AUDIOVESTIBULAR FINDINGS IN PATIENTS WITH DEAFNESS CAUSED BY A MITOCHONDRIAL SUSCEPTIBILITY MUTATION AND PRECIPITATED BY AN INHERITED NUCLEAR MUTATION OR AMINOGLYCOSIDES

Objective: To characterize the audiological and vestibular changes ass ociated with a mitochondrial DNA mutation in an Arab-Israeli family an d in other families with mitochondrial predisposition to aminoglycosid e-induced hearing loss. Design: Evaluation of audiological (pure tone thresholds, speech reception thresholds, speech discrimination, tympan ometry, acoustic reflex thresholds, tone decay, and auditory brain-ste m evoked response recording) and vestibular (complete history, physica l examination, and 2-channel electronystagmography) systems. In 5 pati ents, structural evaluation of the inner ear was done by magnetic reso nance imaging. Patients: Fifteen members of an Arab-Israeli family, an d 1 Chinese woman with the same mitochondrial DNA mutation who experie nced hearing loss after short-term exposure to streptomycin. Results: Most of the patients had a profound hearing loss due to cochlear invol vement. The hearing loss usually was not accompanied by notable periph eral vestibular dysfunction. In the patient with severe hearing loss a fter exposure to aminoglycoside, the vestibular function was completel y normal. Conclusions: In most of the Arab-Israeli patients with conge nital deafness, the vestibular system function was normal, in contrast to the frequency of vestibular abnormality among deaf children, which was described in the literature. This may be related to genetic predi sposition to aminoglycoside-induced deafness.