Radiofrequency Treatment of Idiopathic Trigeminal Neuralgia (Conventional vs. Pulsed): A Prospective Randomized Control Study

Abstract

Background: Idiopathic trigeminal neuralgia (TGN) is a chronic pain disorder causing unilateral, severe brief stabbing recurrent pain in the distribution of one or more branches of the trigeminal nerve. Conventional radiofrequency (CRF) and pulsed radiofrequency (PRF) are two types of minimally invasive treatment. CRF selectively ablates the part of ganglion to provide the relief, but it has been found to be associated with some side effects such as dysesthesia or sensory loss in 6%-28% and loss of corneal reflex in 3%-8% of patients. PRF is a comparatively newer modality which is a nondestructive and neuromodulatory method of delivering radiofrequency energy to the gasserian ganglion to produce a therapeutic effect.

Aims: We aimed to compare the efficacy of CRF with long-duration, fixed voltage PRF in the treatment of idiopathic TGN.

Setting: This study was conducted in a tertiary care center research institute.

Study design: This was a prospective randomized trial.

Materials and methods: Twenty-seven adult patients of TGN were included in the study and randomly allocated into two groups (CRF and PRF). All procedures were performed operation suite with C-arm fluoroscopic guidance. Both, pre- and postprocedure, the patients were assessed for pain on the Visual Analog Scale (VAS) and Barrow Neurological Institute (BNI) Pain Intensity Scale at 1 week and thereafter at 1, 2, 3, and 6 months. Patients with a BNI score ≥4 after 1 month were considered a failure and offered other modes of treatment. A reduction in VAS score ≥50% and a BNI score <4 were considered as effective.

Statistical analysis: Discreet variables were recorded as proportions, ordinal variables and continuous variables with non-Gaussian distribution as medians with interquartile range, and continuous variables with Gaussian distribution as mean ± standard deviation. Association between ordinal variables was tested by Fisher's exact test/Chi-square test whenever appropriate. Equality of means/median was tested by using paired/unpaired t-test or nonparametric tests depending upon the distribution of data. P ≤ 0.5 was considered statistically significant. Data analysis was performed using STATA version 13.04 windows.

Results: Efficacy in terms of decrease in VAS ≥50% at 1 month was 33.33% and 83.33% in the PRF and CRF groups, respectively, which was statistically significant(P = 0.036). Effective reduction in BNI scores at the 7^th day, 1 month, and 2 months postprocedure was evaluated and found in 41.67% and 83.33% of patients in the PRF and CRF groups, respectively, which was statistically insignificant (P = 0.089). There was a statistically significant reduction in BNI scores in PRF and CRF group patients at 3 and 6 months (at 3 months, 33.33% and 83.33%, P = 0.036 and at 6 months, 25% and 83.33%, P = 0.012). In the CRF group, mild hypoesthesia was evident in three patients which improved by the end of 1 month while no side effects were seen in the PRF group.

Conclusion: CRF is a more effective procedure to decrease pain in comparison to long-duration, fixed voltage PRF for the treatment of idiopathic TGN. Although the side effects are more with CRF, they are mild and self-limiting.

Keywords: Conventional radiofrequency; facial pain; pulsed radiofrequency; trigeminal neuralgia.

Figure 1

Fluoroscopic view showing “foramen ovale in submentovertex” view (black arrow)

Figure 2

“Tunnel view” of radiofrequency cannula in foramen ovale

Figure 3

Final position of radiofrequency cannula in Meckel's cave

Figure 4

Pie chart of nerve root involvement