title: Histopathological effects of radiosurgery on a human trigeminal nerve.
abstract: BACKGROUND
  Radiosurgery is a well-established treatment modality for medically refractory trigeminal neuralgia. The exact mechanism of pain relief after radiosurgery is not clearly understood. Histopathology examination of the trigeminal nerve in humans after radiosurgery is rarely performed and has produced controversial results.
  
  
  METHODS
  We report on a 45-year-old female who received radiosurgery treatment for trigeminal neuralgia by Cyberknife. A 6-mm portion of the cisternal segment of trigeminal nerve received a dose of 60 Gy. The clinical benefit started 10 days after therapy and continued for 8 months prior to a recurrence of her previous symptoms associated with mild background pain. She underwent microvascular decompression and partial sensory root sectioning. Atrophied trigeminal nerve rootlets were grossly noted intraoperatively under surgical microscope associated with changes in trigeminal nerve color to gray. A biopsy from the inferolateral surface of the nerve proximal to the midcisternal segment showed histological changes in the form of fibrosis and axonal degeneration.
  
  
  CONCLUSIONS
  This case study supports the evidence of histological damage of the trigeminal nerve fibers after radiosurgery therapy. Whether or not the presence and degree of nerve damage correlate with the degree of clinical benefit and side effects are not revealed by this study and need to be explored in future studies.
authors.affiliation: Division of Neurological Surgery, Neurosciences Department, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
authors.forename: Faisal
authors.initials: F
authors.lastname: Al-Otaibi
authors.affiliation: Division of Radiation Oncology, Oncology Center, Riyadh, Saudi Arabia.
authors.forename: Hindi
authors.initials: H
authors.lastname: Alhindi
authors.affiliation: Department of pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
authors.forename: Adnan
authors.initials: A
authors.lastname: Alhebshi
authors.affiliation: College of Nursing, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Monirah
authors.initials: M
authors.lastname: Albloushi
authors.affiliation: Division of Neurological Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Saleh
authors.initials: S
authors.lastname: Baeesa
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, Faculty of Medicine, Institute of Medical Science, University of Toronto, Toronto, Canada.
authors.forename: Mojgan
authors.initials: M
authors.lastname: Hodaie
keywords: Histopathology; radiosurgery; trigeminal neuralgia