The orbital grading system in pediatric moyamoya: an interrater reliability analysis of angiographic outcomes

The Matsushima grading system is widely used to evaluate angiographic revascularization outcomes after pial synangiosis for moyamoya vasculopathy by quantifying collateral ingrowth. The authors hypothesized that the orbital grading system (OGS), a new scale developed for adults to measure collateral ingrowth, would provide greater consistency and interrater reliability. They aimed to compare the performance of these scales for the first time in the pediatric population.

The authors performed a retrospective analysis of patients with moyamoya vasculopathy with follow-up catheter angiography after indirect revascularization at a single major pediatric center from 2006 to 2023. An interrater reliability analysis was performed using 5 raters with varying levels of training, who provided scores for 30 blinded cases. Fleiss' kappa coefficient (κ) was calculated as a measure of agreement beyond chance.

A total of 101 patients with a median age of 9 years, of predominantly female sex (56.4%) who were mostly affected by moyamoya disease (71.3%) were included. A total of 158 cerebral hemispheres were treated with pial synangiosis (57 patients had bilateral surgeries). Most hemispheres were categorized as Suzuki stage 3 or above (82.9%). At a median of 12.4 months postoperatively, collateral growth was classified as Matsushima grade A in 57.6%, B in 24.1%, C in 14.6%, and as borderline grades in 3.8%. The OGS scores were grade 0 in 7.0%, grade 1 in 8.9%, grade 2 in 43.7%, and grade 3 in 40.5%. Interrater agreement evaluation revealed that the OGS had a superior κ value compared with the Matsushima scale (0.51 vs 0.15, p < 0.001).

The OGS had higher interrater agreement rates than the Matsushima scale for identifying postoperative collateral ingrowth in children after pial synangiosis. This scale provides a more consistent method for evaluating angiographic outcomes after indirect revascularization in the pediatric population.