Facial paralysis.

Detailed knowledge of embryology, anatomy, and function of the facial nerve is essential in treating the devastating functional, aesthetic, and psychological sequelae of facial paralysis. Two basic factors influence the method of repair and the subsequent outcome of the effort to combat facial paralysis. First is the availability of a viable proximal nerve stump which can be used as the source for motor axons, and which is related to the level of the injury. Second is the duration of the paralysis, which will dictate the possibility of reinnervating the facial muscles. Early restoration of nerve continuity, and therefore reestablishment of the neuromuscular junction and preservation of the function of the facial muscles, lead to superior functional and aesthetic rehabilitation. Secondary reconstruction, after the establishment of atrophy of the motor endplates of the facial muscles, is possible with nerve grafts and microsurgical free functional muscle transfer. These techniques, although not perfect, greatly improve aesthetic balance and alleviate the functional and psychological implications of the paralysis.