Direct Superficial Temporal Artery-Proximal Middle Bypass in Moyamoya Disease: Predicting Postoperative Symptomatic Contralateral Stroke Using Clinical Characteristics and Angiographic Collateralization Patterns.

Background: Moyamoya disease (MMD) is a rare cerebrovascular disorder marked by internal carotid artery narrowing, collateral neovascularization, and symptomatic cerebral ischemia. Select patients can benefit from direct bypass (superficial temporal artery [STA]-proximal middle [MCA] bypass) by restoring blood flow to hypoperfused territories. Symptomatic contralateral stroke (CS) following STA-MCA bypass is a devastating, poorly understood complication. We investigate clinical and radiographic risk factors influencing CS incidence after bypass surgery.

Methods: A retrospective review of patients with bilateral MMD undergoing STA-MCA bypass at our institution (2018-2022) included demographic details, comorbidities, average preoperative systolic blood pressure (SBP), postoperative SBP goals, and angiographic patterns. Preoperative diagnostic angiograms were analyzed for collateral vascular patterns. Postoperative clinical course was recorded. Statistical analyses employed parametric and nonparametric tests for small sample size.

Results: Six of 39 patients (15.4%) experienced CS postbypass. No baseline demographic differences were identified between patients with and without CS. CS patients had higher preoperative SBP (146.2 vs. 131.1, P < 0.05), were more likely to have postoperative SBP goals below their average preoperative SBP (66.7% vs. 15.2%, P = 0.018) and had longer time from symptom onset to surgery (51.8 vs. 13 months, P = 0.039). There were no differences in specific angiographic patterns in either hemisphere for patients with CS versus those without CS though overall contralateral Suzuki grade was higher in patients with CS (P < 0.05).

Conclusions: Patients with CS following bypass had significantly higher preoperative SBP, postoperative SBP goals below their average preoperative SBP, and longer time from symptom onset to surgery compared to patients without CS. Patient-specific postoperative SBP management and timely surgical revascularization are crucial for preventing CS in patients with MMD undergoing STA-MCA bypass.