Acute Preoperative Infarcts and Poor Cerebrovascular Reserve Are Independent Risk Factors for Severe Ischemic Complications following Direct Extracranial-Intracranial Bypass for Moyamoya Disease

BACKGROUND AND PURPOSE: Severe ischemic changes are a rare but devastating complication following direct superficial temporal artery to MCA bypass in patients with Moyamoya disease. This study was undertaken to determine whether preoperative MR imaging and/or cerebrovascular reserve assessment by using reference standard stable xenon-enhanced CT could predict such complications. MATERIALS AND METHODS: Among all adult patients undergoing direct bypass at our institution between 2005 and 2010 who received a clinically interpretable xenon-enhanced CT examination, we identified index cases (patients with >15-mL postoperative infarcts) and control cases (patients without postoperative infarcts and without transient or permanent ischemic symptoms). Differences between groups were evaluated by using the Mann-Whitney U test. Univariate and multivariate generalized linear model regression was used to test predictors of postoperative infarct. RESULTS: Six index cases were identified and compared with 25 controls. Infarct size in the index cases was 95 55 mL. Four of 6 index cases (67%), but no control patients, had preoperative acute infarcts. Baseline CBF was similar, but cerebrovascular reserve was significantly lower in the index cases compared with control cases. For example, in the anterior circulation, median cerebrovascular reserve was -0.4% (range, -38.0%-16.6%) in index versus 26.3% (range, -8.2%-60.5%) in control patients (P = .003). Multivariate analysis demonstrated that the presence of a small preoperative infarct (regardless of location) and impaired cerebrovascular reserve were independent, significant predictors of severe postoperative ischemic injury. CONCLUSIONS: Acute infarcts and impaired cerebrovascular reserve on preoperative imaging are independent risk factors for severe ischemic complications following superficial temporal artery to MCA bypass in Moyamoya disease.