Factors influencing successful angiographic occlusion of aneurysms treatedby coil embolization

BACKGROUND AND PURPOSE: Coil embolization of berry aneurysms is a relativel y new treatment whose long-term efficacy has yet to be established. The pur pose of this study was, first, to attempt to identify factors that might be important in predicting success both at the time of treatment and at the t ime of follow-up angiography, and, second, to study changes in the aneurysm between treatment and follow-up to determine the frequency of these change s. METHODS: The pretreatment, posttreatment, and follow-up angiograms of the f irst 63 aneurysms (in 58 patients) treated at our institution between June 1992 and April 1995 were analyzed, and the percentage of occlusion of each aneurysm was calculated. The size of any rest was noted for the posttreatme nt and follow-up angiograms. Treatment success was defined as a residue of less than 2 mm. Aneurysms were said to have changed if the percentage of oc clusion had altered by more than 2.5% or if the difference in rest size was greater than 0.25 mm. Possible factors influencing primary and follow-up s uccess rates were correlated against these calculations. RESULTS: Success rates at treatment and follow-up were 71% and 65%, respect ively. No change occurred in 41% of aneurysms, and 20% had a decrease in si ze of the residue, Twenty-eight percent had coil compaction, and 11% had an eurysmal growth. Neck size was the only significant variable in primary tre atment success. Success at follow-up correlated significantly with neck siz e, initial treatment success, vasospasm at the time of treatment, and clini cal presentation. CONCLUSION: Best long-term angiographic results are obtained when the prima ry treatment is successful, when the aneurysm is small and narrow-necked, w hen the acutely ruptured aneurysm is treated within 15 days of ictus, and w ith anterior communicating and basilar-tip aneurysms.