Brain activity assessment by functional MRI before and after radiofrequency of gasserian ganglia in patients with trigeminal neuralgia

Abstract

Background and Objectives: Trigeminal neuralgia (TN) is one of the common causes of facial pain. However, its treatment is a challenge. Radiofrequency (RF) is an effective and safe option that is available. In our study, we used functional Magnetic resonance imaging (fMRI) to assess levels of brain activity in patients with TN, before and after receiving radiofrequency.

Methodology: This study is a randomized prospective clinical study. It included 30 patients with TN who were scheduled for thermal (i.e. conventional) radiofrequency (CRF) and pulsed radiofrequency (PRF). 15 patients were randomly assigned to each group. All patients were contacted before the intervention and then 1 week, 1 month, 3 months, and 6 months after the intervention.  They were assessed using the Visual Analogue Scale (VAS) score, and their complaints of facial numbness, muscles of mastication dysfunction and carbamazepine dose. fMRI was done before and one month after the intervention.

Results: The study group comprised of 13 men and 17 women; a total of 30 patients. The mean age of patients was 50.60 ±12.06 years in the thermal radiofrequency group and 47.93 ±9.90 years in the pulsed radiofrequency group. The median VAS score before the procedure was 8 in both groups, (7-9) in CRF and (7-8) in PRF. Our study demonstrated a statistically significant difference in VAS score at different stages of follow-up after thermal radiofrequency and pulsed radiofrequency when compared with the pretreatment stage. PRF patients continued on medications. Mild complications as facial numbness and masticatory muscle weakness were reported in the CRF group. In some brain regions, fMRI revealed reduced BOLD signal activation after radiofrequency ablation compared to that before the radiofrequency therapy but it was not significant.

Conclusion:  In our study, post-intervention fMRI revealed a reduction in signal activations of some brain regions but we could not correlate these changes with the clinical improvement. Radiofrequency is an effective treatment for trigeminal neuralgia. CRF is preferable as it had less complications.

Key words: fMRI; Trigeminal neuralgia; Pulsed Radiofrequency; Thermal radiofrequency

Citation: Abdallah M, Khalil S, Hamed A, Soliman RK, Mohamed A. Brain activity assessment by functional MRI before and after radiofrequency of gasserian ganglia in patients with trigeminal neuralgia. Anaesth. pain intensive care 2020;24(6):611-621

Received: 30 July 2020, Reviewed: 6 October 2020, Revised: 29 October 2020, Accepted: 30 October 2020

Abbreviations: fMRI – functional Magnetic Resonance Imaging,  RF – Radiofrequency, CRF – Conventional  Radiofrequency, PRF – Pulsed Radiofrequency, TN – Trigeminal Neuralgia, BMI – Body mass index, VAS – Visual Analogue Scale, BOLD – Blood Oxygen Level-Dependent,  ReHo – Regional Homogeneity, ALFF – Amplitude of Low Frequency fluctuations.