Implantable electrode lead in a growing limb

Akers, J.M.; Smith, BT; Betz, Randal R.

doi:10.1109/86.750550

Cited by 10 publications

(8 citation statements)

References 26 publications

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“…Previous efforts directed at restoring motor function in par-alyzed individuals used stimulation of the motor end plates or the nerve very close to the muscle with surface, percutaneous, or epimysial electrodes (Akers et al 1999;Bhadra and Mortimer 1997;Bhadra and Peckham 1997;Cameron et al 1998a,b;Ferguson et al 1999;Haugland et al 1999;Onishi et al 2000). While these types of electrodes provide a straightforward means for selectively stimulating individual muscles, a number of issues have hindered successful implementation of motor prosthetic systems based on these electrodes.…”

Section: Introductionmentioning

confidence: 99%

Selective Stimulation of Cat Sciatic Nerve Using an Array of Varying-Length Microelectrodes

Branner

Stein

Normann

2001

Journal of Neurophysiology

314

211

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Restoration of motor function to individuals who have had spinal cord injuries or stroke has been hampered by the lack of an interface to the peripheral nervous system. A suitable interface should provide selective stimulation of a large number of individual muscle groups with graded recruitment of force. We have developed a new neural interface, the Utah Slanted Electrode Array (USEA), that was designed to be implanted into peripheral nerves. Its goal is to provide such an interface that could be useful in rehabilitation as well as neuroscience applications. In this study, the stimulation capabilities of the USEA were evaluated in acute experiments in cat sciatic nerve. The recruitment properties and the selectivity of stimulation were examined by determining the target muscles excited by stimulation via each of the 100 electrodes in the array and using force transducers to record the force produced in these muscles. It is shown in the results that groups of up to 15 electrodes were inserted into individual fascicles. Stimulation slightly above threshold was selective to one muscle group for most individual electrodes. At higher currents, co-activation of agonist but not antagonist muscles was observed in some instances. Recruitment curves for the electrode array were broader with twitch thresholds starting at much lower currents than for cuff electrodes. In these experiments, it is also shown that certain combinations of electrode pairs, inserted into an individual fascicle, excite fiber populations with substantial overlap, whereas other pairs appear to address independent populations. We conclude that the USEA permits more selective stimulation at much lower current intensities with more graded recruitment of individual muscles than is achieved by conventional cuff electrodes.

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Section: Introductionmentioning

confidence: 99%

Selective Stimulation of Cat Sciatic Nerve Using an Array of Varying-Length Microelectrodes

Branner

Stein

Normann

2001

Journal of Neurophysiology

314

211

View full text Add to dashboard Cite

show abstract

“…Extra lead wire (mean of 5 cm per subject) was placed for each electrode in an S-shape along the path to the stimulator to accommodate growth of the pelvis and the proximal femur. 21 Growth was estimated via growth charts and by bone age using the GreulichPyle method. 22 Two growing subjects also received bilateral tibial derotational osteotomies due to excessive tibial external rotation (5508), one during the initial implant and one after training.…”

Section: Surgical Proceduresmentioning

confidence: 99%

Implanted functional electrical stimulation: an alternative for standing and walking in pediatric spinal cord injury

et al. 2003

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Study design: Post intervention, repeated measures design, comparing two interventions. Setting: Orthopedic pediatric hospital specializing in spinal cord injury. Methods: Nine subjects, ages 7 ± 20 years, received an eight-channel implanted lower extremity functional electrical stimulation (FES) system for standing and walking. Electrodes were placed to stimulate hip and knee extension, and hip abduction and adduction. Standing and walking were achieved through constant stimulation to the implanted muscles, allowing a swing through gait pattern with an assistive device. After training with FES and long leg braces (LLB), subjects were tested in eight upright mobility activities, which were scored based upon completion time and level of independence. Results: Seven subjects completed data collection. These subjects completed four activities faster (P50.02) and ®ve activities more independently (P50.025) with FES as compared to LLB. Transitions between sitting and standing, which were scored in isolation for two mobility activities, were achieved faster and with more independence with FES. In addition, subjects reported preferring FES for the majority of activities. No activity required more time or more assistance to complete with FES as compared to LLB. Conclusion: The implanted FES system provided these subjects with enhanced functional abilities over traditional LLB and decreased the need for physical assistance by a caregiver, suggesting that it is a realistic alternative for upright mobility in a pediatric population with spinal cord injury.

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“…These studies collected information in terms of electrical performance, number of complications and overall longevity. Other early implantable lead systems such as those used for functional electrical stimulation were also tested using in vivo animal models to evaluate the mechanical and electrical performance of the leads in growing and moving limbs, before implanting them in human patients [35]. More recent studies have combined in vivo animal models, computational models and mechanical fixtures to expose spinal cord stimulation lead systems to repetitive stresses and investigate lead breakage and migration [22].…”

Section: Discussionmentioning

confidence: 99%

Mechanical fatigue resistance of an implantable branched lead system for a distributed set of longitudinal intrafascicular electrodes

et al. 2017

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Objective A neural interface system has been developed that consists of an implantable stimulator/recorder can with a 15-electrode lead that trifurcates into three bundles of five individual wire longitudinal intrafascicular electrodes. This work evaluated the mechanical fatigue resistance of the branched lead and distributed electrode system under conditions designed to mimic anticipated strain profiles that would be observed after implantation in the human upper arm. Approach Custom test setups and procedures were developed to apply linear or angular strain at four critical stress riser points on the lead and electrode system. Each test was performed to evaluate fatigue under a high repetition/low amplitude paradigm designed to test the effects of arm movement on the leads during activities such as walking, or under a low repetition/high amplitude paradigm designed to test the effects of more strenuous upper arm activities. The tests were performed on representative samples of the implantable lead system for human use. The specimens were fabricated using procedures equivalent to those that will be used during production of human-use implants. Electrical and visual inspections of all test specimens were performed before and after the testing procedures to assess lead integrity. Main Results Measurements obtained before and after applying repetitive strain indicated that all test specimens retained electrical continuity and that electrical impedance remained well below pre-specified thresholds for detection of breakage. Visual inspection under a microscope at 10X magnification did not reveal any signs of damage to the wires or silicone sheathing at the stress riser points. Significance These results demonstrate that the branched lead of this implantable neural interface system has sufficient mechanical fatigue resistance to withstand strain profiles anticipated when the system is implanted in an arm. The novel test setups and paradigms may be useful in testing other lead systems.

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Implantable electrode lead in a growing limb

Cited by 10 publications

References 26 publications

Selective Stimulation of Cat Sciatic Nerve Using an Array of Varying-Length Microelectrodes

Selective Stimulation of Cat Sciatic Nerve Using an Array of Varying-Length Microelectrodes

Implanted functional electrical stimulation: an alternative for standing and walking in pediatric spinal cord injury

Mechanical fatigue resistance of an implantable branched lead system for a distributed set of longitudinal intrafascicular electrodes

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