Persistent Periventricular Anastomosis Associated With Rebleeding After Bypass Surgery for Hemorrhagic Moyamoya Disease

Abstract

BACKGROUND: Although bypass surgery can reduce rebleeding risk in hemorrhagic moyamoya disease, the risk remaining after surgery is not negligible. We hypothesized that the postoperative persistence of periventricular anastomosis (PA), a fragile periventricular collateral manifestation, is associated with rebleeding. METHODS: This retrospective cohort study included patients with moyamoya disease who underwent direct bypass at 2 institutions after hemorrhagic presentation. Either presence or absence of PA after surgery was radiologically determined by grading of each subtype, lenticulostriate, thalamic, or choroidal anastomosis, 3–6 months after surgery. The time interval between the surgery and the rebleeding event or last visit was calculated. RESULTS: Of 116 eligible patients comprising 232 hemispheres, 172 hemispheres underwent surgery. Rebleeding occurred in 16 hemispheres of 15 patients (2.0% per person-year) during the median follow‐up period of 6.3 years. The hemisphere‐based annual rebleeding rate was 2.0% in the PA‐positive hemispheres as compared with 0.46% in the PA‐negative hemispheres. The adjusted hazard ratio of rebleeding for positive PA relative to negative PA was 4.11 (95% CI, 1.07-15.82). Among subtypes of PA, lenticulostriate anastomosis was the most likely to persist after surgery (34 of 62 anastomoses) and to cause rebleeding (8 of 16 hemispheres). CONCLUSION: The persistence of PA, especially that of lenticulostriate anastomosis, might be associated with rebleeding after surgery. This suggests the importance of assessing and optimally managing PA for improving long‐term outcomes.