Intracranial aneurysm associated with moyamoya disease in childhood.

We report a 6-year-old girl with an intracranial aneurysm associated with moyamoya disease. The patient did not have a subarachnoid hemorrhage but had an ischemic attack. The aneurysm, located on the proximal portion of the lateral posterior choroidal artery, disappeared after external carotid-internal carotid anastomosis. The characteristics of the aneurysms associated with moyamoya disease are briefly reviewed. We emphasize that the treatment of choice in moyamoya disease is cerebral revascularization, because it reduces the increased blood flow through the moyamoya vessels, basilar artery and other uninvolved cerebral arteries, the sites where the aneurysms in this disease frequently develop, as the blood flow through the external carotid system is increased by such an operation.