[Cortical vertigo].

Dizziness of cortical origin is the subjective correlate of a disturbance of spatial orientation resulting from cerebrocortical dysfunction. Cortical dizziness in the form of vertigo is rare. If present, it most probably reflects a dysfunction of a vestibular representation in the insula. It may be accompanied by tinnitus, sensory disturbance and possibly also spontaneous nystagmus. The dysfunction of this region may result either from a focal seizure or from a lesion, for instance due to ischemia. Nondirectional, visual dizziness is most probably much more common than vertigo. This latter type of dizziness results from a functional disturbance of those parts of parietooccipital cortex, contributing to the discrimination of self-induced and externally-induced retinal image slip. It is not accompanied by additional symptoms and should immediately cease upon closure of the eyes or avoidance of ego motion.