Bell's palsy. Nonrecurrent v recurrent and unilateral v bilateral.

Bell's palsy was classified into five categories--unilateral nonrecurrent , unilateral recurrent, simultaneous bilateral, alternating bilateral, and recurrent bilateral type--based on the clinical statistical study of two large series of patients with Bell's palsy treated at different locations in Japan. One series consisted of 1,217 patients and the other of 1,197 for a total of 2,414 patients in this study. The incidence of each type and the age and sex distributions were similar in the two groups. Clinical features of each type are described. The results imply that more specific causative factors trigger the recurrences and the simultaneous bilateral attacks.