A1 Aneurysm Research Articles

Aneurysms arising from the proximal (A1) segment of the anterior cerebral artery

This study reviews aneurysms of the proximal segment (A1) of the anterior cerebral artery in 38 patients (23 men and 15 women) and their surgical, angiographic, and clinical management. Thirty-seven aneurysms were saccular and one was fusiform. The incidence of A1 aneurysms among a total of 4295 aneurysm cases treated was 0.88%. Multiple aneurysms occurred in 17 patients (44.7%) of the 38 cases; in 10 (58.8%), there was bleeding from the A1 aneurysm. The aneurysms were classified into five categories according to the mode of origin of the aneurysm in relation to the A1 segment: in 21 cases, aneurysms originated from the junction of the A1 segment and a perforating artery; in eight, from the A1 segment directly; in six, from the proximal end of the A1 fenestration; and in two, from the junction of the A1 segment and the cortical branch. One patient had a fusiform aneurysm. Computerized tomography (CT) of these aneurysms revealed bleeding extending to the septum pellucidum similar to that of anterior communicating artery aneurysms. When performing radical surgery it is very important to recognize the characteristics of A1 aneurysms, including multiplicity, a high incidence of vascular anomalies (especially A1 fenestration), and their similarity to anterior communicating artery aneurysms on CT.

脳動脈瘤処置後の新生動脈瘤

In this paper, the authors report three cases of aneurysms newly formed near one that had been clipped and discuss the mechanism of their formation.Case 1. A 48-year-old male was operated on for an AComA aneurysm 40 days after it had ruptured. At the time of the neck dissection, the aneurysm ruptured and a temporary clip was placed at the right Al portion for 15 minutes. The aneurysm was successfully obliterated, but the patient suffered from subarachnoid hemorrhage four days after surgery and following two attacks. A right CAG showed a newly formed anuerysm at the Al portion where the temporary clip had been placed. He died 13 days after operation. Massive subarachnoid hemorrhage from the new A1 aneurysm was found in autopsy and aspergillus hyphae were recognized in the arterial wall of the A1 portion by the microscopic examination.Case 2. A 56-year-old female was operated on for a right IC-PC aneurysm on the 23th day after initial subarachnoid hemorrhage. During operation, the aneurysm ruptured and the right ICA was temporarily clipped at the immediately proximal portion for ten minutes. The neck was successfully obliterated. Postoperative right CAG, which was performed 35 days after operation, showed a new aneurysm at the place where the temporary clip had been applied. The right ICA was ligated and she was discharged without neurological deficits.Case 3. A 38-year-old man was successfully operated on for an aneurysm at the bifurcation of the left MCA on the fifth day after a second subarachnoid hemorrhage. But, left CAG on the eighth day after operation showed a newly formed aneurysm proximal to the clipped aneurysm. On the 12th postoperative day, he suddenly fell into coma and a left CAG at that time showed that the new aneurysm enlarged in size. He died on the 19th day after operation. An autopsy was not performed.

Intracranial Cystic Meningioma associated with Multiple Aneurysms and a Venous Angioma

A 50-year-old male was hospitalized with headache and visual disturbance. Computerized tomography revealed a cystic lesion in the left occipital area as well as a small, hyperdense lesion in the left posterior fossa. On angiograms the left occipital lesion appeared to be a meningioma and the left posterior fossa lesion a venous angioma. In addition, the right carotid angiogram revealed an A2 aneurysm and the right vertebral angiogram showed a basilar top aneurysm. The left occipital lesion and both aneurysms were treated surgically. The left occipital lesion was diagnosed as meningotheliomatous meningioma. Cystic meningioma is rare, accounting for only 1.2-2.2% of all meningiomas. Also, aneurysms are associated with only 2.5-4% of all brain tumors. To the authors' knowledge, this is the first reported case of the cystic meningioma associated with multiple aneurysms and a venous angioma.