Purpose: This study examined clinical and aneurysm characteristics in patients with unruptured aneurysms, treated with either coiling or clipping at a single institution, with the primary outcome-Glasgow Outcome Score (GOS)-measured at 6 months after treatment.
Methods: Data was obtained by a retrospective review of a prospective registry of consecutive cases of unruptured intracranial aneurysms treated at a single institution from 2002 to mid 2007. Demographic data, number, location, and size of aneurysms, calcification, mode of treatment, ASA score, presence of a stroke on post-op imaging, and GOS were recorded. Medical 9.4 for PC was utilized for statistical analysis.
Results: There were 225 procedures performed in 208 patients to treat 252 aneurysms. The mean age was 54.6 years, 74.5% were female, the mean ASA score was 2.45, and 72.2% were smokers. Mean aneurysm size was 8.6 mm. A total of 157 (70%) craniotomies and 68 (30%) coiling procedures were performed. Coiling was utilized more frequently in the posterior circulation [18/32 (56%) posterior circulation, 50/193 (29.9%) anterior circulation, p < 0.001 Chi-square]. Length of hospital stay averaged 5.3 days [6.2 vs. 3.2 clip/coil, p < 0.001, Mann-Whitney]. Overall favorable outcome of GOS 4-5 measured at 6 months post-procedure was 93.3% [145/157 (92.3%) clip, 66/68 (97%) coil, p = 0.3 Chi-square], with a single mortality in the coil group. There was radiographic evidence of a post-procedure stroke on CT in 31 (13.8%) [28/157 (17.8%) clip, 3/68 (4.4%) coil, p < 0.001, Chi-square], but only 11(35%) were symptomatic. All long-term morbidity was attributable to stroke except for one case of late hydrocephalus. Utilizing a logistic regression multivariate analysis (forward), none of the examined factors (age, ASA score, sex, surgeon, posterior circulation, number of aneurysms treated at one sitting, size of aneurysm, smoking status, or type of therapy) related to outcome except calcified aneurysm [20/25 (80%) calcified, 191/200 (95.5%) non-calcified, p < 0.01 Chi-square] with an OR = 7.8 (2.2-28.4, 95% C.I.). Although a univariate analysis of aneurysm size versus outcome achieves statistical significance [p = 0.05, logistic regression (forced)], when the calcified cases are removed from consideration, it does not [p = 0.55, OR = .95, (.82-1.1), 95% C.I.]. Excluding patients with calcified aneurysms resulted in the following calculation of favorable outcome: 94.2% (130/138) clip and 98.4% (61/62) coil [p = 0.33, Chi-square].
Conclusions: In this study, the presence of calcification in an aneurysm was the sole marker of adverse outcome. Larger aneurysms tended to be more likely to be calcified. Size by itself did not have an adverse affect on outcome. Clipping or clip reconstruction of calcified aneurysms is a significant source of morbidity in the treatment of unruptured aneurysms (Odds ratio 7.8).