Endovascular treatment of unruptured intracranial aneurysms: Occurrence of thromboembolic events

OBJECTIVE: The purpose of this study was to evaluate the frequency and causes of thromboembolic events associated with endovascular embolization of asymptomatic aneurysms. Correlations between radiological findings (aneurysm size, localization, embolization time, number of coils used, as well as patient age) were evaluated with the occurrence of thromboembolic events and clinical findings. METHODS: Sixty-eight patients treated for unruptured intracranial aneurysms (mean age, 49 yr) were evaluated. Hyperintense lesions on diffusion weighted imaging were analyzed in 50 patients. Aneurysm size was 3 to 15 mm. RESULTS: Complete occlusion of the aneurysms was achieved in 55 of 68 (82%). One patient had a transient paresis. There was one infarction and one aneurysm rupture during the procedure with no consecutive neurological symptoms. We found new hyperintense lesions in 21 of 50 (42%) diffusion weighted imaging studies. In 43% of these, there was only one lesion smaller than 2 mm. In 33%, there was more than one lesion less than 2 mm; in 19%, we found a lesion of 2 to 10 mm in size. In one case, a lesion greater than 10 mm occurred. There was no correlation between aneurysm location and the occurrence of lesions or among the number of coils used, the size of the aneurysm, patient age, or embolization time. Mortality rate was 0%, morbidity 4.0%. If the 18 aneurysms where no diffusion weighted imaging was obtained are included, morbidity is 2.9%. CONCLUSION: The high rate of thromboembolic events suggests that heparin is not sufficient to prevent ischemic lesions. An antiplatelet therapy, started before or during intervention, might diminish thrombus formation.