Management of Adverse Radiation Effect Associated with Stereotactic Radiosurgery of Brain Metastasis in Multiple Sclerosis

Abstract Radiation therapy is a safe and effective treatment modality for primary and metastatic tumors of the central nervous system. The use of radiation in patients with multiple sclerosis (MS) remains controversial as there are several reports of patients with MS developing severe injuries in or near the radiation field. We report a case of a woman with MS and metastatic breast cancer who developed a progressive cerebellar lesion concerning for metastasis and was treated with Gamma Knife stereotactic radiosurgery. She subsequently developed headaches and was found to have new radiographic changes concerning for adverse radiation treatment effect. MS may lower the threshold for radiation-induced injury with higher risk for both demyelinating and non-demyelinating lesions. The presentation of treatment toxicity varies widely from radiographically isolated syndromes to rapid neurologic deterioration and death. However, the etiology of injuries may be difficult to distinguish on imaging alone. Given the potential for increased toxicity in patients with MS receiving radiation therapy, patients should be closely followed post-treatment with a low threshold for early intracranial imaging and intervention. As adverse radiation effect can be effectively managed with steroids, MS should not be a contraindication to consideration of stereotactic radiosurgery in appropriately selected patients.