Objective: Evaluation of the safety and effectiveness of endovascular retreatment of intracranial aneurysms with detachable coils.
Methods: Retrospective analysis of clinical outcome as well as angiographic studies both before and after coil retreatment. The indication for retreatment was based on either inadequate occlusion after previous treatment or recurrent perfusion of the aneurysm.
Results: A total of 2759 intracranial aneurysms in 2360 patients were treated by endovascular coil occlusion. Of those, 350 (12.3%) aneurysms underwent a second treatment, and 94 (3.4%) aneurysms underwent three or more treatment sessions. The second treatment sessions were performed an average of 27.2 months after the previous procedure. The third and following treatment sessions were conducted an average of 25.3 months after the previous procedure. Initial treatment resulted in 100% occlusion in 63.7% of aneurysms. One hundred percent occlusion was achieved in only 46.9% of the second and 35.2% of the third and following sessions. Stent-assisted coil treatment was used in 5.6% of initial, 28.0% of second, and 20.7% of third and following sessions. Initial treatment sessions were uneventful in 83.2% of cases, second sessions in 86.9% of cases, and third and following sessions in 87.6% of cases. The morbidity-mortality rate for 495 retreatment sessions was 2.2% (n = 11).
Conclusion: The natural course of aneurysm remnants or recurrent aneurysm perfusion after coil treatment is not completely understood. The low risk of bleeding from partially filled aneurysms must be balanced against the procedure-related risks of retreatment. Great caution is recommended for the treatment of asymptomatic recurrent aneurysms.