Double impairment: clinical identification of 33 cases of cerebellar ataxia with bilateral vestibulopathy.

OBJECTIVE: Following recently described small series of patients with the syndrome of cerebellar ataxia with bilateral vestibulopathy (CABV), the authors undertook a careful clinical and laboratory assessment of patients who presented to their unit with characteristics of this syndrome. STUDY
DESIGN: Case note review.
SETTING: Tertiary, university-based, multidisciplinary neurootology clinic.
SUBJECTS: Thirty-three patients whose characteristics fit this syndrome.
METHODS: Patients presenting to the Multidisciplinary Neurotology Clinic with characteristics of CABV were entered into a bespoke database. This was analyzed to identify the clinical findings and results of vestibular investigations for this group.
RESULTS: Patients presented at a mean age of 54 years (SD, 17.6) with symptoms having been present for a median of 3 years (interquartile ratio, 2.0-9.5). Caloric testing greatly underestimated the disorder, being subnormal in only 18% of patients; the head-thrust test was abnormal and dynamic visual acuity testing was abnormal 88% and 91% of the time, respectively. Of the patients, 76% demonstrated gaze-evoked nystagmus. Impaired smooth pursuit (97% of patients showed low gain with saccadic corrections) and impaired cancellation of the vestibulo-ocular reflex (in 97% of patients) were found. Impaired saccular otolithic function was abnormal in 33%, adding to patient imbalance.
CONCLUSION: The unique double-pathway balance impairment in CABV patients causes a high prevalence of subnormal function of both central and peripheral vestibular function. This is an easily missed clinical entity that is often associated with normal caloric investigations. As many patients with this syndrome are poor candidates for vestibular rehabilitation therapy, resources are better devoted to the early implementation of assistance with their safe ambulation and activities of daily living.