[Child with moyamoya disease after bypass surgery. Report of an autopsy case].

&nbsp; Autopsy findings on a 16-year-old boy with moyamoya disease who was previously treated with external carotid-internal carotid (EC-IC) bypasses and encephalo-myo-synangiosis (EMS) are reported.<BR> &nbsp; Five years after the surgery, he was involved in a traffic accident and the resulting head injury caused his death. In the autopsied brain, numerous vessels were observed in the subarachnoid space of the convexity, especially in the area corresponding to the EMS, where traumatic damages and hemorrhages were most drastic. In the histological study of the brain vessels, intimal thickening with elastofibrosis and tortuous internal elastic laminae in the arterial wall were generally observed, not only in the neighborhood of Willis' circle, but in the level of arterioles irrespective of the artificial bypass. Development of new intraluminal vessels, and recanalization were revealed in the terminal portion of the left internal carotid artery. These findings suggest that factors other than the blood flow, such as thrombo-emboli, may participate in the propagation of occlusive processes in moyamoya disease.