Moyamoya-Related Stroke Risk During Pregnancy: An Evidence-Based Reappraisal

Background: Moyamoya is a rare, yet classic etiology of stroke in young adults, affecting predominately women of childbearing age. The impact of pregnancy on the natural history of symptomatic moyamoya remains a matter of extensive debate, however.

Methods: In October 2017, a MEDLINE search was performed using 14 keywords. A total of 12 original articles reporting on cohorts of at least 5 patients were retrieved and reviewed. Individual study data were extracted, pooled, and analyzed.

Results: A total of 736 pregnancies in 483 patients were included in our analysis. The mean age at delivery was 31 years, and the mean age at diagnosis (before pregnancy) was 22.6 years. Clinical presentation was ischemic stroke in 50.8%, hemorrhagic stroke in 45.9%, headaches in 2.1%, and ischemic-hemorrhagic stroke in 1.2%. After excluding patients first diagnosed during or after pregnancy (n = 283) and those who had been revascularized before pregnancy (n = 183), a total of 270 pregnancies in 188 patients were analyzed. During 224.6 patient-years of follow-up, 22 moyamoya-related neurologic events occurred (annual event rate 9.8%), more than two-thirds of which were transient (12 transient ischemic attacks and 3 seizures). Seven strokes occurred (6 hemorrhagic and 1 ischemic), yielding an annual stroke risk of 3.1%. As a result, 1 patient died and 2 were permanently disabled (annual death/disability rate 1.3%). All remaining patients experienced favorable functional outcomes.

Conclusions: The risk of moyamoya-related stroke during pregnancy, delivery, and the postpartum period appears to be similar to or lower than that suggested by published natural history studies in symptomatic patients. A neuroprotective effect of pregnancy in moyamoya patients cannot be excluded.