Background Do central mechanisms account for the variability of clinical recovery following peripheral vestibulo-cochlear lesions?

Objective To investigate structural (morphological) plasticity in the human brain following unilateral vestibulo-cochlear lesions which might contribute to central vestibular compensation.

Methods The authors compared regional grey matter volume (GMV) changes in patients after surgical removal of unilateral acoustic neuroma with age-matched control subjects, and hypothesised morphometric changes in the vestibular and auditory cortices which may be related to functional disability scores. Patients were examined with a battery of neuro-otological tests and clinical scores to assess vestibular and auditory disability.

Results Voxel-based morphometry was used for categorical comparison between patients and age- and gender-matched controls. GMV increase was found bilaterally in primary somatosensory cortices and motion-sensitive areas in the medial temporal gyrus (MT). Simple regression analysis revealed a GMV increase (1) in the contralesional superior temporal gyrus/posterior insula to be correlated with decreasing clinically assessed vestibular deficits; (2) in the contralesional inferior parietal lobe with decreasing functional impairment of daily living activities; and (3) in the contralesional auditory cortex (Heschl gyrus) with decreasing hearing impairment.

Conclusions These data may suggest structural cortical plasticity in multisensory vestibular cortex areas of patients with unilateral peripheral vestibulo-cochlear lesion after surgical removal of acoustic neuroma. As changes of GMV were related to vestibular function, structural brain changes may reflect central mechanisms of vestibular compensation.