Pseudoaneurysm complicating superficial temporal artery-superior cerebellar artery bypass.

A 60-year-old man with vertebrobasilar ischemia unrelieved by anticoagulation was found to have a midbasilar stenosis with an inadequate basilar collateral circulation. He underwent a right superficial temporal-superior cerebellar artery bypass. Following this operation he had a subarachnoid hemorrhage and right third nerve palsy that was due to formation of a pseudoaneurysm at the site of the anastomosis. This aneurysm was managed by ligation of the right superficial temporal artery. Subsequently it became necessary to perform a left superficial temporal artery-superior cerebellar artery bypass because of severe posterior circulation ischemic symptoms.