Effectiveness of indirect revascularization for adult hemorrhagic moyamoya disease: a 10-year follow-up study

OBJECTIVE The optimal surgical approach for hemorrhagic moyamoya disease (hMMD) continues to be a topic of debate. The authors' prior research demonstrated that both combined and indirect revascularization were efficacious. However, questions remain regarding the long-term prognosis consistency between these two treatments. Therefore, the objective of this study was to evaluate and compare the enduring effects of these surgical modalities on adult hMMD, extending the findings of the authors' previous studies. METHODS The authors recruited patients diagnosed with hMMD between 2010 and 2015. The patients were categorized into two groups: those who underwent combined revascularization (superficial temporal artery-middle cerebral artery bypass alongside dural reverse application) and those who underwent indirect revascularization (encephaloduroarteriosynangiosis [EDAS]). The primary and secondary endpoints of this study were instances of rebleeding, confirmed with CT scan, and death resulting from rebleeding, respectively. The authors estimated rebleeding-free and death-free survival rates by utilizing the Kaplan-Meier survival method. They used Cox regression to adjust for confounders and to evaluate the effects of the varying surgical modalities on the endpoints. RESULTS After an average follow-up period of 114 months, 35 patients (28.6%) experienced 40 rebleeding events, yielding an average annual incidence of 3.5%. Of the 79 patients who received combined revascularization, 17 (21.5%) experienced rebleeding events. Similarly, of 43 patients who underwent EDAS, 18 (41.9%) experienced rebleeding events (p = 0.018). Most rebleeding instances occurred 61-120 months after surgery (21 patients [60%]), followed by 12-60 months (11 patients [31.4%]). Multivariate survival analysis highlighted significant differences in surgical outcomes (HR 0.33, 95% CI 0.15-0.74, p = 0.007). The authors observed that 8 patients (10.1%) died of rebleeding events in the combined group, as well as 10 patients (23.3%) in the EDAS group. Despite the lack of a statistically significant difference in mortality (p = 0.051), multivariable survival analysis found a significant difference (HR 0.31, 95% CI 0.10-0.97, p = 0.044). CONCLUSIONS High rebleeding rates persist in adult hMMD patients, even after revascularization. Combined revascularization proved superior to EDAS in preventing long-term rebleeding. In contrast, EDAS alone did not display a clear effect on reducing long-term rebleeding rates.