Predicting the Occurrence of Hemorrhagic Cerebral Hyperperfusion Syndrome Using Regional Cerebral Blood Flow After Direct Bypass Surgery in Patients with Moyamoya Disease

Objective Superficial temporal artery–middle cerebral artery anastomosis is an established treatment for moyamoya disease. However, hemorrhagic cerebral hyperperfusion syndrome (CHS) leads to poor outcomes. This study aimed to identify predictors of hemorrhagic CHS based on regional cerebral blood flow (rCBF) in patients with moyamoya disease. Methods The study included 251 hemispheres in 155 patients with moyamoya disease who underwent preoperative and postoperative rCBF measurements and superficial temporal artery–middle cerebral artery double anastomosis. We used rCBF increase rate for predicting hemorrhagic CHS. rCBF increase rate was calculated by 2 methods. In method 1, the rCBF value on the operated side was compared with the rCBF value on the nonoperated side. In method 2, the postoperative rCBF value on the operated side was compared with the preoperative rCBF value on the operated side. Patients were classified into 4 groups according to rCBF increase rate to predict risk of hemorrhagic CHS. Results Hemorrhagic CHS occurred in 7 (2.8%) hemispheres (no children). Severe hemorrhagic CHS occurred in only 1 (0.4%) hemisphere. Hemorrhagic CHS was observed in patients with ≥30% rCBF increase according to method 1 and ≥50% rCBF increase according to method 2 and was most frequently noted in ≥100% rCBF increase. Conclusions Predictors for hemorrhagic CHS were ≥30% rCBF increase when using method 1 and ≥50% increase when using method 2.