Differing mechanisms between posterior and middle cerebral artery infarctions

Abstract

Cardiac embolism has been thought to be one of the principal causes of posterior cerebral artery territory infarction. To determine stroke mechanisms and stroke risk factors in patients with posterior cerebral artery infarction, we studied 23 consecutive patients with recent infarcts in the posterior cerebral artery distribution (PCA infarcts) and compared these with a case-control group of 46 patients with recent infarcts in the middle cerebral artery distribution (MCA infarcts). All patients were similarly studied, including angiography and echocardiography. Case controls were age- and sex-matched and were randomly chosen from the most recent MCA infarcts seen at our institutions. All subjects were white. PCA infarcts had significantly more cardiac-source emboli (P=.01), less evident atherothrombosis (P=.003), multiplicity of infarctions (P=.05), and documented branch occlusions in the vessel involved (P=.05). MCA infarcts had more preinfarction transient ischemic attacks (P=.03) and evident occlusion of the appropriate extracranial vessel (P=.03). Different stroke mechanisms should lead to different diagnostic and therapeutic decisions.