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. The hemorrhages are usually located in the basal ganglia or thalamus. Ventricular perforation of a hematoma is frequently noted. Although angiography can reveal aneurysmal dilation in moyamoya vessels as a possible cause of hemorrhage in some patients, the angiographic identification of the hemorrhage's origin is usually difficult. Some adult patients may sustain both ischemic and hemorragic attacks.