Usher's syndrome. evaluation of the vestibular system with cervical and ocular vestibular evoked myogenic potentials and the video head impulse test

OBJECTIVE: The Usher's syndrome (USH) is composed of a group of inherited disorders characterized by a dual sensory impairment of the audiovestibular and visual systems. Despite the established hearing loss, few authors have investigated vestibular dysfunction in these patients.The aim of this article is to investigate otolith or ampullary dysfunction in a group of patients affected by USH by means of a diagnostic protocol using caloric vestibular tests, cervical vestibular evoked myogenic potentials (C-VEMPs), ocular vestibular evoked myogenic potentials (O-VEMPs), and video head impulse test (v-HIT) to show any selective damage of the vestibular nerve and also to identify if it is present in patients with a previous diagnosis of USH Type II. STUDY DESIGN: Prospective study with C-VEMPs, O-VEMPs, and v-HIT. SETTING: Tertiary referral center. PATIENTS: Fifteen patients with USH. INTERVENTION: Evaluation of otolith dysfunction with caloric test, C-VEMPs, and O-VEMPs and the measurement of the vestibular-ocular reflex using the v-HIT. RESULTS: Only three cases showed normal values of all the vestibular tests performed. O-VEMPs and C-VEMPs appeared pathologic in nine and seven cases, respectively. V-HITs showed ampullary dysfunction in 10 patients. In our study, eight of the 11 patients belonging to the group of USH Type II showed a pathologic response to at least one of the vestibular tests performed. CONCLUSION: Today, in patients affected by USH, any vestibular diagnostic protocol must include VEMPs and v-HIT to confirm the vestibular damage, identify selective deficit of the vestibular nerve, and provide useful information for a correct classification of USH.