Intraoperative angiography during aneurysm surgery: a prospective evaluation of efficacy.

OBJECT Indications for intraoperative angiography during aneurysm surgery remain unclear. To define its use, the authors report the results of a prospective study in which this modality was used in all patients undergoing surgery for intracranial aneurysms. METHODS Intraoperative angiography was performed prospectively in the surgical treatment of 517 consecutive aneurysms regardless of the lesion's location, size, or complexity. In 64 (12.4%) of 517 aneurysms intraoperative angiography findings prompted a change in surgical treatment. Residual aneurysm (47%) was the most frequent finding leading to clip revision. In 44% of cases, intraoperative angiography revealed vessel compromise. Surgery for aneurysms of the proximal internal carotid artery (ICA) was the most frequently altered, with lesions located at the superior hypophyseal artery (SHA) and clinoidal region having the highest revision rates, eight (40%) of 20 and eight (44%) of 18, respectively. Aneurysm size predicted the need for revision; giant aneurysms (> 24 mm) underwent revision in nine (29%) of 31 cases, whereas large aneurysms (15-24 mm) were revised in 12 (22%) of 54 cases. In a multivariate logistic regression model, factors related to increased revision rates included the SHA and clinoidal locations, as well as giant and large size. Ninety-five patients underwent both intraoperative and postoperative angiography. Five discrepancies were noted (95% accuracy); four were flow-related and one involved a previously unrecognized residual aneurysm. Complications attributable to intraoperative angiography occurred in 0.4% of cases. CONCLUSIONS Proximal ICA location and large aneurysm size significantly predicted revision of surgery following intraoperative angiography. Unexpected findings, even in less complex locations, are frequently identified on intraoperative angiography. Low complication rates, high accuracy, and the unexpected need for clip readjustments favor a more widespread use of intraoperative angiography.