Electromyographic Study of Functional Recovery of Free Vascularized Muscles Grafted to the Face

Abstract

The functional recovery of gracilis muscles grafted for treatment of facial paralysis in combination with a cross-face nerve graft was evaluated on the basis of electromyography in 98 cases. Initial action potentials were recorded, on average, 8 months after transplantation. There was a tendency for such potentials to appear earlier in the case of patients who finally attained good muscle activity. Action potentials were polyphasic in the early stage and of short duration and low amplitude. An increase in the amplitude and duration of potentials and a shortening of the distal latency were observed with increase in the numbers of reinnervated muscle fibers. Thereafter, there was a tendency toward decreases in the duration and number of spikes due to the increasing similarity in the distal latency of each neuromuscular unit. The grafted gracilis muscles attained a stable state about 1 year after the initial recording of action potentials. It was expected that spontaneous action potentials during rest might serve to indicate the condition of reinnervation. Their absence during the first few months after transplantation may suggest necrosis of the grafted muscle, while those of long duration and high amplitude observed after 1 postoperative year may be suggestive of disturbance in the reinnervation process. In this study, we could not find any significant difference in the reinnervation process between that of a gracilis muscle grafted following a cross-face nerve graft and a muscle reinnervated following nerve transection and repair. We therefore believe that free gracilis muscle transplantation combining a cross-face nerve graft is appropriate for the reconstruction of muscle function.