What is the controversy surrounding surgery for secondary prevention of ischemic stroke in moyamoya disease?
Within the realm of surgery, there is considerable controversy as to what constitutes the best surgical option, direct superficial temporal artery to middle cerebral artery bypass or an indirect bypass procedure such as encephaloduroarteriosynangiosis or encephalomyosynagiosis. The differences in surgical technique even within the broad categories of direct and indirect bypass, the frequent use of combined procedures, and the heterogeneity of the patient population make it difficult to draw robust conclusions about the superiority of one procedure over another. Although several meta-analyses and case series favor direct over indirect bypass, there are no prospective RCTs to inform recommendations in this area. A propensity score matched analysis on 220 adult patients with ischemic-type moyamoya disease showed that direct bypass was superior to indirect bypass for the prevention of recurrent stroke. In this series, however, the primary endpoint of recurrent stroke was defined as both ischemic and hemorrhagic events. In contrast, a retrospective multi-center study reported no difference between direct and indirect modalities.