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

Background: 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.

Methods: 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.

Results: 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).

Conclusions: 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.