Familial Progressive Vestibulocochlear Dysfunction Caused by a COCH Mutation (DFNA9)

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Abstract
Objective To describe the decline of vestibulocochlear function in a man with vestibulocochlear dysfunction caused by a Pro51Ser mutation within theCOCHgene on chromosome 14q12-13 (DFNA9). Methods A follow-up of more than 15 years was performed in a single case. Clinical investigations were supplemented by oculomotor, vestibular, and auditory tests. Results A 50-year-old man had had progressive sensorineural hearing loss and dysequilibrium for 15 years; he had been asymptomatic at the age of 35 years. He suffered from instability in the dark, head movement–dependent oscillopsia, paroxysmal positional vertigo, and vertigo with and without nausea. Hearing impairment started unilaterally, predominantly in the high frequencies. He also reported tinnitus. Disease progressed to severe bilateral high-frequency hearing impairment and vestibular areflexia. Fluctuation of vestibulocochlear function was documented and mentioned by the patient. Conclusions Our patient proved to suffer from an autosomal dominant vestibulocochlear disorder caused by aCOCHgene mutation. The remarkable medical history has some features in common with Ménière disease; however, there are also different clinical and neurophysiological features. In the family, phenotypic variability is present.