IMPLANTATION OF A 16-CHANNEL FUNCTIONAL ELECTRICAL-STIMULATION WALKING SYSTEM

A 16-channel electrical stimulation system was implanted in a 39-year- old patient with T10 paraplegia to restore sit to stand, walking, and exercise functions. System implantation required two surgical sessions . in the first session, the posterior muscle set consisting of bilater al semimembranosus, adductor magnus, and gluteus maximus muscles were exposed and epimysial electrodes sutured at the point of greatest musc le contraction. Closed double helix intramuscular electrodes were impl anted in the erector spinae. Two weeks later; epimysial electrodes wer e attached to the eight anterior muscles consisting of the tibialis an terior, sartorius, tensor fasciae latae, and vastus lateralis with all 16 electrode leads passed to the anterior abdominal wall. The electro des were connected to two eight-channel stimulators placed in the ilia c fossae, and the system was checked by activating the individual musc les. The implanted stimulators received stimulation instructions and p ower via a radio frequency link to an external control. Stimulation pa tterns for standing, walking, sitting, and exercise functions were cho sen from a preprogrammed menu via a finger key pad. After 3 weeks of r estricted patient activity all electrodes stimulated either the target muscle or had an acceptable spillover pattern. The patient is undergo ing a 16-week rehabilitation course of stimulated exercises gradually increasing in intensity At the conclusion, the goal is to discharge th e patient with the system for spontaneous use. Although long term foll owup is required to determine system reliability; preliminary clinical results indicate that targeted, repeatable, functional muscle contrac tions in the lower extremity can be achieved with a system consisting of epimysial electrodes.