Morphological characteristics of choroidal anastomosis as predictors of subsequent rupture in adult moyamoya disease: a longitudinal study using vessel wall imaging

OBJECTIVE: Choroidal anastomosis (ChA) is considered a key indicator of increased hemorrhagic risk in adult moyamoya disease (MMD); however, its clinical course remains unclear. The aim of this study was to identify potential predictors of ChA rupture. METHODS: Retrospective evaluation of clinical and radiological data from 132 ChA-positive hemispheres (86 patients with MMD) treated at a single institution from March 2019 to March 2024 was conducted on a hemisphere-by-hemisphere basis. Two independent raters investigated the morphological characteristics of the ChA, including the lumen area (LA), branching pattern, and presence of a ChA-related pseudoaneurysm, using high-resolution vessel wall imaging. The primary endpoint was subsequent ChA-related hemorrhage, indicating ChA rupture. The secondary endpoint was any hemorrhagic stroke. A multivariate Cox proportional hazards model was used to evaluate the predictors of each endpoint. RESULTS: Thirteen hemorrhagic strokes occurred in 12 hemispheres (12 patients) during a mean follow-up period of 35.2 months. Nine ChA-related hemorrhages were observed in 9 hemispheres. The predictors for ChA rupture (primary endpoint) were LA of the ChA (per 1-mm2 increase; HR 36.4, 95% CI 4.50-294; p = 0.001), complex-type ChA (HR 4.64, 95% CI 1.08-19.9; p = 0.039), ChA-related pseudoaneurysm (HR 31.6, 95% CI 2.10-474; p = 0.013), and revascularization surgery (HR 0.12, 95% CI 0.02-0.79; p = 0.028). The predictors for any hemorrhagic stroke (secondary endpoint) were hemorrhagic presentation (HR 4.86, 95% CI 1.20-19.6; p = 0.026), LA of the ChA (per 1-mm2 increase; HR 24.9, 95% CI 3.43-180; p = 0.001), complex-type ChA (HR 4.42, 95% CI 1.19-16.3; p = 0.026), ChA-related pseudoaneurysm (HR 46.3, 95% CI 4.94-433; p = 0.001), and revascularization surgery (HR 0.14, 95% CI 0.03-0.64; p = 0.012). CONCLUSIONS: In ChA-positive hemispheres, a larger LA of the ChA, complex-type ChA, and the presence of ChA-related pseudoaneurysms were significant predictors of subsequent ChA rupture and hemorrhagic stroke, whereas revascularization surgery can reduce the risk of subsequent ChA rupture and hemorrhagic events.