[A case of atypical moyamoya disease with a ruptured aneursym on moyamoya vessel].

A 45-year-old female had sudden onset of severe headache, nausea and vomiting without any inducing moments and was transferred to our hospital by an ambulance car. On admission the patient was alert and showed only signs of meningeal irritation. There were no other neurological deficits at all. Immediate CT examination revealed a small high density spot in the area of the right basal ganglia, and a large high density in the frontal horns of both lateral ventricles. Right carotid angiogram showed completely patent carotid siphon with Moyamoya vessels. A small round aneurysmal shadow of 3 mm in diameter was seen in the area of these Moyamoya vessels of the right basal ganglia, and it was thought to be corresponding to the high density spot in the CT examination. Left carotid angiogram showed stenosis of C portion with typical Moyamoya vessels. Therefore, diagnosis of atypical Moyamoya disease with a ruptured aneurysm and ventricular penetration of hematoma was made. The patient was placed on conservative treatment. On 25th day from onset, repeated angiogram showed enlargement of the aneurysmal shadow from 3 mm to 5 mm in diameter. So, on 33rd day, right STA-MCA anastomosis and encephalomyosynangiosis were carried out. Angiogram on 12th day after surgery revealed no aneurysmal shadow. The patient was discharged without any neurological deficit at all. Previous paper, which reported cases of Moyamoya disease with aneurysm, were reviewed. According to the location of the aneurysm, these cases were classified into 3 types angiographically; type I: aneurysm in the area of Moyamoya vessels, type II: aneurysm of cerebral-peripheral artery, and type III: aneurysm of the circle of Willis. It has been generally believed that the Moyamoya disease may be associated with either a true or a pseudoaneurysm in the case of type I. However, pseudoaneurysm in the area of Moyamoya vessels has not been found in postmortem examination but true aneurysms so far. Therefore it may not be denied that the aneurysm of this case was true aneurysm although it showed an enlarging tendency and disappeared rather spontaneously.