Characterizing Revascularization After Encephalo-Duro-Arterio-Synangiosis (EDAS) in Adult Patients With Moyamoya Disease Using the Orbital Grading System

The Matsushima grade has traditionally been used to evaluate vessel ingrowth from the superficial temporal artery after encephalo-duro-arterio-synangiosis (EDAS) for Moyamoya disease (MMD) patients. However, this grading is subjective and prone to measurement variability. Herein, we propose the orbital grading system quantifying leptomeningeal and burr hole–related vessel-ingrowth from the superficial temporal artery and/or middle meningeal artery to the middle and anterior cerebral arteries post EDAS in MMD patients. An anatomical classification was developed by reference to 2 parallel vertical lines from the bony landmarks of the orbit, categorized from Grade 0–3. Regression models were used to compare clinical and functional outcomes of our grading system with the Matsushima scale. Forty MMD patients, with median age of 48 years, mostly females (72.5%), underwent 56 EDAS procedures. Presentation included ischemic events (65.0%), hemorrhage (22.5%), and seizures (7.5%). Most patients were categorized as Suzuki ≥ IV (69.5%). Fifty EDAS (89.9%) had concurrent burr holes placed (parietal and frontal regions). At a median follow-up of 13.7 months, collateral growth was graded as follows: grade 0 (6; 10.8%), grade 1 (12; 21.4%), grade 2 (23; 41.1%), and grade 3 (15; 26.8%). Linear regression showed similarities in the distribution between the orbital grading system and Matsushima grading (r = 0.86; P < 0.01). Ischemic events were fewer in hemispheres categorized as grade 2–3 compared to grade 0–1 (P = 0.047) as well as in Matsushima grading A or B compared to C (P = 0.047). The orbital grading system demonstrated agreement in identifying postoperative ischemic events as the Matsushima grade and provides a more practical and objective evaluation of collateral vessel ingrowth after EDAS with and without burr holes.