Causative factors, epidemiology, and follow-up of bilateral vestibulopathy.

Bilateral vestibulopathy (BV) is characterized by impaired or lost function of both peripheral labyrinths or of the eighth nerves. In a review of 255 patients (mean age +/- SD, 62 +/- 16 years) with BV diagnosed in the authors' dizziness unit between 1988 and 2005, 62% of the patients were male. Previous vertigo attacks had occurred in 36%, indicating a sequential manifestation. The definite cause of BV was determined in 24% and the probable cause in 25%. The most common causes were ototoxic aminoglycosides (13%), Ménière's disease (7%), and meningitis (5%). Strikingly, 25% exhibited cerebellar signs. Cerebellar dysfunction was associated with peripheral polyneuropathy in 32% compared with 18% in BV patients without cerebellar signs. In a follow-up study on 82 BV-patients (mean age at the time of diagnosis 56.3 +/- 17.6 years), the frequency and degree of recovery or worsening of vestibular function over time were determined. The patients were reexamined 51 +/- 6 months after the first examination. Electronystagmography with bithermal caloric irrigation was analyzed by measurement of the mean peak slow-phase velocity (SPV) of the induced nystagmus. Statistical analysis of the mean peak SPV revealed a nonsignificant worsening over time (initial mean peak SPV 3.0 +/- 3.5 degrees/s vs. 2.1 +/- 2.8 degrees/s). Only patients with BV due to meningitis exhibited an increasing, but nonsignificant SPV (1.0 +/- 1.4 degrees/s vs. 1.9 +/- 1.6 degrees/s). Forty-three percent of patients subjectively rated the course of their disease as stable, 28% as worsened, and 29% as improved.