, Tai C. Mechanisms Underlying Poststimulation Block Induced by High-Frequency Biphasic Stimulation. Neuromodulation 2023; 26:577-588. [PMID: 34278654 PMCID: PMC8766610 DOI: 10.1111/ner.13501] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/30/2021] [Accepted: 06/21/2021] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To reveal the possible mechanisms underlying poststimulation block induced by high-frequency biphasic stimulation (HFBS). MATERIALS AND METHODS A new axonal conduction model is developed for unmyelinated axons. This new model is different from the classical axonal conduction model by including both ion concentrations and membrane ion pumps to allow analysis of axonal responses to long-duration stimulation. Using the new model, the post-HFBS block phenomenon reported in animal studies is simulated and analyzed for a wide range of stimulation frequencies (100 Hz-10 kHz). RESULTS HFBS can significantly change the Na+ and K+ concentrations inside and outside the axon to produce a post-HFBS block of either short-duration (<500 msec) or long-duration (>3 sec) depending on the duration of HFBS. The short-duration block is due to the fast recovery of the Na+ and K+ concentrations outside the axon in periaxonal space by diffusion of ions into and from the large extracellular space, while the long-duration block is due to the slow restoration of the normal Na+ concentration inside the axon by membrane ion pumps. The 100 Hz HFBS requires the minimal electrical energy to achieve the post-HFBS block, while the 10 kHz stimulation is the least effective frequency requiring high intensity and long duration to achieve the block. CONCLUSION This study reveals two possible ionic mechanisms underlying post-HFBS block of axonal conduction. Understanding these mechanisms is important for improving clinical applications of HFBS block and for developing new nerve block methods employing HFBS.
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Affiliation(s)
- Yihua Zhong
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Jicheng Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jonathan Beckel
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Changfeng Tai
- Department of Urology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
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8
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Kamelian Rad M, Ahmadi-Pajouh MA, Saviz M. Selective electrical stimulation of low versus high diameter myelinated fibers and its application in pain relief: a modeling study. J Math Biol 2022; 86:3. [PMID: 36436158 DOI: 10.1007/s00285-022-01833-0] [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: 06/21/2022] [Revised: 10/29/2022] [Accepted: 11/04/2022] [Indexed: 11/29/2022]
Abstract
Electrical stimulation of peripheral nerve fibers has always been an attractive field of research. Due to the higher activation threshold, the stimulation of small fibers is accompanied by the stimulation of larger ones. It is therefore necessary to design a specific stimulation theme in order to only activate narrow fibers. There is evidence that stimulating Aδ fibers can activate endogenous pain-relieving mechanisms. However, both selective stimulation and reducing pain by activating small nociceptive fibers are still poorly investigated. In this study, using high-frequency stimulation waveforms (5-20 kHz), computational modeling provides a simple framework for activating narrow nociceptive fibers. Additionally, a model of myelinated nerve fibers is modified by including sodium-potassium pump and investigating its effects on neuronal stimulation. Besides, a modified mathematical model of pain processing circuits in the dorsal horn is presented that consists of supraspinal pain control mechanisms. Hence, by employing this pain-modulating model, the mechanism of the reduction of pain by activating nociceptive fibers is explored. In the case of two fibers with the same distance from the point source electrode, a single stimulation waveform is capable of blocking one large fiber and stimulating another small fiber. Noteworthy, the Na/K pump model demonstrated that it does not have a significant effect on the activation threshold and firing frequency of fiber. Ultimately, results suggest that the descending pathways of Locus coeruleus may effectively contribute to pain relief through stimulation of nociceptive fibers, which will be beneficial for clinical interventions.
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Affiliation(s)
- Mohsen Kamelian Rad
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | | | - Mehrdad Saviz
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
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9
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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.
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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
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10
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Cellular mechanisms underlying state-dependent neural inhibition with magnetic stimulation. Sci Rep 2022; 12:12131. [PMID: 35840656 PMCID: PMC9287388 DOI: 10.1038/s41598-022-16494-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 07/11/2022] [Indexed: 12/29/2022] Open
Abstract
Novel stimulation protocols for neuromodulation with magnetic fields are explored in clinical and laboratory settings. Recent evidence suggests that the activation state of the nervous system plays a significant role in the outcome of magnetic stimulation, but the underlying cellular and molecular mechanisms of state-dependency have not been completely investigated. We recently reported that high frequency magnetic stimulation could inhibit neural activity when the neuron was in a low active state. In this paper, we investigate state-dependent neural modulation by applying a magnetic field to single neurons, using the novel micro-coil technology. High frequency magnetic stimulation suppressed single neuron activity in a state-dependent manner. It inhibited neurons in slow-firing states, but spared neurons from fast-firing states, when the same magnetic stimuli were applied. Using a multi-compartment NEURON model, we found that dynamics of voltage-dependent sodium and potassium channels were significantly altered by the magnetic stimulation in the slow-firing neurons, but not in the fast-firing neurons. Variability in neural activity should be monitored and explored to optimize the outcome of magnetic stimulation in basic laboratory research and clinical practice. If selective stimulation can be programmed to match the appropriate neural state, prosthetic implants and brain-machine interfaces can be designed based on these concepts to achieve optimal results.
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11
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Rapeaux A, Constandinou TG. HFAC Dose Repetition and Accumulation Leads to Progressively Longer Block Carryover Effect in Rat Sciatic Nerve. Front Neurosci 2022; 16:852166. [PMID: 35712453 PMCID: PMC9197154 DOI: 10.3389/fnins.2022.852166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
This paper describes high-frequency nerve block experiments carried out on rat sciatic nerves to measure the speed of recovery of A fibres from block carryover. Block carryover is the process by which nerve excitability remains suppressed temporarily after High Frequency Alternative (HFAC) block is turned off following its application. In this series of experiments 5 rat sciatic nerves were extracted and prepared for ex-vivo stimulation and recording in a specially designed perfusion chamber. For each nerve repeated HFAC block and concurrent stimulation trials were carried out to observe block carryover after signal shutoff. The nerve was allowed to recover fully between each trial. Time to recovery from block was measured by monitoring for when relative nerve activity returned to within 90% of baseline levels measured at the start of each trial. HFAC block carryover duration was found to be dependent on accumulated dose by statistical test for two different HFAC durations. The carryover property of HFAC block on A fibres could enable selective stimulation of autonomic nerve fibres such as C fibres for the duration of carryover. Block carryover is particularly relevant to potential chronic clinical applications of block as it reduces power requirements for stimulation to provide the blocking effect. This work characterizes this process toward the creation of a model describing its behavior.
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Affiliation(s)
- Adrien Rapeaux
- Next Generation Neural Interfaces Lab, Centre for Bioinspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom.,Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
| | - Timothy G Constandinou
- Next Generation Neural Interfaces Lab, Centre for Bioinspired Technology, Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom.,Care Research and Technology Centre, UK Dementia Research Institute, London, United Kingdom
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12
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Eggers T, Kilgore J, Green D, Vrabec T, Kilgore K, Bhadra N. Combining direct current and kilohertz frequency alternating current to mitigate onset activity during electrical nerve block. J Neural Eng 2021; 18. [PMID: 33662942 PMCID: PMC9511888 DOI: 10.1088/1741-2552/abebed] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 03/04/2021] [Indexed: 11/12/2022]
Abstract
Objective. Electrical nerve block offers the ability to immediately and reversibly block peripheral nerve conduction and would have applications in the emerging field of bioelectronics. Two modalities of electrical nerve block have been investigated—kilohertz frequency alternating current (KHFAC) and direct current (DC). KHFAC can be safely delivered with conventional electrodes, but has the disadvantage of having an onset response, which is a period of increased neural activation before block is established and currently limits clinical translation. DC has long been known to block neural conduction without an onset response but creates damaging reactive species. Typical electrodes can safely deliver DC for less than one second, but advances in high capacitance electrodes allow DC delivery up to 10 s without damage. The present work aimed to combine DC and KHFAC into a single waveform, named the combined reduced onset waveform (CROW), which can initiate block without an onset response while also maintaining safe block for long durations. This waveform consists of a short, DC pre-pulse before initiating KHFAC. Approach. Simulations of this novel waveform were carried out in the axonal simulation environment NEURON to test feasibility and gain insight into the mechanisms of action. Two sets of acute experiments were then conducted in adult Sprague–Dawley rats to determine the effectiveness of the waveform in mitigating the onset response. Main results. The CROW reduced the onset response both in silico and in vivo. The onset area was reduced by over 90% with the tested parameters in the acute experiments. The amplitude of the DC pulse was shown to be particularly important for effective onset mitigation, requiring amplitudes 6–8 times the DC block threshold. Significance. This waveform can reliably reduce the onset response due to KHFAC and could allow for wider clinical implementation of electrical nerve block.
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Affiliation(s)
- Thomas Eggers
- Emory University School of Medicine, Atlanta, GA, United States of America
| | - Joseph Kilgore
- MetroHealth Medical Center, Cleveland, OH, United States of America
| | - David Green
- MetroHealth Medical Center, Cleveland, OH, United States of America
| | - Tina Vrabec
- MetroHealth Medical Center, Cleveland, OH, United States of America
| | - Kevin Kilgore
- MetroHealth Medical Center, Cleveland, OH, United States of America.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.,Louis Stokes Cleveland Department Veterans Affairs Medical Center, Cleveland, OH, United States of America
| | - Niloy Bhadra
- MetroHealth Medical Center, Cleveland, OH, United States of America
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13
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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: 32] [Impact Index Per Article: 10.7] [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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Non-monotonic kilohertz frequency neural block thresholds arise from amplitude- and frequency-dependent charge imbalance. Sci Rep 2021; 11:5077. [PMID: 33658552 PMCID: PMC7930193 DOI: 10.1038/s41598-021-84503-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 02/17/2021] [Indexed: 12/17/2022] Open
Abstract
Reversible block of nerve conduction using kilohertz frequency electrical signals has substantial potential for treatment of disease. However, the ability to block nerve fibers selectively is limited by poor understanding of the relationship between waveform parameters and the nerve fibers that are blocked. Previous in vivo studies reported non-monotonic relationships between block signal frequency and block threshold, suggesting the potential for fiber-selective block. However, the mechanisms of non-monotonic block thresholds were unclear, and these findings were not replicated in a subsequent in vivo study. We used high-fidelity computational models and in vivo experiments in anesthetized rats to show that non-monotonic threshold-frequency relationships do occur, that they result from amplitude- and frequency-dependent charge imbalances that cause a shift between kilohertz frequency and direct current block regimes, and that these relationships can differ across fiber diameters such that smaller fibers can be blocked at lower thresholds than larger fibers. These results reconcile previous contradictory studies, clarify the mechanisms of interaction between kilohertz frequency and direct current block, and demonstrate the potential for selective block of small fiber diameters.
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15
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Skach J, Conway C, Barrett L, Ye H. Axonal blockage with microscopic magnetic stimulation. Sci Rep 2020; 10:18030. [PMID: 33093520 PMCID: PMC7582966 DOI: 10.1038/s41598-020-74891-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/05/2020] [Indexed: 12/27/2022] Open
Abstract
Numerous neurological dysfunctions are characterized by undesirable nerve activity. By providing reversible nerve blockage, electric stimulation with an implanted electrode holds promise in the treatment of these conditions. However, there are several limitations to its application, including poor bio-compatibility and decreased efficacy during chronic implantation. A magnetic coil of miniature size can mitigate some of these problems, by coating it with biocompatible material for chronic implantation. However, it is unknown if miniature coils could be effective in axonal blockage and, if so, what the underlying mechanisms are. Here we demonstrate that a submillimeter magnetic coil can reversibly block action potentials in the unmyelinated axons from the marine mollusk Aplysia californica. Using a multi-compartment model of the Aplysia axon, we demonstrate that the miniature coil causes a significant local depolarization in the axon, alters activation dynamics of the sodium channels, and prevents the traveling of the invading action potentials. With improved biocompatibility and capability of emitting high-frequency stimuli, micro coils provide an interesting alternative for electric blockage of axonal conductance in clinical settings.
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Affiliation(s)
- Jordan Skach
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Catherine Conway
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Lauryn Barrett
- Department of Biology, Loyola University Chicago, Chicago, IL, USA
| | - Hui Ye
- Department of Biology, Loyola University Chicago, Chicago, IL, USA. .,Department of Biology, Quinlan Life Sciences Education and Research Center, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL, 60660, USA.
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16
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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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17
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Li Q, Lu T, Zhang C, Hansen MR, Li S. Electrical stimulation induces synaptic changes in the peripheral auditory system. J Comp Neurol 2019; 528:893-905. [PMID: 31658367 DOI: 10.1002/cne.24802] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 09/24/2019] [Accepted: 10/12/2019] [Indexed: 12/13/2022]
Abstract
Since a rapidly increasing number of neurostimulation devices are used clinically to modulate specific neural functions, the impact of electrical stimulation on targeted neural structure and function has become a key issue. In particular, the specific effect of electrical stimulation via a cochlear implant (CI) on inner hair cell (IHC) synapses remains unclear. Importantly, CI candidacy has recently expanded to include patients with partial hearing loss. Unfortunately, some CI recipients experience progressive hearing loss after activation of electrical stimulation. The mechanism(s) accounting for loss of residual hearing following electrical stimulation is unknown. Here normal-hearing guinea pigs were implanted with customized CIs. Intracochlear electrical stimulation with an intensity equal to or above electrically evoked compound action potential (ECAP) threshold decreased the excitability of auditory nerve. Furthermore, the number of synapses between IHCs and the afferent spiral ganglion neurons (SGNs) also decreased after electrical stimulation with higher intensities. However, no significant change was observed in the packing density and perikaryal area of SGNs as well as the quantity of hair cells. These results carry important implications for use of CIs in patients with residual hearing and for an increasing number of patients treated with other neurostimulation devices. Notably, the results were based on acute electrical stimulation. Considering the complex interaction between CIs and targeted tissues, it is urgent to conduct further research to clarify whether the similar changes could be induced by chronic electrical stimulation.
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Affiliation(s)
- Qiang Li
- Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Tianhao Lu
- Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Chen Zhang
- Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, Iowa
| | - Shufeng Li
- Department of Otolaryngology & Head-Neck Surgery, Eye & ENT Hospital of Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China
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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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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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20
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Anderson RW, Farokhniaee A, Gunalan K, Howell B, McIntyre CC. Action potential initiation, propagation, and cortical invasion in the hyperdirect pathway during subthalamic deep brain stimulation. Brain Stimul 2018; 11:1140-1150. [PMID: 29779963 DOI: 10.1016/j.brs.2018.05.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/05/2018] [Accepted: 05/10/2018] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND High frequency (∼130 Hz) deep brain stimulation (DBS) of the subthalamic region is an established clinical therapy for the treatment of late stage Parkinson's disease (PD). Direct modulation of the hyperdirect pathway, defined as cortical layer V pyramidal neurons that send an axon collateral to the subthalamic nucleus (STN), has emerged as a possible component of the therapeutic mechanisms. However, numerous questions remain to be addressed on the basic biophysics of hyperdirect pathway stimulation. OBJECTIVE Quantify action potential (AP) initiation, propagation, and cortical invasion in hyperdirect neurons during subthalamic stimulation. METHODS We developed an anatomically and electrically detailed computational model of hyperdirect neuron stimulation with explicit representation of the stimulating electric field, axonal response, AP propagation, and synaptic transmission. RESULTS We found robust AP propagation throughout the complex axonal arbor of the hyperdirect neuron. Even at therapeutic DBS frequencies, stimulation induced APs could reach all of the intracortical axon terminals with ∼100% fidelity. The functional result of this high frequency axonal driving of the thousands of synaptic connections made by each directly stimulated hyperdirect neuron is a profound synaptic suppression that would effectively disconnect the neuron from the cortical circuitry. CONCLUSIONS The synaptic suppression hypothesis integrates the fundamental biophysics of electrical stimulation, axonal transmission, and synaptic physiology to explain a generic mechanism of DBS.
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Affiliation(s)
- Ross W Anderson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - AmirAli Farokhniaee
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Kabilar Gunalan
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Bryan Howell
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Cameron C McIntyre
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Lesperance LS, Lankarany M, Zhang TC, Esteller R, Ratté S, Prescott SA. Artifactual hyperpolarization during extracellular electrical stimulation: Proposed mechanism of high-rate neuromodulation disproved. Brain Stimul 2018; 11:582-591. [DOI: 10.1016/j.brs.2017.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 12/07/2017] [Accepted: 12/11/2017] [Indexed: 01/18/2023] Open
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22
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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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23
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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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Bhadra N, Vrabec TL, Bhadra N, Kilgore KL. Reversible conduction block in peripheral nerve using electrical waveforms. BIOELECTRONICS IN MEDICINE 2018; 1:39-54. [PMID: 29480897 PMCID: PMC5811084 DOI: 10.2217/bem-2017-0004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 11/15/2017] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Electrical nerve block uses electrical waveforms to block action potential propagation. MATERIALS & METHODS Two key features that distinguish electrical nerve block from other nonelectrical means of nerve block: block occurs instantly, typically within 1 s; and block is fully and rapidly reversible (within seconds). RESULTS Approaches for achieving electrical nerve block are reviewed, including kilohertz frequency alternating current and charge-balanced polarizing current. We conclude with a discussion of the future directions of electrical nerve block. CONCLUSION Electrical nerve block is an emerging technique that has many significant advantages over other methods of nerve block. This field is still in its infancy, but a significant expansion in the clinical application of this technique is expected in the coming years.
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Affiliation(s)
- Niloy Bhadra
- Department of Physical Medicine & Rehabilitation, MetroHealth Medical Center, Cleveland, OH 44109, USA
| | - Tina L Vrabec
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Narendra Bhadra
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Kevin L Kilgore
- Department of Orthopaedics, MetroHealth Medical Center & Case Western Reserve University, Cleveland, OH 44109, USA
- Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA
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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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Pelot NA, Behrend CE, Grill WM. Modeling the response of small myelinated axons in a compound nerve to kilohertz frequency signals. J Neural Eng 2017; 14:046022. [PMID: 28361793 PMCID: PMC5677574 DOI: 10.1088/1741-2552/aa6a5f] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE There is growing interest in electrical neuromodulation of peripheral nerves, particularly autonomic nerves, to treat various diseases. Electrical signals in the kilohertz frequency (KHF) range can produce different responses, including conduction block. For example, EnteroMedics' vBloc® therapy for obesity delivers 5 kHz stimulation to block the abdominal vagus nerves, but the mechanisms of action are unclear. APPROACH We developed a two-part computational model, coupling a 3D finite element model of a cuff electrode around the human abdominal vagus nerve with biophysically-realistic electrical circuit equivalent (cable) model axons (1, 2, and 5.7 µm in diameter). We developed an automated algorithm to classify conduction responses as subthreshold (transmission), KHF-evoked activity (excitation), or block. We quantified neural responses across kilohertz frequencies (5-20 kHz), amplitudes (1-8 mA), and electrode designs. MAIN RESULTS We found heterogeneous conduction responses across the modeled nerve trunk, both for a given parameter set and across parameter sets, although most suprathreshold responses were excitation, rather than block. The firing patterns were irregular near transmission and block boundaries, but otherwise regular, and mean firing rates varied with electrode-fibre distance. Further, we identified excitation responses at amplitudes above block threshold, termed 're-excitation', arising from action potentials initiated at virtual cathodes. Excitation and block thresholds decreased with smaller electrode-fibre distances, larger fibre diameters, and lower kilohertz frequencies. A point source model predicted a larger fraction of blocked fibres and greater change of threshold with distance as compared to the realistic cuff and nerve model. SIGNIFICANCE Our findings of widespread asynchronous KHF-evoked activity suggest that conduction block in the abdominal vagus nerves is unlikely with current clinical parameters. Our results indicate that compound neural or downstream muscle force recordings may be unreliable as quantitative measures of neural activity for in vivo studies or as biomarkers in closed-loop clinical devices.
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Affiliation(s)
- N A Pelot
- Department of Biomedical Engineering, Duke University, Room 1427, Fitzpatrick CIEMAS, 101 Science Drive, Campus Box 90281, Durham, NC 27708, United States of America
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Buckley U, Chui RW, Rajendran PS, Vrabec T, Shivkumar K, Ardell JL. Bioelectronic neuromodulation of the paravertebral cardiac efferent sympathetic outflow and its effect on ventricular electrical indices. Heart Rhythm 2017; 14:1063-1070. [PMID: 28219848 DOI: 10.1016/j.hrthm.2017.02.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND Neuromodulation of the paravertebral ganglia by using symmetric voltage controlled kilohertz frequency alternating current (KHFAC) has the potential to be a reversible alternative to surgical intervention in patients with refractory ventricular arrhythmias. KHFAC creates scalable focal inhibition of action potential conduction. OBJECTIVE The purpose of this article was to evaluate the efficacy of KHFAC when applied to the T1-T2 paravertebral chain to mitigate sympathetic outflow to the heart. METHODS In anesthetized, vagotomized, porcine subjects, the heart was exposed via a midline sternotomy along with paravertebral chain ganglia. The T3 paravertebral ganglion was electrically stimulated, and activation recovery intervals (ARIs) were obtained from a 56-electrode sock placed over both ventricles. A bipolar Ag electrode was wrapped around the paravertebral chain between T1 and T2 and connected to a symmetric voltage controlled KHFAC generator. A comparison of cardiac indices during T3 stimulation conditions, with and without KHFAC, provided a measure of block efficacy. RESULTS Right-sided T3 stimulation (at 4 Hz) was titrated to produce reproducible ARI changes from baseline (52 ± 30 ms). KHFAC resulted in a 67% mitigation of T3 electrical stimulation effects on ARI (18.5 ± 22 ms; P < .005). T3 stimulation repeated after KHFAC produced equivalent ARI changes as control. KHFAC evoked a transient functional sympathoexcitation at onset that was inversely related to frequency and directly related to intensity. The optimum block threshold was 15 kHz and 15 V. CONCLUSION KHFAC applied to nexus (convergence) points of the cardiac nervous system produces a graded and reversible block of underlying axons. As such, KHFAC has the therapeutic potential for on-demand and reversible mitigation of sympathoexcitation.
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Affiliation(s)
- Una Buckley
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, California
| | - Ray W Chui
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, California; Molecular, Cellular, & Integrative Physiology Program, UCLA, Los Angeles, California
| | - Pradeep S Rajendran
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, California; Molecular, Cellular, & Integrative Physiology Program, UCLA, Los Angeles, California
| | - Tina Vrabec
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Kalyanam Shivkumar
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, California; Molecular, Cellular, & Integrative Physiology Program, UCLA, Los Angeles, California
| | - Jeffrey L Ardell
- University of California - Los Angeles (UCLA) Cardiac Arrhythmia Center, David Geffen School of Medicine, Los Angeles, California; UCLA Neurocardiology Research Center of Excellence, David Geffen School of Medicine, Los Angeles, California; Molecular, Cellular, & Integrative Physiology Program, UCLA, Los Angeles, California.
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Bicket MC, Dunn RY, Ahmed SU. High-Frequency Spinal Cord Stimulation for Chronic Pain: Pre-Clinical Overview and Systematic Review of Controlled Trials. PAIN MEDICINE 2016; 17:2326-2336. [PMID: 28025366 DOI: 10.1093/pm/pnw156] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To assess the evidence base for high-frequency spinal cord stimulation (HFSCS). HFSCS has the potential to provide paresthesia-free pain relief for patients with chronic pain, in contrast to conventional spinal cord stimulation, which produces distracting and potentially unpleasant paresthesias. DESIGN A systematic review following standard methodological guidelines (Prospero #CRD42015029215). METHODS We searched PubMed to March 14, 2016 without language restriction and hand-checked reference lists. Two authors independently performed study selection, bias evaluations, and data extraction. The pre-clinical review selected studies focusing on the mechanism and non-human experience with HFSCS. Clinically, any prospective study of adults using HFSCS (≥ 1000 Hz) was included. RESULTS Pre-clinical studies have characterized many aspects underlying the mechanism of HFSCS. For the clinical systematic review, eight trials (236 participants randomized or 160 followed prospectively) met inclusion criteria. All trials of HFSCS focused on patients with chronic low back pain with one exception, which included patients with chronic migraine. All but one trial documented funding by industry. Performance bias due to unmasked participants, physicians, and outcome assessors limited the quality of all but one study. CONCLUSIONS Significant growth in the preclinical and clinical evidence base for HFSCS suggests that HFSCS may differ from conventional SCS in mechanism of action and efficacy of treatment, respectively. Addressing current knowledge gaps in clinical evidence will require standardization in trial reporting and leveraging the paresthesia-free characteristic of HFSCS to enable masking in high-quality randomized controlled trials.
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Affiliation(s)
- Mark C Bicket
- *Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Roger Y Dunn
- Tufts University School of Medicine, Boston, Massachusetts
| | - Shihab U Ahmed
- Department of Anesthesiology, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
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Arle JE, Mei L, Carlson KW, Shils JL. High-Frequency Stimulation of Dorsal Column Axons: Potential Underlying Mechanism of Paresthesia-Free Neuropathic Pain Relief. Neuromodulation 2016; 19:385-97. [DOI: 10.1111/ner.12436] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 02/22/2016] [Accepted: 03/02/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Jeffrey E. Arle
- Department of Neurosurgery; Beth Israel Deaconess Medical Center; Boston MA USA
- Department of Neurosurgery; Harvard Medical School; Boston MA USA
| | - Longzhi Mei
- Department of Neurosurgery; Beth Israel Deaconess Medical Center; Boston MA USA
| | - Kristen W. Carlson
- Department of Neurosurgery; Beth Israel Deaconess Medical Center; Boston MA USA
| | - Jay L. Shils
- Department of Anesthesiology; Rush University Medical Center; Chicago IL USA
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Kameneva T, Maturana MI, Hadjinicolaou AE, Cloherty SL, Ibbotson MR, Grayden DB, Burkitt AN, Meffin H. Retinal ganglion cells: mechanisms underlying depolarization block and differential responses to high frequency electrical stimulation of ON and OFF cells. J Neural Eng 2016; 13:016017. [DOI: 10.1088/1741-2560/13/1/016017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Howell B, Medina LE, Grill WM. Effects of frequency-dependent membrane capacitance on neural excitability. J Neural Eng 2015; 12:056015-56015. [PMID: 26348707 DOI: 10.1088/1741-2560/12/5/056015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Models of excitable cells consider the membrane specific capacitance as a ubiquitous and constant parameter. However, experimental measurements show that the membrane capacitance declines with increasing frequency, i.e., exhibits dispersion. We quantified the effects of frequency-dependent membrane capacitance, c(f), on the excitability of cells and nerve fibers across the frequency range from dc to hundreds of kilohertz. APPROACH We implemented a model of c(f) using linear circuit elements, and incorporated it into several models of neurons with different channel kinetics: the Hodgkin-Huxley model of an unmyelinated axon, the McIntyre-Richardson-Grill (MRG) of a mammalian myelinated axon, and a model of a cortical neuron from prefrontal cortex (PFC). We calculated thresholds for excitation and kHz frequency conduction block, the conduction velocity, recovery cycle, strength-distance relationship and firing rate. MAIN RESULTS The impact of c(f) on activation thresholds depended on the stimulation waveform and channel kinetics. We observed no effect using rectangular pulse stimulation, and a reduction for frequencies of 10 kHz and above using sinusoidal signals only for the MRG model. c(f) had minimal impact on the recovery cycle and the strength-distance relationship, whereas the conduction velocity increased by up to 7.9% and 1.7% for myelinated and unmyelinated fibers, respectively. Block thresholds declined moderately when incorporating c(f), the effect was greater at higher frequencies, and the maximum reduction was 11.5%. Finally, c(f) marginally altered the firing pattern of a model of a PFC cell, reducing the median interspike interval by less than 2%. SIGNIFICANCE This is the first comprehensive analysis of the effects of dispersive capacitance on neural excitability, and as the interest on stimulation with kHz signals gains more attention, it defines the regions over which frequency-dependent membrane capacitance, c(f), should be considered.
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Affiliation(s)
- Bryan Howell
- Duke University, Department of Biomedical Engineering, Durham, NC, USA
| | - Leonel E Medina
- Duke University, Department of Biomedical Engineering, Durham, NC, USA
| | - Warren M Grill
- Duke University, Department of Biomedical Engineering, Durham, NC, USA.,Duke University, Department of Electrical and Computer Engineering, Durham, NC, USA.,Duke University, Department of Neurobiology, Durham, NC, USA.,Duke University, Department of Surgery, Durham, NC, USA
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Computational analysis of kilohertz frequency spinal cord stimulation for chronic pain management. Anesthesiology 2015; 122:1362-76. [PMID: 25822589 DOI: 10.1097/aln.0000000000000649] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Kilohertz frequency spinal cord stimulation (KHFSCS) is an emerging therapy for treating refractory neuropathic pain. Although KHFSCS has the potential to improve the lives of patients experiencing debilitating pain, its mechanisms of action are unknown and thus it is difficult to optimize its development. Therefore, the goal of this study was to use a computer model to investigate the direct effects of KHFSCS on specific neural elements of the spinal cord. METHODS This computer model consisted of two main components: (1) finite element models of the electric field generated by KHFSCS and (2) multicompartment cable models of axons in the spinal cord. Model analysis permitted systematic investigation into a number of variables (e.g., dorsal cerebrospinal fluid thickness, lead location, fiber collateralization, and fiber size) and their corresponding effects on excitation and conduction block thresholds during KHFSCS. RESULTS The results of this study suggest that direct excitation of large-diameter dorsal column or dorsal root fibers require high stimulation amplitudes that are at the upper end or outside of the range used in clinical KHFSCS (i.e., 0.5 to 5 mA). Conduction block was only possible within the clinical range for a thin dorsal cerebrospinal fluid layer. CONCLUSIONS These results suggest that clinical KHFSCS may not function through direct activation or conduction block of dorsal column or dorsal root fibers. Although these results should be validated with further studies, the authors propose that additional concepts and/or alternative hypotheses should be considered when examining the pain relief mechanisms of KHFSCS.
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Zhao S, Yang G, Wang J, Roppolo JR, de Groat WC, Tai C. Conduction block in myelinated axons induced by high-frequency (kHz) non-symmetric biphasic stimulation. Front Comput Neurosci 2015. [PMID: 26217217 PMCID: PMC4491630 DOI: 10.3389/fncom.2015.00086] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study used the Frankenhaeuser-Huxley axonal model to analyze the effects of non-symmetric waveforms on conduction block of myelinated axons induced by high-frequency (10-300 kHz) biphasic electrical stimulation. The results predict a monotonic relationship between block threshold and stimulation frequency for symmetric waveform and a non-monotonic relationship for non-symmetric waveforms. The symmetric waveform causes conduction block by constantly activating both sodium and potassium channels at frequencies of 20-300 kHz, while the non-symmetric waveforms share the same blocking mechanism from 20 kHz up to the peak threshold frequency. At the frequencies above the peak threshold frequency the non-symmetric waveforms block axonal conduction by either hyperpolarizing the membrane (if the positive pulse is longer) or depolarizing the membrane (if the negative pulse is longer). This simulation study further increases our understanding of conduction block in myelinated axons induced by high-frequency biphasic electrical stimulation, and can guide future animal experiments as well as optimize stimulation parameters that might be used for electrically induced nerve block in clinical applications.
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Affiliation(s)
- Shouguo Zhao
- Department of Urology, University of Pittsburgh Pittsburgh, PA, USA ; Department of Biomedical Engineering, Beijing Jiaotong University Beijing, China
| | - Guangning Yang
- Department of Urology, University of Pittsburgh Pittsburgh, PA, USA ; Department of Biomedical Engineering, Beijing Jiaotong University Beijing, China
| | - Jicheng Wang
- Department of Urology, University of Pittsburgh Pittsburgh, PA, USA
| | - James R Roppolo
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Pittsburgh, PA, USA
| | - William C de Groat
- Department of Pharmacology and Chemical Biology, University of Pittsburgh Pittsburgh, PA, USA
| | - Changfeng Tai
- Department of Urology, University of Pittsburgh Pittsburgh, PA, USA ; Department of Pharmacology and Chemical Biology, University of Pittsburgh Pittsburgh, PA, USA
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Weinberg SH. High frequency stimulation of cardiac myocytes: a theoretical and computational study. CHAOS (WOODBURY, N.Y.) 2014; 24:043104. [PMID: 25554024 DOI: 10.1063/1.4897618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
High-frequency stimulation (HFS) has recently been identified as a novel approach for terminating life-threatening cardiac arrhythmias. HFS elevates myocyte membrane potential and blocks electrical conduction for the duration of the stimulus. However, low amplitude HFS can induce rapidly firing action potentials, which may reinitiate an arrhythmia. The cellular level mechanisms underlying HFS-induced electrical activity are not well understood. Using a multiscale method, we show that a minimal myocyte model qualitatively reproduces the influence of HFS on cardiac electrical activity. Theoretical analysis and simulations suggest that persistent activation and de-inactivation of ionic currents, in particular a fast inward window current, underlie HFS-induced action potentials and membrane potential elevation, providing hypotheses for future experiments. We derive analytical expressions to describe how HFS modifies ionic current amplitude and gating dynamics. We show how fast inward current parameters influence the parameter regimes for HFS-induced electrical activity, demonstrating how the efficacy of HFS as a therapy for terminating arrhythmias may depend on the presence of pathological conditions or pharmacological treatments. Finally, we demonstrate that HFS terminates cardiac arrhythmias in a one-dimensional ring of cardiac tissue. In this study, we demonstrate a novel approach to characterize the influence of HFS on ionic current gating dynamics, provide new insight into HFS of the myocardium, and suggest mechanisms underlying HFS-induced electrical activity.
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Affiliation(s)
- Seth H Weinberg
- Virginia Modeling, Analysis and Simulation Center, Old Dominion University, Suffolk, Virginia 23435, USA
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Medina LE, Grill WM. Volume conductor model of transcutaneous electrical stimulation with kilohertz signals. J Neural Eng 2014; 11:066012. [PMID: 25380254 DOI: 10.1088/1741-2560/11/6/066012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Incorporating high-frequency components in transcutaneous electrical stimulation (TES) waveforms may make it possible to stimulate deeper nerve fibers since the impedance of tissue declines with increasing frequency. However, the mechanisms of high-frequency TES remain largely unexplored. We investigated the properties of TES with frequencies beyond those typically used in neural stimulation. APPROACH We implemented a multilayer volume conductor model including dispersion and capacitive effects, coupled to a cable model of a nerve fiber. We simulated voltage- and current-controlled transcutaneous stimulation, and quantified the effects of frequency on the distribution of potentials and fiber excitation. We also quantified the effects of a novel transdermal amplitude modulated signal (TAMS) consisting of a non-zero offset sinusoidal carrier modulated by a square-pulse train. MAIN RESULTS The model revealed that high-frequency signals generated larger potentials at depth than did low frequencies, but this did not translate into lower stimulation thresholds. Both TAMS and conventional rectangular pulses activated more superficial fibers in addition to the deeper, target fibers, and at no frequency did we observe an inversion of the strength-distance relationship. Current regulated stimulation was more strongly influenced by fiber depth, whereas voltage regulated stimulation was more strongly influenced by skin thickness. Finally, our model reproduced the threshold-frequency relationship of experimentally measured motor thresholds. SIGNIFICANCE The model may be used for prediction of motor thresholds in TES, and contributes to the understanding of high-frequency TES.
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Affiliation(s)
- Leonel E Medina
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Franke M, Vrabec T, Wainright J, Bhadra N, Bhadra N, Kilgore K. Combined KHFAC + DC nerve block without onset or reduced nerve conductivity after block. J Neural Eng 2014; 11:056012. [PMID: 25115572 DOI: 10.1088/1741-2560/11/5/056012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Kilohertz frequency alternating current (KHFAC) waveforms have been shown to provide peripheral nerve conductivity block in many acute and chronic animal models. KHFAC nerve block could be used to address multiple disorders caused by neural over-activity, including blocking pain and spasticity. However, one drawback of KHFAC block is a transient activation of nerve fibers during the initiation of the nerve block, called the onset response. The objective of this study is to evaluate the feasibility of using charge balanced direct current (CBDC) waveforms to temporarily block motor nerve conductivity distally to the KHFAC electrodes to mitigate the block onset-response. APPROACH A total of eight animals were used in this study. A set of four animals were used to assess feasibility and reproducibility of a combined KHFAC + CBDC block. A following randomized study, conducted on a second set of four animals, compared the onset response resulting from KHFAC alone and combined KHFAC + CBDC waveforms. To quantify the onset, peak forces and the force-time integral were measured during KHFAC block initiation. Nerve conductivity was monitored throughout the study by comparing muscle twitch forces evoked by supra-maximal stimulation proximal and distal to the block electrodes. Each animal of the randomized study received at least 300 s (range: 318-1563 s) of cumulative dc to investigate the impact of combined KHFAC + CBDC on nerve viability. MAIN RESULTS The peak onset force was reduced significantly from 20.73 N (range: 18.6-26.5 N) with KHFAC alone to 0.45 N (range: 0.2-0.7 N) with the combined CBDC and KHFAC block waveform (p < 0.001). The area under the force curve was reduced from 6.8 Ns (range: 3.5-21.9 Ns) to 0.54 Ns (range: 0.18-0.86 Ns) (p < 0.01). No change in nerve conductivity was observed after application of the combined KHFAC + CBDC block relative to KHFAC waveforms. SIGNIFICANCE The distal application of CBDC can significantly reduce or even completely prevent the KHFAC onset response without a change in nerve conductivity.
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Affiliation(s)
- Manfred Franke
- Case Western Reserve University, Cleveland, OH, USA. Oculeve, Inc., South San Francisco, CA, USA
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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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