A clinical pilot study to assess functional return following continuous muscle stimulation after nerve injury and repair in the upper extremity using a completely implantable electrical system.

This clinical pilot study evolved from a 10-year experience in the experimental laboratory using continuous muscle stimulation in a series of animal studies following nerve injury and microsurgical repair. A completely implantable system was developed (Medtronic) to provide electrical stimulation to the denervated muscles until nerve regeneration had occurred. Both peripheral nerve injuries in the extremities and facial nerve severances were studied, and a definite improvement in functional capacity was obtained as well as improved morphology compared with nonstimulated controls. In this study, 13 patients with peripheral nerve injuries in the upper extremity are included. All patients had muscle stimulation for extended periods until nerve regeneration was evident; a careful analysis of their functional capacity was then completed. There were five patients with median nerve injuries, four with ulnar nerve or combined median-ulnar nerve injuries, and four with severed radial nerves. All patients showed satisfactory nerve regeneration on clinical examination and electromyographic studies. Motor recovery was usually better than sensory return. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. Patients with low nerve lesions had better results, but muscle recovery even in patients with mid-forearm or higher nerve injuries was most encouraging. Functional recovery in radial nerve injuries was close to normal in all cases. The results from this pilot study have clearly shown the benefits of continuous muscle stimulation using an implantable system following nerve injury and repair.