Abstract
Objective: 1) Report the largest series to date of patients with cerebellar ataxia with bilateral vestibulopathy (CABV). 2) Understand the unique balance problems in this disorder; we studied the eye movements crucial for gaze stabilization.
Method: From over 16 years at a multidisciplinary neuro-otology clinic, 32 patients (mean age, 51.7 (SD = 19.3)) with symptoms of CABV syndrome over a median of 5 (IQR = 2-10) years were selected for both clinical and oculographic analysis of their central and peripheral vestibular function.
Results: Vestibulo-ocular reflex (VOR) function was impaired on Halmagyi head thrust testing in 74% of patients; patients studied by oculography revealed a subnormal mean VOR gain of 0.67. Impaired dynamic visual acuity was abnormal in 88%. Importantly, this impairment would have been underestimated by bithermal caloric testing, in which only 22% were subnormal. Gaze-evoked nystagmus (70%), impaired smooth pursuit (88%), and impaired cancellation of the VOR (93%) revealed the associated vestibulocerebellar dysfunction. Impaired saccular otolithic function (44% abnormal VEMP) added to patient imbalance. 77% of patients displayed obvious gait ataxia, and a further 41% had dysmetric limb function.
Conclusion: The unique double-pathway balance impairments in patients with CABV are evident in the high prevalence of subnormal function of both peripheral and central vestibular signals seen in their dysfunctional eye movements. This is an easily missed clinical entity that is often associated with normal caloric investigations.
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