Moyamoya disease in adult: Post-bypass symptomatic hyperperfusion

Abstract

Physicians have tried various nonsurgical treatments for moyamoya disease (MMD), but none has so far proven effective [1]. Surgical revascularization, by contrast, increases collateral irrigation and improves cerebral hemodynamics in MMD, thereby reducing the risk of subsequent ischemic insult by improving cerebral hemodynamics in MMD [2]. The various revas-cularization techniques used with MMD can be roughly classified into three categories according to the use of arterial anastomosis: (1) indirect nonanastomotic revascularization surgery; (2) direct anastomotic bypass surgery, usually superficial temporal artery (STA)-middle cerebral artery (MCA) bypass; and (3) combined surgery. Many kinds of indirect revascularization are effectively used for pediatric MMD [3], but surgical options for adult MMD are quite different. The two situations differ for the following reasons: (1) adults have less fragile cortical branches with larger diameter than children, so direct bypass is technically less challenging [4, 5]; and (2) direct bypass theoretically provides more immediate resolution of ischemic conditions by improving cerebral hemodynamics shortly after surgery [6]. Postoperative changes in cerebral hemodynamics are both marked and abrupt, however, and often induce symptomatic hyperperfusion, particularly in MMD patients with preoperative chronic sustained profound ischemia [7, 8]. Consequently, patients should be carefully managed after direct bypass surgery. In this chapter, the authors review the pertinent literature and relate their personal experience, paying special attention to hyperperfusion after direct bypass in the treatment of adult MMD. © 2010 Springer-Verlag Tokyo.