[The pathogenesis of brain infarction in the posterior cerebral artery territory]

In order to clarify the etiology of brain infarction in the posterior cerebral artery (PCA) territory, we investigated 85 patients (29 women and 56 men, mean age: 63.6 years old) with PCA territory infarction confirmed by computed tomography or magnetic resonance imaging. Patients with thalamic infarction alone were excluded from the present study. Cerebral angiography was performed in 72 subjects. The diagnosis of the mechanism of brain infarction was made on the basis of cerebral angiographic and echocardiographic (presence of cardiac disease as a potential embolic source) findings. Embolism was inferred when the presence of the patent PCA ipsilateral to the infarction, reopening of the occluded PCA or intraluminal filling defect was demonstrated by angiographic studies. In addition, we divided these patients into three groups according to potential source of emboli; cardiogenic, atherothrombotic (so-called artery-to-artery embolism) and embolism of undetermined origin. We diagnosed the patient to have thrombotic mechanism, when an occlusion of the PCA was demonstrated without presence of an embolic source (heart diseases or stenotic arterial lesions proximal to the occluded PCA). When the mechanism (embolic or thrombotic) could not be clearly distinguished, we categorized them "unclassified". When other apparent mechanisms such as arterial dissection, moyamoya disease etc, were demonstrated, we classified them in "miscellaneous". According to the above criteria, 50 patients (59%) were diagnosed as having embolism, only two patients (2%) had definite thrombosis, 28 patients (33%) "unclassified", and five patients (6%) "miscellaneous" (2 arterial dissection, 1 radiation vasculopathy, 1 migraine, 1 moyamoya disease).(ABSTRACT TRUNCATED AT 250 WORDS)