Intracranial aneurysm: Anatomic factors that predict the usefulness of intraoperative angiography

PURPOSE: To correlate the size and location of intracranial aneurysm with the need to reposition the aneurysm clip after intraoperative angiography. MATERIALS AND METHODS: In 199 consecutive patients with 234 clipped intracranial aneurysms, 273 intraoperative angiographic studies were retrospectively reviewed. Aneurysm size and location, determined with preoperative angiographic and surgical reports, were correlated with the frequency of clip repositioning because of parent- or branch-vessel compromise or unexpected residual aneurysm. RESULTS: Findings from intraoperative angiograms resulted in clip repositioning in 46 of 273 (16.8%) studies. Clip repositioning was statistically significantly less frequent with aneurysms of the posterior communicating (three of 52 [5.7%] studies) and anterior choroidal (none of 12 studies) arteries. High rates of clip repositioning were found in aneurysms of the superior hypophyseal artery (seven of 18 [38.9%] studies), superior cerebellar artery (three of five [60.0%] studies), and bifurcation of the internal carotid artery (three of nine [33.3%] aneurysms). In 98 conventional follow-up angiographic studies, seven (7%) false-negative cases with unsuspected aneurysm neck remnant were found. CONCLUSION: The rate of clip repositioning in aneurysms of the posterior communicating or anterior choroidal arteries was less than that at other locations (P < .05). Intraoperative angiography may not be necessary when aneurysms are at these two locations.