Facial nerve paralysis can be a major handicap. From a functional standpoint, loss of the normal blink reflex represents a potentially grave hazard that may lead to chronic discomfort and, in some cases, cause permanent loss of sight. Efforts to restore this reflex have been found wanting. In the proposed studies, adult cats with experimentally-induced unilateral facial paralysis will be subjected to one of two new surgical procedures in an attempt to restore normal orbicularis oculi function. One procedure will involve neurotization of the paralyzed orbicularis oculi muscle by the transfer of an innervated flap developed from the contralateral orbicularis oculi. A second technique would employ neuromuscular pedicles as cross-facial interposition grafts. The posterior auricular and temporal branches of the VIIth nerve and their muscles would be implanted into the paralyzed orbicularis oculi, and the nerves anastomosed microsurgically to zygomatic branches of the facial nerve. These animals would be compared with a subgroup the nerves of which would be allowed to regenerate in mesothelial chambers. Throughout the experimental period, orbicularis oculi EMG's will be recorded daily, and eye movements monitored. At the end of an experiment, the animal will be sacrificed by an overdose of sodium pentobarbital, and tissues fixed for histological study. The latter will include careful examination of end-plates and muscle fibers in both control and experimental animals. The results from the proposed studies would form part of a long-term investigation guided by the concept of strategic reinnervation of specific paralyzed muscle groups as opposed to reinnervation of all branches of the facial nerve. And the advantages to be gained from a model that would employ the VIIth nerve to restore function to paralyzed orbicularis oculi muscles are numerous, including the potential for appropriate unconscious movements, and a more complete closure of the eye lid, thus restoring a vital protective mechanism to the eye.
