Cerebral vasoreactivity and internal carotid artery flow help to identify patients at risk for hyperperfusion after carotid endarterectomy

Background and Purpose-Hyperperfusion syndrome is a rare but potentially de vastating complication after carotid endarterectomy (CEA), The aim of this study was to investigate whether preoperative measurement of cerebral vasor eactivity (CVR) and intraoperative measurement of internal carotid artery ( ICA) flow could identify patients at risk for hyperperfusion after CEA, Methods-For 26 patients with unilateral ICA stenosis greater than or equal to 70%, cerebral blood flow (CBF) and CVR were investigated before and 1 mo nth after CEA, with resting and acetazolamide-challenge single-photon emiss ion CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter durin g surgery. Results-Ipsilateral CBF on the first postoperative day significantly increa sed relatively (56.6 +/- 53.2%) as well as absolutely (37.9 +/-8.8 to 57.7 +/- 18.0 mL/100 g per minute) in the reduced CVR group (CVR < 12%) but not in the normal CVR group (CVR greater than or equal to 12%) (10.3 +/- 15.5% and 40.6 +/-7.9 to 43.9 +/-5.7 mL/100 g per minute, respectively). One mont h later, this difference almost disappeared. Two patients showed ipsilatera l CBF increase of greater than or equal to 100%. A significant association of intracerebral steal with hyperperfusion (CBF increase greater than or eq ual to 100%) on the first postoperative day was also observed. ICA flow inc rease after reconstruction significantly correlated with CBF increase on th e first postoperative day in the reduced CVR group but not in the normal CV R group. The threshold of ICA flow increase for hyperperfusion was estimate d to be 330 mL/min in the reduced CVR group. Conclusions-Single-photon emission CT with acetazolamide challenge and ICA flow measurement during surgery could identify patients at risk for hyperpe rfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively.