[Fusiform aneurysm of the anterior cerebral artery (A1 segment)--a case report].

A very rare case of fusiform aneurysm of A1 segment of the anterior cerebral artery is reported. A 54-year-old man was admitted with dull headache and speech disturbance for 6 days before admission. CT scan revealed hypertensive subcortical small hemorrhage in the left temporal lobe. Angiography showed no vascular lesion concerning to the subcortical hemorrhage in the left temporal lobe, but showed a spherical aneurysmal dilatation in the left A1 segment of the anterior cerebral artery. At operation a fusiform aneurysm of the left A1 segment was confirmed. The aneurysm was obliterated, and new parent artery was reconstructed using a curved and a straight Yasargil aneurysm clips. The postoperative course was uneventful. Surgical treatment should be directed toward exclusion of large fusiform aneurysm and arteriosclerotic saccular aneurysm from cerebral circulation.