Virus-associated demyelination in the pathogenesis of Bell's palsy.

We examined the cerebrospinal fluid findings, including the activity of the myelin-associated enzyme 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), and virus serology in patients with Bell's palsy. Eighty-nine of 164 patients showed hematological and/or serological evidence of an inflammatory reaction. Examinations of the CSF disclosed an elevated total protein level and pleocytosis in 33% and 10% of the 91 patients, respectively. The activity of CNP was significantly elevated in the patient group (15.5 +/- 3.8 nmol/h/ml) as compared with the control (13.2 +/- 1.3 nmol/h/ml) (p < 0.01), suggesting the presence of intrathecal myelin breakdown. Furthermore, there was an association between antibodies against herpes simplex virus (HSV) and elevated CNP activity. The inflammatory alterations and accompanying spinal fluid abnormalities, together with the high frequency of HSV antibodies suggest that HSV-associated demyelination may play a pathogenetic role in Bell's palsy.