Hypothesis / aims of study
Pudendal neuralgia is caused by inflammation, compression and traction of the pudendal nerve. It may be associated with childbirth, strenuous exercise, perineal trauma, infections of urogenital tract and also, it is connected to age-related changes. Currently, the clinical treatments of pudendal neuralgia include drug therapy, pudendal nerve block (NB), pudendal nerve decompression, nervous regulation by the implanted pulse generator, radiofrequency ablation, spinal cord electrical stimulation and so on. The aim of this prospective study was to investigate the feasibility and to report the results of a new procedure for the treatment of persistent and resistant pudendal neuralgia. It consists in pudendal nerve pulsed radiofrequency (PRF) ablation under neurophysiological guide and local anaesthesia with a posterior transgluteal approach. Recent literature suggest that PRF may be effective for the treatment of refractory neuropathic pain and so far there is a lack of effective therapies to treat unresponsive chronic pelvic pain syndromes due to a pudendal neuropathy, most of them being quite invasive and costly.
Study design, materials and methods
Seven patients ( 5 M, 2 F, mean age 42.2 years ) out of seventeen affected by pudendal neuralgia and meeting all the Nantes criteria, not responsive to 3-months conservative medical therapy, were clinically evaluated with VAS score, validated SF-36 questionnaire, physical examination and pudendal neurophysiological study ( SSEPs and BCR). They underwent first to a pudendal nerve block on the side where neurophysiological and physical evaluations were pathological and those who had a complete relief of pain for at least 24 hours after the block underwent a pudendal nerve radiofrequency ablation. PRF was delivered after the nerve was identified at 1mA intensity current and a replicable and consistent BCR was found. We used a 2 Hz, 42 ˚C 150 seconds protocol for nerve ablation, followed by 60 more seconds PRF delivery, 2 minutes after the first one. Both, pudendal nerve block and PRF were carried out under local anesthesia and on an outpatient basis. Clinical evaluation was scheduled during a 12 months follow-up, with the incidence of pain recurrence (VAS > 5) as the primary outcome measure for a further PRF treatment. At the end of each single procedure, the VAS score was 0.
Interpretation of results
Basically, there are two interesting aspects of this study. The first is the number of patients and in current literature, only one study has a higher number of treated patient (1). The second is the neurophysiological guide to target the nerve, assuring a very sharp delivery of energy in its close proximity, bypassing all possible failures related to the nerve anatomical variability (2). Clinical result is intriguing as most of the patients had almost a complete relief of pelvic pain lasting 6 months or more after one or two treatments. This technique is not only effective but also cost and time saving, because performed under local anesthesia, on an outpatient basis and mostly well accepted by the patient themselves. Almost all patients were able to stop the drug therapy at the six months follow up and the procedure was easily and safely performed again in those patients failing the first procedure. It represents the ideal tool to treat patients affected by a long-lasting and not responsive chronic pelvic pain . The neurophysiological guide represents the most original part of this study because there is no evidence in the current literature of PRF pudendal nerve ablation using the neurophysiology guidance to target the nerve. It improves for sure accuracy and efficacy of the procedure with great anatomical proximity of the thermal probe to the nerve, utilizing at the best both thermal and electromagnetic properties of PRF.
The ideal clinical treatment for pudendal neuralgia has not yet been determined, even though PRF performed under neurophysiology guide might represent the future for the minimally invasive therapy of chronic pelvic pain due to a pudendal neuropathy. It could be the mid-step between the initial conservative therapy and the more invasive sacral root neuromodulation or pudendal nerve surgery. In association with neurophysiology guide, it represents a revolutionary minimally invasive therapy, cheap, effective and carried out on an outpatient basis in 30 minutes. Compared to pudendal nerve block, PRF gives more or less the same result in term of pain control, but with a long lasting efficacy up to 6 or more months. It improves not only pain but also the quality of life of patients. Even if our patients sample size is small to draw definitive conclusions , it represents the second numerous clinical records in current literature and brings something new in the chronic pelvic pain therapy scenario, in terms of technique and clinical experience.