Introduction: Moyamoya is a rare, yet classic etiology of stroke in young adults, predominantly affecting women of childbearing age. However, the impact of pregnancy on the natural history of symptomatic moyamoya remains a matter of extensive debate. Through a systematic review and pooled analysis of the literature, the authors sought to assess the risk of moyamoya-related neurologic events during pregnancy, delivery, and the postpartum.
Methods: In October 2017, a MEDLINE search was performed using the combination of the keywords "moyamoya" or "moya-moya" with the keywords "pregnancy" or "pregnant" or "gravid" or "gestation" or "gestational" or "labor" or "delivery" or "parturition" or "parturient" or "postpartum" or "puerperium" or "puerperal". A total of 12 original papers 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. Mean age at delivery was 31 years and mean age at diagnosis (before pregnancy) was 22.6 years. Clinical presentation was: ischemic in 50.8%, hemorrhagic in 45.9%, headaches in 2.1%, ischemic-hemorrhagic in 1.2%. After excluding patients diagnosed during or after pregnancy (n=283) and those who were 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%), over two-thirds of which were transient (13 TIAs, 2 seizures). There were 7 strokes (6 hemorrhagic, 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 appears lower than what published natural history studies in symptomatic patients suggest. A neuroprotective effect of pregnancy in moyamoya patients cannot be excluded.
Patient Care: This paper demonstrates that stroke risk during pregnancy may be significantly lower than previously thought in moyamoya patients. This may have significant impact on how we counsel female patients of childbearing age with moyamoya disease. It also raises the question as to whether physiologic changes in pregnancy may carry some sort of neuroprotective effect in moyamoya patients.
Learning Objectives: 1. Recognize that published literature on stroke risk during pregnancy in moyamoya patients is heavily biased.
2. Recognize that evidence-based, systematic, and critical review of the published literature suggests that the risk of stroke in this population is actually lower than previously thought.
3. Consider the possibility that, contrary to traditional belief, pregnancy might actually have a neuroprotective effect in moyamoya patients.