title: Role of enhanced MRI in the follow-up of patients with medically refractory trigeminal neuralgia undergoing stereotactic radiosurgery using the gamma knife: initial experience.
abstract: OBJECTIVE
  The purpose of this work was to evaluate the early posttreatment MR findings, and their clinical utility, in patients with trigeminal neuralgia undergoing stereotactic radiosurgery using the gamma knife.
  
  
  METHODS
  Twenty-six patients with medically refractory trigeminal neuralgia underwent stereotactic radiosurgery. A single dose of 70-90 Gy was administered to the proximal root entry zone (n = 21) or the retrogasserian portion (n = 5) of the trigeminal nerve. Posttreatment enhanced MRI and clinical assessment were performed at 3-6 months.
  
  
  RESULTS
  Five patients did not have radiologic follow-up. There were no changes identified in the treated trigeminal nerve or adjacent brainstem in 19 of 21 patients. Two patients with multiple sclerosis developed abnormal signal and enhancement in the brainstem and/or trigeminal nerve; neither had clinical complications. Onset of therapeutic effect ranged from 3 weeks to 3 months; 19 patients had a beneficial response.
  
  
  CONCLUSIONS
  Results of enhanced MRI 3-6 months after stereotactic radiosurgical treatment of trigeminal neuralgia do not correlate with the clinical response. Because beneficial clinical responses or treatment failures are apparent by 3 months, routine posttreatment MRI in these patients is not warranted.
authors.affiliation: Department of Radiology, Neurosensory Institute, Wills Eye Hospital, Philadelphia, PA, USA. David.Friedman@mail.tju.edu
authors.forename: D P
authors.initials: DP
authors.lastname: Friedman
authors.forename: R E
authors.initials: RE
authors.lastname: Morales
authors.forename: H W
authors.initials: HW
authors.lastname: Goldman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014277:Trigeminal Neuralgia / Q000601:surgery*