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Forward and inverse electroencephalographic modeling in health and in acute traumatic brain injury. Clin Neurophysiol 2013; 124:2129-45. [PMID: 23746499 DOI: 10.1016/j.clinph.2013.04.336] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/04/2013] [Accepted: 04/17/2013] [Indexed: 11/20/2022]
Abstract
OBJECTIVE EEG source localization is demonstrated in three cases of acute traumatic brain injury (TBI) with progressive lesion loads using anatomically faithful models of the head which account for pathology. METHODS Multimodal magnetic resonance imaging (MRI) volumes were used to generate head models via the finite element method (FEM). A total of 25 tissue types-including 6 types accounting for pathology-were included. To determine the effects of TBI upon source localization accuracy, a minimum-norm operator was used to perform inverse localization and to determine the accuracy of the latter. RESULTS The importance of using a more comprehensive number of tissue types is confirmed in both health and in TBI. Pathology omission is found to cause substantial inaccuracies in EEG forward matrix calculations, with lead field sensitivity being underestimated by as much as ≈ 200% in (peri-) contusional regions when TBI-related changes are ignored. Failing to account for such conductivity changes is found to misestimate substantial localization error by up to 35 mm. CONCLUSIONS Changes in head conductivity profiles should be accounted for when performing EEG modeling in acute TBI. SIGNIFICANCE Given the challenges of inverse localization in TBI, this framework can benefit neurotrauma patients by providing useful insights on pathophysiology.
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Valente V, Demosthenous A, Bayford R. A tripolar current-steering stimulator ASIC for field shaping in deep brain stimulation. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2012; 6:197-207. [PMID: 23853142 DOI: 10.1109/tbcas.2011.2171036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A significant problem with clinical deep brain stimulation (DBS) is the high variability of its efficacy and the frequency of side effects, related to the spreading of current beyond the anatomical target area. This is the result of the lack of control that current DBS systems offer on the shaping of the electric potential distribution around the electrode. This paper presents a stimulator ASIC with a tripolar current-steering output stage, aiming at achieving more selectivity and field shaping than current DBS systems. The ASIC was fabricated in a 0.35-μ m CMOS technology occupying a core area of 0.71 mm(2). It consists of three current sourcing/sinking channels. It is capable of generating square and exponential-decay biphasic current pulses with five different time constants up to 28 ms and delivering up to 1.85 mA of cathodic current, in steps of 4 μA, from a 12 V power supply. Field shaping was validated by mapping the potential distribution when injecting current pulses through a multicontact DBS electrode in saline.
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Affiliation(s)
- Virgilio Valente
- Department of Electrical and Electronic Engineering, University College of London, London WC1E 7JE, UK.
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Kabakov AY, Muller PA, Pascual-Leone A, Jensen FE, Rotenberg A. Contribution of axonal orientation to pathway-dependent modulation of excitatory transmission by direct current stimulation in isolated rat hippocampus. J Neurophysiol 2012; 107:1881-9. [PMID: 22219028 PMCID: PMC3331663 DOI: 10.1152/jn.00715.2011] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 01/03/2012] [Indexed: 11/22/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) is a method for modulating cortical excitability by weak constant electrical current that is applied through scalp electrodes. Although often described in terms of anodal or cathodal stimulation, depending on which scalp electrode pole is proximal to the cortical region of interest, it is the orientation of neuronal structures relative to the direct current (DC) vector that determines the effect of tDCS. To investigate the contribution of neural pathway orientation, we studied DCS-mediated neuromodulation in an in vitro rat hippocampal slice preparation. We examined the contribution of dendritic orientation to the direct current stimulation (DCS) neuromodulatory effect by recording field excitatory postsynaptic potentials (fEPSPs) in apical and basal dendrites of CA1 neurons within a constant DC field. In addition, we assessed the contribution of axonal orientation by recording CA1 and CA3 apical fEPSPs generated by stimulation of oppositely oriented Schaffer collateral and mossy fiber axons, respectively, during DCS. Finally, nonsynaptic excitatory signal propagation was measured along antidromically stimulated CA1 axons at different DCS amplitudes and polarity. We find that modulation of both the fEPSP and population spike depends on axonal orientation relative to the electric field vector. Axonal orientation determines whether the DC field is excitatory or inhibitory and dendritic orientation affects the magnitude, but not the overall direction, of the DC effect. These data suggest that tDCS may oppositely affect neurons in a stimulated cortical volume if these neurons are excited by oppositely orientated axons in a constant electrical field.
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Affiliation(s)
- Anatoli Y Kabakov
- Department of Neurology, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115, USA
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Kuhn A, Keller T, Lawrence M, Morari M. The Influence of Electrode Size on Selectivity and Comfort in Transcutaneous Electrical Stimulation of the Forearm. IEEE Trans Neural Syst Rehabil Eng 2010; 18:255-62. [PMID: 20071267 DOI: 10.1109/tnsre.2009.2039807] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Andreas Kuhn
- Automatic Control Laboratory, ETH Zurich, 8092 Zurich, Switzerland
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Kuhn A, Keller T, Micera S, Morari M. Array electrode design for transcutaneous electrical stimulation: A simulation study. Med Eng Phys 2009; 31:945-51. [PMID: 19540788 DOI: 10.1016/j.medengphy.2009.05.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Revised: 04/29/2009] [Accepted: 05/01/2009] [Indexed: 11/29/2022]
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Rectal evacuation and antegrade colonic luminal transport by sacral anterior root stimulation in pigs. Dis Colon Rectum 2009; 52:1650-6. [PMID: 19690496 DOI: 10.1007/dcr.0b013e3181a872fb] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE Electrical sacral anterior root stimulation with a selective anodal block may relieve difficulties with bowel evacuation by selective colorectal activation and anal sphincter suppression. This study compares rectal evacuation induced by anodal block with that induced by unselective stimulation. METHODS The sacral anterior roots were stimulated with cuff electrodes in seven chloralose-anesthetized minipigs. Anodal block and unselective stimulation were applied in random order and compared by anorectal manometry and by the obtained colorectal evacuation. Evacuation was quantified scintigraphically after retrograde radioactive paste installation. RESULTS Unselective stimulation evoked sphincter activation which obstructed rectal evacuation during the 30-second stimulation period, after which poststimulation evacuation occurred (mean, 13%; P < 0.05). Anodal block reduced the anal canal pressure by median 83% compared with unselective stimulation. With unrestrained evacuation, a different evacuation pattern (mean, 18%; P < 0.05) occurred within the first ten seconds of the stimulation period and evacuated volume was higher (P = 0.08). Colonic evacuation reached a mean of 17% with unselective stimulation and 11% with anodal block. CONCLUSION Anodal block and unselective sacral root stimulation induce rectal evacuation and colonic luminal transport in pigs. However, anodal block may improve stimulation-induced defecation by enabling a near-physiologic defecation pattern.
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Kuhn A, Keller T, Lawrence M, Morari M. A model for transcutaneous current stimulation: simulations and experiments. Med Biol Eng Comput 2008; 47:279-89. [PMID: 19005714 DOI: 10.1007/s11517-008-0422-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 10/01/2008] [Indexed: 11/28/2022]
Abstract
Complex nerve models have been developed for describing the generation of action potentials in humans. Such nerve models have primarily been used to model implantable electrical stimulation systems, where the stimulation electrodes are close to the nerve (near-field). To address if these nerve models can also be used to model transcutaneous electrical stimulation (TES) (far-field), we have developed a TES model that comprises a volume conductor and different previously published non-linear nerve models. The volume conductor models the resistive and capacitive properties of electrodes, electrode-skin interface, skin, fat, muscle, and bone. The non-linear nerve models were used to conclude from the potential field within the volume conductor on nerve activation. A comparison of simulated and experimentally measured chronaxie values (a measure for the excitability of nerves) and muscle twitch forces on human volunteers allowed us to conclude that some of the published nerve models can be used in TES models. The presented TES model provides a first step to more extensive model implementations for TES in which e.g., multi-array electrode configurations can be tested.
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Affiliation(s)
- Andreas Kuhn
- Automatic Control Laboratory, ETH Zurich, Physikstrasse 3, 8092 Zurich, Switzerland.
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Demosthenous A, Donaldson N. An Integrated Implantable Stimulator That is Fail-Safe Without Off-Chip Blocking-Capacitors. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2008; 2:231-244. [PMID: 23852972 DOI: 10.1109/tbcas.2008.2003199] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption compared to previous works. The current generator uses voltage-controlled resistors implemented by MOS transistors in the deep triode region. The second technique is a new stimulator output stage circuit with blocking-capacitor safety protection using a high-frequency current-switching (HFCS) technique. Unlike conventional stimulator output stage circuits for implantable functional electrical stimulation (FES) systems which require blocking-capacitors in the microfarad range, our proposed approach allows capacitance reduction to the picofarad range, thus the blocking-capacitors can be integrated on-chip. The prototype four-channel neural stimulator chip was fabricated in XFAB's 1-mum silicon-on-insulator CMOS technology and can operate from a power supply between 5-18 V. The stimulus current is generated by active charging and passive discharging. We obtained recordings of action potentials and a strength-duration curve from the sciatic nerve of a frog with the stimulator chip which demonstrate the HFCS technique. The average power consumption for a typical 1-mA 20-Hz single-channel stimulation using a book electrode, is 200 muW from a 6 V power supply. The silicon area occupation is 0.38 mm(2) per channel.
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Jarvis JC, Rijkhoff NJM. Functional Electrical Stimulation for Control of Internal Organ Function. Neuromodulation 2008; 4:155-64. [DOI: 10.1046/j.1525-1403.2001.00155.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Vuckovic A, Tosato M, Struijk JJ. A comparative study of three techniques for diameter selective fiber activation in the vagal nerve: anodal block, depolarizing prepulses and slowly rising pulses. J Neural Eng 2008; 5:275-86. [DOI: 10.1088/1741-2560/5/3/002] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Jacquir S, Fruitet J, Guiraud D, Clerc M. Computation of the electrical potential inside the nerve induced by an electrical stimulus. ACTA ACUST UNITED AC 2008; 2007:1711-4. [PMID: 18002305 DOI: 10.1109/iembs.2007.4352639] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aim is to investigate the activation conditions of the different nerves which control the bladder. The selective stimulation of the nerve fibers depends on electrode configuration and intensity of applied current. The goal of this study is to compute the electrical potential inside the nerve due to an applied boundary currents. A symmetrically cylindrical model, representing the geometry and electrical conductivity of a nerve surrounded by a connective tissue and a cuff is used. In the quasistatic approximation, the problem can be modeled by a Poisson equation with Neumann boundary conditions. A symmetric boundary integral formulation is discretized using mixed finite elements. We can thus compute an electrical potential distribution depending on the electrode configuration and the applied current inside a nerve. Our results show that the distribution of the electrical potential inside a nerve or a fascicle depends on the geometry of the electrode and the shape of the applied current.
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Affiliation(s)
- Sabir Jacquir
- Odyssée Laboratory-ENPC/ENS/INRIA, 2004 Route des Lucioles, BP93, 06902, Sophia-Antipolis, France.
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Gordon AT, Zou SP, Kim Y, Gharibo C. Challenges to Setting Spinal Cord Stimulator Parameters During Intraoperative Testing: Factors Affecting Coverage of Low Back and Leg Pain. Neuromodulation 2007; 10:133-41. [DOI: 10.1111/j.1525-1403.2007.00101.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Hu Y, Xie XB, Pang LY, Li XH, Luk KDK. Current density distribution under surface electrode on posterior tibial nerve electrical stimulation. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2005:3650-2. [PMID: 17281018 DOI: 10.1109/iembs.2005.1617273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Electrical stimulation on the posterior tibial nerve is commonly used in the measurement of somatosensory evoked potential (SEP). To improve the efficiency of stimulation, the potential field and current density distributions under the surface electrodes were simulated with a three layer theoretical model. The mirror method was used to analyze the potential field of point charge. Integration of the field and the stimulus area provide the potential field for one surface electric pole. Potential field distribution of the bipolar electrodes was calculated by superimposition of two unipolar fields. Finally, the current density distribution was calculated by Laplace equation. An analytical solution of the potential field was obtained; thereafter the numerical solution of the current density distribution was calculated. The potential field and current density distribution were simulated by 2-D plot. From the model and simulation, the potential and current density distributions were not found to be evenly distributed under transcutaneous stimulation electrode and the maximum current density is located under the poles. The result suggests that bipolar stimulator should be applied axially along the stimulated nerve course.
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Affiliation(s)
- Yong Hu
- Institute of Biomedical Engineering, Chinese Academy Of Medical Sciences and Peking Union Medical College; Department of Orthopaedics and Traumatology, The University of Hong Kong. E-mail:
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Hennings K, Kamavuako EN, Farina D. The recruitment order of electrically activated motor neurons investigated with a novel collision technique. Clin Neurophysiol 2006; 118:283-91. [PMID: 17174598 DOI: 10.1016/j.clinph.2006.10.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 09/12/2006] [Accepted: 10/25/2006] [Indexed: 11/21/2022]
Abstract
OBJECTIVE The development of a novel collision technique for assessment of the activation order of electrically activated nerve fibers, which is an important question in functional electrical therapy or for interpretation of results of motor unit number estimates. METHODS Compound muscle action potentials were recorded with the belly-tendon configuration from the abductor digiti minimi. A novel modified Hopf's collision technique was applied on ten healthy male subjects to determine the distributions of conduction velocities (DCV) of all ulnar nerve fibers and of the fibers activated by electrical stimuli eliciting 20%, 50%, and 80% of the maximal muscle response. RESULTS The maximum nerve conduction velocity was (means+/-SE) 64.1+/-0.85m/s. The median conduction velocity of estimated DCV was 58.9+/-0.97m/s (stimulus at 20%), 58.0+/-0.98m/s (50%), 57.2+/-0.91m/s (80%), and 56.5+/-0.84m/s (whole nerve) (all different between each other, P<0.001). CONCLUSIONS The proposed collision technique allows the assessment of nerve conduction velocity distributions at maximal and sub-maximal stimulation levels and provided evidence for an inverse activation order of nerve fibers with electrical stimulation. SIGNIFICANCE The excessive fatigue seen with nerve electrical stimulation can be explained by a preferential activation of large diameter nerve fibers. The motor units first activated with electrical stimulation are likely not representative of the motor unit pool in the muscle, which poses limitations in the reliability of some of the proposed methods for motor unit counting.
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Affiliation(s)
- Kristian Hennings
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-2, DK-9220 Aalborg, Denmark
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Patolsky F, Timko BP, Yu G, Fang Y, Greytak AB, Zheng G, Lieber CM. Detection, Stimulation, and Inhibition of Neuronal Signals with High-Density Nanowire Transistor Arrays. Science 2006; 313:1100-4. [PMID: 16931757 DOI: 10.1126/science.1128640] [Citation(s) in RCA: 477] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report electrical properties of hybrid structures consisting of arrays of nanowire field-effect transistors integrated with the individual axons and dendrites of live mammalian neurons, where each nanoscale junction can be used for spatially resolved, highly sensitive detection, stimulation, and/or inhibition of neuronal signal propagation. Arrays of nanowire-neuron junctions enable simultaneous measurement of the rate, amplitude, and shape of signals propagating along individual axons and dendrites. The configuration of nanowire-axon junctions in arrays, as both inputs and outputs, makes possible controlled studies of partial to complete inhibition of signal propagation by both local electrical and chemical stimuli. In addition, nanowire-axon junction arrays were integrated and tested at a level of at least 50 "artificial synapses" per neuron.
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Affiliation(s)
- Fernando Patolsky
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
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Abstract
A commonly used simple spiking cell model is modified for extracellular current activation. It is proposed to simplify the simulation of a myelinated fiber nerve cell at the electrode-tissue interface by substituting for the activation site(s) identified with a more complex neuron model.
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Affiliation(s)
- Mark E Robert
- 'In silico et fibro' ltd., P.O. Box 342, Pasadena, CA 91102, USA.
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Gaunt RA, Prochazka A. Control of urinary bladder function with devices: successes and failures. PROGRESS IN BRAIN RESEARCH 2006; 152:163-94. [PMID: 16198700 DOI: 10.1016/s0079-6123(05)52011-9] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The management of urinary tract dysfunction is crucial for the health and well-being of people with spinal cord injury. Devices, specifically catheters, play an important role in the daily regime of bladder management for most people with spinal cord injury. However, the high incidence of complications associated with the use of catheters, and the fact that the spinal segments involved in lower urinary tract control remain intact in most cord-injured people, continue to motivate research into devices that could harness the nervous system to provide greater control over lower urinary tract function. Mechanical devices discussed in this review include catheters, artificial urethral sphincters, urethral stents and intraurethral pumps. Additionally, many attempts to restore control of the lower urinary tract with electrical stimulation have been made. Stimulation sites have included: inside the bladder, bladder wall, thigh, pelvic floor, dorsal penile nerve, pelvic nerve, tibial nerve, sacral roots, sacral nerves and spinal cord. Catheters and sacral root stimulators are two techniques whose efficacy is well established. Some approaches have proven less successful and others are still in the development stage. Modifications to sacral root stimulation including posterior root stimulation, anodal blockade and high-frequency blockade as well as new techniques including intraspinal microstimulation, urethral afferent stimulation and injectable microstimulators are also discussed. No single device has yet restored the control and function of the lower urinary tract to the pre-injury state, but new techniques are bringing this possibility closer to reality.
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Affiliation(s)
- Robert A Gaunt
- Department of Biomedical Engineering and Center for Neuroscience, University of Alberta, 507 HMRC, Edmonton, AB T6G 2S2, Canada
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Vucković A, Struijk JJ, Rijkhoff NJM. Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study. Med Biol Eng Comput 2005; 43:365-74. [PMID: 16035225 DOI: 10.1007/bf02345814] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aim of the study was to investigate how variable fibre geometry influences the excitation and blocking threshold of an undulating peripheral nerve fibre. The sensitivity of the excitation and blocking thresholds of the nerve fibres to various geometric and stimulation parameters was examined. The nerve fibres had a spiral shape (defined by the undulation wavelength, undulation amplitude and phase), and the internodal length varied. Diameter-selective stimulation of nerve fibres was obtained using anodal block. Simulation was performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a model of a peripheral undulating human nerve fibre to simulate the fibre response to stimulation. The excitation threshold of the undulating fibres was up to 100% higher than the excitation threshold of the straight fibres. When a nerve was stimulated with long pulses, which are typically applied for anodal block (> 400 micros), the blocking threshold of the undulating fibres was up to four times higher than the blocking threshold of the straight fibres. Dependencies of the excitation threshold on geometric and stimulation parameters were the same as for a straight fibre. Dependencies of the blocking threshold on geometric and stimulation parameters were different compared with a straight fibre. Owing to the fibre undulation and variable internodal length, the blocking threshold and the minimum pulse duration to obtain anodal block were generally different in the proximal and distal directions. Owing to variable fibre geometry, the excitation threshold varied by up to +/- 40% of the mean value, and the blocking threshold varied by up to +/- 60 % of the mean value. Owing to undulation, the blocking threshold of large fibres could be higher than the blocking threshold of small-diameter fibres, even if they had the same geometry. The results indicate that, during skeletal muscle stretching and contracting or during variation in joint angle, the excitation and blocking thresholds of the nerve fibres change owing to variations in fibre geometry. A straight fibre model could be too simple for modelling the response of peripheral nerve fibres to electrical stimulation.
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Affiliation(s)
- A Vucković
- Center for Sensory-Motor Interaction (SMI), Department of Health Science & Technology, Aalborg University, Aalborg, Denmark.
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Andersen IS, Rijkhoff NJM, Vukovic A, Buntzen S, Djurhuus JC, Laurberg S. Anorectal motility responses to selective stimulation of the ventral sacral nerve roots in an experimental model. Br J Surg 2005; 92:1513-9. [PMID: 16273528 DOI: 10.1002/bjs.4987] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract
Background
Control of defaecation and continence may be lost in patients with spinal cord injury. Electrical stimulation of sacral nerve roots to promote defaecation simultaneously activates both the rectum and the external anal sphincter (EAS), and may actually obstruct defaecation. The aim of this study was to investigate whether the EAS could be blocked selectively by selective stimulation of the ventral sacral nerve roots, and whether activation of the rectum without activation of the EAS could be obtained by stimulation of the ventral sacral nerve roots.
Methods
Selective electrical stimulation was performed using anodal blocking, a tripolar cuff electrode and monophasic rectangular current pulses applied to the sacral nerve roots in nine Göttingen minipigs.
Results
Simultaneous responses in the rectum and the anal canal were observed in five animals, whereas only anal responses were noted in four. Variations in cross-sectional area and an increase in rectal pressure seemed to facilitate defaecation. Without blocking, the increase in anal canal pressure was 16–45 cmH2O. With blocking, this increase was abolished in seven and reduced to 3–6 cmH2O in two animals.
Conclusion
Selective activation of the rectum is possible using an anodal block of somatic motor fibres. This technique holds promise in further development of electro-defaecation.
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Affiliation(s)
- I S Andersen
- Institute of Experimental Clinical Research, Skejby Sygehus, Aarhus University Hospital, Brendstrupgaardsvej, DK-8200 Aarhus N, Denmark.
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Hennings K, Arendt-Nielsen L, Christensen SS, Andersen OK. Selective activation of small-diameter motor fibres using exponentially rising waveforms: A theoretical study. Med Biol Eng Comput 2005; 43:493-500. [PMID: 16255432 DOI: 10.1007/bf02344731] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The present study investigated the possibility of using exponentially rising waveforms for selectively activating small motor fibres in a nerve bundle enclosed by a cuff electrode. Exponentially rising waveforms were studied using models of motor fibres and a volume conductor model. With an exponentially rising waveform (duration: 2 ms, time constant: 1 ms) large (15.5 microm) and small (8 microm) nerve fibres located at the edge of the nerve bundle had a current threshold of 125 microA and 53 microA, respectively. These reversals in the recruitment order of large and small nerve fibres located at the edge of the nerve bundle were observed for exponentially rising waveforms of 2, 4, and 6 ms in duration with time constants of 0.9, 0.6 and 0.6 ms, respectively. Reversals of the same nerve fibres located at the centre of the nerve bundle were observed for exponentially rising waveforms of 4 and 6 ms in duration, with a time constant of 0.6 ms for both waveforms. The underlying mechanism for selective activation of small nerve fibres with exponentially rising waveforms was found to be a combination of a decrease in the size of the local excitations in the centre node due to sodium channel inactivation and blocking of action potentials in large nerve fibres due to their larger difference in the membrane potential of adjacent nodes. The exponentially rising waveforms were compared with both rectangular prepulses and ramp prepulses. The rectangular prepulses were found to be unable selectively to activate small nerve fibres with the volume conductor model and criteria used in the present study, whereas the ramp prepulses performed as well as the exponentially rising waveforms. In conclusion, a novel stimulation paradigm has been proposed that may provide smooth, gradual control of muscle force with minimum fatigue.
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Affiliation(s)
- K Hennings
- Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
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Harney D, Magner JJ, O'Keeffe D. Complex regional pain syndrome: the case for spinal cord stimulation (a brief review). Injury 2005; 36:357-62. [PMID: 15710150 DOI: 10.1016/j.injury.2004.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/26/2004] [Indexed: 02/02/2023]
Abstract
Complex regional pain syndrome is a disabling disorder with an unknown mechanism which is extremely resistant to conventional pharmaceutical and therapeutic therapies. In this paper we present the underlying theories of this disorder. We present spinal cord stimulation as an alternative to conventional interventions in the management of this disabling condition spinal cord stimulation significantly improves pain, reduces narcotic intake and improves activity levels and overall quality of life. There is now a significant body of evidence to support the utilization of spinal cord stimulation in the management of complex regional pain syndrome.
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Affiliation(s)
- D Harney
- Department of Anaesthesia Intensive Care and Pain Medicine, St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
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Vucković A, Rijkhoff NJM. Different pulse shapes for selective large fibre block in sacral nerve roots using a technique of anodal block: an experimental study. Med Biol Eng Comput 2005; 42:817-24. [PMID: 15587474 DOI: 10.1007/bf02345216] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The aim of this study was experimentally to investigate whether it is possible to reduce the charge per phase that is applied during selective large fibre block. Sacral roots in pigs were stimulated. Sacral roots contain large somatic nerve fibres and small parasympathetic nerve fibres. Large nerve fibres that innervate the external urethral and external anal sphincters were selectively blocked using a technique of anodal block. In that way, selective activation of the detrusor muscle and the rectum innervated by parasympathetic fibres could be obtained. The square stimulation pulse was replaced with three different pulse shapes that had the same duration as the square pulse and consisted of a depolarising prepulse and a blocking part of the pulse. Compared with the square pulse, the charge per phase needed for anodal block could be reduced with all three pulse shapes. Maximum reduction of the charge per pulse was 17+/-6%. A lower charge might make anodal block safer in long-term applications.
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Affiliation(s)
- A Vucković
- Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
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23
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Vucković A, Rijkhoff NJM, Struijk JJ. Different Pulse Shapes to Obtain Small Fiber Selective Activation by Anodal Blocking— A Simulation Study. IEEE Trans Biomed Eng 2004; 51:698-706. [PMID: 15132495 DOI: 10.1109/tbme.2004.826663] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study was to investigate whether it is possible to reduce a charge per pulse, which is needed for selective nerve stimulation. Simulation is performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a human fiber model to simulate the fiber response to simulation. Selective stimulation is obtained by anodal block. To obtain anodal block of large fibers, long square pulses (> 350 micros) with a relatively high currents (1-2.5 mA) are usually required. These pulses might not be safe for a long-term application because of a high charge per pulse. In this study, several pulse shapes are proposed that have less charge per pulse compared with the conventional square pulse and would therefore be safer in a chronic application. Compared with the conventional square pulse, it was possible to reduce the charge with all proposed pulse shapes, but the best results are obtained with a combination of a square depolarizing pulse and a blocking pulse. The charge per pulse was up to 32% less with that pulse shape than with a square pulse. Using a hyperpolarizing anodal prepulse preceding a square pulse, it was not possible to block nerve fibers in a whole nerve bundle and to obtain reduction of a charge per phase. Reduction of the charge could be achieved only with spatially selective blocking. The charge per phase was larger for the combination of a hyperpolarizing anodal prepulse and a two-step pulse than for the two-step pulse alone.
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Affiliation(s)
- Aleksandra Vucković
- Center for Sensory Motor Interaction, Aalborg University, DK-9220 Aalborg, Denmark.
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24
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Rijkhoff NJM. Comment on ?Selective block of urethral sphincter contraction using a modified Brindley electrode in sacral anterior root stimulation of the dog,? Neurourol Urodynam (2002) 21:502-510. Neurourol Urodyn 2004; 23:284-5. [PMID: 15098229 DOI: 10.1002/nau.10132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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25
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Deurloo KEI, Holsheimer J, Bergveld P. Fascicular Selectivity in Transverse Stimulation with a Nerve Cuff Electrode: A Theoretical Approach. Neuromodulation 2003; 6:258-69. [DOI: 10.1046/j.1525-1403.2003.03034.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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26
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Rijkhoff NJM. Comment on "Physiologic bladder evacuation with selective sacral root stimulation: sinusoidal signal and organ-specific frequency," Neurourol urodyn 2002;21:80-91. Neurourol Urodyn 2003; 22:183-4. [PMID: 12579637 DOI: 10.1002/nau.10102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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27
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Uranga A, Barniol N, Marín D, Villa R, Aguiló J. An Integrated Implantable Electrical Sacral Root Stimulator for Bladder Control. Neuromodulation 2003; 5:238-47. [DOI: 10.1046/j.1525-1403.2002.02034.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
To achieve selective electrical interfacing to the neural system it is necessary to approach neuronal elements on a scale of micrometers. This necessitates microtechnology fabrication and introduces the interdisciplinary field of neurotechnology, lying at the juncture of neuroscience with microtechnology. The neuroelectronic interface occurs where the membrane of a cell soma or axon meets a metal microelectrode surface. The seal between these may be narrow or may be leaky. In the latter case the surrounding volume conductor becomes part of the interface. Electrode design for successful interfacing, either for stimulation or recording, requires good understanding of membrane phenomena, natural and evoked action potential generation, volume conduction, and electrode behavior. Penetrating multimicroelectrodes have been produced as one-, two-, and three-dimensional arrays, mainly in silicon, glass, and metal microtechnology. Cuff electrodes circumvent a nerve; their selectivity aims at fascicles more than at nerve fibers. Other types of electrodes are regenerating sieves and cone-ingrowth electrodes. The latter may play a role in brain-computer interfaces. Planar substrate-embedded electrode arrays with cultured neural cells on top are used to study the activity and plasticity of developing neural networks. They also serve as substrates for future so-called cultured probes.
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Affiliation(s)
- Wim L C Rutten
- University of Twente, Biomedical Engineering Department, Faculty of Electrical Engineering & Institute for Biomedical Technology, 7500 AE Enschede, The Netherlands.
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29
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Jezernik S, Craggs M, Grill WM, Creasey G, Rijkhoff NJM. Electrical stimulation for the treatment of bladder dysfunction: current status and future possibilities. Neurol Res 2002; 24:413-30. [PMID: 12117310 DOI: 10.1179/016164102101200294] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Electrical stimulation of peripheral nerves can be used to cause muscle contraction, to activate reflexes, and to modulate some functions of the central nervous system (neuromodulation). If applied to the spinal cord or nerves controlling the lower urinary tract, electrical stimulation can produce bladder or sphincter contraction, produce micturition, and can be applied as a medical treatment in cases of incontinence and urinary retention. This article first reviews the history of electrical stimulation applied for treatment of bladder dysfunction and then focuses on the implantable Finetech-Brindley stimulator to produce bladder emptying, and on external and implantable neuromodulation systems for treatment of incontinence. We conclude by summarizing some recent research efforts including: (a) combined sacral posterior and anterior sacral root stimulator implant (SPARSI), (b) selective stimulation of nerve fibers for selective detrusor activation by sacral ventral root stimulation, (c) microstimulation of the spinal cord, and (d) a newly proposed closed-loop bladder neuroprosthesis to treat incontinence caused by bladder overactivity.
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Affiliation(s)
- Saso Jezernik
- Swiss Federal Institute of Technology ETHZ, Automatic Control Laboratory, Zürich.
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Abstract
The development of man-made systems to restore functional vision in the profoundly blind has recently undergone a renaissance that has been fueled by a combination of celebrity and government interest, advances in the field of bioengineering, and successes with existing neuroprosthetic systems. This chapter presents the underlying physiologic principles of artificial vision, discusses three contemporary approaches to restoring functional vision in the blind, and concludes by presenting several relevant questions to vision prostheses. While there has been significant progress in the individual components constituting an artificial vision system, the remaining challenge of integrating these components with each other and the nervous system does not lie strictly in the realm of neuroscience, medicine, or engineering but at the interface of all three. In spite of the apparent complexity of an artificial vision system, it is not unreasonable to be optimistic about its eventual success.
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Affiliation(s)
- E M Maynard
- Center for Neural Interfaces, Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA.
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31
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Stanton‐Hicks M. Spinal Cord Stimulation for the Management of Complex Regional Pain Syndromes. Neuromodulation 2002; 2:193-201. [DOI: 10.1046/j.1525-1403.1999.00193.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Michael Stanton‐Hicks
- Division of Anesthesiology and Critical Care Medicine, Pain Management and Research, The Cleveland Clinic Foundation, Cleveland, Ohio
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32
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Bugbee M, Donaldson NN, Lickel A, Rijkhoff NJ, Taylor J. An implant for chronic selective stimulation of nerves. Med Eng Phys 2001; 23:29-36. [PMID: 11344005 DOI: 10.1016/s1350-4533(01)00013-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
An implantable stimulator system has been developed for nerve stimulation. The system is capable of stimulating selectively, either by fibre position, fibre size or by sending action potentials in one direction only, based on the use of nerve cuffs. The stimulator produces either quasi-trapezoidal current pulses, to allow anodal blocking, or conventional rectangular-shaped current pulses, of amplitude 20 microA to 5 mA (in 20 microA steps) with duration of 16 micros to 1 ms (in 8 micros steps). For safety, both active and passive charge balancing is used. The amplitude of the active charge-balancing phase can be varied between 1/7 and 1/47 of the pulse amplitude. During manufacture, each implant is customised so as to drive either 6 quasi-tripolar (dipolar), 4 tripolar or 2 pentapolar cuffs. Possible applications of the device are: improved defaecation and bladder voiding after spinal cord injury, by stimulation of the sacral motor roots; neuromodulation to reduce hyperreflexia without concomitant muscle contractions; in stroke patients, to enable balanced inversion-eversion while dorsiflexing the ankle by stimulating the peroneal nerve. It may also be used in chronic animal experiments.This paper describes the implant system, its hardware and communication protocol, and shows results from in vitro tests of the device and the first acute anodal-blocking experiments in pigs.
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Affiliation(s)
- M Bugbee
- Department of Electronic and Electrical Engineering, University College London, Torrington Place, WC1E 7JE, London, UK.
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33
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Rijkhoff NJ, Wijkstra H, van Kerrebroeck PE, Debruyne FM. Urinary bladder control by electrical stimulation: review of electrical stimulation techniques in spinal cord injury. Neurourol Urodyn 2000; 16:39-53. [PMID: 9021789 DOI: 10.1002/(sici)1520-6777(1997)16:1<39::aid-nau6>3.0.co;2-f] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Evacuation of urine in paraplegics without the need for catheters would be possible when voiding could be induced by eliciting a bladder contraction. A challenging option to obtain detrusor contraction is electrical stimulation of the detrusor muscle or its motor nerves. This article reviews the 4 possible stimulation sites where stimulation would result in a detrusor contraction: the bladder wall, the pelvic nerves, the sacral roots, and the spinal cord. With respect to electrode application, sacral root stimulation is most attractive. However, in general, sacral root stimulation results in simultaneous activation of both the detrusor muscle and the urethral sphincter, leading to little or no voiding. Several methods are available to overcome the stimulation-induced detrusor-sphincter dyssynergia and allow urine evacuation. These methods, including poststimulus voiding, fatiguing of the sphincter, blocking pudendal nerve transmission, and selective stimulation techniques that allow selective detrusor activation by sacral root stimulation, are reviewed in this paper.
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Affiliation(s)
- N J Rijkhoff
- Department of Urology, University Hospital Nijmegen, The Netherlands
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34
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Arabi K, Sawan MA. Electronic design of a multichannel programmable implant for neuromuscular electrical stimulation. IEEE TRANSACTIONS ON REHABILITATION ENGINEERING : A PUBLICATION OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY 1999; 7:204-14. [PMID: 10391591 DOI: 10.1109/86.769411] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An advanced stimulator for neuromuscular stimulation of spinal cord injured patients has been developed. The stimulator is externally controlled and powered by a single encoded radio frequency carrier and has four independently controlled bipolar stimulation channels. It offers a wide range of reprogrammability and flexibility, and can be used in many neuromuscular electrical stimulation applications. The implant system is adaptable to patient's needs and to future developments in stimulation algorithms by reprogramming the stimulator. The stimulator is capable of generating a wide range of stimulation waveforms and stimulation patterns and therefore is very suitable for selective nerve stimulation techniques. The reliability of the implant has been increased by using a forward error detection and correction communication protocol and by designing the chip for structural testability based on scan test approach. Implemented testability scheme makes it possible to verify the complete functionality of the implant before and after implantation. The stimulators architecture is designed to be modular and therefore its different blocks can be reused as standard building blocks in the design and implementation of other neuromuscular prostheses. Design for low-power techniques have also been employed to reduce power consumption of the electronic circuitry.
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Affiliation(s)
- K Arabi
- Department of Electrical Engineering, Ecole de Technologie Supérieure, Montreal, P.Q., Canada
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35
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Hoekema R, Venner K, Struijk JJ, Holsheimer J. Multigrid solution of the potential field in modeling electrical nerve stimulation. COMPUTERS AND BIOMEDICAL RESEARCH, AN INTERNATIONAL JOURNAL 1998; 31:348-62. [PMID: 9790740 DOI: 10.1006/cbmr.1998.1486] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this paper, multilevel techniques are introduced as a fast numerical method to compute 3-D potential field in nerve stimulation configurations. It is shown that with these techniques the computing time is reduced significantly compared to conventional methods. Consequently, these techniques greatly enhance the possibilities for parameter studies and electrode design. Following a general description of the model of nerve stimulation configurations, the basic principles of multilevel solvers for the numerical solution of partial differential equations are briefly summarized. Subsequently, some essential elements for successful application are discussed. Finally, results are presented for the potential field in a nerve bundle induced by tripolar stimulation with a cuff electrode surrounding part of the nerve.
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Affiliation(s)
- R Hoekema
- Institute for Biomedical Technology, University of Twente, AE Enschede, 7500, The Netherlands
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36
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Abstract
Neuronal cells are unique within the organism. In addition to forming long-distance connections with other nerve cells and non-neuronal targets, they lose the ability to regenerate their neurites and to divide during maturation. Consequently, external violations like trauma or disease frequently lead to their disappearance and replacement by non-neuronal, and thus not properly functioning cells. The advent of microtechnology and construction of artificial implants prompted to create particular devices for specialised regions of the nervous system, in order to compensate for the loss of function. The scope of the present work is to review the current devices in connection with their applicability and functional perspectives. (1) Successful implants like the cochlea implant and peripherally implantable stimulators are discussed. (2) Less developed and not yet applicable devices like retinal or cortical implants are introduced, with particular emphasis given to the reasons for their failure to replace very complex functions like vision. (3) Material research is presented both from the technological aspect and from their biocompatibility as prerequisite of any implantation. (4) Finally, basic studies are presented, which deal with methods of shaping the implants, procedures of testing biocompatibility and modification of improving the interfaces between a technical device and the biological environment. The review ends by pointing to future perspectives in neuroimplantation and restoration of interrupted neuronal pathways.
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Affiliation(s)
- P Heiduschka
- University Eye Hospital Münster, Experimental Ophthalmology, Germany
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37
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Struijk JJ. The extracellular potential of a myelinated nerve fiber in an unbounded medium and in nerve cuff models. Biophys J 1997; 72:2457-69. [PMID: 9168022 PMCID: PMC1184444 DOI: 10.1016/s0006-3495(97)78890-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A model is presented for the calculation of single myelinated fiber action potentials in an unbounded homogeneous medium and in nerve cuff electrodes. The model consists of a fiber model, used to calculate the action currents at the nodes of Ranvier, and a cylindrically symmetrical volume conductor model in which the fiber's nodes are represented as point current sources. The extracellular action potentials were shown to remain unchanged if the fiber diameter and the volume conductor geometry are scaled by the same factor (principle of corresponding states), both in an unbounded homogeneous medium and in an inhomogeneous volume conductor. The influence of several cuff electrode parameters, among others, cuff length and cuff diameter, were studied, and the results were compared, where possible, with theoretical and experimental results as reported in the literature.
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Affiliation(s)
- J J Struijk
- Center for Sensory Motor Interaction, Aalborg University, Aalborg Ost, Denmark.
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38
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39
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40
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Rijkhoff NJ, Hendrikx LB, van Kerrebroeck PE, Debruyne FM, Wijkstra H. Selective detrusor activation by electrical stimulation of the human sacral nerve roots. Artif Organs 1997; 21:223-6. [PMID: 9148711 DOI: 10.1111/j.1525-1594.1997.tb04654.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to investigate the feasibility of selective detrusor activation without activation of the urethral sphincter by sacral root stimulation in patients. The sacral roots were stimulated using a tripolar electrode. An anodal block was used to prevent the urethral sphincter from contraction. Using square current pulses (700 microseconds, 6-7 mA), no increase in intraurethral pressure was measured, while a normal increase in intravesical pressure occurred. The minimum pulse duration to obtain a complete block was 550 microseconds. The study shows that anodal blocking of action potentials is possible in humans and can result in selective detrusor activation when used in sacral root stimulation.
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Affiliation(s)
- N J Rijkhoff
- Department of Urology, University Hospital Nijmegen, The Netherlands
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41
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Stanton-Hicks M, Salamon J. Stimulation of the central and peripheral nervous system for the control of pain. J Clin Neurophysiol 1997; 14:46-62. [PMID: 9013359 DOI: 10.1097/00004691-199701000-00004] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
After suffering some setbacks since its introduction in 1967, stimulation of the spinal and peripheral nervous systems has undergone rapid development in the last ten years. Based on principles enunciated in the Gate Control Hypothesis that was published in 1968, stimulation-produced analgesia [SPA] has been subjected to intensive laboratory and clinical investigation. Historically, most new clinical ideas in medicine have tended to follow a three-tiered course. Initial enthusiasm gives way to a reappraisal of the treatment or modality as side-effects or unanticipated problems arise. The last and third phase proceeds at a more measured pace as the treatment is refined by experience. This review is divided into three parts as it traces the progress of spinal cord stimulation [SCS] and peripheral nerve stimulation [PNS]. The review commences with a discussion of the theory of SCS and PNS, and is followed by early reports during which it became apparent that the modality is essentially only effective in the treatment of neuropathic pain. The last section describes the modern experience including efficacy in specific types of pain and concludes with recent accomplishments that dramatize the relief of pain which can be achieved in nonoperable peripheral vascular disease or myocardial ischemia. Over the years, a search for those transmitters that might be influenced by spinal cord stimulation focused on somatostatin, cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), neurotensin and other amines, although only substance "P" was implicated. More recently, in animal studies, evidence that GABA-ergic systems are affected may explain the frequent successful suppression of allodynia that follows spinal cord stimulation. During the past eight years, much attention has been directed to studies that use a chronic neuropathic pain model. While PNS held significant promise as a pain relieving modality, early electrode systems and their surgical implantation yielded variable results due to evolving technical and surgical skills. These results dramatically reduced the continued development of PNS, which then gave way to a preoccupation with SCS. Modern development of SCS with outcome studies, particularly in relation to failed back surgery syndrome [FBSS] and the outcome of peripheral nerve surgery for chronic regional pain syndromes, has earned both modalities a place in the ongoing management of patients with intractable neuropathic pain. The last section, dealing with pain of peripheral vascular and myocardial ischemia, is perhaps one of the more exciting developments in stimulation produced analgesia and as the papers discussed demonstrate, can provide a level of analgesia and efficacy that is unattainable by other treatment modalities. SCS and PNS has an important role to play in the management of conditions that are otherwise refractory to conservative or other conventional management.
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Affiliation(s)
- M Stanton-Hicks
- Anaesthesia Pain Management Center, Cleveland Clinic Foundation, OH 44195, USA
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42
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Jolly CN, Spelman FA, Clopton BM. Quadrupolar stimulation for Cochlear prostheses: modeling and experimental data. IEEE Trans Biomed Eng 1996; 43:857-65. [PMID: 9216159 DOI: 10.1109/10.508549] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cochlear implants are electrically driven in monopolar, bipolar, or common ground mode. Ideally, a quadrupolar mode is created with three colinear electrodes, where the outer poles are half the inverse polarity value of the center electrode. The resulting field is highly focused. Models of point sources show that the quadrupolar paradigm offers a greater choice of parameters to shape the field. Simulation with a lumped-parameter model of the cochlea confirms the focusing action of the quadrupole in the layers of the inner ear. Field measurements in saline solution and in the scala tympani of guinea pigs show that focusing occurs with the quadrupolar mode. It is conceivable that quadrupolar stimulation will affect the pitch place coding, reduce channel interaction and limit facial or tactile stimulation induced by current spread.
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Affiliation(s)
- C N Jolly
- Center for Bioengineering, University of Washington, Seattle 89195-7962, USA.
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43
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Rijkhoff NJ, Koldewijn EL, d'Hollosy W, Debruyne FM, Wijkstra H. Morphometric data of canine sacral nerve roots with reference to electrical sacral root stimulation. Neurourol Urodyn 1996; 15:235-48. [PMID: 8732990 DOI: 10.1002/(sici)1520-6777(1996)15:3<235::aid-nau8>3.0.co;2-g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Experiments to investigate restoration of lower urinary tract control by electrical stimulation of the sacral nerve roots are mostly performed on dogs, yet little morphometric data (such as canine root and fiber diameter distributions) are available. The aim of this study was to acquire morphometric data of the intradural canine sacral dorsal and ventral roots (S1-S3). Cross-sections of sacral roots of two beagle dogs were analyzed using a light microscope and image processing software. The cross-sectional area of each root was measured. The diameters of the fibers and the axons in the cross-sections of the S2 and S3 roots were measured and used to construct nerve fiber diameter frequency distribution histograms. The results show a unimodal diameter distribution for the dorsal roots and a bimodal distribution for the ventral roots. In addition the average ratio g of the axon diameter to fiber diameter was calculated for each root.
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Affiliation(s)
- N J Rijkhoff
- Department of Urology, University Hospital Nijmegen, The Netherlands
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44
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Goodall E, Kosterman L, Holsheimer J, Struijk J. Modeling study of activation and propagation delays during stimulation of peripheral nerve fibers with a tripolar cuff electrode. ACTA ACUST UNITED AC 1995. [DOI: 10.1109/86.413200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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45
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Acute animal studies on the use of an anodal block to reduce urethral resistance in sacral root stimulation. ACTA ACUST UNITED AC 1994. [DOI: 10.1109/86.313150] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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