Thus the incidence of completed stroke is higher in the patients whose onset of symptoms occurs before 2 years of age. Moyamoya disease is frequently familial and may occur in monozygotic twins. These findings suggest that some genetic factors possibly take part in the pathogenesis. However, the paucity of clinical materials for investigations has not allowed a direct determination of the pathogenesis of moyamoya disease. One of the most prominent features of moyamoya disease is the progressive intimal thickening of the intracranial arterial trunks.
Further investigations are necessary to elucidate the pathogenesis of moyamoya disease.
In children with moyamoya disease, TIAs are induced by activities associated with hyperventilation, such as crying, running, eating hot noodles, and singing. Blood flow compromise is demonstrated in the borderzone areas between anterior and middle cerebral artery distributions or between middle and posterior cerebral artery distributions in the initial stage of moyamoya disease. Along with the progression of occlusive lesions, CBF becomes diffusely decreased in the cerebral hemisphere, finally causing brain atrophy. Most pediatric patients suffer from cerebral ischemic episodes. Approximately half of the adult patients, by contrast, experience hemorrhagic attacks.