title: High-Resolution MRI Findings following Trigeminal Rhizotomy.
abstract: OBJECTIVE
  Patients with trigeminal neuralgia often undergo trigeminal rhizotomy via radiofrequency thermocoagulation or glycerol injection for treatment of symptoms. To date, radiologic changes in patients with trigeminal neuralgia post-rhizotomy have not been described, to our knowledge. The aim of this study was to evaluate patients after trigeminal rhizotomy to characterize post-rhizotomy changes on 3D high-resolution MR imaging.
  
  
  METHODS
  A retrospective review of trigeminal neuralgia protocol studies was performed in 26 patients after rhizotomy compared with 54 treatment-naïve subjects with trigeminal neuralgia. Examinations were reviewed independently by 2 neuroradiologists blinded to the side of symptoms and treatment history. The symmetry of Meckel's cave on constructive interference in steady-state and the presence of contrast enhancement within the trigeminal nerves on volumetric interpolated breath-hold examination images were assessed subjectively. The signal intensity of Meckel's cave was measured on coronal noncontrast constructive interference in steady-state imaging on each side.
  
  
  RESULTS
  Post-rhizotomy changes included subjective clumping of nerve roots and/or decreased constructive interference in steady-state signal intensity within Meckel's cave, which was identified in 17/26 (65%) patients after rhizotomy and 3/54 (6%) treatment-naïve patients (P< .001). Constructive interference in steady-state signal intensity within Meckel's cave was, on average, 13% lower on the side of the rhizotomy in patients posttreatment compared with a 1% difference in controls (P< .001). Small regions of temporal encephalomalacia were noted in 8/26 (31%) patients after rhizotomy and 0/54 (0%) treatment-naïve patients (P< .001).
  
  
  CONCLUSIONS
  Post-trigeminal rhizotomy findings frequently include nerve clumping and decreased constructive interference in steady-state signal intensity in Meckel's cave. Small areas of temporal lobe encephalomalacia are encountered less frequently.
authors.affiliation: From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.).
authors.forename: B G
authors.identifier: http://orcid.org/0000-0003-1658-0372
authors.initials: BG
authors.lastname: Northcutt
authors.affiliation: From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.).
authors.forename: D P
authors.identifier: http://orcid.org/0000-0001-5537-5780
authors.initials: DP
authors.lastname: Seeburg
authors.affiliation: From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.).
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-0878-6023
authors.initials: J
authors.lastname: Shin
authors.affiliation: From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.).
authors.forename: N
authors.identifier: http://orcid.org/0000-0003-4631-0533
authors.initials: N
authors.lastname: Aygun
authors.affiliation: Biomedical Engineering (D.A.H.).
authors.forename: D A
authors.identifier: http://orcid.org/0000-0002-9400-7814
authors.initials: DA
authors.lastname: Herzka
authors.affiliation: Neurosurgery (D.T., C.R.G., C.B., M.L.), Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: D
authors.identifier: http://orcid.org/0000-0002-2189-5013
authors.initials: D
authors.lastname: Theodros
authors.affiliation: Neurosurgery (D.T., C.R.G., C.B., M.L.), Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: C R
authors.identifier: http://orcid.org/0000-0002-6540-2751
authors.initials: CR
authors.lastname: Goodwin
authors.affiliation: Neurosurgery (D.T., C.R.G., C.B., M.L.), Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: C
authors.identifier: http://orcid.org/0000-0001-9991-7123
authors.initials: C
authors.lastname: Bettegowda
authors.affiliation: Neurosurgery (D.T., C.R.G., C.B., M.L.), Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: M
authors.identifier: http://orcid.org/0000-0003-0523-3076
authors.initials: M
authors.lastname: Lim
authors.affiliation: From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.) ablitz1@jhmi.edu.
authors.forename: A M
authors.identifier: http://orcid.org/0000-0002-6763-2112
authors.initials: AM
authors.lastname: Blitz