VESTIBULAR CORTEX LESIONS AFFECT THE PERCEPTION OF VERTICALITY

Seventy-one patients with unilateral supratentorial infarctions were e valuated with respect to static vestibular function in the roll plane, including determinations of the subjective visual vertical, skew devi ation, and ocular torsion. Since animal studied have revealed at least four different areas of the parietal and temporal cortex involved in vestibular function, we tried to identify cortical areas in humans res ponsible for vestibular function in the roll plane. Infarcted areas, a s demonstrated in magnetic resonance and computed tomography scans, we re projected onto the appropriate sections of an atlas of the humin br ain. Infarctions in the territories of the posterior and anterior cere bral arteries did not affect static vestibular function in roll. Twent y-three of 52 patients with infarctions in the middle cerebral artery territory showed significant (P < 0.0005), mostly contraversive, patho logical subjective visual vertical tilts. The overlapping area bf thes e infarctions centered oh the posterior insula, probably homologous to the parieto-insular vestibular cortex in the monkey. Although electro physiological and cytoarchitectonic data in animals demonstrate severa l multisensory areas rather than a single primary vestibular cortex, t he parieto-insular vestibular cortex seem's to represent the integrati on center of the multisensory vestibular cortex areas within the parie tal lobe.