A new clinical classification for Usher's syndrome based on a new subtype of Usher's syndrome type I

Objectives: Usher's syndrome is an autosomal recessive disorder characteriz ed by sensorineural hearing loss and progressive visual loss secondary to r etinitis pigmentosa, Usher's syndrome is both clinically and genetically he terogeneous. Three clinical types are known today. Methods: We conducted a study on 74 patients with Usher's syndrome, performing complete audiologica l and neurotological examinations. Results: Twenty-six patients had total p rofound hearing loss and retinitis pigmentosa (Usher's syndrome type I), an d 48 patients had moderate to severe sensorineural hearing loss and retinit is pigmentosa (Usher's syndrome type II). We identified 9 of the 26 Usher's syndrome patients with profound hearing loss who showed a normal response to bithermal vestibular testing. Conclusions: The combination of profound h earing loss and normal response to bithermal vestibular testing has not bee n previously described in Usher's syndrome. Therefore we describe a new sub type of Usher's syndrome type I and suggest a modified clinical classificat ion for Usher's syndrome.