High-Resolution MRI Findings following Trigeminal Rhizotomy

B G Northcutt; D P Seeburg; J Shin; N Aygun; D A Herzka; D Theodros; C R Goodwin; C Bettegowda; M Lim; A M Blitz

doi:10.3174/ajnr.A4868

High-Resolution MRI Findings following Trigeminal Rhizotomy

AJNR Am J Neuroradiol. 2016 Oct;37(10):1920-1924. doi: 10.3174/ajnr.A4868. Epub 2016 Jun 30.

Authors

B G Northcutt¹, D P Seeburg¹, J Shin¹, N Aygun¹, D A Herzka², D Theodros³, C R Goodwin³, C Bettegowda³, M Lim³, A M Blitz⁴

Affiliations

¹ From the Departments of Radiology and Radiologic Sciences, Division of Neuroradiology (B.G.N., D.P.S., J.S., N.A., A.M.B.).
² Biomedical Engineering (D.A.H.).
³ Neurosurgery (D.T., C.R.G., C.B., M.L.), Johns Hopkins Hospital, Baltimore, Maryland.
⁴ 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.

Abstract

Background and purpose: 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.

Materials and 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.

Grants and funding

T32 GM136577/GM/NIGMS NIH HHS/United States