Rapidly progressive dementia in an elderly man

His marked cognitive decline suggested diffuse cortical dysfunction. Frontal release signs suggested frontal lobe involvement while the episode of incoherent speech might suggest a focal seizure localising to Wernicke's area on the left. Ideomotor apraxia localises to the premotor cortex in the dominant hemisphere, and the right homonymous hemianopia to the left hemisphere, either along the optic tract, at the lateral geniculate body, or in the calcarine cortex.