Multiple arachnoid membrane opening to promote angiogenesis in adult patients with moyamoya disease after combined bypass surgery: a multicenter randomized controlled clinical trial.

Objective: In adult patients with moyamoya disease (MMD), insufficient postoperative collateral formation is usually seen after combined bypass surgery. The arachnoid membrane, a critical anatomical barrier between extracranial and intracranial vascular systems, has an unclear role in postoperative angiogenesis. The aim of this study was to investigate whether intraoperative arachnoid membrane opening enhances angiogenesis in adult patients undergoing combined bypass surgery for MMD.

Methods: This multicenter, prospective, randomized controlled trial (Membrane Opening to Promote Angiogenesis in Adult MMD [MOPOAM]) was conducted across 8 institutions in China. Between June 2022 and August 2023, 104 patients diagnosed with MMD through digital subtraction angiography were randomly assigned to two groups: one group underwent arachnoid opening (n = 51), while the other group had arachnoid preservation (n = 53). The primary endpoint was the rate of good angiogenesis (Matsushima grade A and B) assessed 6-12 months postoperatively, and the secondary endpoint was the incidence of surgical complications within 1 month postsurgery.

Results: All 104 patients completed the study. The rate of good angiogenesis was 54.9% in the arachnoid opening group and 64.2% in the arachnoid preservation group, with no significant difference between groups (OR 1.470, 95% CI 0.669-3.229; p = 0.337). Postoperative complications were observed in 2 patients (3.9%) in the arachnoid opening group and in 5 patients (9.4%) in the arachnoid preservation group, showing no significant difference (OR 2.552, 95% CI, 0.472-13.796; p = 0.276). No significant association between arachnoid opening procedures and functional recovery (assessed by modified Rankin Scale scores) was found during the 6- to 12-month follow-up period (p = 0.831).

Conclusions: In adults with MMD, arachnoid membrane opening during combined bypass surgery did not significantly improve postoperative angiogenesis rates or increase perioperative complications.