The prognosis and treatment effectiveness of de novo aneurysm formation after radiation therapy for brain tumor.

Radiation therapy is a well-established, minimally invasive method of treating brain tumors. In recent years, the number of post-radiotherapy patients has increased, and delayed side effects are evident. De novo aneurysm formation after radiation often manifests as fatal subarachnoid hemorrhage (SAH), resulting in severe clinical outcomes. Nevertheless, the prognosis and therapeutic efficacy of radiation-induced aneurysms (RIAs) remain unclear. Using the PubMed database from 1980 to 2021, we screened 45 articles (53 individual cases) on RIAs; approximately 70% of RIAs were diagnosed after rupture. Of 38 ruptured RIAs, 12 (31.6%) had modified Rankin scale (mRS) 5-6. On the other hand, all unruptured RIAs (15 cases) recovered without neurological deficits (p = 0.012). Ten of the 39 ruptured RIAs were treated surgically, and 22 were treated endovascularly. There was no significant difference in mRS between treatment modalities (p = 0.393), but conservative therapy was significantly related to unfavorable outcomes (p = 0.025). To improve clinical outcomes, RIAs need to be diagnosed before rupture. Surgeons should be aware of de novo aneurysm formation in patients long after radiation therapy.