Neuro-ophthalmologic findings in vestibulocerebellar ataxia.

A young adult who presents with periodic vertigo, diplopia, and tinnitus, later followed by progressive ataxia, may not have multiple sclerosis as might initially be suspected, but rather may represent a type of familial spinocerebellar degeneration previously described by Farmer and Mustian as "vestibulocerebellar ataxia." We recently encountered a patient who presented with these symptoms, and who was found to have downbeat nystagmus, ocular dysmetria, skew deviation, optokinetic dissociation, and a vertical gain bias on horizontal eye movements. Although family involvement was specifically denied by the patient, seven members of her family representing four generations were examined, and found to have similar findings. The importance of a careful neuro-ophthalmologic examination in each available family member of any patient presenting with this constellation of symptoms is emphasized. A discussion of the spinocerebellar degenerations, differential diagnosis, and literature review are included.