Facial palsy: interpretation of neurologic findings

A review of the otoneurologic findings in 500 patients with facial paralysis revealed their importance for diagnosis, prognosis, and understanding the pathophysiology of Bell's palsy. Diagnosis. The presence of simultaneous bilateral palsy, facial paralysis associated with lateral rectus palsy, slowly progressive facial weakness with or without hyperkinesis, and facial paralysis that showed no recovery after six months excluded Bell's palsy from the diagnosis. Ipsilateral recurrent palsies were another indication to suspect an underlying cause, since a tumor of the facial nerve caused the paralysis in 30% of the patients with this finding. Signs such as intact forehead movement, alterations in facial sensation, and corneal hypesthesia--although often associated with lesions in the cerebral cortex, cerebellopontine angle, or internal auditory canal--were also found in patients with Bell's palsy. Prognosis. A spontaneous complete recovery following Bell's palsy occurs in about 70% of the patients; but in the presence of a dry eye or dysacousis, the prognosis for a complete recovery drops 10 and 25%, respectively. Pathophysiology. It is proposed that the wide range of neurologic findings associated with Bell's palsy is due to a viral polyneuropathy. This is a disorder that primarily involves sensory nerves, and the facial motor deficit results from involvement of the sensory fibers carried with the facial nerve within the fallopian canal.