Abstract
While STA-MCA bypass is a standard intervention for Moyamoya disease (MMD), it may occasionally lead to cerebral hyperperfusion syndrome (CHS), a rare but serious postoperative complication. While perfusion imaging is emerging as a potential tool to predict the risk of developing CHS, its utility remains underexplored. This meta-regression assesses the prognostic value of preoperative, postoperative, and differential CTP parameters in predicting CHS among adult patients with MMD undergoing STA-MCA bypass. A systematic review was conducted per PRISMA guidelines using MEDLINE and Embase databases through July 2026. Studies included reported perfusion parameters derived from CT perfusion (CTP), comprising relative cerebral blood flow (rCBF), cerebral blood volume (rCBV), mean transit time (rMTT), and time-to-peak (rTTP), as well as postoperative CHS incidence. Included studies reported relative perfusion values and incidence of CHS. A univariate random-effects meta-regression was conducted, as well as a multivariate meta-regression in an expanded cohort sensitivity analysis, which additionally included one dynamic susceptibility contrast (DSC) MR perfusion cohort and one DCU-7 full color Doppler cohort. Among 177 citations screened, 40 underwent full-text review, and five studies representing 379 patients (23 CHS events) met criteria and were included in the primary analysis, with a pooled CHS incidence of 4.9% (95% CI 1.7-9.4%); six additional studies with externally calculated values were included in an expanded-cohort sensitivity analysis only (11 studies, 962 patients). No preoperative, postoperative, or differential parameter was significantly associated with CHS in the primary analysis or in any sensitivity analysis, including the expanded multivariate cohort. No perfusion parameter was reliably associated with CHS in adult patients undergoing STA-MCA bypass for MMD. Future patient-level studies with standardized CHS definitions are necessary before perfusion imaging can be applied clinically in this setting.