Increased Radiosurgery Toxicity Associated With Treatment of Vestibular Schwannoma in Multiple Sclerosis.

OBJECTIVE

Explore the risk of radiation-induced neurotoxicity in patients with multiple sclerosis (MS) treated with stereotactic radiosurgery (SRS) and better understand the pathophysiology of radiation-induced injury in the central nervous system (CNS).

PATIENTS/INTERVENTION: We present the clinical course and magnetic resonance imaging (MRI) findings of a 52-year-old woman with a history of relapsing remitting MS, who developed radiation-induced neurotoxicity following CyberKnife SRS (25 Gy in five fractions) for a left-sided vestibular schwannoma (VS).

MAIN OUTCOME MEASURE: Risk of radiation-induced damage following SRS to the CNS, including radiation type and dose, toxicity, and time to symptom onset, in patients with MS.

RESULTS

Our patient developed increased imbalance (grade 2 toxicity) 3 months following CyberKnife SRS. Brain MRI showed new fluid-attenuated inversion recovery (FLAIR) hyperintensity in the pons and cerebellum. Neurotoxicity from SRS is rare. However, our literature review showed that 19 patients with MS who underwent intracranial radiation therapy sustained radiation-induced toxicity. The potential mechanisms for increased toxicity in MS could be due to a combination of demyelination, inflammatory, and/or vascular changes. Efficacy of treatments including steroids, bevacizumab, and hyperbaric oxygen therapy is currently unknown.

CONCLUSION

Treatment options of SRS and surgery for VS should be carefully considered as patients with known MS may be at increased risk for radiation-induced damage following SRS to the CNS. Thoughtful radiosurgical planning and dosing accounting for this inherent risk is essential for managing patients with MS and VS.