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.
