Spiral Cuff Research Articles

ID: 223207 Evaluating Spiral Cuff Electrode Safety: A Device to Measure Pressure Induced on Peripheral Nerves

To develop more efficient leads for peripheral nerve stimulation, we have constructed self-sizing spiral cuff electrodes. By snugly fitting around the nerve, these electrodes demonstrate improved stimulation performance. A potential drawback of this design is that sufficiently high pressure applied by the lead to the nerve might lead to nerve damage. To evaluate this potential problem, we optimized the lead design and manufactured a declination of prototypes which were then evaluated using a custom-designed device to measure the pressure induced by a circumferential lead. This device uses dummy nerves ranging from 2 to 3 mm and allows for simulation of post-surgical inflammatory edema and nerve swelling.

The Fifth Bioelectronic Medicine Summit Hosted by the Feinstein Institutes for Medical Research (Manhasset, NY) and Columbia Engineering (NY, NY) at The Garden City Hotel, Garden City, NY 11530 on October 11-12th, 2022- Bioelectronic Medicine: Today’s Tools, Tomorrow’s Therapies

The Fifth Bioelectronic Medicine Summit Hosted by the Feinstein Institutes for Medical Research (Manhasset, NY) and Columbia Engineering (NY, NY) at The Garden City Hotel, Garden City, NY 11530 on October 11-12th, 2022- Bioelectronic Medicine: Today’s Tools, Tomorrow’s Therapies

O008 / #887 EVALUATING SPIRAL CUFF ELECTRODE SAFETY: A DEVICE TO MEASURE PRESSURE INDUCED ON PERIPHERAL NERVES: TRACK 1: NEUROMODULATION FOR PAINFUL NEUROPATHIES / PERIPHERAL NERVE STIMULATION

To develop more efficient leads for peripheral nerve stimulation, we have constructed self-sizing spiral cuff electrodes. By snugly fitting around the nerve, these electrodes demonstrate improved stimulation performance. A potential drawback of this design is that sufficiently high pressure applied by the lead to the nerve might lead to nerve damage. To evaluate this potential problem, we optimized the lead design and manufactured a declination of prototypes which were then evaluated using a custom-designed device to measure the pressure induced by a circumferential lead.

An Infant Case of Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery Successfully Treated with Modified Spiral Cuff Technique

An Infant Case of Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery Successfully Treated with Modified Spiral Cuff Technique

An improved method of crafting a multi-electrode spiral cuff for the selective stimulation of peripheral nerves

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.

\u201cLong-term stability of stimulating spiral nerve cuff electrodes on human peripheral nerves\u201d

BackgroundElectrical 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.MethodsSince 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.ResultsIn 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.ConclusionsThe 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.

Electrochemical and Electrophysiological Performance of Platinum Electrodes Within the Ninety-Nine-Electrode Stimulating Nerve Cuff.

The trend in neural prostheses using selective nerve stimulation for electrical stimulation therapies is headed toward single-part systems having a large number of working electrodes (WEs), each of which selectively stimulate neural tissue or record neural response (NR). The present article reviews the electrochemical and electrophysiological performance of platinum WE within a ninety-nine-electrode spiral cuff for selective nerve stimulation and recording of peripheral nerves, with a focus on the vagus nerve (VN). The electrochemical properties of the WE were studied in vitro using the electrochemical impedance spectroscopy (EIS) technique. The equivalent circuit model (ECM) of the interface between the WE and neural tissue was extracted from the EIS data and simulated in the time domain using a preset current stimulus. Electrophysiological performance of in-space and fiber-type highly selective vagus nerve stimulation (VNS) was tested using an isolated segment of a porcine VN and carotid artery as a reference. A quasitrapezoidal current-controlled pulse (stimulus) was applied to the VN or arterial segment using an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate B-fibers and minimize the stimulation of A-fibers. The EIS results revealed capacitive charge transfer predominance, which is a highly desirable property. Electrophysiological performance testing indicated the potential existence of certain parameters and waveforms of the stimulus for which the contribution of the A-fibers to the NR decreased slightly and that of the B-fibers increased slightly. Findings show that the design of the stimulating electrodes, based on the EIS and ECM results, could act as a useful tool for nerve cuff development.

Electrochemical performance of platinum electrodes within the multi-electrode spiral nerve cuff.

In this study, the electrochemical performance of platinum electrodes within a multi-electrode spiral cuff to be used for selective nerve stimulation was investigated. The original cuff, simplified into a half-cuff, contained a single row of nine electrodes (0.5×2mm) at a distance of 2mm from its inner surface. Cyclic voltammetry was used to investigate the electrochemical reactions at the electrode-electrolyte interface, to define a potential window within which the electrode could be safely used in selective nerve stimulation, to calculate the charge injection capacity and cathodal charge storage capacity. Voltage transients retrieved during excitation with quasitrapezoidal biphasic current pulses, tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment, were used to determine the maximum polarization across the electrode-electrolyte interface and to calculate cathodic charge injection capacity of the electrode. The results show that the most negative and most positive potentials across the electrode-electrolyte interface reached -0.54 and 0.59V; these did not exceed the safe potential limits for water electrolysis. Furthermore, the time integral of the cathodic current by cyclic voltammetry measured over the potential range of water electrolysis, actually representing the cathodal charge storage capacity, was approximately -4mCcm(-2). The charge injection capacity, representing the maximum charge density injected in a current stimulation pulse, using only reversible processes, however, was around 75µCcm(-2). In conclusion, both, the tested stimulation pulse and electrode are suitable for efficient and safe selective nerve stimulation.

Implanted Neuroprosthesis for Restoring Arm and Hand Function in People With High Level Tetraplegia

ObjectiveTo develop and apply an implanted neuroprosthesis to restore arm and hand function to individuals with high level tetraplegia. DesignCase study. SettingClinical research laboratory. ParticipantsIndividuals with spinal cord injuries (N=2) at or above the C4 motor level. InterventionsThe 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 MeasuresSuccessful installation and operation of the neuroprosthesis and electrode performance, range of motion, grasp strength, joint moments, and performance in activities of daily living. ResultsThe 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. ConclusionsFunctional 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.

Alternative Paradigm of Selective Vagus Nerve Stimulation Tested on an Isolated Porcine Vagus Nerve

Alternative paradigm for spatial and fibre-type selective vagus nerve stimulation (VNS) was developed using realistic structural topography and tested in an isolated segment of a porcine cervical left vagus nerve (LVN). A spiral cuff (cuff) containing a matrix of ninety-nine electrodes was developed for selective VNS. A quasitrapezoidal stimulating pulse (stimulus) was applied to the LVN via an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate the B-fibres, minimizing stimulation of the A-fibres and by-passing the stimulation of the C-fibres. To assess which fibres made the most probable contribution to the neural response (NR) during selective VNS, the distribution of conduction velocity (CV) within the LVN was considered. Experimental testing of the paradigm showed the existence of certain parameters and waveforms of the stimulus, for which the contribution of the A-fibres to the NR was slightly reduced and that of the B-fibres was slightly enlarged. The cuff provided satisfactory fascicle discrimination in selective VNS as well as satisfactory fascicle discrimination during NR recording. However, in the present stage of development, fibre-type VNS remained rather limited.

A chamber for biomechanical, electrochemical and electrophysiological measurements in functional segments of peripheral nerves

The aim of the work was to develop the chamber to be used in biomechanical, electrochemical and electrophysiological measurements in functional segments of peripheral nerves, when electrical stimulating pulses are selectively applied to preselected locations along the nerve and neural responses are measured.The main part of the chamber is the silicone multi-electrode spiral cuff system (cuff). It includes a spirally rolled matrix of 99 platinum electrodes, arranged in eleven longitudinal spiral configurations of nine electrodes for establishing electrical contact with specific sites on the peripheral nerve.The chamber is constructed to enable simulation of various mechanical actions which could occur when the spiral cuff is installed on the nerve. For this purpose the chamber is equipped with sensors for measurement of stretching forces, spiral cuff diameter/radial pressure and stretching elongation. Nevertheless, the chamber is equipped also with a 3D micro-manipulator for precise positioning of various stimulating or recording microelectrodes.To perform electrochemical measurements using the method of cyclic voltammetry, the chamber is instrumented also with a Ag/AgCl reference electrode.To maintain appropriate thermal conditions, the chamber body was machined out from Plexiglas using a CNC milling machine and is instrumented with a water bath circulator and with a precision temperature probe for precise temperature regulation.A functionality of both, the developed experimental chamber and a single-part cuff was tested on the isolated and functional segment of the left vagus nerve of a pig at simulated physiological conditions.

Time-Lapse Imaging of the Dynamics of CNS Glial-Axonal Interactions In Vitro and Ex Vivo

BackgroundMyelination is an exquisite and dynamic example of heterologous cell-cell interaction, which consists of the concentric wrapping of multiple layers of oligodendrocyte membrane around neuronal axons. Understanding the mechanism by which oligodendrocytes ensheath axons may bring us closer to designing strategies to promote remyelination in demyelinating diseases. The main aim of this study was to follow glial-axonal interactions over time both in vitro and ex vivo to visualize the various stages of myelination.Methodology/Principal FindingsWe took two approaches to follow myelination over time: i) time-lapse imaging of mixed CNS myelinating cultures generated from mouse spinal cord to which exogenous GFP-labelled murine cells were added, and ii) ex vivo imaging of the spinal cord of shiverer (Mbp mutant) mice, transplanted with GFP-labelled murine neurospheres. We demonstrate that oligodendrocyte-axonal interactions are dynamic events with continuous retraction and extension of oligodendroglial processes. Using cytoplasmic and membrane-GFP labelled cells to examine different components of the myelin-like sheath, we provide evidence from time-lapse fluorescence microscopy and confocal microscopy that the oligodendrocytes' cytoplasm-filled processes initially spiral around the axon in a corkscrew-like manner. This is followed subsequently by focal expansion of the corkscrew process to form short cuffs, which then extend longitudinally along the axons. We predict from this model that these spiral cuffs must extend over each other first before extending to form internodes of myelin.ConclusionThese experiments show the feasibility of visualizing the dynamics of glial-axonal interaction during myelination over time. Moreover, these approaches complement each other with the in vitro approach allowing visualization of an entire internodal length of myelin and the ex vivo approach validating the in vitro data.

Electrodes and Chronic Optic Nerve Stimulation

Visual pathways are often schematized as a parallel afferent transmission of pixel image matrices. Suggested interfaces would thus have numerous contacts in close proximity to the target elements. However, well organised tissue reactions would actively keep electrodes away from the neural units. Alternatively, self sizing spiral cuffs were wrapped around the optic nerve of two blind volunteers in an attempt to develop a visual prosthesis. Unexpected features of the optic nerve code have emerged. This interface remained well tolerated for more than ten years. However, there is still a long way to go before to reach useful vision rehabilitation.

Perineal Colostomy With Spiral Smooth Muscle Graft for Neosphincter Reconstruction Following Abdominoperineal Resection of Very Low Rectal Cancer: Long-Term Outcome

To avoid abdominal colostomy and improve quality of life, several types of anorectal reconstruction following abdominoperineal resection have been proposed. The aim of this study was to assess functional results and the quality of life of patients with very low rectal cancer after abdominoperineal resection and neosphincter reconstruction by perineal colostomy with a colonic muscular cuff. Twenty-seven patients who had undergone neosphincter reconstruction with a perineal spiral cuff plasty after abdominoperineal resection were included in a retrospective study to evaluate long-term outcome. The functional results were analyzed using anal manometry and the continence score. The quality of life was measured with the global and disease-specific questionnaires European Organization for Research and Treatment of Cancer QLQ-C30 and C38. Median follow-up time was 105 months (range, 18-185 mo). The median Holschneider continence score of the study sample was 13 (continent), with a range of 10 (partially continent) to 16 (continent), thus demonstrating satisfactory functional results. The functional assessment was completed by neosphincter manometry which revealed a median resting vs compression pressure of 40 vs 96 cmH2O with a range of 5 to 81 cmH2O vs 49 to 364 cmH2O. The quality-of-life analyses showed an above-average score for both global health and disease-specific status. Spiral cuff colostomy with reconstruction after abdominoperineal resection of very low distal rectal cancer offers a surgical option for a selective group of patients with reasonable functional long-term results and an improved quality of life.

Intraoperative evaluation of the spiral nerve cuff electrode on the femoral nerve trunk

Evaluation of the Case Western Reserve University spiral nerve cuff electrode on the femoral nerve trunk was performed intraoperatively in four subjects undergoing femoral-popliteal bypass surgery. The threshold, nerve size and selective activation capabilities of the electrode were examined. The activation thresholds for the first muscle to be recruited were 6.3, 9, 10.6, and 37.4 nC with pulse amplitudes ranging from 0.3 to 1 mA. The femoral nerve was found to have an elliptical cross-section with a major axis average length of 9 mm (8–12 mm) and a minor axis length of 1.5 mm. In all four subjects selective activation of the sartorius was obtained. In two subjects, the rectus femoris could also be selectively activated and in one subject the vastus medialis was selectively activated. Each electrode had four independent contacts that were evaluated separately. Small air bubbles were formed in the space over some contacts, preventing stimulation. This occurred in one contact in each electrode, leaving three effective stimulation channels. This issue has been corrected for future studies.

Pt metallization of laser transformed medical grade silicone rubber: Last step toward a miniaturized nerve electrode fabrication process

Chronic nerve recording and stimulation became possible through the use of implanted electrodes cuffs. In particular, self-sizing spiral electrode cuffs limit mechanical damage to the tissue: these have been shown to be suitable for long term implantation in animal and in man. However, up to now, such electrode cuffs were handmade and were hardly reproducible. They possessed a small number of electrodes (dot contacts), each being linked to its own wire. In order to improve the selectivity of nerve recording and/or stimulation (functional electrical stimulation), the numbers of electrodes and tracks have to be increased within the same electrode cuff surface. To fulfill this requirement, we have developed a fabrication process that uses an UV laser to induce surface modification, which activates the silicone rubber and is used with a mask to give high definition tracks and electrodes. After this primary step, silicone rubber is immersed in a Pt autocatalytic bath leading to a selective Pt metallization of the laser activated tracks and electrodes. We report our process as well as the results on the Pt metallization, including its morphology, how the DC resistance of Pt tracks depends on the laser used and the irradiation conditions, and also the electrical resistance of Pt tracks submitted to Scotch tape tests or to imposed strains. We show that (i) the type of laser and the irradiation conditions have a strong influence on the nucleation and growth rate of platinum and thus on the DC resistance of the tracks, (ii) the tracks of width 400 μm and thickness 10 μm have a sheet resistivity of 0.2 Ω/sq, (iii) DC resistance does not change much during a 6 month soak in saline, (iv) strains above 2% breaks the track continuity, and (v) when strains below 53% are relaxed, the DC resistance returns to a low value. This recovery from large tensile strains means that nerve cuffs with such metallization could be handled by the surgeon without great care before and during implantation.

Stimulation Stability and Selectivity of Chronically Implanted Multicontact Nerve Cuff Electrodes in the Human Upper Extremity

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.

Selective Stimulation of Autonomic Nerves and Recording of Electroneurograms in a Canine Model

The article presents the results of modeling, design, and experimental testing of a multielectrode spiral cuff (CUFF) to determine to what extent a CUFF could be used for selective stimulation of different types of nerve fibers within particular compartments and for selective recording of electoneurograms (ENGs) from particular compartments of the peripheral autonomic nerve. The CUFF was implanted on the left cervical vagus nerve (LVN) of a dog. The relative positions of the particular nerve regions that innervated the cardiovascular (CV) and respiratory system (RS) were identified by delivering the stimuli to the particular group of three electrodes (GTE). The stimuli caused both selective stimulation of mainly B fibers within the particular compartments, and differential block of A fibers by membrane hyperpolarization. It was shown that when the stimuli were delivered to GTE9, the heart rate began to fall and when the stimuli were delivered to GTE4, the rate of breathing decreased. The defined and randomly chosen GTEs were used also as recording GTEs while CV or RS were stimulated by carotid artery massage, epinephrine injection, and noninvasive positive end-expiratory pressure ventilation (NIPEEPV). Results demonstrate that the function of a particular internal organ can be modulated via the selective stimulation of the innervating compartment of the peripheral nerve. Results also showed that stimulations elicited site-specific changes in ENG power spectra recorded from the particular compartments of the LVN.

Time course of tissue remodelling and electrophysiology in the rat sciatic nerve after spiral cuff electrode implantation

Implantation of nerve cuff electrodes induces inflammatory cell infiltration and loose connective tissue accumulation. Along with time, morphological changes evolve towards a thicker epi/perineurium as part of mechanisms that protect nerve functionality when a foreign body is wrapped around it. The rise in electrode impedance is linked to the nature of the epineurial tissue. Changes involve an increased expression of neuroprotective factors that is stronger in the endoneurium with axonal degeneration. Our data indicate that epineurial and endoneurial changes after electrode cuff implantation are part of axonal protection mechanisms. Their control is important to improve the yield of FES applications.

Human Nerve Stimulation Thresholds and Selectivity Using a Multi-contact Nerve Cuff Electrode

Testing of the recruitment properties and selective activation capabilities of a multi-contact spiral nerve cuff electrode was performed intraoperatively in 21 human subjects. The study was conducted in two phases. An exploratory phase with ten subjects gave a preliminary overview of the data and data collection process and a systematic phase with eleven subjects provided detailed recruitment properties. The mean stimulation threshold of 25 +/- 17 nC was not significantly different than previous studies in animal models but much lower than muscle electrodes. The selectivity, defined as the percent of total activation of the first muscle recruited before another muscle reached threshold, ranged from 27% to 97% with a mean of 55%. In each case, the muscle that was selectively activated was the first muscle to branch distal to the cuff location. This study serves as a preliminary evaluation of nerve cuff electrodes in humans prior to chronic implant in subjects with high tetraplegia.