Hereditary otovestibular dysfunction and Meniere's disease in a large Belgian family is caused by a missense mutation in the COCH gene

Objective: To report the clinical, auditory, and vestibular characteristics of a nonsyndromic otovestibular dysfunction in a large Belgian family caus ed by a missense mutation of the DFNA9 gene: COCH. Study Design: Retrospective study of the clinical, audiologic, and vestibul ar data of 60 genetically affected cases. Setting: Tertiary referral center. Patients: All members of a Belgian kindred who carry the genetic (P51S) def ect linked to the inherited hearing and vestibular impairment. Interventions: Diagnostic otologic, audiometric, and vestibular analysis an d imaging. Main Outcome Measures: Pure tone audiometry, supraliminary audiometry. and vestibular investigation. Results: The autosomal dominant inherited impairm ent was characterized by peripheral degeneration of the inner ear, leading to total deafness and bilateral vestibular areflexia. Conclusions: The genetically affected persons of a Belgian family shared a progressive sensorineural hearing loss starting between the third and sixth decade. Vestibular symptoms started at about the same age as the hearing l oss. The vestibular symptoms consisted of instability in darkness, a tenden cy to fall sideways, light-headiness, a drunken feeling, and attacks of ver tigo. Most of the patients reported tinnitus, and half of them reported pre ssure in the cars. Clinically, 9 of the 60 patients met the criteria for de finite Meniere's disease, and another 13 and 17 patients met the criteria f or probable or possible Meniere's disease, respectively. All 9 were older t han the age of 35, but only 1 was older than 55 years, so more than 30% of the patients were between 35 and 55 years old. A specific pattern could be recognized in the evolution of the otovestibula r impairment. Under the age of 35 years, almost all the affected family mem bers had normal hearing, whereas above the age of 55 years, the hearing los s was at least moderate, and vestibular hypofunction occurred. In between, there was a transition period of two to three decades, when deterioration o f the cochleovestibular function occurred, with a temporary audiometric and vestibular asymmetry.