Hyperacute cognitive stroke syndromes.

Cognitive syndromes are common clinical manifestations of hyperacute stroke and may be the single or dominant presenting features. They are related to acute dysfunction of complex integrated distributed functional networks serving different cognitive domains. The most common cortical syndromes include nonfluent or fluent aphasia, neglect, collor agnosia, pure alexia and Balint's syndrome. Disturbances of declarative memory are common following posterior cerebral artery and thalamic strokes. Abulia can follow thalamic, caudate and capsular lesions. Intraventricular and subarachnoid haemorrhages can cause preeminent neuropsychological changes. Disorientation is present in about 40% of acute stroke patients and delirium complicates the course of 25% of acute strokes. Some hyperacute cognitive stroke syndromes are useful indicators of later disability. Cognitive syndromes may pose special difficulties to neurology residents, unless formal teaching in neuropsychology and psychiatry is included in their training programs.