Idiopathic facial nerve paralysis, or Bell's palsy, is characterized by the following1: (1) complete or partial paralysis of the entire side of the face, (2) absence of symptoms or signs of other neurologic disorders, and (3) absence of symptoms or signs of disease of the ear or posterior fossa.
It is seen fairly often in clinical practice, with an annual incidence between 13 and 23/100,000 population.2,3
In contrast, bilateral Bell's palsy is rare.4 In a series of 308 patients with Bell's palsy, Adour and Swanson5 found only one patient with bilateral involvement. Hauser2 reported that two of his 121 patients with idiopathic facial paralysis had bilateral disease. Leibowitz'6 series of 582 cases included only five patients who had bilateral involvement. The ages of the patients with bilateral Bell's palsy in these three large series were not specified. Iso-Patients With Bilateral Bell's Palsy Patient/Age, yr/Sex
GOFF CW, CERCIELLO R, HOLMES GL. Bilateral Bell's Palsy. Am J Dis Child. 1983;137(1):83. doi:10.1001/archpedi.1983.02140270073023