Vestibular and auditory function in Usher's syndrome.

Usher's syndrome is a recessive hereditary disorder in which a congenital hearing loss is combined with nyctalopia, retinal degeneration, and restriction of visual fields. The results of a comprehensive ophthalmic and neurotologic study on 70 patients are reported. Two distinct clinical and presumed genetic types were discernible on the basis of hearing impairment and vestibular sensitivity and, to a lesser extent, deterioration of retinal photoreceptor function. Such a classification has proved valuable in diagnosis, prognosis, and genetic counselling.