VOLUMETRIC NEUROIMAGING IN USHER-SYNDROME - EVIDENCE OF GLOBAL INVOLVEMENT

Usher syndrome is a group of genetic disorders consisting of congenita l sensorineural hearing loss and retinitis pigmentosa of variable onse t and severity depending on the genetic type. It was suggested that th e psychosis of Usher syndrome might be secondary to a metabolic degene ration involving the brain more diffusely, There have been reports of focal and diffuse atrophic changes in the supratentorial brain as well as atrophy of some of the structures of the posterior fossa, We previ ously performed quantitative analysis of magnetic resonance imaging st udies of 19 Usher syndrome patients (12 with type I and 7 with type II ) looking at the cerebellum and various cerebellar components. We foun d atrophy of the cerebellum in both types and sparing of cerebellar ve rmis lobules I-V in type II Usher syndrome patients only. We now have studied another group of 19 patients (with some overlap in the patient s studied from the previous report) with Usher syndrome (8 with type I , 11 with type II). We performed quantitative volumetric measurements of various brain structures compared to age- and sex-matched controls. We found a significant decrease in intracranial volume and in size of the brain and cerebellum with a trend toward an increase in the size of the subarachnoid spaces. These data suggest that the disease proces s in Usher syndrome involves the entire brain and is not limited to th e posterior fossa or auditory and visual systems. (C) 1998 Wiley-Liss, Inc.