Overview

Moyamoya disease is a unique cerebrovascular disease with steno-occlusive changes at the terminal portion of the internal carotid artery and fine vascular network, the so-called moyamoya vessels [1]. This vascular network forms a collateral pathway and compensates reduced cerebral blood flow due to steno-occlusive changes of the trunk arteries. The characteristics of moyamoya disease can be summarized as follows. Moyamoya disease shows racial difference in incidence and predominantly occurs in the Eastern Asia among a worldwide distribution. Clinical manifestation includes ischemia and hemorrhage, epilepsy, headache, etc., and young patients usually present with ischemia and adult patients with either ischemia or hemorrhage [2]. Evidence indicates that revascularization surgery can prevent an ischemic event, although its effect on prevention of hemorrhagic events is yet to be determined [-6]. Since the familial occurrence reaches 12%, an intense effort has been focused on genetic analysis during the past decade which has found that several genetic loci associate with this disease [7, 8]. Nevertheless, the conclusive pathogenesis of this disease still remains unknown. In this chapter, the author seeks to focus on the diagnostic criteria, the definition, and the history of this disease.