Radiation-induced brain aneurysms. institutional experience and state of the art in the contemporary literature

Background: Brain aneurysms (BAs) are the most common intracranial vascular condition, with an overall incidence of 1%–2%. Among the common causes of their initial formation and growth, the role of radiation therapy (RT) has been reported in some studies. The aim of the present study is to report the most relevant features of BA related to a previous cranial RT. Methods: Data deriving from 1 patient treated for RT-induced BA in our institution were added to reports of another 66 BAs retrieved from the literature. The following parameters were evaluated: age, sex, location, primary lesion, clinical presentation, dosage/amount of radiation delivered, type of treatment for the BA, dimension, morphology, chemotherapy, comorbidities, risk factors, and number of BAs. Results: The most commonly involved vessel was the internal carotid artery (34%). In general, the anterior circulation showed higher vulnerability compared with the posterior circulation and middle cerebral artery (56.7%). The average latency between RT and the first imaging showing the BA was 9.01 ± 6.85 years. Vessels coursing in the posterior cranial fossa showed a significant univariate association with lower X-ray dosages (P = 0.014) compared with the other locations. No statistically significant correlation between the continuous variables age, latency of BA appearance, RT delivered dose, and dimension of the BA was shown. Conclusions: The apparent higher fragility of the vascular structures of the posterior cranial fossa was statistically outlined, and the X-ray dosage, the primary condition target of the RT, the age of the patients, and no statistically significant correlation were outlined. Biological factors could play a significant role.