The Efficacy and Safety of the Application of Pulsed Radiofrequency, Combined With Low-Temperature Continuous Radiofrequency, to the Gasserian Ganglion for the Treatment of Primary Trigeminal Neuralgia: Study Protocol for a Prospective, Open-Label, Parallel, Randomized Controlled Trial

Background: Trigeminal neuralgia is a very painful condition, and radiofrequency therapy is reserved for patients who are resistant or intolerant to pharmacologic therapy. Continuous radiofrequency (CRF) and pulsed radiofrequency (PRF) both have advantages and disadvantages. Recently, studies have found that PRF combined with low-temperature (< 65 degrees C) CRF increases the efficacy of treatment, without leading to a significant increase in complications caused by nerve lesions. However, these reports have some limitations. Objectives: We plan to conduct a randomized, controlled study to compare the efficacy of applying high-voltage PRF, with and without low-temperature CRF, to the Gasserian ganglion for the treatment of trigeminal neuralgia. Study Design: A study protocol for a prospective, open-label, parallel, randomized controlled trial (clinicaltrials.gov; NCT04174443). Setting: The Department of Pain Management, Beijing Tiantan Hospital, Capital Medical University in Beijing, China. Methods: One hundred forty-six patients with primary trigeminal neuralgia will be randomly assigned to 1 of 2 groups using an allocation ratio of 1:1. In the high-voltage PRF combined with low-temperature CRF group, 2 Hz of PRF will be applied under the following conditions: a voltage of 70 V, temperature of 42 degrees C, pulse width of 20 ms, and treatment time of 600 s. Low-temperature CRF will then be performed at 60 degrees C, with a treatment time of 270 s. In the high-voltage PRF group, only high-voltage PRF will be performed, using the same treatment parameters. Follow-up process will last for a duration of 1 year. Results: The primary outcome will be the effectiveness of the treatment after 12 months, which is the percentage of patients with a modified Barrow Neurological Institute Pain Intensity Score (BNI) between I and III. The secondary outcome will include the following: BNI score, Numeric Rating Scale, dose of carbamazepine or oxcarbazepine, patient satisfaction score, quality of life, numbness, side effects, and adverse reactions. These will be recorded over a 1-year follow-up period. Limitations: The open-label study design may influence the measurement of outcomes and introduce bias, for example, performance or ascertainment bias. Conclusions: To our knowledge, this will be the first prospective, open-label, parallel, randomized controlled trial to compare the efficacy and safety of the application of high-voltage PRF, combined with and without low-temperature (60 degrees C) CRF, for the patients who have failed to respond to pharmacologic treatments for primary trigeminal neuralgia. If proven effective, this will be an important, safe, minimally destructive alternative treatment modality for primary trigeminal neuralgia following an ineffective conservative treatment.