Early collateral blood supply and late parenchymal brain damage in patients with middle cerebral artery occlusion.

We angiographically studied 80 patients within 6 hours after the onset of ischemic supratentorial infarction. From this group we selected 36 patients with middle cerebral artery occlusion who survived. In these 36 patients, we compared the presence of a collateral blood supply during the early phase with the extent of final parenchymal brain damage obtained by computed tomography 3 months after the event. The presence of a collateral circulation during the first few hours after the stroke reduced the size of the final parenchymal brain damage in patients with middle cerebral artery stem-trunk occlusion. The collateral blood supply was more efficient in patients who had no significant stenosing lesions of the extracranial internal carotid artery. Our data confirm that the lenticulostriate arteries are end arteries not supplied by collateral blood vessels and suggest that lesions formerly thought to be caused by hemodynamic mechanisms (watershed infarcts) or arteriolar lesions (lacunar infarcts) may be due to middle cerebral artery occlusions.