This is a multicenter, prospective, observational, propensity score matching, cohort, and assessor-blinded study designed to compare the effectiveness and safety of PRP injections combined with PRF treatment with PRF alone in patients with IONa who are responded poorly to conventional therapies and are reluctant to receive destructive therapies for seeking a better minimally invasive treatment strategy.

Infraorbital neuralgia (IONa) is one of a rare but devastating type of facial pain and lack of current consensus on the management. Previously, we have proved the efficacy of pulsed radiofrequency (PRF) in treatment of IONa. However, refractory patients have not received more ideal treatment until now. Platelet-rich plasma (PRP), as supraphysiological concentration of platelets, can provide prolonged neuropathic pain relief with almost no complications. To date, the efficacy of PRP combined with PRF in the treatment of IONa has not yet been proved. We will conduct this multicenter, prospective, observational, propensity score matching, cohort, and assessor-blinded study to evaluate the efficacy and safety of PRP combined with PRF in treating refractory IONa patients who were reluctant to receive destructive therapies.

Inclusion Criteria:

1. Age between 18 to 75 years;
2. Paroxysmal or persistent stabbing pain in the distribution area of the infraorbital nerve and positive response to diagnostic block (1 ml of 2% lidocaine) prior to treatment;
3. NRS score≥7;
4. Scheduled for PRF treatment for IONa；
5. Signed informed consent.

Exclusion Criteria:

1. Platelet count <105*109/L, ongoing anticoagulation therapy or antiplatelets treatment, coagulation disorders or bleeding disorders;
2. Severe cardiopulmonary or hepatorenal dysfunction;
3. Infection at the puncture site; .
4. Neuralgia secondary to tissue damage around the infraorbital foramen from causes such as maxillary sinusitis or tumor;
5. History of destructive treatments such as radiofrequency thermocoagulation, chemical ablation, infraorbital neurectomy, infraorbital nerve avulsion, etc;
6. History of mental disorders；
7. History of narcotic drug abuse;
8. Unable to cooperation.

Power Analysis and Sample Size (PASS) V.15.0 software (NCSS Corporation, Kaysville, UT, USA) is used to compute the sample size. The results indicate that a study with a power of 80% and two-sided statistical significance level (alpha) of 0.05 would require 64 participants each group. Considering 10% loss to follow-up and an additional 40% loss after propensity score matching, the total sample size of this study will be 237 patients. And we are planning to enroll 240 patients totally considering the convenience of sample collection and statistics

not yet decided