Bilateral Vestibular Hypofunction in a Tertiary Dizziness Center: Occurrence and Etiology

BACKGROUND: The primary goal of this study was to determine the occurrence of bilateral vestibular hypofunction in a specialized dizziness clinic and to assess the etiology in patients diagnosed with bilateral vestibular hypofunction. Secondary goal was to find out if the diagnosis was already made before the patient was seen at our clinic. METHODS: A retrospective cohort study, including patients who visited our specialized dizziness center between January 1, 2008, and December 31, 2018, fulfilling the criteria for bilateral vestibular hypofunction according to the Classification Committee of the Bárány Society (2017). Data were collected regarding symptoms, causes, and vestibular function. RESULTS: In total, 126 patients met our initial inclusion criteria, of which 103 patients met the Classification Committee of the Bárány Society criteria for bilateral vestibular hypofunction, so patients with bilateral vestibular hypofunction comprised 0.9% of the total population seen at our clinic. Mean age was 65.2 years and 49.5% were female. In only 29.1% of patients, the diagnosis was already made elsewhere. A definite cause was identified in 39.8%, the most common cause being ototoxicity. CONCLUSION: About 1% of the patients visiting our dizziness clinic has bilateral vestibular hypofunction. In our patient population, ototoxicity was the most common cause of bilateral vestibular hypofunction, and in more than 40%, the cause remains unknown. In the majority of the cases, the diagnosis of bilateral vestibular hypofunction was first made at our clinic and not by the referring general practitioner or specialist. When using the Classification Committee of the Bárány Society criteria for bilateral vestibular hypofunction and presbyvestibulopathy, some patients with bilateral vestibular weakness and complaints cannot be categorized in either group.