Radiofrequency thermocoagulation for the treatment of trigeminal neuralgia associated with a focal pontine lesion: illustrative case

Abstract

Background: Trigeminal neuralgia (TN) associated with a focal pontine lesion is a rare but challenging condition. The origin of the lesion, which does not fulfill the diagnostic criteria for multiple sclerosis, remains disputable. Pain in such conditions is often refractory to treatment, including microvascular decompression.

Observations: A 36-year-old female presented with a 3.5-year history of shooting pain in the right V2 distribution triggered by talking and chewing. She became less responsive to high-dose carbamazepine over time. Magnetic resonance imaging (MRI) revealed no neurovascular compression but an elongated lesion hyperintense on T2-weighted imaging and T2- fluid-attenuated inversion recovery and hypointense and nonenhancing on T1-magnetization prepared rapid gradient-echo imaging without restricted diffusion, hemorrhage, or supposed malformation along the right pontine trigeminal pathway (PTP). Two other similar lesions were found in the corpus callosum and left thalamus. All lesions were stable compared to MRI data obtained 2 years before. Cerebrospinal fluid contained no oligoclonal bands. Pain attacks ceased with right-sided gasserian radiofrequency thermocoagulation (RFTC), and at the 6-month follow-up, there was no recurrence.

Lessons: In patients with TN, preoperative neuroimaging should assess for brainstem lesions along the PTP. RFTC can be considered a treatment option in medication-refractory TN associated with a focal pontine lesion.

Keywords: focal pontine lesion; radiofrequency thermocoagulation; trigeminal neuralgia.

FIG. 1

Axial MRI demonstrating a lesion (white arrows) at the junction of the pons and the right middle cerebellar peduncle: T2-FLAIR (A), T2-weighted TSE (B), precontrast T1-MPRAGE (C), and postcontrast T1-MPRAGE (D). DWI (E) shows no restricted diffusion. SWI (F) shows neither hemorrhagic inclusion nor supposed malformation.

FIG. 2

MRI demonstrating a lesion in the corpus callosum (white arrows) and another lesion in the left thalamus (black arrows): T2-FLAIR (A–C) and postcontrast T1-MPRAGE (D–F).