Morphologic Parameters and Location Associated with Rupture Status of Intracranial Aneurysms in Elderly Patients

BACKGROUND: Treatment of unruptured intracranial aneurysms (IAs) in elderly patients is associated with a high risk of morbidity and mortality, necessitating a thorough understanding of the potential rupture risk. The aim of this study was to identify morphologic parameters and anatomic locations that could discriminate ruptured IAs in patients >= 70 years old. METHODS: Retrospective analysis was performed of three-dimensional angiograms and medical records of 344 patients with 411 saccular IAs. Patients >= 70 years old were defined as elderly. IAs were subdivided into ruptured and unruptured. Morphologic parameters and anatomic locations were compared in elderly and younger (<70 years old) patients with ruptured and unruptured IAs. RESULTS: The study included 266 patients <70 years old and 78 patients >= 70 years old with 411 aneurysms (102 ruptured and 309 unruptured). In the elderly group, 22 of 95 aneurysms were ruptured (23.15%) compared with 80 of 316 (25.3%) in the younger group. Size ratio and aspect ratio were higher in ruptured IAs, but only in the younger group. Undulation index, indicating IA shape irregularity, was significantly different between ruptured and unruptured IAs in younger and elderly groups. The only variables associated with rupture in the elderly group were undulation index (0.11 +/- 0.07 vs. 0.07 +/- 0.06, P = 0.02) and location (P = 0.001). CONCLUSIONS: Aneurysm size, size ratio, and aspect ratio may not be reliable discriminants of rupture in elderly patients. Unruptured IAs in elderly patients should be evaluated on the basis of shape irregularity and anatomic location.