Experience with implanted electrodes.

Implant units, manufactured by Medtronic, Inc., have been implanted in 31 patients for treatment of drop-foot. The principal problem encountered in this series was inflammatory reaction. This was observed in seven patients, and was serious enough in five to require removal of the implant. On the positive side, there have been no failures of the implanted equipment for periods of up to 7.3 years, although there is currently a question on one patient. There has also been no documented damage to the nerve from chronic stimulation. Fine wire elctrodes have been implanted intraneurally in a series of animals and in three patients. Preliminary results look encouraging, and this approach seems to hold considerable promise for a new generation of electrode design.