Association between intracranial vascular vulnerability and indirect revascularization development in moyamoya...

Negative remodeling, characterized by a decrease in the outer diameter of cerebral arteries, is a hallmark of moyamoya disease (MMD). Postoperative fluid-attenuated inversion recovery (FLAIR) cortical hyperintensity (FCH), indicative of leptomeningeal vasogenic edema, and indirect bypass development are also distinctive features. We investigated the relationships between negative remodeling and these postoperative phenomena. We analyzed 42 hemispheres from 37 adult patients with MMD who underwent combined direct and indirect revascularization. Negative remodeling was assessed by measuring the terminal portion (C1) vessel diameter of the internal carotid artery on preoperative heavy T2-weighted images. FCH was scored from 0 to 6 based on its extent on FLAIR images obtained 2 days postoperatively; indirect bypass development was evaluated qualitatively using magnetic resonance angiography 6 months post-surgery. The participants' median age was 45 years; 76% were female and 90% presented with ischemic onset. The median C1 diameter was 2.39 mm, median FCH score was 2.5, and favorable indirect bypass development was observed in 64% of cases. Smaller preoperative C1 diameters (2.27 mm vs. 3.02 mm, p < 0.0001) and higher FCH scores (median 3 vs. 2, p < 0.05) correlated with favorable indirect bypass development. Smaller C1 diameters also aligned with extensive FCH (2.94 mm vs. 2.20 mm, p < 0.001). Multivariate analysis revealed a significant association between reduced preoperative C1 diameter and favorable indirect bypass development (odds ratio 0.019, 95% confidence interval 0.010-0.17, p < 0.01). These findings suggest that advanced intracranial vascular remodeling in MMD correlates with vascular vulnerability and favorable indirect bypass development.