The Efficacy and Safety of Applying the Combination of Pulsed Radiofrequency and Platelet-Rich Plasma to the Gasserian Ganglion for the Treatment of Idiopathic Trigeminal Neuralgia: A Protocol for a Multi-Center, Prospective, Open-Label, Propensity Score Match Cohort Study.

Background: Trigeminal neuralgia (TN) is one of the severest and most common forms of neuropathic pain, and the current standard treatments for TN still have some disadvantages and limitations. Pulsed radiofrequency (PRF) has great potential as a micro-destructive method in treating refractory TN, but the long-term outcomes of PRF have been reported to be unsatisfactory. Autologous platelet-rich plasma (PRP) can reduce inflammation and promote nerve repair and has been proven effective in a previously published case report. So far, there have been no reports on combining PRF with PRP for the treatment of TN.

Objective: We plan to conduct an open-label cohort study to compare the efficacy of PRF to that of PRF with PRP when each is applied to the Gasserian ganglion for the treatment of TN.

Study Design: A study protocol for a multicentric, prospective, observational, propensity score matching (PSM), parallel, cohort, non-randomized, and assessor-blinded trial.

Setting: Department of Pain Management, Beijing Tiantan Hospital, Capital Medical University in Beijing, China; Department of Pain Management, Henan Provincial People's Hospital, Henan, China; Department of Pain Management, Huadong Hospital, Fudan University, Shanghai.

Methods: A total of 270 patients with idiopathic TN will be assigned equally to one of 2 groups, based on their willingness. Both groups will receive 2 Hz of PRF, with the PRP group also receiving 2 mL of leukocyte-poor platelet-rich plasma (LP-PRP) mixture, which will be injected slowly into the Gasserian ganglion and the mandibular nerve. It is estimated that 81 patients who receive the combination of PRF and PRP will be matched with 81 PRF-alone controls after a propensity score match (PSM) to ensure balanced comparisons between the 2 groups.

Results: The primary outcome will be the response rate of the treatment after 12 months, which is the percentage of patients with a modified Barrow Neurological Institute (BNI) pain intensity score between I and III. The secondary outcome will include the following: BNI score, Numeric Rating Scale score, dose of carbamazepine, patient satisfaction score, score on the World Health Organization Quality of Life Questionnaire (WHOQOL-BREF), and adverse reactions. These data will be recorded over a one-year follow-up period.

Limitations: The open-label study design may influence the measurement of outcomes and introduce bias, such as performance or ascertainment bias.

Conclusions: To our knowledge, this trial will be the first multi-centric, prospective, observational study that has a relatively large sample size and compares the efficacy and safety of applied PRF to that of combined PRF and PRP for patients who have not responded to pharmacologic treatments for idiopathic TN. If the combination PRF-and-PRP treatment is proven effective, it will be an important, safe, minimally destructive alternative treatment modality for idiopathic TN that persists after ineffective conservative treatment.