Muscle preservation using an implantable electrical system after nerve injury and repair

The value of continuous electrical stimulation of denervated muscles after nerve injury and repair has been clearly shown in a series of laboratory experiments in three animal models. This experimental background, which showed improved muscle preservation and better functional results, evolved into a clinical study that included 15 patients with peripheral nerve injuries in the upper extremities, 3 patients with brachial plexus injuries, and three patients with facial nerve paralysis. Improved functional results were obtained using this implantable system, which were similar to those achieved with the animal experiments. All patients had muscle stimulation for extended periods ranging from 127 to 346 days. Analysis of the results showed satisfactory nerve regeneration on clinical examination and with electromyographic studies. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. The results from this study have clearly shown the benefits of continuous muscle stimulation using an implantable electrical system after nerve injury and repair expansion of the project to a larger patient cohort is indicated. © 2001 Wiley-Liss, Inc. MICROSURGERY 21:241‐247 2001 BACKGROUND There are 19,500 new cases of peripheral nerve injury each year in the United States. The incidence of obstetrical brachial plexus palsy ranges from 0.038% to 0.26% of fullterm births; approximately 20% of these involve total plexus injury. Despite our best microsurgical techniques, the functional results achieved after repair of severed peripheral nerves or reconstruction of the brachial plexus are less than optimal due to the muscle atrophy that takes place during the period of denervation. Nerve growth is estimated to occur at a rate of approximately 1 mm per day, or 1 inch per month; therefore, more proximal injuries lead to longer denervation periods. In a total brachial plexus injury at birth, for example, repair as early as 6 months of age will not lead to re-innervation of the intrinsic muscles of the hand until about 17 months of age, offering little chance for functional recovery. What happens to muscle during this period of denervation? In 1944, Bowden and Guttman 1 performed 140 muscle biopsies on the patients of Sir Herbert Seddon and found progressive atrophy and fibrosis during the first 3 years after