Natural history of dolichoectatic vertebrobasilar aneurysms: a multinational study

OBJECTIVE Dolichoectatic vertebrobasilar aneurysms (DVBAs) are expansions of arterial tissue leading to aneurysmal formations without an obvious neck. Their natural history is poorly understood; usually patients are admitted with thromboembolic complications and/or neurological symptoms from the mass effect. There have not been international collective data, and correct timing for highly risky treatments has been under discussion. The goal of this study was to define the natural history of DVBA by long-term follow-up in an international population of patients with DVBA. METHODS The authors collected data in 382 patients with DVBAs from 11 centers in Europe, the US, and Japan. The patients were followed until new ischemic or hemorrhagic stroke, symptomatic compression of the brainstem or cranial nerves, decline in modified Rankin Scale score, or death. Treatment excluded patients from further analysis. Demographic and radiological characteristics of patients were collected and a new classification was created based on the radiological characteristics of the DVBA. In total 223 patients were treated conservatively in the first phase of treatment. The data required for natural history calculations were available for 221 patients, with a cumulative follow-up of 622.3 patient-years. Kaplan-Meier and Cox regression analyses were used to assess risk factors with an influence on patient outcomes. RESULTS In total, 21.5% of patients were admitted due to the mass effect, and there were 67 (30%) patient deaths during follow-up, 45 (20.2%) of which were related to aneurysms. The annual mortality and morbidity were 10.8% and 1.6%, respectively. Most of the patients with DVBAs were male, although sex did not affect prognosis when compared to the radiological characteristics of the lesion. The natural history of DVBAs was also impacted by a new classification, in which an age 50 years and older predicted mortality. Furthermore, a DVBA’s maximum diameter was directly proportional to adverse events. CONCLUSIONS This study verifies the malignancy of DVBAs and encourages invasive treatment in the early phase of disease progression based on radiological characteristics and patient age when a treatment option is considered suitable. This also stresses the need for continued investigations to develop new therapeutics with acceptable safety profiles.