[Spontaneous middle cerebral artery occlusion with moyamoya-like vessels associated with contralateral middle cerebral artery aneurysm; a case report].

A case of spontaneous middle cerebral artery occlusion with moyamoya-like vessels associated with contralateral middle cerebral artery aneurysm is reported. A 23-year-old male was admitted to our hospital with complaints of severe headache and vomiting. On admission CT scan demonstrated subarachnoid hemorrhage with high density in the left Sylvian fissure and suggested a ruptured left middle cerebral artery aneurysm. Carotid angiograms demonstrated a left middle cerebral artery aneurysm and an occlusion of the right middle cerebral artery at its origin with moyamoya-like vessels. There was no occlusion or stenosis in the bilateral intracranial internal carotid arteries. Furthermore, bilateral vertebral angiograms were also normal. The aneurysm was successfully clipped. The postoperative course was uneventful and the patient was discharged with no neurological deficit. So far as we could ascertain, there have been only 21 cases reported previously of spontaneous middle cerebral artery stenosis or occlusion with moyamoya-like vessels. According to angiographic studies and transcranial Doppler ultrasound findings, we are more inclined to believe that hemodynamic changes secondary to arterial occlusion lead to the formation and growth of aneurysms of the contralateral middle cerebral artery.