A surgically-implanted intramuscular electrode for an implantable neuromuscular stimulation system

An intramuscular electrode has been developed for use with an implantable neuromuscular stimulator. In vitro tests indicate that the electrode will maintain a stable position within the muscle, but is capable of being removed intact. When tested in a buffered saline environment at the maximum stimulation parameters (0.4 /spl mu/C/mm/sup 2//phase), there was no corrosion of the stimulating surface. In vivo evaluations were conducted, in which four sets of 4 intramuscular electrodes and 4 epimysial electrodes, were surgically implanted in the forelimb of 4 dogs. Each set was connected to an implanted neuromuscular stimulator. All but 1 of the 16 intramuscular electrodes operated properly throughout the study, producing responses functionally indistinguishable from epimysial electrodes. One electrode fractured due to improper surgical placement. After removal, some pitting corrosion was observed in 2 of the 15 retrieved intramuscular electrodes, possibly due to minute surface defects resulting from the electrode manufacturing process.>