Cerebral Vasoreactivity and Internal Carotid Artery Flow Help to Identify Patients at Risk for Hyperperfusion After Carotid Endarterectomy

Abstract

Background and Purpose-Hyperperfusion syndrome is a rare but potentially devastating complication after carotid endarterectomy (CEA). The aim of this study was to investigate whether preoperative measurement of cerebral vasoreactivity (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 Ն70%, cerebral blood flow (CBF) and CVR were investigated before and 1 month after CEA, with resting and acetazolamide-challenge single-photon emission CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter during surgery. Results-Ipsilateral CBF on the first postoperative day significantly increased relatively (56.6Ϯ53.2%) as well as absolutely (37.9Ϯ8.8 to 57.7Ϯ18.0 mL/100 g per minute) in the reduced CVR group (CVR Ͻ12%) but not in the normal CVR group (CVR Ն12%) (10.3Ϯ15.5% and 40.6Ϯ7.9 to 43.9Ϯ5.7 mL/100 g per minute, respectively). One month later, this difference almost disappeared. Two patients showed ipsilateral CBF increase of Ն100%. A significant association of intracerebral steal with hyperperfusion (CBF increase Ն100%) on the first postoperative day was also observed. ICA flow increase after reconstruction significantly correlated with CBF increase on the first postoperative day in the reduced CVR group but not in the normal CVR group. The threshold of ICA flow increase for hyperperfusion was estimated 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 hyperperfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively. (Stroke. 2001;32:1567-1573.)

Hemodynamic Alterations in Vertebrobasilar Large Artery Disease Assessed by Arterial Spin-Labeling MR Imaging

“…29 Consequently, we do not expect this to be a major issue in the current study. Third, absolute CBF values were comparable with other perfusion studies involving older or patient populations, 21,[30][31][32] but were still generally lower than might be expected. We attribute this to through-plane partial volume blurring associated with the current ASL implementation, which accentuates partial volume effects with whitematter voxels.…”

Cerebral Blood Flow and Metabolism of Hyperperfusion after Cerebral Revascularization in Patients with Moyamoya Disease

“…Decreased vascular reserve on preoperative SPECT images has been reported as a predictor of hyperperfusion syndrome after CEA (Hosoda et al, 2001;Ogasawara et al, 2003). Cerebral perfusion pressure is generally considered to reflect cerebral vascular reserve and the CBF/CBV ratio is an index of cerebral perfusion pressure (Gibbs et al, 1984).…”

Preoperative Cerebral Oxygen Extraction Fraction Imaging Generated from 7T MR Quantitative Susceptibility Mapping Predicts Development of Cerebral Hyperperfusion following Carotid Endarterectomy

“…8 The risk factors for cerebral hyperperfusion include highgrade stenosis, poor collateral blood flow, contralateral carotid occlusion, and long-standing hypertension, and they often result in impaired cerebral hemodynamics. [11][12][13][14] When normal perfusion pressure is rapidly restored after CEA, hyperperfusion may occur in regions of the brain with impaired autoregulation due to chronic ischemia. This hypothesis is like the "normal perfusion pressure breakthrough" theory of Spetzler et al 13,15 Indeed, preoperative misery perfusion in the affected cerebral hemisphere is reportedly associated with the development of cerebral hyperperfusion following CEA or carotid stent placement for cervical ICA stenosis.…”