Background: Few studies have explored whether sevoflurane impacts cerebral vascular reactivity (CVR) or increases postoperative cognitive dysfunction in ischemic moyamoya disease (IMMD). We aimed to evaluate the effects of sevoflurane anesthesia on cerebral blood flow (CBF) and CVR in IMMD.

Methods: This prospective cohort study recruited 15 patients with IMMD and 17 with intraspinal space-occupying lesions, as healthy controls (HCs), between September 2023 and March 2024 in Peking University International Hospital. CBF in the whole brain and anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries was measured using 3.0 T magnetic resonance imaging (MRI) with pulsed arterial spin labeling (PASL) sequences. Measurements were taken in the awake and sevoflurane-anesthetized states (sedation depth BIS 40-60). CVR was then calculated. PASL data were processed using SPM8 and ASLtbx. Continuous variables were compared using t-tests; categorical variables were compared using chi-squared tests.

Results: Under sevoflurane anesthesia, CBF and CVR decreased in IMMD (P<0.05) in the whole brain and bilateral ACA, MCA, and PCA regions. Whole-brain CBF was higher in IMMD than in the HCs pre-anesthesia and decreased post-anesthesia (P < 0.05); there was little change pre- and post-anesthesia in the HCs (P > 0.05). CVR differed pre- and post-anesthesia in the IMMD group (P<0.05) in all arteries except the left MCA. No significant difference in CVR was observed in the HCs pre- and post-anesthesia.

Conclusions: PASL-MRI is a feasible, non-invasive, quantitative tool for assessing global and regional CBF changes in mechanically ventilated patients under anesthesia. Sevoflurane anesthesia may further reduce CVR in IMMD, potentially increasing cerebral ischemia risk during and after surgery. Inhalational anesthetics should be carefully selected for these patients. Alternative drugs, or techniques that optimize CBF regulation, should be considered to improve postoperative recovery and long-term outcomes.