Vestibular cortex lesions affect the perception of verticality.

Seventy-one patients with unilateral supratentorial infarctions were evaluated with respect to static vestibular function in the roll plane, including determinations of the subjective visual vertical, skew deviation, and ocular torsion. Since animal studies 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 responsible for vestibular function in the roll plane. Infarcted areas, as demonstrated in magnetic resonance and computed tomography scans, were projected onto the appropriate sections of an atlas of the human brain. Infarctions in the territories of the posterior and anterior cerebral arteries did not affect static vestibular function in roll. Twenty-three of 52 patients with infarctions in the middle cerebral artery territory showed significant (p < 0.0005), mostly contraversive, pathological subjective visual vertical tilts. The overlapping area of these infarctions centered on the posterior insula, probably homologous to the parieto-insular vestibular cortex in the monkey. Although electrophysiological and cytoarchitectonic data in animals demonstrate several multisensory areas rather than a single primary vestibular cortex, the parieto-insular vestibular cortex seems to represent the integration center of the multisensory vestibular cortex areas within the parietal lobe.