[The study of neuropsychological alterations following coronary artery bypass operation as predicted by computed tomography scan of the brain].

The objective of this clinical study is to provide information regarding the association between coexistent cerebrovascular disease and neuropsychological abnormalities after coronary artery bypass operations. Computed tomography scan of the brain was performed in 104 patients pre-operatively, and their post-operative neuropsychological functions were evaluated. The patients were categorized as follows according to the CT findings: Seventy-three patients showed normal or slight cerebral cortical atrophy which usually seen in patients over fifty of age (group A). Sixteen showed moderate or severe cortical atrophy (group B). Fifteen patients demonstrated the characteristic findings of Binswanger type; severe white matter hypodensity especially in frontal horns and dilated ventricles (group C). Overt neuropsychological dysfunction was not observed in patient in groups A and B. Six patients in group C showed a combination of dementia, bizarre behavior, disorientation and gait dyspraxia following bypass operations. The pseudobulbar signs were also found in 3 patients. These clinical abnormalities persisted for six days to three weeks, and were most often reversible. Although the underlying mechanism of these deleterious alterations is not elucidated, the ischemic nature of the characteristic white matter lesions was highly suspected. The arteriosclerotic changes of the arteriole of the cerebral cortex and hypoperfusion during cardio-pulmonary bypass were supposed to be responsible. Therefore it was concluded that special attention should be focused on neurological evaluation for bypass surgery in group C patients.