Background Mechanical thrombectomy has emerged as a standard of care for acute stroke from large vessel occlusion in adults but remains controversial in children. Cerebral vessels are nearly adult size by 5 years of age but the technical feasibility of achieving recanalization in younger and smaller children with current endovascular tools remains unclear. Objective To systematically review the literature on mechanical thrombectomy for stroke in children less than 5 years of age. Results Mechanical thrombectomy for acute stroke has been reported in 11 children under the age of 5 years (range 9 months to 4 years). The mean time from symptom onset to groin puncture was 12 hours (range 4–50 hours). Complete recanalization was achieved in 7/12 (58%) vessels attempted, and partial recanalization in 4/12 (33%). Two procedure related complications were reported, with small vessel size felt to be contributory to basilar vasospasm in one case. Favorable neurological outcomes were reported in 7 cases (64%). Conclusions Our review of the literature demonstrates that mechanical thrombectomy for acute ischemic stroke may be feasible in carefully selected infants and young children less than 5 years of age using currently available devices. Efficacy in promoting better neurologic outcomes remains unproven, and other questions persist, including whether complications such as vasospasm occur more frequently in young children compared with adults. Further study is needed to determine the safety and efficacy of pediatric mechanical thrombectomy. These data suggest that young children should not be excluded from future studies or clinical treatment on the basis of age alone.

Moyamoya arteriopathy, which can be idiopathic or associated with sickle cell disease, neurofibromatosis, Down syndrome, or cranial radiation therapy, is a progressive cerebral arteriopathy associated with high rates of incident and recurrent stroke. Little is known about how these subgroups differ with respect to clinical presentation, radiographic findings, stroke risk, and functional outcomes. Using ICD codes, we identified children ages 28 days to 18 years treated for moyamoya arteriopathy at our tertiary care center between 2003 and 2019. Demographic, clinical, and radiographic data were extracted from the medical record. The Pediatric Stroke Recurrence and Recovery Questionnaire was administered to consenting participants. Sixty-nine patients met inclusion criteria (33 idiopathic, 18 sickle cell disease, 11 neurofibromatosis, 6 Down syndrome, 1 cranial radiation therapy). Median follow-up time was 7.7 years; 24 patients had at least 5 years of follow-up data. Frequency of stroke at presentation differed by subgroup (P < .001). Of patients with at least 2 years of follow-up, 33 (55%) experienced stroke. The proportion of patients experiencing stroke differed by subgroup (50% of idiopathic cases, 72% of sickle cell disease, 11% of neurofibromatosis, and 100% of Down syndrome, P = .003). The frequency of bilateral versus unilateral disease (P = .001) and stroke-free survival following presentation (P = .01) also differed by subgroup. In this single-center cohort, moyamoya subgroups differed with respect to clinical and radiographic characteristics, with neurofibromatosis-associated moyamoya syndrome having a milder phenotype and Down syndrome–associated moyamoya portending a more aggressive course. These findings need confirmation in a larger, multi-center cohort with longer duration of follow-up.