Enlargement and rupture of distal basilar artery aneurysm after iatrogenic carotid occlusion.

A case of angiographic enlargement and fatal rupture of a previously asymptomatic distal basilar aneurysm in a 12-year-old girl is reported. She had been treated by carotid sacrifice for a giant intracavernous carotid aneurysm. After superficial temporal-middle cerebral artery bypass, this patient underwent a trapping procedure and decompression of her symptomatic giant aneurysm. Despite postoperative patency of her bypass graft, the involved middle cerebral circulation was irrigated substantially by retrograde flow through her posterior communicating artery. An incidental distal basilar aneurysm involving the origin of her superior cerebellar arteries, posterior cerebral arteries, and multiple perforators was treated by a wrapping procedure. Eleven days after carotid ligation, she suffered a fatal subarachnoid hemorrhage from her basilar aneurysm. This catastrophe was undoubtedly produced by our failure to consider the additional hemodynamic stress placed upon the distal basilar artery by carotid sacrifice and may have been preventable by a more aggressive attack on this previously asymptomatic lesion.