[Ruptured aneurysm of the marginal branch of the superior cerebellar artery: case report]

The authors report a rare case of a ruptured aneurysm arising from the marginal branch of the left superior cerebellar artery. At the first retrosigmoid craniectomy carried out on the day of hospitalization, the clip was wrongly placed on the anterior inferior cerebellar artery (AICA). The unanticipated accident was due to incomplete dissection of a thick and severely adhered subarachnoid clot and the mistake was made because the course of the marginal artery was similar to that of the AICA. At the second operation undergone 1 week later, the aneurysm was easily and successfully clipped. After ventriculoperitoneal shunting, the patient returned to normal except for left hearing loss. The authors suppose that delayed surgery would be beneficial as a rule for ruptured aneurysms of the peripheral branch of the cerebellar arteries not only because dissection is easier but also because the risk of rebleeding and vasospasm are reported to be low in such aneurysms.