Surgical treatment of unruptured aneurysms of the posterior circulation.

With the ever-increasing number of intact aneurysms revealed by modern imaging, the options for their management are assuming great importance. While some knowledge has emerged as to their natural history and the results of surgical treatment of those in the anterior circulation, little information has been published concerning unruptured aneurysms arising from the posterior circulation. The authors report their experience since 1971 with 167 patients operated on for 179 unruptured vertebrobasilar aneurysms up to 25 mm in diameter. Overall, 160 aneurysms were treated by direct clip obliteration, while 19 were managed by alternative methods. Fifty-three patients (32%) had solitary aneurysms and the other 114 patients (68%) had multiple aneurysms or an associated arteriovenous malformation, which were commonly treated concurrently. Many of these coexisting vascular anomalies had ruptured in the recent or remote past, adding to the complexity of management and interpretation of specific surgical results related to the intact posterior circulation aneurysm. There were 78 documented postoperative complications including 23 systemic complications, seven postoperative hematomas, six brain injuries from retraction, five cases of aseptic meningitis, three instances of seizures, three wound infections, and three patients with hydrocephalus. Multiple complications occurred in 23 patients. Seventy-one of the patients with these untoward events recovered, without disability, with time or treatment. There were only six poor results and one death in the series, resulting in a 4.2% combined morbidity/mortality rate. However, since two of these poor outcomes and the single death were attributable to a coexisting aneurysm, the actual surgical morbidity related specifically to the posterior circulation aneurysm was only 2.4%. This experience suggests that non-giant, intact vertebrobasilar aneurysms can be obliterated surgically at a very low risk, and this treatment should eliminate the greater lifetime risk related to an unsecured aneurysm.