Bloody fluids located between the temporal muscle and targeted cerebral cortex affect the establishment of indirect collaterals in Moyamoya disease with surgical bypass: A case-control study.

Objective: Bypass yields favorable outcomes in the treatment of Moyamoya disease (MMD). Bloody fluids accumulate between the targeted cortex and the temporal muscle after surgical bypass. These fluids are handled empirically via subcutaneous tubes or conservative treatments. However, substances located in certain positions may adversely affect the establishment of indirect collaterals (ICs) from muscular grafts. Methods: Patients in our hospital from January 2014 to December 2019 were eligible for inclusion. Digital subtraction angiography (DSA) and radiological examinations were used during the perioperative and follow-up periods. Bloody fluid volumes were calculated using computed tomography- (CT-) based 3D Slicer software. The characteristics of bloody fluids, patient demographics, and clinical data were retrospectively analyzed. Results: In total, 110 patients underwent indirect or combined bypass with follow-up DSA. The mean age of the enrolled patients was 42.4 ± 11.8 years. Previous ischemia (p = 0.001), previous hemorrhage (p = 0.013), bloody fluid volume (p = 0.049), and the time of imaging (p = 0.081) were associated with indirect outcomes. Ordinal regression analysis confirmed that good indirect outcomes were associated with previous ischemia (p < 0.001) and a large bloody fluid volume (p = 0.013). Further subgroups based on fluid volume were significantly correlated with IC establishment (p = 0.030). Conclusions: A large bloody fluid volume and previous ischemic history were associated with good indirect outcomes. The presence of bloody fluids may reflect impaired degrees of muscular donors due to bipolar electrocoagulation, thus highlighting the importance of appropriate application of bipolar forceps.