Twenty-four patients of comparable age, blood pressure, and degree of dementia were classified by an "Ischemic Score" based on clinical features into "multi-infarct" and "primary degenerative" dementia. Regional cerebral blood flow (CBF) was measured by the intracarotid xenon 133 method. Both groups showed a decreased proportion of rapidly clearing brain tissue (largely gray matter). Cerebral blood flow per 100 gm brain per minute was normal in the primary degenerative group but low in the multi-infarct group. This suggests the blood flow is adequate for metabolic needs of the brain in patients with primary degenerative dementia but inadequate for those with multi-infarct dementia. There was no correlation between degree of dementia and CBF in the primary degenerative group but an inverse relationship existed in the multi-infarct group. Reactivity of blood vessels to reduction of arterial carbon dioxide pressure was normal in both groups.
SUMMARY 71 patients with an ischaemic stroke were studied. The patients were separated into two groups on the basis of the results of clinical investigation, computed tomography and psychological testing (WAIS). 40 patients showed an early dementia and 31 were without mental impairment. The mean age was 57 years in the demented group and 54 years in the non-demented group. The mean duration of the history of cerebrovascular disease was also not statistically different in both groups. The frequency of strokes was identical since 50 % of the patients in both groups had more than one stroke. The history of neurological symptoms together with the neurological deficits seen on admission were distributed evenly. The dominant hemisphere was more often diseased in the demented group. Bilateral symptoms were also more common in the demented stroke patients. The WAIS showed a similar IQ in both groups but the deterioration index was significantly altered in the demented group. Hypertension was the only risk factor which differed between both groups. Cardiac disease, diabetes, viscosity and fibrinogen did not differ in both groups. The CT showed more normal scans in the non-demented group, the distribution of atrophy on its own and infarction in the left or right hemisphere were both inconclusive, whilst patients with bilateral infarcts were more common in the dementia group. Also, generalised atrophy in combination with an infarct was found more often in the demented patients.Epidemiological studies have shown that dementia is present in between 4-4-8% of the population over the age of 65 years.'-3 The occurrence of dementia increases with age, from 2-3% in people of 65-69 years to 22 % in those aged 80 years or older.' Pathological studies have shown that dementia is caused by primary degenerative disease in 50 % of the cases in contrast to 20-22% being caused by cerebrovascular disease.4 5 Clinical investigations, however, have shown cerebrovascular disease to be the cause of dementia more often than primary degenerative disease.2 6 Because only some patients with cerebrovascular disease eventually develop dementia, it would seem important to study the processes leading to, or associated with, dementia. This type of dementia was called "multi-infarct" dementia because it is Address for reprint requests: G Ladurner,
248 patients with an ischaemic stroke were investigated with computer tomography. A hypodense lesion was observed in 18% of TIAs, 76% of PRINDS and 95% of completed stroke patients. In the patients with TIA the hypodense lesions were mainly single ones, whereas completed stroke patients also had a significantly higher proportion of more bilateral lesions. Atrophy was present in 44% of TIA patients, 68% of PRIND patients and 82% of completed stroke patients. Atrophy was generalised in 60% of the patients and homolateral in only 16%. Contrast medium enhancement in a hypodense area occurred only in patients with PRIND and completed stroke and never in TIA patients. Multiple lesions and atrophy were significantly more common in patients with dementia. The time course showed oedema initially in 47% of patients which fell to 25% after the 1st week. Contrast medium enhancement was present initially in 42% of the patients, rose to 70% until the 3rd week and then fell continuously until the 6th week. The change from an indistinct to a distinct outline of a lesion coincided with this.
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