Bilateral loss of vestibular function.

The clinical findings in 53 patients with bilateral vestibular failure (BVF) seen in a neurological hospital are reported. Bilateral acoustic neuromas were excluded. Seven patients (13%) had progressive cerebellar degeneration; these patients had no hearing complaints but showed gait ataxia, abnormal eye movements and cerebellar atrophy on neuro-imaging. Referral in these patients was primarily for eye movement assessment, and BVF was usually unsuspected. Neuropathies were present in 5 patients (9%), usually with normal central (brainstem-cerebellar) ocular motor function and variable patterns of hearing loss. The single largest group was idiopathic BVF (11 patients, 21%), patients presenting with vertiginous episodes, progressive unsteadiness or brief paroxysms of oscillopsia; auditory function, eye movements, neurological examination and imaging were usually normal. Nine patients (17%) suffered ototoxicity, mostly due to gentamicin; hearing was normal or mildly impaired. 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 neoplastic diseases accounted for the remaining 10 patients. This study suggests that i) in patients with cerebellar degenerations, BVF may be underdiagnosed as the unsteadiness may be attributed only to the cerebellar disorder, ii) some patients with idiopathic BVF present with only minor visual or vestibular symptoms, and iii) detailed immunological screenings should be undertaken more often, in view of the significant proportion of patients with autoimmune and idiopathic BVF.