Changes in Cerebral Hemodynamics after Extracranial-intracranial Bypass

Abstract

A group of 25 patients with patent extracranial-intracranial anastomoses were followed for 18 months in an effort to determine the long-term effects on regional cerebral blood flow (rCBF). The 133Xe inhalation method was used to measure rCBF. In patients whose preoperative mean rCBF (mCBF) on the affected side was low, i.e., less than 40 ml/100 gm/min, or who had internal carotid artery occlusion (ICO) or middle cerebral artery occlusion (MCO), mCBF on the affected side increased postoperatively. In patients with high preoperative mCBF rates on the affected side, i.e., 40 ml/100 gm/min or more, or internal carotid artery stenosis (ICS) or middle cerebral artery stenosis (MCS), mCBF on the affected side did not change after bypass. Postoperatively, the hemispheric difference in mCBF between the anastomosed and opposite sides was small in cases with ICO or MCO and negligible in patients with ICS or MCS, relative to the preoperative values. The rCBF significantly increased in the frontal, precentral, and superior temporal areas in patients with ICO, MCO, or low preoperative mCBF rates on the affected side.