Single-Barrel vs. Double-Barrel Superficial Temporal Artery-to-Middle Cerebral Artery Bypass Bypass in Moyamoya Disease: A Systematic Review and Meta-Analysis of Postoperative Stroke Outcomes

Background Moyamoya disease (MMD) involves progressive stenosis of intracranial arteries and compensatory collateral vessel formation. A novel modification of the single-barrel STA-MCA bypass, the double-barrel bypass, offers increased postoperative flow or draw, although longer in operative time. Currently, there is a lack of consensus regarding the impact of the novel double-barrel bypass STA-MCA bypass on the incidence of postoperative stroke for patients undergoing direct extracranial-intracranial bypass for MMD. Methods We performed a PRISMA-compliant systematic review of MEDLINE and Embase from inception through March 2024. A supplemental bibliographic review in Google Scholar was also performed to screen for additional candidate citations. Among 95 candidate citations, 16 underwent full-text review; 5 met study criteria and were included in a meta-analysis of proportions using random-effects modeling. Results There was no significant difference in postoperative stroke following single-barrel compared to double-barrel bypass (OR=1.28, 95%CI=0.26-6.3, p=0.77). Studies reported either median or mean follow-up times, with an approximate mean of 20.2 months (range, 7-190). Inter-study heterogeneity was minimal (I²=0%). Sensitivity analyses excluding studies with follow-up times under 12 months (OR=1.12, 95%CI=0.18-8.39, p=0.85) and studies using STA-MCA bypass with adjunct indirect procedures (OR=0.65, 95%CI=0.08-5.09, p=0.68) validated primary findings. Funnel plots and Egger's test were negative for publication bias. Conclusion Double-barrel STA-MCA bypass does not appear to provide additional postoperative stroke protection or vulnerability compared to the single-barrel; however, given the relatively limited follow-up times, these results may under-represent long-term benefits. Well-controlled long-term studies are needed to better interrogate the optimal treatment strategies for this vulnerable patient population.