Types of multi-infarct dementia.

A series of 79 patients with multi-infarct dementia (MID) were divided into 2 groups designated cortical MID and subcortical MID, according to whether the computed tomography (CT) scan showed the presence or absence of cortical infarcts, and an absent to mild or moderate to severe degree of white matter low attenuation (WMLA). Cortical MID was characterized by repeated atherothrombotic and cardiogenic strokes, moto-sensory hemiparesis, a severer degree of aphasia, and abrupt onset of cognitive failure. Subcortical MID typically showed the following features: lacunar strokes, bulbar signs including dysarthria, pure motor hemiparesis, depression and emotional lability. WMLA was found in all patients with subcortical MID but also in over 60% of those with cortical MID. In the 2 groups CT scans showed equal frequencies of deep infarcts. When divided according to severity of WMLA, 92% of patients in the cortical MID group and 44% of those in the subcortical MID group were found to have at least one cortical infarct on the CT scan. Although cortical and subcortical MID differed in several clinical features, they did not show major differences in the risk factors for stroke, and clearly overlapped each other as regards ischaemic scores and the findings in neurological examinations and CT. Thus, it is still an open question whether cortical MID and subcortical MID, including the lacunar state and Binswanger's disease, are 2 distinct entities or merely represent the expression of biological variation while having the same etiopathogenesis.