Structural brain changes following peripheral vestibulo-cochlear lesion may indicate multisensory compensation

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.