Gray-matter atrophy after chronic complete unilateral vestibular deafferentation.

It has been shown in blind patients that the abolition of sensory input can lead to changes in white- and cortical gray-matter volumes. Here the white- and gray-matter changes found with whole brain voxel-based morphometry in 16 patients with complete chronic unilateral vestibular deafferentation (UVD) due to vestibular schwannoma removal several years prior are reported on. Subtle deficits in spatial memory and navigation were previously shown in patients with right UVD. Images of the brains of right-UVD patients were flipped, standard preprocessing steps were performed, and the data were modulated. Patients showed a gray-matter volume reduction in the cerebellum due to schwannoma removal, in the supramarginal gyrus ipsilateral to the lesion, as well as in the postcentral and superior temporal gyrus, areas involved in the vestibular cortical network, and in the motion-sensitive area MT/V5. There was no correlation with behavioral navigational abilities. No gray-matter atrophy was found in the insular cortical vestibular region or the hippocampus, both of which receive bilateral vestibular projections. The thalamus and tegmentum of the mesencephalon showed gray-matter reduction on the opposite side; this was possibly due to reduced auditory input, which is known to cross at this level. In comparison to healthy controls, no regional increases in gray-matter volume were seen. No white-matter changes were detected at the selected threshold.