Trigeminal Rhizotomy Performed with Modern Image-guided Linac: Case Report

Abstract

Introduction: There are substantive articles published within the last ten years describing the use of linear accelerator (Linac) based treatment of trigeminal neuralgia (TN). In this paper, we report a single case of a patient with classic TN successfully treated by radiosurgical rhizotomy using a modern image-guided linear accelerator with a high-definition multileaf collimator and an optically guided targeting system. The measurement of absolute dose prior to treatment greatly facilitated our confidence with radiosurgical lesioning.\r\rMaterials and Methods: This 54-year-old patient had a six-year history of lancinating pain involving the lower third of the right face which dramatically intensified in December of 2012, shortly after beginning Vincristine. A treatment plan was generated using a nine-field dynamic arc technique. A target volume was placed at 2-3 mm from the root entry zone measuring 6 x 3 x 3 mm. The PTV dose was prescribed to 60 Gy to the 80% isodose line. Initial verification of absolute dose using Gafchromic film resulted in an increase of the planned MU’s by 7.5%. Remeasurement improved the absolute dose to within ±2 % of the calculated dose.\r\rResults: The patient was evaluated two weeks and three months following treatment. Her trigeminal pain was 80% resolved after two weeks and 100% at the three-month evaluation. She required none of her chronic pre-treatment medications and demonstrated no clinically detected sensory deficits. \r\rConclusions: Linear accelerator-based radiosurgery utilizing intrafraction motion management and image guidance offers an acceptable alternative for the radiation treatment of trigeminal neuralgia patients if absolute doses are measured prior to treatment.