Cerebral microbleeds and cavernomas after radiotherapy for brain tumors: a literature review and illustrative cases

Improved survival after multimodal treatment of primary brain tumors has increased recognition of long-term neurologic sequelae, particularly radiation-induced vascular injury. Cerebral microbleeds (CMBs), visible as hypointense foci on susceptibility-sensitive Magnetic Resonance Imaging (MRI), and radiation-induced cavernomas (RICMs) represent related manifestations of microvascular damage. Their clinical significance and optimal management remain incompletely defined. To present three illustrative cases of radiation-induced cavernomas and CMBs in patients with primary brain tumors and to conduct a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant literature review synthesizing current evidence to inform management. PubMed, Embase, and Web of Science were searched according to PRISMA guidelines. Eligible studies included patients with primary brain tumors treated with radiation therapy that reported outcomes related to radiation-induced vascular injury. CMBs and RICMs share overlapping mechanisms, including aberrant angiogenesis, and common risk factors, with radiation dose and latency most strongly associated with lesion development. CMBs are more frequent, occurring in approximately 50–90% of patients, reflecting diffuse microvascular injury and contributing to gradual cognitive decline. In contrast, cavernomas are less common, occurring in less than 20% of patients in most series, but carry a higher risk of focal neurologic deficits due to intracerebral hemorrhage. Existing evidence is largely retrospective and heterogeneous, limiting firm management recommendations. Risk mitigation centers on radiation dose minimization and precision targeting of lesions. Current data support routine tumor surveillance imaging rather than dedicated screening for microvascular injury, except in cavernomas at elevated hemorrhagic risk, and warrant cautious use of antithrombotic therapy. Prospective adult studies are needed to refine surveillance, anticoagulation management, and interventional thresholds.