Regional predilection of lesions and stages of moyamoya disease

Moyamoya disease (MMD) is an idiopathic entity characterized by progressive occlusion of the distal internal carotid arteries (ICAs), as well as the proximal anterior artery (ACA) and middle cerebral artery (MCA). Although the vast majority of cases are sporadic, familial factors have been implicated in a small subset of cases. The frequency of familial occurrence of MMD is estimated to be approximately 7-10% of all reported cases [1] and the incidence among Asians is high. In addition, studies looking at the pathogenesis of MMD have uncovered both genetic predisposing factors as well as acquired factors. Single nucleotide polymorphism, sickle cell anemia, and neurofibromatosis are among some of the purported genetic factors. Acquired conditions such as tuberculosis meningitis infection and atherosclerosis have also been identified [2].