Rotational vertigo in embolic stroke of the vestibular and auditory cortices.

We describe the unique case of a woman with embolic infarction within the right middle cerebral artery territory who had nonepileptic rotational vertigo, nausea, and unsteady gait that gradually resolved within a week. A well-demarcated lesion of the posterior insula (homologous to parieto-insular vestibular cortex in monkeys) was probably the cause. This is supported by a contraversive tilt of perceived vertical and by involvement of the adjacent auditory (Heschl's) cortex. Dipole source analysis of late auditory evoked potentials revealed a decreased amplitude of a dipole source in the right insular cortex, whereas two other dipoles situated in the temporal lobe showed symmetric activity.