title: Imaging the trigeminal nerve and pons before and after surgical intervention for trigeminal neuralgia.
abstract: OBJECTIVE
  To study the various imaging changes occurring in the trigeminal nerve and brainstem in patients before or after trigeminal neuralgia surgery.
  
  
  METHODS
  During a 7-year period, 275 patients with trigeminal neuralgia underwent high-resolution, contrast-enhanced magnetic resonance imaging (MRI) of the pons during gamma knife radiosurgery. Ninety-seven patients had no previous surgical intervention for trigeminal neuralgia, and 178 patients had undergone one or more previous procedures. Two independent observers, one of whom was blinded to patients' clinical details, reviewed MRI scans retrospectively. The analysis of the independent observers was then correlated with all previous therapeutic interventions.
  
  
  RESULTS
  One hundred one MRI scans demonstrated no radiological changes related to trigeminal neuralgia, and 174 MRI scans exhibited some radiological abnormality. The average axial plane diameter of the nerve for all patients was 4 mm (range, 2-6 mm). In the group that had not undergone previous surgery, 65 patients (67%) exhibited vascular compression. In the 88 patients who had undergone previous microvascular decompression, 21 (24%) had evidence of a pontine infarction. Twenty-six patients experienced facial sensory loss, 22 (88%) of whom had undergone previous surgery with evidence of a pontine infarction (n = 11) or perineural scarring (n = 6).
  
  
  CONCLUSIONS
  The majority of patients who had undergone previous trigeminal neuralgia surgery demonstrated readily identifiable abnormalities of the trigeminal nerve or brainstem. The frequency of such changes correlated with the type and number of procedures. Evidence of vascular compression was detected in the majority of patients. Most patients with postoperative facial sensory loss demonstrate changes in the nerve or pons on MR images.
authors.affiliation: Department of Neurological Surgery, University of Pittsburgh Medical Center, Pennsylvania, USA.
authors.forename: A
authors.initials: A
authors.lastname: Jawahar
authors.forename: D
authors.initials: D
authors.lastname: Kondziolka
authors.forename: E
authors.initials: E
authors.lastname: Kanal
authors.forename: D J
authors.initials: DJ
authors.lastname: Bissonette
authors.forename: L D
authors.initials: LD
authors.lastname: Lunsford
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005145:Face / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011149:Pons / Q000473:pathology*; D011183:Postoperative Complications; D011184:Postoperative Period; D016634:Radiosurgery; D012086:Reoperation; D012189:Retrospective Studies; D012678:Sensation Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D016037:Single-Blind Method; D013238:Stereotaxic Techniques; D014276:Trigeminal Nerve / Q000473:pathology*; D014277:Trigeminal Neuralgia / Q000175:diagnosis* / Q000601:surgery*