BILATERAL LOSS OF VESTIBULAR FUNCTION

The clinical findings in 53 patients with bilateral vestibular failure (BVF) seen in a neurological hospital are reported. Bilateral acousti c neuromas were excluded. Seven patients (13%) had progressive cerebel lar degeneration; these patients had no hearing complaints but showed gait ataxia, abnormal eye movements and cerebellar atrophy on neuro-im aging. Referral in these patients was primarily for eye movement asses sment, and BVF was usually unsuspected. Neuropathies were present in 5 patients (9%), usually with normal central (brainstem-cerebellar) ocu lar motor function and variable patterns of hearing loss. The single l argest group was idiopathic BVF (11 patients, 21%): patients presentin g with vertiginous episodes, progressive unsteadiness or brief paroxys ms of oscillopsia; auditory function, eye movements, neurological exam ination and imaging were usually normal. Nine patients (17%) suffered ototoxicity, mostly due to gentamicin; hearing was normal or mildly im paired. In 6 patients (11%) BVF was post-meningitic, with concomitant auditory loss. Autoimmune disease was found in 5 patients (9%); other organs were involved by the disease, and hearing was impaired but eye movements were spared. Miscellaneous neurological, otological or neopl astic diseases accounted for the remaining 10 patients. This study sug gests that i) in patients with cerebellar degenerations, BVF may be un derdiagnosed as the unsteadiness may be attributed only to the cerebel lar disorder, ii) some patients with idiopathic BVF present with only minor visual or vestibular symptoms, and iii) detailed immunological s creenings should be undertaken more often, in view of the significant proportion of patients with autoimmune and idiopathic BVF.