Multifocal and Multiphasic Demyelinating Lesions After Radiation for Ependymoma in a Pediatric Population

Radiation treatment is widely used to address unresectable intracranial tumors. Owing to the nature of therapy, healthy tissue and diseased regions will be affected. New insights have shown that not only does this impact brain parenchyma but it causes changes in fluid status, myelination, and the integrity of the blood-brain barrier. This alters how peripheral and central immune systems interact, perpetuating neuroinflammation. Rare case reports in the adult literature have described multifocal, multiphasic demyelinating lesions after radiation. Here we describe 2 pediatric cases of relapsing demyelination after and in conjunction with radiation therapy for ependymoma, consistent with a multiple sclerosis phenotype. Insights into the underpinnings of multiple sclerosis show peripheral inflammation, blood-brain barrier disruption, and antigenic mimicry stimulating neuroinflammation. Here we investigate the role that radiation, tumor burden, and systemic inflammation may play in creating demyelinating disorders. We strive to elucidate common pathophysiology between radiation-induced brain injury and multiple sclerosis.