[A Ruptured Middle Cerebral Artery Dissecting Aneurysm Operation in a 2-Year-Old Boy].

We report the case of a ruptured dissecting aneurysm in an infant. A 2-year-old boy suffered sudden headache and nausea. CT scan revealed a subarachnoid hemorrhage, and digital subtraction angiography(DSA)revealed a dissecting aneurysm(3.9mm)at a branch of the right middle cerebral artery(MCA). Eight days after onset, carotid angiography revealed enlargement of the aneurysm(up to 6.8 mm). Right frontotemporal craniotomy and aneurysm trapping with STA-MCA bypass was performed. Two years and two months later, the aneurysm recurred as assessed by magnetic resonance angiography(MRA). DSA revealed the recurrence of the aneurysm(7.8mm)proximal to the previous aneurysm and displayed development of collateral flow through leptomeningeal anastomosis between the branches of the MCA. During the second operation, the aneurysm extended to the artery branch proximal to the previous trapping. Parent artery occlusion without bypass was performed. Postoperative DSA revealed collateral flows through leptomeningeal anastomosis between the branch of the MCA and the branch of anterior cerebral artery. At the 3-year follow-up period, abnormal findings on MRI did not appear and he was healthy without any neurologic abnormalities.