Bilateral Vestibular Hypofunction: Insights in Etiologies, Clinical Subtypes, and Diagnostics

Objective: To evaluate the different etiologies and clinical subtypes of bilateral vestibular hypofunction (BVH) and the value of diagnostic tools in the diagnostic process of BVH. Materials and methods: A retrospective case review was performed on 154 patients diagnosed with BVH in a tertiary referral center, between 2013 and 2015. Inclusion criteria comprised 1) imbalance and/or oscillopsia during locomotion, and 2) summated slow phase velocity of nystagmus of less than 20 degrees per second during bithermal caloric tests. Results: The definite etiology of BVH was determined in 47% of the cases and the probable etiology in 22%. In 31%, the etiology of BVH remained idiopathic. BVH resulted from more than 20 different etiologies. In the idiopathic group, the percentage of migraine was significantly higher compared to the non-idiopathic group (50% versus 11%, p