Failures in Revascularization for Pediatric Moyamoya Disease and Syndrome: A Scoping Review

Background: Moyamoya disease (MMD) and moyamoya syndrome (MMS) are a rare cause of stroke commonly managed surgically. We conducted a scoping review to identify the current scope of the literature regarding factors associated with failure of revascularization surgery for MMD and MMS in pediatric patients and to catalyze future research. Methods: A scoping review was conducted to explore failures of revascularization surgery for MMD and MMS in pediatric patients using the PubMed, Embase, and Scopus databases. Titles and abstracts returned from searches were screened for full-text review. Studies meeting inclusion criteria were reviewed in full, and relevant data were extracted. Results: Of 2450 resultant articles, 15 were included. Angiographic outcomes were reported for 900 hemispheres, of which 442 (49.1%) were denoted as Matsushima grade A, 299 (33.2%) as Matsushima grade B, and 159 (17.7%) as Matsushima grade C. Patients with MMS had poorer angiographic outcomes than did patients with MMD. Patients with poor neovascularization had a greater degree of moyamoya vessels on follow-up angiogram. Suzuki stage was not associated with angiographic outcome in individual patients. Angiographic outcomes differed by surgical approach and were not associated with clinical outcomes. Literature identifying factors was sparse. Conclusions: The existing literature indicates that factors such as cause, degree of moyamoya vessels, and surgical approach may affect the likelihood of Matsushima grade C revascularization in pediatric patients with MMD and MMS. Future studies are necessary to definitively elucidate factors associated with failure of revascularization surgery for pediatric MMD.