Radiation Necrosis Secondary to Trigeminal Nerve TomoTherapy: A Cautionary Case Study.

New radiation delivery modalities have recently challenged Gamma Knife surgery as the historic gold standard in the treatment of trigeminal neuralgia (TN). TomoTherapy, a relative newcomer, has been approved by the U.S. FDA for various intracranial pathologies but is currently off label for the treatment of TN. A 73-year-old female presented with gait instability, intermittent headaches, and confusion. She was treated with TomoTherapy for refractory TN at an outside facility, which failed to reduce her symptoms. Magnetic resonance imaging demonstrated a lesion in the right mesial temporal lobe. A standard right anterior temporal lobectomy was performed and the final pathological report was notable for necrosis, gliosis, and edema consistent with a remote radiation injury. The patient improved postoperatively, but at her two-year follow up, she continued to have persistent bilateral TN and new onset seizures. Imaging revealed no new mass in the resection field. Stereotactic radiosurgery (SRS) is an evolving field with broadening indications, which makes it ever more important for physicians to be aware of differences between various SRS modalities. This case report highlights a cautionary example, and emphasizes the need for a more systematic evaluation of novel SRS methods before clinical application.