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Kundu A, Patrick E, Currlin S, Madler R, Delgado F, Fahmy A, Verplancke R, Ballini M, Braeken D, de Beeck MO, Maghari N, Otto KJ, Bashirullah R. Using Compound Neural Action Potentials for Functional Validation of a High-Density Intraneural Interface: A Preliminary Study. MICROMACHINES 2024; 15:280. [PMID: 38399008 PMCID: PMC10891740 DOI: 10.3390/mi15020280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/14/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024]
Abstract
Compound nerve action potentials (CNAPs) were used as a metric to assess the stimulation performance of a novel high-density, transverse, intrafascicular electrode in rat models. We show characteristic CNAPs recorded from distally implanted cuff electrodes. Evaluation of the CNAPs as a function of stimulus current and calculation of recruitment plots were used to obtain a qualitative approximation of the neural interface's placement and orientation inside the nerve. This method avoids elaborate surgeries required for the implantation of EMG electrodes and thus minimizes surgical complications and may accelerate the healing process of the implanted subject.
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Affiliation(s)
- Aritra Kundu
- Department of Bioengineering, Imperial College London, SW7 2AZ London, UK
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
| | - Erin Patrick
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
| | - Seth Currlin
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA (K.J.O.)
| | - Ryan Madler
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
| | - Francisco Delgado
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA (K.J.O.)
| | - Ahmed Fahmy
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
| | - Rik Verplancke
- Centre for Microsystems Technology (CMST), IMEC and Ghent University, 9052 Zwijnaarde, Belgium (M.O.d.B.)
| | | | | | - Maaike Op de Beeck
- Centre for Microsystems Technology (CMST), IMEC and Ghent University, 9052 Zwijnaarde, Belgium (M.O.d.B.)
- IMEC, Kapeldreef 75, 3001 Leuven, Belgium;
| | - Nima Maghari
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
| | - Kevin J. Otto
- Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA (K.J.O.)
| | - Rizwan Bashirullah
- Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL 32611, USA; (E.P.); (N.M.)
- Galvani Bioelectronics, South San Francisco, CA 94080, USA
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Holly NL, Hasse BA, Gothard KM, Fuglevand AJ. Large-scale intramuscular electrode system for chronic electromyography and functional electrical stimulation. J Neurophysiol 2022; 128:1011-1024. [PMID: 36129191 PMCID: PMC9550579 DOI: 10.1152/jn.00325.2022] [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: 07/29/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/22/2022] Open
Abstract
To understand how the central nervous system (CNS) enacts movements, it seems important to monitor the activities of the many muscles involved. Likewise, to restore complex movements to paralyzed limbs with electrical stimulation requires access to most limb muscles. Intramuscular electrodes are needed to obtain isolated recordings or stimulation of individual muscles. As such, we developed and tested the stability of large arrays of implanted intramuscular electrodes. We implanted 58 electrodes in 29 upper limb muscles in each of three macaques. Electrode connectors were protected within a skull-mounted chamber. During surgery, wires were tunneled subcutaneously to target muscles, where gold anchors were crimped onto the leads. The anchors were then deployed with an insertion device. In two monkeys, the chamber was fixed to the skull with a titanium baseplate rather than acrylic cement. In multiple sessions up to 15 wk after surgery, electromyographic (EMG) signals were recorded while monkeys made the same reaching movement. EMG signals were stable, with an average (SD) coefficient of variation across sessions of 0.24 ± 0.15. In addition, at 4, 8, and 16 wk after surgery, forces to incrementing stimulus pulses were measured for each electrode. The threshold current needed to evoke a response at 16 wk was not different from that at 4 wk. Likewise, peak force evoked by 16 mA of current at 16 wk was not different from 4 wk. The stability of this system implies it could be effectively used to monitor and stimulate large numbers of muscles needed to understand the control of natural and evoked movements.NEW AND NOTEWORTHY A new method was developed to enable long-lasting recording and stimulation of large numbers of muscles with intramuscular electrodes. Electromyographic signals and evoked force responses in 29 upper limb muscles remained stable over several months when tested in nonhuman primates. This system could be used effectively to monitor and stimulate numerous muscles needed to more fully understand the control of natural and evoked movements.
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Affiliation(s)
- Nicole L Holly
- Department of Physiology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Brady A Hasse
- Graduate Program in Neuroscience, University of Arizona, Tucson, Arizona
| | - Katalin M Gothard
- Department of Physiology, College of Medicine, University of Arizona, Tucson, Arizona
- Department of Neuroscience, University of Arizona, Tucson, Arizona
- Department of Neurology, College of Medicine, University of Arizona, Tucson, Arizona
| | - Andrew J Fuglevand
- Department of Physiology, College of Medicine, University of Arizona, Tucson, Arizona
- Department of Neuroscience, University of Arizona, Tucson, Arizona
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Hasse BA, Sheets DEG, Holly NL, Gothard KM, Fuglevand AJ. Restoration of complex movement in the paralyzed upper limb. J Neural Eng 2022; 19. [PMID: 35728568 DOI: 10.1088/1741-2552/ac7ad7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 06/21/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Functional electrical stimulation (FES) involves artificial activation of skeletal muscles to reinstate motor function in paralyzed individuals. While FES applied to the upper limb has improved the ability of tetraplegics to perform activities of daily living, there are key shortcomings impeding its widespread use. One major limitation is that the range of motor behaviors that can be generated is restricted to a small set of simple, preprogrammed movements. This limitation stems from the substantial difficulty in determining the patterns of stimulation across many muscles required to produce more complex movements. Therefore, the objective of this study was to use machine learning to flexibly identify patterns of muscle stimulation needed to evoke a wide array of multi-joint arm movements. APPROACH Arm kinematics and electromyographic activity from 29 muscles were recorded while a 'trainer' monkey made an extensive range of arm movements. Those data were used to train an artificial neural network that predicted patterns of muscle activity associated with a new set of movements. Those patterns were converted into trains of stimulus pulses that were delivered to upper limb muscles in two other temporarily paralyzed monkeys. RESULTS Machine-learning based prediction of EMG was good for within-subject predictions but appreciably poorer for across-subject predictions. Evoked responses matched the desired movements with good fidelity only in some cases. Means to mitigate errors associated with FES-evoked movements are discussed. SIGNIFICANCE Because the range of movements that can be produced with our approach is virtually unlimited, this system could greatly expand the repertoire of movements available to individuals with high level paralysis.
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Affiliation(s)
- Brady A Hasse
- Department of Physiology, The University of Arizona College of Medicine Tucson, 1501 N Campbell Avenue, Tucson, Arizona, 85724-5051, UNITED STATES
| | - Drew E G Sheets
- Department of Organismal Biology & Anatomy, University of Chicago Biological Sciences Division, Anatomy, 1027 E 57th Street Chicago, IL 60637, Chicago, Illinois, 60637-5416, UNITED STATES
| | - Nicole L Holly
- Physiology, The University of Arizona College of Medicine Tucson, 1501 N Campbell Avenue, Tucson, Arizona, 85724-5051, UNITED STATES
| | - Katalin M Gothard
- Physiology, The University of Arizona College of Medicine Tucson, 1501 N Campbell Ave, Tucson, Arizona, 85724-5051, UNITED STATES
| | - Andrew J Fuglevand
- Department of Physiology, University of Arizona, Arizona Health Sciences Center, 1501 N. Campbell Ave, Tucson, Arizona, 85724-5051, UNITED STATES
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Eiber CD, Payne SC, Biscola NP, Havton LA, Keast JR, Osborne PB, Fallon JB. Computational modelling of nerve stimulation and recording with peripheral visceral neural interfaces. J Neural Eng 2021; 18. [PMID: 34740201 DOI: 10.1088/1741-2552/ac36e2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 11/05/2021] [Indexed: 12/30/2022]
Abstract
Objective.Neuromodulation of visceral nerves is being intensively studied for treating a wide range of conditions, but effective translation requires increasing the efficacy and predictability of neural interface performance. Here we use computational models of rat visceral nerve to predict how neuroanatomical variability could affect both electrical stimulation and recording with an experimental planar neural interface.Approach.We developed a hybrid computational pipeline,VisceralNerveEnsembleRecording andStimulation (ViNERS), to couple finite-element modelling of extracellular electrical fields with biophysical simulations of individual axons. Anatomical properties of fascicles and axons in rat pelvic and vagus nerves were measured or obtained from public datasets. To validate ViNERS, we simulated pelvic nerve stimulation and recording with an experimental four-electrode planar array.Main results.Axon diameters measured from pelvic nerve were used to model a population of myelinated and unmyelinated axons and simulate recordings of electrically evoked single-unit field potentials (SUFPs). Across visceral nerve fascicles of increasing size, our simulations predicted an increase in stimulation threshold and a decrease in SUFP amplitude. Simulated threshold changes were dominated by changes in perineurium thickness, which correlates with fascicle diameter. We also demonstrated that ViNERS could simulate recordings of electrically-evoked compound action potentials (ECAPs) that were qualitatively similar to pelvic nerve recording made with the array used for simulation.Significance.We introduce ViNERS as a new open-source computational tool for modelling large-scale stimulation and recording from visceral nerves. ViNERS predicts how neuroanatomical variation in rat pelvic nerve affects stimulation and recording with an experimental planar electrode array. We show ViNERS can simulate ECAPS that capture features of our recordings, but our results suggest the underlying NEURON models need to be further refined and specifically adapted to accurately simulate visceral nerve axons.
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Affiliation(s)
- Calvin D Eiber
- Department of Anatomy and Physiology, The University of Melbourne, Victoria, Australia
| | - Sophie C Payne
- Bionics Institute, East Melbourne, Victoria, Australia.,Medical Bionics Department, The University of Melbourne, Victoria, Australia
| | - Natalia P Biscola
- Icahn School of Medicine at Mount Sinai, New York, United States of America
| | - Leif A Havton
- Icahn School of Medicine at Mount Sinai, New York, United States of America
| | - Janet R Keast
- Department of Anatomy and Physiology, The University of Melbourne, Victoria, Australia
| | - Peregrine B Osborne
- Department of Anatomy and Physiology, The University of Melbourne, Victoria, Australia
| | - James B Fallon
- Bionics Institute, East Melbourne, Victoria, Australia.,Medical Bionics Department, The University of Melbourne, Victoria, Australia
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Johnson MD, Dweiri YM, Cornelius J, Strohl KP, Steffen A, Suurna M, Soose RJ, Coleman M, Rondoni J, Durand DM, Ni Q. Model-based analysis of implanted hypoglossal nerve stimulation for the treatment of obstructive sleep apnea. Sleep 2021; 44:S11-S19. [PMID: 33647987 DOI: 10.1093/sleep/zsaa269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/12/2020] [Indexed: 11/15/2022] Open
Abstract
STUDY OBJECTIVES Individuals with obstructive sleep apnea (OSA), characterized by frequent sleep disruptions from tongue muscle relaxation and airway blockage, are known to benefit from on-demand electrical stimulation of the hypoglossal nerve. Hypoglossal nerve stimulation (HNS) therapy, which activates the protrusor muscles of the tongue during inspiration, has been established in multiple clinical studies as safe and effective, but the mechanistic understanding for why some stimulation parameters work better than others has not been thoroughly investigated. METHODS In this study, we developed a detailed biophysical model that can predict the spatial recruitment of hypoglossal nerve fascicles and axons within these fascicles during stimulation through nerve cuff electrodes. Using this model, three HNS programming scenarios were investigated including grouped cathode (---), single cathode (o-o), and guarded cathode bipolar (+-+) electrode configurations. RESULTS Regardless of electrode configuration, nearly all hypoglossal nerve axons circumscribed by the nerve cuff were recruited for stimulation amplitudes <3 V. Within this range, monopolar configurations required lower stimulation amplitudes than the guarded bipolar configuration to elicit action potentials within hypoglossal nerve axons. Further, the spatial distribution of the activated axons was more uniform for monopolar versus guarded bipolar configurations. CONCLUSIONS The computational models predicted that monopolar HNS provided the lowest threshold and the least sensitivity to rotational angle of the nerve cuff around the hypoglossal nerve; however, this setting also increased the likelihood for current leakage outside the nerve cuff, which could potentially activate axons in unintended branches of the hypoglossal nerve. CLINICAL TRIAL REGISTRATION NCT01161420.
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Affiliation(s)
- Matthew D Johnson
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN
| | - Yazan M Dweiri
- Department of Biomedical Engineering, Jordan University of Science and Technology, Irbid, Jordan
| | - Jason Cornelius
- Minneapolis Clinic of Neurology and North Memorial Help Sleep Medicine, Maple Grove, MN
| | - Kingman P Strohl
- Division of Pulmonary, Critical Care, and Sleep Medicine, Louis Stokes Veterans Affairs Medical Center and Case Medical Center, Case Western Reserve University, Cleveland, OH
| | - Armin Steffen
- Department of Otorhinolaryngology, University of Lübeck, Lübeck, Germany
| | - Maria Suurna
- Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medicine, New York, NY
| | - Ryan J Soose
- Department of Otolaryngology, University of Pittsburgh, Pittsburgh, PA
| | | | | | - Dominique M Durand
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH
| | - Quan Ni
- Inspire Medical Systems, Inc., Minneapolis, MN
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A review for the peripheral nerve interface designer. J Neurosci Methods 2019; 332:108523. [PMID: 31743684 DOI: 10.1016/j.jneumeth.2019.108523] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 12/11/2022]
Abstract
Informational density and relative accessibility of the peripheral nervous system make it an attractive site for therapeutic intervention. Electrode-based electrophysiological interfaces with peripheral nerves have been under development since the 1960s and, for several applications, have seen widespread clinical implementation. However, many applications require a combination of neural target resolution and stability which has thus far eluded existing peripheral nerve interfaces (PNIs). With the goal of aiding PNI designers in development of devices that meet the demands of next-generation applications, this review seeks to collect and present practical considerations and best practices which emerge from the literature, including both lessons learned during early PNI development and recent ideas. Fundamental and practical principles guiding PNI design are reviewed, followed by an updated and critical account of existing PNI designs and strategies. Finally, a brief survey of in vitro and in vivo PNI characterization methods is presented.
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Charkhkar H, Christie BP, Pinault GJ, Tyler DJ, Triolo RJ. A translational framework for peripheral nerve stimulating electrodes: Reviewing the journey from concept to clinic. J Neurosci Methods 2019; 328:108414. [PMID: 31472187 DOI: 10.1016/j.jneumeth.2019.108414] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/31/2019] [Accepted: 08/26/2019] [Indexed: 12/22/2022]
Abstract
The purpose of this review article is to describe the underlying methodology for successfully translating novel interfaces for electrical modulation of the peripheral nervous system (PNS) from basic design concepts to clinical applications and chronic human use. Despite advances in technologies to communicate directly with the nervous system, the pathway to clinical translation for most neural interfaces is not clear. FDA guidelines provide information on necessary evidence which should be generated and submitted to allow the agency evaluate safety and efficacy of a new medical device. However, a knowledge gap exists on translating neural interfaces from pre-clinical studies into the clinical domain. Our article is intended to inform the field on some of the key considerations for such a transition process specific to neural interfaces that may not be already covered by FDA guidances. This framework focuses on non-penetrating peripheral nerve stimulating electrodes that have been proven effective for motor and sensory neural prostheses and successfully transitioned from pre-clinical through first-in-human and chronic clinical deployment. We discuss the challenges of moving these neural interfaces along the translational continuum and ultimately through FDA approval for human feasibility studies. Specifically, we describe a translational process involving: quantitative human anatomy, neural modeling and simulation, acute intraoperative testing and verification, clinical demonstration with temporary percutaneous access, and finally chronic clinical deployment and functional performance. To clarify and demonstrate the importance of each step of this translational framework, we present case studies from electrodes developed at Case Western Reserve University (CWRU), specifically the spiral cuff, the Flat Interface Nerve Electrode (FINE), and the Composite FINE (C-FINE). In addition, we demonstrate that success along this translational pathway can be further expedited by: appropriate selection of well-characterized materials, validation of fabrication and sterilization protocols, well-implemented quality control measures, and quantification of impact on neural structure, health, and function. The issues and approaches identified in this review for the peripheral nervous system may also serve to accelerate the dissemination of any new neural interface into clinical practice, and consequently advance the performance, utility, and clinical value of new neural prostheses or neuromodulation systems.
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Affiliation(s)
- Hamid Charkhkar
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veteran Affairs Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA.
| | - Breanne P Christie
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veteran Affairs Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
| | - Gilles J Pinault
- Louis Stokes Cleveland Veteran Affairs Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
| | - Dustin J Tyler
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veteran Affairs Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
| | - Ronald J Triolo
- Department of Biomedical Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veteran Affairs Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
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Trel'ová D, Salgarella AR, Ricotti L, Giudetti G, Cutrone A, Šrámková P, Zahoranová A, Chorvát D, Haško D, Canale C, Micera S, Kronek J, Menciassi A, Lacík I. Soft Hydrogel Zwitterionic Coatings Minimize Fibroblast and Macrophage Adhesion on Polyimide Substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:1085-1099. [PMID: 29792034 DOI: 10.1021/acs.langmuir.8b00765] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Minimizing the foreign body reaction to polyimide-based implanted devices plays a pivotal role in several biomedical applications. In this work, we propose materials exhibiting nonbiofouling properties and a Young's modulus reflecting that of soft human tissues. We describe the synthesis, characterization, and in vitro validation of poly(carboxybetaine) hydrogel coatings covalently attached to polyimide substrates via a photolabile 4-azidophenyl group, incorporated in poly(carboxybetaine) chains at two concentrations of 1.6 and 3.1 mol %. The presence of coatings was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy. White light interferometry was used to evaluate the coating continuity and thickness (between 3 and 6 μm under dry conditions). Confocal laser scanning microscopy allowed us to quantify the thickness of the swollen hydrogel coatings that ranged between 13 and 32 μm. The different hydrogel formulations resulted in stiffness values ranging from 2 to 19 kPa and led to different fibroblast and macrophage responses in vitro. Both cell types showed a minimum adhesion on the softest hydrogel type. In addition, both the overall macrophage activation and cytotoxicity were observed to be negligible for all of the tested material formulations. These results are a promising starting point toward future advanced implantable systems. In particular, such technology paves the way for novel neural interfaces able to minimize the fibrotic reaction, once implanted in vivo, and to maximize their long-term stability and functionality.
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Affiliation(s)
- Dušana Trel'ová
- Department for Biomaterials Research , Polymer Institute of the Slovak Academy of Sciences , Dúbravská cesta 9 , 845 41 Bratislava , Slovakia
| | - Alice Rita Salgarella
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
| | - Leonardo Ricotti
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
| | - Guido Giudetti
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
| | - Annarita Cutrone
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
- SMANIA srl, via G. Volpe 12 , 56121 Pisa , Italy
| | - Petra Šrámková
- Department for Biomaterials Research , Polymer Institute of the Slovak Academy of Sciences , Dúbravská cesta 9 , 845 41 Bratislava , Slovakia
| | - Anna Zahoranová
- Department for Biomaterials Research , Polymer Institute of the Slovak Academy of Sciences , Dúbravská cesta 9 , 845 41 Bratislava , Slovakia
| | - Dušan Chorvát
- International Laser Centre , Ilkovičova 3 , Bratislava 841 04 , Slovak Republic
| | - Daniel Haško
- International Laser Centre , Ilkovičova 3 , Bratislava 841 04 , Slovak Republic
| | - Claudio Canale
- Department of Physics , University of Genova , Via dodecaneso 33 , 16133 Genova , Italy
- Department of Nanophysics , Istituto Italiano di Tecnologia (IIT) , Via Morego 30 , 16163 Genova , Italy
| | - Silvestro Micera
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
- Bertarelli Foundation Chair in Translational Neuroengineering, Center for Neuroprosthetics and Institute of Bioengineering , Ecole Polytechnique Federale de Lausanne , 1015 , Lausanne , Switzerland
| | - Juraj Kronek
- Department for Biomaterials Research , Polymer Institute of the Slovak Academy of Sciences , Dúbravská cesta 9 , 845 41 Bratislava , Slovakia
| | - Arianna Menciassi
- The BioRobotics Institute, Scuola Superiore Sant'Anna , Viale R. Piaggio 34 , 56025 Pontedera ( PI ), Italy
| | - Igor Lacík
- Department for Biomaterials Research , Polymer Institute of the Slovak Academy of Sciences , Dúbravská cesta 9 , 845 41 Bratislava , Slovakia
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Günter C, Delbeke J, Ortiz-Catalan M. Safety of long-term electrical peripheral nerve stimulation: review of the state of the art. J Neuroeng Rehabil 2019; 16:13. [PMID: 30658656 PMCID: PMC6339286 DOI: 10.1186/s12984-018-0474-8] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/11/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Electrical stimulation of peripheral nerves is used in a variety of applications such as restoring motor function in paralyzed limbs, and more recently, as means to provide intuitive sensory feedback in limb prostheses. However, literature on the safety requirements for stimulation is scarce, particularly for chronic applications. Some aspects of nerve interfacing such as the effect of stimulation parameters on electrochemical processes and charge limitations have been reviewed, but often only for applications in the central nervous system. This review focuses on the safety of electrical stimulation of peripheral nerve in humans. METHODS We analyzed early animal studies evaluating damage thresholds, as well as more recent investigations in humans. Safety requirements were divided into two main categories: passive and active safety. We made the distinction between short-term (< 30 days) and chronic (> 30 days) applications, as well as between electrode preservation (biostability) and body tissue healthy survival (harmlessness). In addition, transferability of experimental results between different tissues and species was considered. RESULTS At present, extraneural electrodes have shown superior long-term stability in comparison to intraneural electrodes. Safety limitations on pulse amplitude (and consequently, charge injection) are dependent on geometrical factors such as electrode placement, size, and proximity to the stimulated fiber. In contrast, other parameters such as stimulation frequency and percentage of effective stimulation time are more generally applicable. Currently, chronic stimulation at frequencies below 30 Hz and percentages of effective stimulation time below 50% is considered safe, but more precise data drawn from large databases are necessary. Unfortunately, stimulation protocols are not systematically documented in the literature, which limits the feasibility of meta-analysis and impedes the generalization of conclusions. We therefore propose a standardized list of parameters necessary to define electrical stimulation and allow future studies to contribute to meta-analyses. CONCLUSION The safety of chronic continuous peripheral nerve stimulation at frequencies higher than 30 Hz has yet to be documented. Precise parameter values leading to stimulation-induced depression of neuronal excitability (SIDNE) and neuronal damage, as well as the transition between the two, are still lacking. At present, neural damage mechanisms through electrical stimulation remain obscure.
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Affiliation(s)
- Clara Günter
- Biomechatronics and Neurorehabilitation Laboratory, Department of Electrical Engineering, Chalmers University of Technology, 41296, Gothenburg, Sweden
| | - Jean Delbeke
- LCEN3, Department of Neurology, Institute of Neuroscience, Ghent University, C. Heymanslaan, 10, 9000, Ghent, Belgium
| | - Max Ortiz-Catalan
- Biomechatronics and Neurorehabilitation Laboratory, Department of Electrical Engineering, Chalmers University of Technology, 41296, Gothenburg, Sweden. .,Integrum AB, Krokslätts Fabriker 50, 43137, Mölndal, Sweden.
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Silveira C, Brunton E, Spendiff S, Nazarpour K. Positioning the Nerve Cuff Distally on the Sciatic Nerve Improves the Classification of Ankle-Movement Proprioceptive ENG Signals. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:2430-2433. [PMID: 30440898 DOI: 10.1109/embc.2018.8512751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recording of neural signals from intact peripheral nerves in patients with spinal cord injury or stroke survivors offers the possibility for the development of closed-loop sensorimotor prostheses. However, questions remain over the positioning of neural interfaces such that the separability of neural data recorded from the peripheral nerves is improved. Afferent electroneurographic signals were recorded with nerve cuffs placed on the sciatic nerve of rats in response to various mechanical stimuli to the hindpaw. The mean absolute value of the signal was extracted and fed into classifiers. The performance of the classifier was evaluated when information was available from a single cuff placed either distally or proximally on the sciatic nerve. Results confirmed earlier findings that proprioceptive ENG signals, elicited by the movement of the ankle, can be identified and separated in neural recordings made with a cuff electrode. In addition, classification scores improved when the nerve cuff was placed distally on the nerve rather than proximally, taking advantage of the nerve's underlying anatomy.
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11
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Modeling the interactions between stimulation and physiologically induced APs in a mammalian nerve fiber: dependence on frequency and fiber diameter. J Comput Neurosci 2018; 45:193-206. [PMID: 30443813 DOI: 10.1007/s10827-018-0703-y] [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: 04/17/2018] [Revised: 10/18/2018] [Accepted: 10/22/2018] [Indexed: 10/27/2022]
Abstract
Electrical stimulation of nerve fibers is used as a therapeutic tool to treat neurophysiological disorders. Despite efforts to model the effects of stimulation, its underlying mechanisms remain unclear. Current mechanistic models quantify the effects that the electrical field produces near the fiber but do not capture interactions between action potentials (APs) initiated by stimulus and APs initiated by underlying physiological activity. In this study, we aim to quantify the effects of stimulation frequency and fiber diameter on AP interactions involving collisions and loss of excitability. We constructed a mechanistic model of a myelinated nerve fiber receiving two inputs: the underlying physiological activity at the terminal end of the fiber, and an external stimulus applied to the middle of the fiber. We define conduction reliability as the percentage of physiological APs that make it to the somatic end of the nerve fiber. At low input frequencies, conduction reliability is greater than 95% and decreases with increasing frequency due to an increase in AP interactions. Conduction reliability is less sensitive to fiber diameter and only decreases slightly with increasing fiber diameter. Finally, both the number and type of AP interactions significantly vary with both input frequencies and fiber diameter. Modeling the interactions between APs initiated by stimulus and APs initiated by underlying physiological activity in a nerve fiber opens opportunities towards understanding mechanisms of electrical stimulation therapies.
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12
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González-González MA, Kanneganti A, Joshi-Imre A, Hernandez-Reynoso AG, Bendale G, Modi R, Ecker M, Khurram A, Cogan SF, Voit WE, Romero-Ortega MI. Thin Film Multi-Electrode Softening Cuffs for Selective Neuromodulation. Sci Rep 2018; 8:16390. [PMID: 30401906 PMCID: PMC6219541 DOI: 10.1038/s41598-018-34566-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 10/18/2018] [Indexed: 01/21/2023] Open
Abstract
Silicone nerve cuff electrodes are commonly implanted on relatively large and accessible somatic nerves as peripheral neural interfaces. While these cuff electrodes are soft (1–50 MPa), their self-closing mechanism requires of thick walls (200–600 µm), which in turn contribute to fibrotic tissue growth around and inside the device, compromising the neural interface. We report the use of thiol-ene/acrylate shape memory polymer (SMP) for the fabrication of thin film multi-electrode softening cuffs (MSC). We fabricated multi-size MSC with eight titanium nitride (TiN) electrodes ranging from 1.35 to 13.95 × 10−4 cm2 (1–3 kΩ) and eight smaller gold (Au) electrodes (3.3 × 10−5 cm2; 750 kΩ), that soften at physiological conditions to a modulus of 550 MPa. While the SMP material is not as soft as silicone, the flexural forces of the SMP cuff are about 70–700 times lower in the MSC devices due to the 30 μm thick film compared to the 600 μm thick walls of the silicone cuffs. We demonstrated the efficacy of the MSC to record neural signals from rat sciatic and pelvic nerves (1000 µm and 200 µm diameter, respectively), and the selective fascicular stimulation by current steering. When implanted side-by-side and histologically compared 30 days thereafter, the MSC devices showed significantly less inflammation, indicated by a 70–80% reduction in ED1 positive macrophages, and 54–56% less fibrotic vimentin immunoreactivity. Together, the data supports the use of MSC as compliant and adaptable technology for the interfacing of somatic and autonomic peripheral nerves.
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Affiliation(s)
- María A González-González
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Aswini Kanneganti
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Alexandra Joshi-Imre
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Ana G Hernandez-Reynoso
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Geetanjali Bendale
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Romil Modi
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Melanie Ecker
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Ali Khurram
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Stuart F Cogan
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Walter E Voit
- Department of Material Science and Engineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA
| | - Mario I Romero-Ortega
- Department of Bioengineering, University of Texas at Dallas, 800 W. Campbell Road, Richardson, TX, 75080, USA.
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13
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Schiefer M, Gamble J, Strohl KP. Sciatic nerve stimulation and its effects on upper airway resistance in the anesthetized rabbit model relevant to sleep apnea. J Appl Physiol (1985) 2018; 125:763-769. [PMID: 29878871 DOI: 10.1152/japplphysiol.00225.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Obstructive sleep apnea (OSA) is a disorder characterized by collapse of the velopharynx and/or oropharynx during sleep when drive to the upper airway is reduced. Here, we explore an indirect approach for activation of upper airway muscles that might affect airway dynamics, namely, unilateral electrical stimulation of the afferent fibers of the sciatic nerve, in an anesthetized rabbit model. A nerve cuff electrode was placed around the sciatic and hypoglossal nerves to deliver stimulus while airflow, air pressure, and alae nasi electromyogram (EMG) were monitored both before and after sciatic transection. Sciatic nerve stimulation increased respiratory effort, rate, and alae nasi EMG, which persisted for seconds after stimulation; however, upper airway resistance was unchanged. Hypoglossal stimulation reduced resistance without altering drive. Although sciatic nerve stimulation is not ideal for treating OSA, it remains a target for altering respiratory drive. NEW & NOTEWORTHY Previously, sciatic nerve stimulation has been shown to activate upper airway and chest wall muscles. The supposition that resistance through the upper airway would be reduced with this afferent reflex was disproven. Findings were in contrast with the effect of hypoglossal nerve stimulation, which was shown to decrease resistance without changing muscle activation or ventilatory drive.
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Affiliation(s)
- Matthew Schiefer
- Louis Stokes Cleveland Veterans Affairs Medical Center , Cleveland, Ohio.,Case Western Reserve University , Cleveland, Ohio
| | - Jenniffer Gamble
- Louis Stokes Cleveland Veterans Affairs Medical Center , Cleveland, Ohio.,Case Western Reserve University , Cleveland, Ohio
| | - Kingman P Strohl
- Louis Stokes Cleveland Veterans Affairs Medical Center , Cleveland, Ohio.,Case Western Reserve University , Cleveland, Ohio
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14
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Silveira C, Brunton E, Spendiff S, Nazarpour K. Influence of nerve cuff channel count and implantation site on the separability of afferent ENG. J Neural Eng 2018; 15:046004. [PMID: 29629880 PMCID: PMC5964361 DOI: 10.1088/1741-2552/aabca0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Objective. Recording of neural signals from intact peripheral nerves
in patients with spinal cord injury or stroke survivors offers the possibility for
the development of closed-loop sensorimotor prostheses. Nerve cuffs have been found
to provide stable recordings from peripheral nerves for prolonged periods of time.
However, questions remain over the design and positioning of nerve cuffs such that
the separability of neural data recorded from the peripheral nerves is improved.
Approach. Afferent electroneurographic (ENG) signals were
recorded with nerve cuffs placed on the sciatic nerve of rats in response to various
mechanical stimuli to the hindpaw. The mean absolute value of the signal was
extracted and input to a classifier. The performance of the classifier was evaluated
under two conditions: (1) when information from either a 3- or 16-channel cuff was
used; (2) when information was available from a cuff placed either distally or
proximally along the nerve. Main results. We show that both 3- and
16-channel cuffs were able to separate afferent ENG signals with an accuracy greater
than chance. The highest classification scores were achieved when the classifier was
fed with information obtained from a 16-channel cuff placed distally. While the
16-channel cuff always outperformed the 3-channel cuff, the difference in performance
was increased when the 16-channel cuff was placed distally rather than proximally on
the nerve. Significance. The results indicate that increasing the
complexity of a nerve cuff may only be advantageous if the nerve cuff is to be
implanted distally, where the nerve has begun to divide into individual
fascicles.
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Affiliation(s)
- Carolina Silveira
- Intelligent Sensing Laboratory, School of Engineering, Newcastle University, NE1 7RU, United Kingdom
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15
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Wellman SM, Eles JR, Ludwig KA, Seymour JP, Michelson NJ, McFadden WE, Vazquez AL, Kozai TDY. A Materials Roadmap to Functional Neural Interface Design. ADVANCED FUNCTIONAL MATERIALS 2018; 28:1701269. [PMID: 29805350 PMCID: PMC5963731 DOI: 10.1002/adfm.201701269] [Citation(s) in RCA: 181] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Advancement in neurotechnologies for electrophysiology, neurochemical sensing, neuromodulation, and optogenetics are revolutionizing scientific understanding of the brain while enabling treatments, cures, and preventative measures for a variety of neurological disorders. The grand challenge in neural interface engineering is to seamlessly integrate the interface between neurobiology and engineered technology, to record from and modulate neurons over chronic timescales. However, the biological inflammatory response to implants, neural degeneration, and long-term material stability diminish the quality of interface overtime. Recent advances in functional materials have been aimed at engineering solutions for chronic neural interfaces. Yet, the development and deployment of neural interfaces designed from novel materials have introduced new challenges that have largely avoided being addressed. Many engineering efforts that solely focus on optimizing individual probe design parameters, such as softness or flexibility, downplay critical multi-dimensional interactions between different physical properties of the device that contribute to overall performance and biocompatibility. Moreover, the use of these new materials present substantial new difficulties that must be addressed before regulatory approval for use in human patients will be achievable. In this review, the interdependence of different electrode components are highlighted to demonstrate the current materials-based challenges facing the field of neural interface engineering.
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Affiliation(s)
- Steven M Wellman
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - James R Eles
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Kip A Ludwig
- Department of Neurologic Surgery, 200 First St. SW, Rochester, MN 55905
| | - John P Seymour
- Electrical & Computer Engineering, 1301 Beal Ave., 2227 EECS, Ann Arbor, MI 48109
| | - Nicholas J Michelson
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - William E McFadden
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Alberto L Vazquez
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
| | - Takashi D Y Kozai
- Department of Bioengineering, Center for the Basis of Neural Cognition, McGowan Institute of Regenerative Medicine, NeuroTech Center, University of Pittsburgh Brain Institute, Center for Neuroscience at the University of Pittsburgh, University of Pittsburgh, 208 Center for Biotechnology, 300 Technology Dr., Pittsburgh, PA 15219, United States
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16
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Rozman J, Pečlin P, Ribarič S, Godec M, Burja J. An improved method of crafting a multi-electrode spiral cuff for the selective. Sci Rep 2018; 8:915. [PMID: 29343774 PMCID: PMC5772407 DOI: 10.1038/s41598-018-19318-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 12/27/2017] [Indexed: 11/09/2022] Open
Abstract
This article reviews an improved methodology and technology for crafting a multi-electrode spiral cuff for the selective activation of nerve fibres in particular superficial regions of a peripheral nerve. The analysis, structural and mechanical properties of the spot welds used for the interconnections between the stimulating electrodes and stainless-steel lead wires are presented. The cuff consisted of 33 platinum electrodes embedded within a self-curling 17-mm-long silicone spiral sheet with a nominal internal diameter of 2.5 mm. The weld was analyzed using scanning electron microscopy and nanohardness tests, while the interconnection was investigated using destructive load tests. The functionality of the cuff was tested in an isolated porcine vagus nerve. The results of the scanning electron microscopy show good alloying and none of the typical welding defects that occur between the wire and the platinum foil. The results of the destructive load tests show that the breaking loads were between 3.22 and 5 N. The results of the nanohardness testing show that the hardness of the weld was different for the particular sites on the weld sample. Finally, the results of the functional testing show that for different stimulation intensities both the compound action potential deflection and the shape are modulated.
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Affiliation(s)
- Janez Rozman
- Center for Implantable Technology and Sensors, ITIS d. o. o. Ljubljana, Lepi pot 11, 1000, Ljubljana, Slovenia.,Institute of Pathophysiology, Medical Faculty, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Polona Pečlin
- Center for Implantable Technology and Sensors, ITIS d. o. o. Ljubljana, Lepi pot 11, 1000, Ljubljana, Slovenia
| | - Samo Ribarič
- Institute of Pathophysiology, Medical Faculty, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Matjaž Godec
- Institute of Metals and Technology, Lepi pot 11, 1000, Ljubljana, Slovenia.
| | - Jaka Burja
- Institute of Metals and Technology, Lepi pot 11, 1000, Ljubljana, Slovenia
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17
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18
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Kim HJ, Heo DN, Lee YJ, Lee SJ, Kang JY, Lee SH, Kwon IIK, Do SH. Biological assessments of multifunctional hydrogel-decorated implantable neural cuff electrode for clinical neurology application. Sci Rep 2017; 7:15245. [PMID: 29127334 PMCID: PMC5681553 DOI: 10.1038/s41598-017-15551-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/30/2017] [Indexed: 01/11/2023] Open
Abstract
The implantable cuff electrode is an effective neuroprosthetic device in current nerve tissue engineering. However, biocompatibility and stability are still a serious dispute in terms of in vivo function and continuous monitoring. In this regard, assessing the host's biological response to biomaterials is one of the key factors of chronic implantation. In this article, we analyzed the peripheral nerve specific-biological responses to the application of multi-functional hydrogel-coated electrodes. The surface of the cuff electrode was modified using a multifunctional hydrogel composed of PEG hydrogel, cyclosporin A(CsA)-microsphere(MS) and electrodeposited PEDOT:PSS. Through our approach, we have found that the multifunctional hydrogel coatings improve the neural electrode function, such as peak-to-peak amplitude increase. Additionally, the multifunctional hydrogel coated electrodes exhibited improved biocompatibility, such as reduced apoptotic properties and increased axonal myelination. Furthermore, 12 genes (BDNF, Gfra1, IL-6, Sox 10, S100B, P75 NTR , GAP43, MBP, MPZ, NrCAM, NE-FL, CB1) were upregulated at 5 weeks post-implant. Finally, double immunofluorescence revealed the effect of endocannabinoid system on neuroprotective properties and tissue remodeling of peripheral nerves during cuff electrode implantation. These results clearly confirmed that multifunctional hydrogel coatings could improve electrode function and biocompatibility by enhancing neuroprotective properties, which may provide a valuable paradigm for clinical neurology application.
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Affiliation(s)
- Han-Jun Kim
- Konkuk University, Department of Clinical Pathology, College of Veterinary Medicine, Seoul, 05029, Republic of Korea
| | - Dong Nyoung Heo
- Kyung Hee University, Department of Dental Materials, School of Dentistry, Seoul, 02477, Republic of Korea
| | - Yi Jae Lee
- Korea Institute of Science and Technology, Center for BioMicrosystems, Seoul, 02792, Republic of Korea
| | - Sang Jin Lee
- Kyung Hee University, Department of Dental Materials, School of Dentistry, Seoul, 02477, Republic of Korea
| | - Ji Yoon Kang
- Korea Institute of Science and Technology, Center for BioMicrosystems, Seoul, 02792, Republic of Korea
| | - Soo Hyun Lee
- Korea Institute of Science and Technology, Center for BioMicrosystems, Seoul, 02792, Republic of Korea.
| | - I I Keun Kwon
- Kyung Hee University, Department of Dental Materials, School of Dentistry, Seoul, 02477, Republic of Korea.
| | - Sun Hee Do
- Konkuk University, Department of Clinical Pathology, College of Veterinary Medicine, Seoul, 05029, Republic of Korea.
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19
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Interfacing with the nervous system: a review of current bioelectric technologies. Neurosurg Rev 2017; 42:227-241. [PMID: 29063229 DOI: 10.1007/s10143-017-0920-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/15/2017] [Accepted: 10/09/2017] [Indexed: 02/07/2023]
Abstract
The aim of this study is to discuss the state of the art with regard to established or promising bioelectric therapies meant to alter or control neurologic function. We present recent reports on bioelectric technologies that interface with the nervous system at three potential sites-(1) the end organ, (2) the peripheral nervous system, and (3) the central nervous system-while exploring practical and clinical considerations. A literature search was executed on PubMed, IEEE, and Web of Science databases. A review of the current literature was conducted to examine functional and histomorphological effects of neuroprosthetic interfaces with a focus on end-organ, peripheral, and central nervous system interfaces. Innovations in bioelectric technologies are providing increasing selectivity in stimulating distinct nerve fiber populations in order to activate discrete muscles. Significant advances in electrode array design focus on increasing selectivity, stability, and functionality of implantable neuroprosthetics. The application of neuroprosthetics to paretic nerves or even directly stimulating or recording from the central nervous system holds great potential in advancing the field of nerve and tissue bioelectric engineering and contributing to clinical care. Although current physiotherapeutic and surgical treatments seek to restore function, structure, or comfort, they bear significant limitations in enabling cosmetic or functional recovery. Instead, the introduction of bioelectric technology may play a role in the restoration of function in patients with neurologic deficits.
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20
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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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21
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Patel YA, Willsie A, Clements IP, Aguilar R, Rajaraman S, Butera RJ. Microneedle cuff electrodes for extrafascicular peripheral nerve interfacing. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2016:1741-1744. [PMID: 28268663 DOI: 10.1109/embc.2016.7591053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The work presented here describes a new tool for peripheral nerve interfacing, called the microneedle cuff (μN-cuff) electrode. APPROACH μN arrays are designed and integrated into cuff electrodes for penetrating superficial tissues while remaining non-invasive to delicate axonal tracts. MAIN RESULTS In acute testing, the presence of 75 μm height μNs decreased the electrode-tissue interface impedance by 0.34 kΩ, resulting in a 0.9 mA reduction in functional stimulation thresholds and increased the signal-to-noise ratio by 9.1 dB compared to standard (needle-less) nerve cuff electrodes. Preliminary acute characterization suggests that μN-cuff electrodes provide the stability and ease of use of standard cuff electrodes while enhancing electrical interfacing characteristics. SIGNIFICANCE The ability to stimulate, block, and record peripheral nerve activity with greater specificity, resolution, and fidelity can enable more precise spatiotemporal control and measurement of neural circuits.
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22
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Lotti F, Ranieri F, Vadalà G, Zollo L, Di Pino G. Invasive Intraneural Interfaces: Foreign Body Reaction Issues. Front Neurosci 2017; 11:497. [PMID: 28932181 PMCID: PMC5592213 DOI: 10.3389/fnins.2017.00497] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 08/23/2017] [Indexed: 12/20/2022] Open
Abstract
Intraneural interfaces are stimulation/registration devices designed to couple the peripheral nervous system (PNS) with the environment. Over the last years, their use has increased in a wide range of applications, such as the control of a new generation of neural-interfaced prostheses. At present, the success of this technology is limited by an electrical impedance increase, due to an inflammatory response called foreign body reaction (FBR), which leads to the formation of a fibrotic tissue around the interface, eventually causing an inefficient transduction of the electrical signal. Based on recent developments in biomaterials and inflammatory/fibrotic pathologies, we explore and select the biological solutions that might be adopted in the neural interfaces FBR context: modifications of the interface surface, such as organic and synthetic coatings; the use of specific drugs or molecular biology tools to target the microenvironment around the interface; the development of bio-engineered-scaffold to reduce immune response and promote interface-tissue integration. By linking what we believe are the major crucial steps of the FBR process with related solutions, we point out the main issues that future research has to focus on: biocompatibility without losing signal conduction properties, good reproducible in vitro/in vivo models, drugs exhaustion and undesired side effects. The underlined pros and cons of proposed solutions show clearly the importance of a better understanding of all the molecular and cellular pathways involved and the need of a multi-target action based on a bio-engineered combination approach.
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Affiliation(s)
- Fiorenza Lotti
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Research Unit of Orthopaedic and Trauma Surgery, Università Campus Bio-MedicoRome, Italy
| | - Federico Ranieri
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Fondazione Alberto Sordi-Research Institute for AgingRome, Italy.,Research Unit of Neurology, Neurophysiology and Neurobiology, Università Campus Bio-MedicoRome, Italy
| | - Gianluca Vadalà
- Research Unit of Orthopaedic and Trauma Surgery, Università Campus Bio-MedicoRome, Italy
| | - Loredana Zollo
- Research Unit of Biomedical Robotics and Biomicrosystems, Università Campus Bio-MedicoRome, Italy
| | - Giovanni Di Pino
- NeXT: Neurophysiology and Neuroengineering of Human-Technology Interaction Research Unit, Università Campus Bio-MedicoRome, Italy.,Research Unit of Neurology, Neurophysiology and Neurobiology, Università Campus Bio-MedicoRome, Italy
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23
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Christie BP, Freeberg M, Memberg WD, Pinault GJC, Hoyen HA, Tyler DJ, Triolo RJ. "Long-term stability of stimulating spiral nerve cuff electrodes on human peripheral nerves". J Neuroeng Rehabil 2017; 14:70. [PMID: 28693584 PMCID: PMC5504677 DOI: 10.1186/s12984-017-0285-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/28/2017] [Indexed: 11/10/2022] Open
Abstract
Background Electrical stimulation of the peripheral nerves has been shown to be effective in restoring sensory and motor functions in the lower and upper extremities. This neural stimulation can be applied via non-penetrating spiral nerve cuff electrodes, though minimal information has been published regarding their long-term performance for multiple years after implantation. Methods Since 2005, 14 human volunteers with cervical or thoracic spinal cord injuries, or upper limb amputation, were chronically implanted with a total of 50 spiral nerve cuff electrodes on 10 different nerves (mean time post-implant 6.7 ± 3.1 years). The primary outcome measures utilized in this study were muscle recruitment curves, charge thresholds, and percent overlap of recruited motor unit populations. Results In the eight recipients still actively involved in research studies, 44/45 of the spiral contacts were still functional. In four participants regularly studied over the course of 1 month to 10.4 years, the charge thresholds of the majority of individual contacts remained stable over time. The four participants with spiral cuffs on their femoral nerves were all able to generate sufficient moment to keep the knees locked during standing after 2–4.5 years. The dorsiflexion moment produced by all four fibular nerve cuffs in the active participants exceeded the value required to prevent foot drop, but no tibial nerve cuffs were able to meet the plantarflexion moment that occurs during push-off at a normal walking speed. The selectivity of two multi-contact spiral cuffs was examined and both were still highly selective for different motor unit populations for up to 6.3 years after implantation. Conclusions The spiral nerve cuffs examined remain functional in motor and sensory neuroprostheses for 2–11 years after implantation. They exhibit stable charge thresholds, clinically relevant recruitment properties, and functional muscle selectivity. Non-penetrating spiral nerve cuff electrodes appear to be a suitable option for long-term clinical use on human peripheral nerves in implanted neuroprostheses.
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Affiliation(s)
- Breanne P Christie
- Case Western Reserve University, Cleveland, OH, USA. .,Department of Veterans' Affairs, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA.
| | - Max Freeberg
- Case Western Reserve University, Cleveland, OH, USA.,Department of Veterans' Affairs, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA
| | | | - Gilles J C Pinault
- Department of Veterans' Affairs, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA
| | | | - Dustin J Tyler
- Case Western Reserve University, Cleveland, OH, USA.,Department of Veterans' Affairs, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA
| | - Ronald J Triolo
- Case Western Reserve University, Cleveland, OH, USA.,Department of Veterans' Affairs, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA
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24
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Schendel AA, Eliceiri KW, Williams JC. Advanced Materials for Neural Surface Electrodes. CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE 2014; 18:301-307. [PMID: 26392802 PMCID: PMC4574303 DOI: 10.1016/j.cossms.2014.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Designing electrodes for neural interfacing applications requires deep consideration of a multitude of materials factors. These factors include, but are not limited to, the stiffness, biocompatibility, biostability, dielectric, and conductivity properties of the materials involved. The combination of materials properties chosen not only determines the ability of the device to perform its intended function, but also the extent to which the body reacts to the presence of the device after implantation. Advances in the field of materials science continue to yield new and improved materials with properties well-suited for neural applications. Although many of these materials have been well-established for non-biological applications, their use in medical devices is still relatively novel. The intention of this review is to outline new material advances for neural electrode arrays, in particular those that interface with the surface of the nervous tissue, as well as to propose future directions for neural surface electrode development.
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Affiliation(s)
- Amelia A Schendel
- Materials Science Program, University of Wisconsin - Madison, 1550 Engineering Drive, Madison, WI 53703
| | - Kevin W Eliceiri
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, 1675 Observatory Drive, Madison, WI USA 53706
| | - Justin C Williams
- Department of Biomedical Engineering, University of Wisconsin - Madison, 1550 Engineering Drive, Madison, WI 53703
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Crago PE, Makowski NS. Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location. J Neural Eng 2014; 11:056016. [PMID: 25161163 DOI: 10.1088/1741-2560/11/5/056016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Stimulation of peripheral nerves is often superimposed on ongoing motor and sensory activity in the same axons, without a quantitative model of the net action potential train at the axon endpoint. APPROACH We develop a model of action potential patterns elicited by superimposing constant frequency axonal stimulation on the action potentials arriving from a physiologically activated neural source. The model includes interactions due to collision block, resetting of the neural impulse generator, and the refractory period of the axon at the point of stimulation. MAIN RESULTS Both the mean endpoint firing rate and the probability distribution of the action potential firing periods depend strongly on the relative firing rates of the two sources and the intersite conduction time between them. When the stimulus rate exceeds the neural rate, neural action potentials do not reach the endpoint and the rate of endpoint action potentials is the same as the stimulus rate, regardless of the intersite conduction time. However, when the stimulus rate is less than the neural rate, and the intersite conduction time is short, the two rates partially sum. Increases in stimulus rate produce non-monotonic increases in endpoint rate and continuously increasing block of neurally generated action potentials. Rate summation is reduced and more neural action potentials are blocked as the intersite conduction time increases. At long intersite conduction times, the endpoint rate simplifies to being the maximum of either the neural or the stimulus rate. SIGNIFICANCE This study highlights the potential of increasing the endpoint action potential rate and preserving neural information transmission by low rate stimulation with short intersite conduction times. Intersite conduction times can be decreased with proximal stimulation sites for muscles and distal stimulation sites for sensory endings. The model provides a basis for optimizing experiments and designing neuroprosthetic interventions involving motor or sensory stimulation.
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Affiliation(s)
- Patrick E Crago
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. Cleveland Functional Electrical Stimulation (FES) Center, Cleveland, OH 44106 USA
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Harreby KR, Kundu A, Yoshida K, Boretius T, Stieglitz T, Jensen W. Subchronic Stimulation Performance of Transverse Intrafascicular Multichannel Electrodes in the Median Nerve of the Göttingen Minipig. Artif Organs 2014; 39:E36-48. [DOI: 10.1111/aor.12347] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Kristian R. Harreby
- Department of Health Science and Technology; Aalborg University; Aalborg Denmark
| | - Aritra Kundu
- Department of Health Science and Technology; Aalborg University; Aalborg Denmark
| | - Ken Yoshida
- Department of Biomedical Engineering; Indiana University-Purdue University Indianapolis; Indianapolis IN USA
| | - Tim Boretius
- Department of Microsystems Engineering (IMTEK); University of Freiburg; Freiburg Germany
| | - Thomas Stieglitz
- Department of Microsystems Engineering (IMTEK); University of Freiburg; Freiburg Germany
| | - Winnie Jensen
- Department of Health Science and Technology; Aalborg University; Aalborg Denmark
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Memberg WD, Polasek KH, Hart RL, Bryden AM, Kilgore KL, Nemunaitis GA, Hoyen HA, Keith MW, Kirsch RF. Implanted neuroprosthesis for restoring arm and hand function in people with high level tetraplegia. Arch Phys Med Rehabil 2014; 95:1201-1211.e1. [PMID: 24561055 PMCID: PMC4470503 DOI: 10.1016/j.apmr.2014.01.028] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 01/28/2014] [Accepted: 01/29/2014] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To develop and apply an implanted neuroprosthesis to restore arm and hand function to individuals with high level tetraplegia. DESIGN Case study. SETTING Clinical research laboratory. PARTICIPANTS Individuals with spinal cord injuries (N=2) at or above the C4 motor level. INTERVENTIONS The individuals were each implanted with 2 stimulators (24 stimulation channels and 4 myoelectric recording channels total). Stimulating electrodes were placed in the shoulder and arm, being, to our knowledge, the first long-term application of spiral nerve cuff electrodes to activate a human limb. Myoelectric recording electrodes were placed in the head and neck areas. MAIN OUTCOME MEASURES Successful installation and operation of the neuroprosthesis and electrode performance, range of motion, grasp strength, joint moments, and performance in activities of daily living. RESULTS The neuroprosthesis system was successfully implanted in both individuals. Spiral nerve cuff electrodes were placed around upper extremity nerves and activated the intended muscles. In both individuals, the neuroprosthesis has functioned properly for at least 2.5 years postimplant. Hand, wrist, forearm, elbow, and shoulder movements were achieved. A mobile arm support was needed to support the mass of the arm during functional activities. One individual was able to perform several activities of daily living with some limitations as a result of spasticity. The second individual was able to partially complete 2 activities of daily living. CONCLUSIONS Functional electrical stimulation is a feasible intervention for restoring arm and hand functions to individuals with high tetraplegia. Forces and movements were generated at the hand, wrist, elbow, and shoulder that allowed the performance of activities of daily living, with some limitations requiring the use of a mobile arm support to assist the stimulated shoulder forces.
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Affiliation(s)
| | | | - Ronald L Hart
- Louis Stokes Veterans Affairs Medical Center, Cleveland, OH
| | | | - Kevin L Kilgore
- Case Western Reserve University, Cleveland, OH; Louis Stokes Veterans Affairs Medical Center, Cleveland, OH; MetroHealth Medical Center, Cleveland, OH
| | | | | | | | - Robert F Kirsch
- Case Western Reserve University, Cleveland, OH; Louis Stokes Veterans Affairs Medical Center, Cleveland, OH; MetroHealth Medical Center, Cleveland, OH
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Schiefer MA, Freeberg M, Pinault GJC, Anderson J, Hoyen H, Tyler DJ, Triolo RJ. Selective activation of the human tibial and common peroneal nerves with a flat interface nerve electrode. J Neural Eng 2013; 10:056006. [PMID: 23918148 DOI: 10.1088/1741-2560/10/5/056006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrical stimulation has been shown effective in restoring basic lower extremity motor function in individuals with paralysis. We tested the hypothesis that a flat interface nerve electrode (FINE) placed around the human tibial or common peroneal nerve above the knee can selectively activate each of the most important muscles these nerves innervate for use in a neuroprosthesis to control ankle motion. APPROACH During intraoperative trials involving three subjects, an eight-contact FINE was placed around the tibial and/or common peroneal nerve, proximal to the popliteal fossa. The FINE's ability to selectively recruit muscles innervated by these nerves was assessed. Data were used to estimate the potential to restore active plantarflexion or dorsiflexion while balancing inversion and eversion using a biomechanical simulation. MAIN RESULTS With minimal spillover to non-targets, at least three of the four targets in the tibial nerve, including two of the three muscles constituting the triceps surae, were independently and selectively recruited in all subjects. As acceptable levels of spillover increased, recruitment of the target muscles increased. Selective activation of muscles innervated by the peroneal nerve was more challenging. SIGNIFICANCE Estimated joint moments suggest that plantarflexion sufficient for propulsion during stance phase of gait and dorsiflexion sufficient to prevent foot drop during swing can be achieved, accompanied by a small but tolerable inversion or eversion moment.
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Affiliation(s)
- M A Schiefer
- Louis Stokes Cleveland Department of Veterans' Affairs Medical Center, Cleveland OH, USA. Department of Biomedical Engineering, Case Western Reserve University, Cleveland OH, USA. MetroHealth Medical Center, Cleveland OH, USA
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29
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Integrated electrode and high density feedthrough system for chip-scale implantable devices. Biomaterials 2013; 34:6109-18. [DOI: 10.1016/j.biomaterials.2013.04.054] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 04/29/2013] [Indexed: 11/18/2022]
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Kameswaran N, Cullen DK, Pfister BJ, Ranalli NJ, Huang JH, Zager EL, Smith DH. A novel neuroprosthetic interface with the peripheral nervous system using artificially engineered axonal tracts. Neurol Res 2013; 30:1063-7. [DOI: 10.1179/174313208x362541] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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31
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Gierthmuehlen M, Freiman TM, Haastert-Talini K, Mueller A, Kaminsky J, Stieglitz T, Plachta DTT. Computational tissue volume reconstruction of a peripheral nerve using high-resolution light-microscopy and reconstruct. PLoS One 2013; 8:e66191. [PMID: 23785485 PMCID: PMC3681936 DOI: 10.1371/journal.pone.0066191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 05/07/2013] [Indexed: 11/18/2022] Open
Abstract
The development of neural cuff-electrodes requires several in vivo studies and revisions of the electrode design before the electrode is completely adapted to its target nerve. It is therefore favorable to simulate many of the steps involved in this process to reduce costs and animal testing. As the restoration of motor function is one of the most interesting applications of cuff-electrodes, the position and trajectories of myelinated fibers in the simulated nerve are important. In this paper, we investigate a method for building a precise neuroanatomical model of myelinated fibers in a peripheral nerve based on images obtained using high-resolution light microscopy. This anatomical model describes the first aim of our "Virtual workbench" project to establish a method for creating realistic neural simulation models based on image datasets. The imaging, processing, segmentation and technical limitations are described, and the steps involved in the transition into a simulation model are presented. The results showed that the position and trajectories of the myelinated axons were traced and virtualized using our technique, and small nerves could be reliably modeled based on of light microscopy images using low-cost OpenSource software and standard hardware. The anatomical model will be released to the scientific community.
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32
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Fisher LE, Tyler DJ, Triolo RJ. Optimization of selective stimulation parameters for multi-contact electrodes. J Neuroeng Rehabil 2013; 10:25. [PMID: 23442372 PMCID: PMC3599334 DOI: 10.1186/1743-0003-10-25] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 02/21/2013] [Indexed: 11/15/2022] Open
Abstract
Background Multi-contact stimulating electrodes are gaining acceptance as a means for interfacing with the peripheral nervous system. These electrodes can potentially activate many independent populations of motor units within a single peripheral nerve, but quantifying their recruitment properties and the overlap in stimulation between contacts is difficult and time consuming. Further, current methods for quantifying overlap between contacts are ambiguous and can lead to suboptimal selective stimulation parameters. This study describes a novel method for optimizing stimulation parameters for multi-contact peripheral stimulating electrodes to produce strong, selective muscle contractions. The method is tested with four-contact spiral nerve-cuff electrodes implanted on bilateral femoral nerves of two individuals with spinal cord injury, but it is designed to be extendable to other electrode technologies with higher densities of contacts. Methods To optimize selective stimulation parameters for multi-contact electrodes, first, recruitment and overlap are characterized for all contacts within an electrode. Recruitment is measured with the twitch response to single stimulus pulses, and overlap between pairs of contacts is quantified by the deviation in their combined response from linear addition of individual responses. Simple mathematical models are fit to recruitment and overlap data, and a cost function is defined to maximize recruitment and minimize overlap between all contacts. Results Results are presented for four-contact nerve-cuff electrodes stimulating bilateral femoral nerves of two human subjects with spinal cord injury. Knee extension moments between 11.6 and 43.2 Nm were achieved with selective stimulation through multiple contacts of each nerve-cuff with less than 10% overlap between pairs of contacts. The overlap in stimulation measured in response to selective stimulation parameters was stable at multiple repeated time points after implantation. Conclusions These results suggest that the method described here can provide an automated means of determining stimulus parameters to achieve strong muscle contractions via selective stimulation through multi-contact peripheral nerve electrodes.
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Affiliation(s)
- Lee E Fisher
- Case Western Reserve University, Cleveland, OH 44106, USA.
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33
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Effect on signal-to-noise ratio of splitting the continuous contacts of cuff electrodes into smaller recording areas. J Neuroeng Rehabil 2013; 10:22. [PMID: 23433089 PMCID: PMC3652731 DOI: 10.1186/1743-0003-10-22] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 02/05/2013] [Indexed: 12/05/2022] Open
Abstract
Background Cuff electrodes have been widely used chronically in different clinical applications. This neural interface has been dominantly used for nerve stimulation while interfering noise is the major issue when employed for recording purposes. Advancements have been made in rejecting extra-neural interference by using continuous ring contacts in tripolar topologies. Ring contacts provide an average of the neural activity, and thus reduce the information retrieved. Splitting these contacts into smaller recording areas could potentially increase the information content. In this study, we investigate the impact of such discretization on the Signal-to-Noise Ratio (SNR). The effect of contacts positioning and an additional short circuited pair of electrodes were also addressed. Methods Different recording configurations using ring, dot, and a mixed of both contacts were studied in vitro in a frog model. An interfering signal was induced in the medium to simulate myoelectric noise. The experimental setup was design in such a way that the only difference between recordings was the configuration used. The inter-session experimental differences were taken care of by a common configuration that allowed normalization between electrode designs. Results It was found that splitting all contacts into small recording areas had negative effects on noise rejection. However, if this is only applied to the central contact creating a mixed tripole configuration, a considerable and statistically significant improvement was observed. Moreover, the signal to noise ratio was equal or larger than what can be achieved with the best known configuration, namely the short circuited tripole. This suggests that for recording purposes, any tripole topology would benefit from splitting the central contact into one or more discrete contacts. Conclusions Our results showed that a mixed tripole configuration performs better than the configuration including only ring contacts. Therefore, splitting the central ring contact of a cuff electrode into a number of dot contacts not only provides additional information but also an improved SNR. In addition, the effect of an additional pair of short circuited electrodes and the “end effect” observed with the presented method are in line with previous findings by other authors.
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34
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Ortiz-Catalan M, Brånemark R, Håkansson B, Delbeke J. On the viability of implantable electrodes for the natural control of artificial limbs: review and discussion. Biomed Eng Online 2012; 11:33. [PMID: 22715940 PMCID: PMC3438028 DOI: 10.1186/1475-925x-11-33] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 05/14/2012] [Indexed: 01/06/2023] Open
Abstract
The control of robotic prostheses based on pattern recognition algorithms is a widely studied subject that has shown promising results in acute experiments. The long-term implementation of this technology, however, has not yet been achieved due to practical issues that can be mainly attributed to the use of surface electrodes and their highly environmental dependency. This paper describes several implantable electrodes and discusses them as a solution for the natural control of artificial limbs. In this context "natural" is defined as producing control over limb movement analogous to that of an intact physiological system. This includes coordinated and simultaneous movements of different degrees of freedom. It also implies that the input signals must come from nerves or muscles that were originally meant to produce the intended movement and that feedback is perceived as originating in the missing limb without requiring burdensome levels of concentration. After scrutinizing different electrode designs and their clinical implementation, we concluded that the epimysial and cuff electrodes are currently promising candidates to achieving a long-term stable and natural control of robotic prosthetics, provided that communication from the electrodes to the outside of the body is guaranteed.
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Affiliation(s)
- Max Ortiz-Catalan
- Department of Signals and Systems, Biomedical Engineering Division, Chalmers University of Technology, Göteborg, Sweden
- Centre of Orthopaedic Osseointegration, Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Rickard Brånemark
- Centre of Orthopaedic Osseointegration, Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Bo Håkansson
- Department of Signals and Systems, Biomedical Engineering Division, Chalmers University of Technology, Göteborg, Sweden
| | - Jean Delbeke
- School of Medicine (MD), Institute of Neuroscience (SSS/IoNS/COSY), Université catholique de Louvain, Brussels, Belgium
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35
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Keohan F, Wei XF, Wongsarnpigoon A, Lazaro E, Darga JE, Grill WM. Fabrication and evaluation of conductive elastomer electrodes for neural stimulation. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 18:1057-73. [PMID: 17705998 DOI: 10.1163/156856207781494395] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study explored the feasibility of applying nanocomposites derived from conducting organic polymers and silicone elastomers to fabricate electrodes for neural stimulation. A novel combination of nanoparticulate polypyrrole polymerized within a processable elastomeric silicone host polymer was evaluated in vitro and in vivo. The electrical properties of the elastomeric conductors were strongly dependent on their composition, and mixtures were identified that provided high and stable conductivity. Methods were developed for incorporating conductive polymer-siloxane co-polymer nanocomposite and silicone insulating polymers into thin-layered structures for simple single-poled electrode fabrication. In vitro testing revealed that the materials were stable under continuous pulsing for at least 10 days. Single contact prototype nerve cuff electrodes were fabricated and device functionality was demonstrated in vivo following acute implantation. The results of this study demonstrate the feasibility of conductive elastomers for peripheral nerve stimulating electrodes. Matching the mechanical properties of cuff electrode to those of the underlying neural tissue is expected to improve the long-term tissue response to the presence of the electrode.
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36
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Dowden BR, Frankel MA, Normann RA, Clark GA. Non-invasive method for selection of electrodes and stimulus parameters for FES applications with intrafascicular arrays. J Neural Eng 2011; 9:016006. [PMID: 22173566 DOI: 10.1088/1741-2560/9/1/016006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
High-channel-count intrafascicular electrode arrays provide comprehensive and selective access to the peripheral nervous system. One practical difficulty in using several electrode arrays to evoke coordinated movements in paralyzed limbs is the identification of the appropriate stimulation channels and stimulus parameters to evoke desired movements. Here we present the use of a six degree-of-freedom load cell placed under the foot of a feline to characterize the muscle activation produced by three 100-electrode Utah Slanted Electrode Arrays (USEAs) implanted into the femoral nerves, sciatic nerves, and muscular branches of the sciatic nerves of three cats. Intramuscular stimulation was used to identify the endpoint force directions produced by 15 muscles of the hind limb, and these directions were used to classify the forces produced by each intrafascicular USEA electrode as flexion or extension. For 451 USEA electrodes, stimulus intensities for threshold and saturation muscle forces were identified, and the 3D direction and linearity of the force recruitment curves were determined. Further, motor unit excitation independence for 198 electrode pairs was measured using the refractory technique. This study demonstrates the utility of 3D endpoint force monitoring as a simple and non-invasive metric for characterizing the muscle-activation properties of hundreds of implanted peripheral nerve electrodes, allowing for electrode and parameter selection for neuroprosthetic applications.
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Affiliation(s)
- B R Dowden
- Department of Bioengineering, University of Utah, Salt Lake City, UT 84112, USA
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37
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Lin HL, Lin CCK, Ju MS, Liao JD. In vivo impedance evaluation of Au/PI microelectrode with surface modulated by alkanethiolate self-assembled monolayers. Biomed Microdevices 2010; 13:243-53. [PMID: 20972888 DOI: 10.1007/s10544-010-9489-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The goal of this study was to verify that a fully implanted microelectrode with modulated surface may have a reduced rising rate of total impedance and a longer life time. In the previous work, alkanethiolate self-assembled monolayers (SAMs) surface as protein-resistant spacer or cell-repulsive dense-packed spacer has been verified from in vitro experiments. In this study, microelectrodes with the same surface modulation were implanted into the subcutaneous layers of Wistar rats. Nine rats were implanted with the microelectrodes and the total impedance data were measured every 24 h for 2 weeks after implantation. An equivalent electrical circuit model of the electrode-tissue interface was established and parameters were estimated by using an optimization algorithm. Four out of nine rats had manifested acute inflammation reaction and the rests revealed only slight tissue response. Histological examination for the inflammatory group showed fibroblasts, macrophages, and polymorphonuclear leukocytes in adjacent to the electrode contact surface. In the inflammatory group, no significantly difference in total impedance was found in both types of electrodes. However, the trend of total impedance of SAMs-treated electrodes could maintain a steady state value after 1 week. For the non-inflammatory group, both types of electrodes could reduce the impedance value within implanted days. The tissue resistance might be related to the thickness of cells adhered upon the electrode contacts.
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Affiliation(s)
- Hwa-Li Lin
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of China
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38
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Schiefer MA, Polasek KH, Triolo RJ, Pinault GCJ, Tyler DJ. Selective stimulation of the human femoral nerve with a flat interface nerve electrode. J Neural Eng 2010; 7:26006. [PMID: 20208125 DOI: 10.1088/1741-2560/7/2/026006] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In humans, we tested the hypothesis that a flat interface nerve electrode (FINE) placed around the femoral nerve trunk can selectively stimulate each muscle the nerve innervates. In a series of intraoperative trials during routine vascular surgeries, an eight-contact FINE was placed around the femoral nerve between the inguinal ligament and the first nerve branching point. The capability of the FINE to selectively recruit muscles innervated by the femoral nerve was assessed with electromyograms (EMGs) of the twitch responses to electrical stimulation. At least four of the six muscles innervated by the femoral nerve were independently and selectively recruited in all subjects. Of these, at least one muscle was a hip flexor and at least two were knee extensors. Results from the intraoperative experiments were used to estimate the potential for the electrode to restore knee extension and hip flexion through functional electrical stimulation. Normalized EMGs and biomechanical simulations were used to estimate joint moments and functional efficacy. Estimated knee extension moments exceed the threshold required for the sit-to-stand transition.
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Affiliation(s)
- M A Schiefer
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA.
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39
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Gan LS, Prochazka A. Properties of the Stimulus Router System, a Novel Neural Prosthesis. IEEE Trans Biomed Eng 2010; 57:450-9. [PMID: 19770087 DOI: 10.1109/tbme.2009.2031427] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Liu Shi Gan
- Department of Biomedical Engineering and Center for Neuroscience, 5005 Katz Group/Rexall Center for Pharmacy and Health Research, University of Alberta, Edmonton, AB T6G2E1, Canada.
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40
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Hoffer JA, Kallesøe K. How to Use Nerve Cuffs to Stimulate, Record or Modulate Neural Activity. ACTA ACUST UNITED AC 2009. [DOI: 10.1201/9781420039054.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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Polasek KH, Hoyen HA, Keith MW, Kirsch RF, Tyler DJ. Stimulation stability and selectivity of chronically implanted multicontact nerve cuff electrodes in the human upper extremity. IEEE Trans Neural Syst Rehabil Eng 2009; 17:428-37. [PMID: 19775987 DOI: 10.1109/tnsre.2009.2032603] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nine spiral nerve cuff electrodes were implanted in two human subjects for up to three years with no adverse functional effects. The objective of this study was to look at the long term nerve and muscle response to stimulation through nerve cuff electrodes. The nerve conduction velocity remained within the clinically accepted range for the entire testing period. The stimulation thresholds stabilized after approximately 20 weeks. The variability in the activation over time was not different from muscle-based electrodes used in implanted functional electrical stimulation systems. Three electrodes had multiple, independent contacts to evaluate selective recruitment of muscles. A single muscle could be selectively activated from each electrode using single-contact stimulation and the selectivity was increased with the use of field steering techniques. The selectivity after three years was consistent with selectivity measured during the implant surgery. Nerve cuff electrodes are effective for chronic muscle activation and multichannel functional electrical stimulation in humans.
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Affiliation(s)
- Katharine H Polasek
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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42
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Grill WM, Norman SE, Bellamkonda RV. Implanted Neural Interfaces: Biochallenges and Engineered Solutions. Annu Rev Biomed Eng 2009; 11:1-24. [DOI: 10.1146/annurev-bioeng-061008-124927] [Citation(s) in RCA: 368] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Warren M. Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281;
| | - Sharon E. Norman
- Bioengineering Program Department of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Ravi V. Bellamkonda
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia 30332
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43
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Fisher LE, Tyler DJ, Anderson JS, Triolo RJ. Chronic stability and selectivity of four-contact spiral nerve-cuff electrodes in stimulating the human femoral nerve. J Neural Eng 2009; 6:046010. [PMID: 19602729 DOI: 10.1088/1741-2560/6/4/046010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study describes the stability and selectivity of four-contact spiral nerve-cuff electrodes implanted bilaterally on distal branches of the femoral nerves of a human volunteer with spinal cord injury as part of a neuroprosthesis for standing and transfers. Stimulation charge threshold, the minimum charge required to elicit a visible muscle contraction, was consistent and low (mean threshold charge at 63 weeks post-implantation: 23.3 +/- 8.5 nC) for all nerve-cuff electrode contacts over 63 weeks after implantation, indicating a stable interface with the peripheral nervous system. The ability of individual nerve-cuff electrode contacts to selectively stimulate separate components of the femoral nerve to activate individual heads of the quadriceps was assessed with fine-wire intramuscular electromyography while measuring isometric twitch knee extension moment. Six of eight electrode contacts could selectively activate one head of the quadriceps while selectively excluding others to produce maximum twitch responses of between 3.8 and 8.1 N m. The relationship between isometric twitch and tetanic knee extension moment was quantified, and selective twitch muscle responses scaled to between 15 and 35 N m in tetanic response to pulse trains with similar stimulation parameters. These results suggest that this nerve-cuff electrode can be an effective and chronically stable tool for selectively stimulating distal nerve branches in the lower extremities for neuroprosthetic applications.
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Affiliation(s)
- L E Fisher
- Case Western Reserve University, Cleveland, OH 44106, USA.
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44
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Pohlmeyer EA, Jordon LR, Kim P, Miller LE. A fully implanted drug delivery system for peripheral nerve blocks in behaving animals. J Neurosci Methods 2009; 182:165-71. [PMID: 19524613 DOI: 10.1016/j.jneumeth.2009.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 06/02/2009] [Accepted: 06/02/2009] [Indexed: 11/20/2022]
Abstract
Inhibiting peripheral nerve function can be useful for many studies of the nervous system or motor control. Accomplishing this in a temporary fashion in animal models by using peripheral nerve blocks permits studies of the immediate effects of the loss, and/or any resulting short-term changes and adaptations in behavior or motor control, while avoiding the complications commonly associated with permanent lesions, such as sores or self-mutilation. We have developed a method of quickly and repeatedly inducing temporary, controlled motor deficits in rhesus macaque monkeys via a chronically implanted drug delivery system. This assembly consists of a nerve cuff and a subdermal injection dome, and has proved effective for delivering local anesthetics directly to peripheral nerves for many months. Using this assembly for median and ulnar nerve blocks routinely resulted in over 80% losses in hand and wrist strength for rhesus monkeys. The assembly was also effective for inducing ambulatory motor deficits in rabbits through blocks of the sciatic nerve. Interestingly, while standard anesthetics were sufficient for the rabbit nerve blocks, the inclusion of epinephrine was essential for achieving significant motor blockade in the monkeys.
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Affiliation(s)
- Eric A Pohlmeyer
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
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Fisher LE, Miller ME, Bailey SN, Davis JA, Anderson JS, Rhode L, Tyler DJ, Triolo RJ. Standing after spinal cord injury with four-contact nerve-cuff electrodes for quadriceps stimulation. IEEE Trans Neural Syst Rehabil Eng 2009; 16:473-8. [PMID: 18990650 DOI: 10.1109/tnsre.2008.2003390] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper describes the performance of a 16-channel implanted neuroprosthesis for standing and transfers after spinal cord injury including four-contact nerve-cuff electrodes stimulating the femoral nerve for knee extension. Responses of the nerve-cuffs were stable and standing times increased by 600% over time-matched values with a similar eight-channel neuroprosthesis utilizing muscle-based electrodes on vastus lateralis for knee extension.
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Affiliation(s)
- Lee E Fisher
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
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Fitzgerald JJ, Lacour SP, McMahon SB, Fawcett JW. Microchannels as axonal amplifiers. IEEE Trans Biomed Eng 2008; 55:1136-46. [PMID: 18334406 DOI: 10.1109/tbme.2007.909533] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
An implantable neural interface capable of reliable long-term high-resolution recording from peripheral nerves has yet to be developed. Device design is challenging because extracellular axonal signals are very small, decay rapidly with distance from the axon, and in myelinated fibres are concentrated close to nodes of Ranvier, which are around 1 mum long and spaced several hundred micrometers apart. We present a finite element model examining the electrical behavior of axons in microchannels, and demonstrate that confining axons in such channels substantially amplifies the extracellular signal. For example, housing a 10-microm myelinated axon in a 1-cm-long channel with a 1000-microm(2) cross section is predicted to generate a peak extracellular voltage of over 10 mV. Furthermore, there is little radial signal decay within the channel, and a smooth axial variation of signal amplitude along the channel, irrespective of node location. Additional benefits include a greater extracellular voltage generated by large myelinated fibres compared to small unmyelinated axons, and the reduction of gain to unity at the end of the channel which ensures that there can be no crosstalk with electrodes in other channels nearby. A microchannel architecture seems well suited to the requirements of a peripheral nerve interface.
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Affiliation(s)
- James J Fitzgerald
- Cambridge Centre for Brain Repair, University of Cambridge, E.D. Adrian Building, Forvie Site, Robinson Way, Cambridge CB2 2PY, UK.
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Polasek KH, Hoyen HA, Keith MW, Kirsch RF, Tyler DJ. Spiral nerve cuff electrodes for an upper extremity neuroprosthesis. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2008; 2006:3584-7. [PMID: 17947040 DOI: 10.1109/iembs.2006.259625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Four nerve cuff electrodes were implanted in the shoulder and arm of one subject with high tetraplegia. Stimulation produced shoulder abduction, elbow flexion and extension, and wrist and finger extension. Recruitment properties were quantified using twitch EMG recruitment curves and tetanic moment measurements. The chronic qualitative 'function' of each channel of stimulation could be predicted from the intraoperative data collection. The average threshold was 11.3 +/- 9 nC and stabilized to this value over the 35 weeks of testing. The moment production of most muscles increased over the testing period due to exercise of the atrophied muscles. No muscle decreased its moment and most appeared to plateau after 15 weeks. Sensation was also evaluated since this subject had an incomplete injury and nerve stimulation was not found to painful throughout the range of muscle activation. Nerve electrodes have been shown to be a stable, effective means of activating muscles for neuroprosthetics.
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Abstract
A range of passive and active devices are under development or are already in clinical use to partially restore function after spinal cord injury (SCI). Prosthetic devices to promote host tissue regeneration and plasticity and reconnection are under development, comprising bioengineered bridging materials free of cells. Alternatively, artificial electrical stimulation and robotic bridges may be used, which is our focus here. A range of neuroprostheses interfacing either with CNS or peripheral nervous system both above and below the lesion are under investigation and are at different stages of development or translation to the clinic. In addition, there are orthotic and robotic devices which are being developed and tested in the laboratory and clinic that can provide mechanical assistance, training or substitution after SCI. The range of different approaches used draw on many different aspects of our current but limited understanding of neural regeneration and plasticity, and spinal cord function and interactions with the cortex. The best therapeutic practice will ultimately likely depend on combinations of these approaches and technologies and on balancing the combined effects of these on the biological mechanisms and their interactions after injury. An increased understanding of plasticity of brain and spinal cord, and of the behavior of innate modular mechanisms in intact and injured systems, will likely assist in future developments. We review the range of device designs under development and in use, the basic understanding of spinal cord organization and plasticity, the problems and design issues in device interactions with the nervous system, and the possible benefits of active motor devices.
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Affiliation(s)
- Simon F Giszter
- Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA.
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Winter JO, Cogan SF, Rizzo JF. Retinal prostheses: current challenges and future outlook. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2007; 18:1031-55. [PMID: 17705997 DOI: 10.1163/156856207781494403] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Blindness from retinal diseases, including age-related macular degeneration (AMD) and retinitis pigmentosa (RP), usually causes a significant decline in quality of life for affected patients. Currently there is no cure for these conditions. However, over the last decade, several groups have been developing retinal prostheses which hopefully will provide some degree of improved visual function to these patients. Several such devices are now in clinical trials. Unfortunately, the possibility of electrode or tissue damage limits excitation schemes to those that may be employed with electrodes that have relatively low charge densities. Further, the excitation thresholds that have been required to achieve vision to date, in general, are relatively high. This may result in part from poor apposition between neurons and the stimulating electrodes and is confounded by the effects of the photoreceptor loss, which initiates other pathology in the surviving retinal tissue. The combination of these and other factors imposes a restriction on the pixel density that can be used for devices that actively deliver electrical stimulation to the retina. The resultant use of devices with relatively low pixel densities presumably will limit the degree of visual resolution that can be obtained with these devices. Further increases in pixel density, and therefore increased visual acuity, will necessitate either improved electrode-tissue biocompatibility or lower stimulation thresholds. To meet this challenge, innovations in materials and devices have been proposed. Here, we review the types of retinal prostheses investigated, the extent of their current biocompatibility and future improvements designed to surmount these limitations.
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Affiliation(s)
- Jessica O Winter
- Center for Innovative Visual Rehabilitation, VA Medical Center, Boston, MA, USA.
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