Ultrasound-Guided Pudendal Nerve Pulsed Radiofrequency in Patients with Refractory Pudendal Neuralgia -Three Cases Report

Anesth Pain Med 2014; 9: 250-253 ￭Case Report￭

Ultrasound-guided pudendal nerve pulsed radiofrequency in patients with refractory pudendal neuralgia -Three cases report-

Department of Anesthesiology and Pain Medicine, The Catholic University of Korea, Seoul St.Mary's Hospital, Seoul, *Department of Anesthesiology and Pain Medicine, The Catholic University of Korea, Incheon St.Mary's Hospital, Incheon, Korea

Seong Min Han*, Dong Eon Moon, Young Hoon Kim, Hue-Jung Park, Min Kyu Lee, and Gye-Jeol Sa

Pudendal neuralgia is characterized by severe sharp pain along the pain involving the anorectal, vaginal, labial, penile, and scrotal innervation area of pudendal nerve, which may be worsened when regions [1]. A diagnostic pudendal nerve block may be crucial. sitting position. Successful pudendal nerve block is crucial to the Although there have been reports on successful cases of diagnosis of pudendal neuralgia. Although fluoroscopy-guided pudendal nerve blocks have traditionally been performed, recently nerve block using fluoroscopy-guided pulsed radiofrequency ultrasound-guided pudendal nerve blocks were reported. For the (PRF) or ultrasound (US) guidance, there has been no case of long term effect of nerve block, pulsed radiofrequency was perfor- PRF using US guidance [5,6]. Herein we present a case series med under fluoroscopic guidance in some reports. We report our successful experiences of three cases using ultrasound-guided of successful US-guided pudendal nerve PRFs in pudendal pulsed radiofrequency. (Anesth Pain Med 2014; 9: 250-253) neuralgia patients experiencing a sharp and burning pain in the perineal area. Key Words: Perineal pain, Pudendal nerve, Pudendal neuralgia, Pulsed radiofrequency, Ultrasound guidance. CASE REPORTS

The diagnosis of pudendal neuralgia is essentially clinical Case 1 and pudendal neuralgia presents no specific clinical signs of complementary tests of other diseases [1]. Labat et al. [2] A 72-year-old male had been diagnosed with prostate cancer defined the diagnostic criteria for pudendal neuralgia charac- when he had visited a different hospital three years prior. He terized by pudendal nerve entrapment. Pudendal neuralgia is had undergone robot-assisted retropubic radical prostatectomy. clinically characterized by a severe sharp pain along the The patient complained of erectile dysfunction and urinary innervation area of the pudendal nerve, which is worsened in a incontinence after recovery. He underwent sling surgery a year sitting position and relieved in a standing position [3]. The later, because the symptoms had not improved following onset may develop after a surgery such as prostatectomy [4] conservative management. After that, a perineoscrotal and or after repetitive bicycling [3]. Pudendal neuralgia significantly urethral pain appeared which took the form of a lancinating, decreases the patient’s quality of life due to aggravated sharp, and burning sensation with a numeric rating scale symptoms during the day time and having to work in a sitting (NRS) of 8/10. The pain was aggravated by static activity and position [3]. in a sitting position, and was relieved by dynamic activity. Entrapment of the pudendal nerve can give rise to perineal Urination was not associated with the nature of the pain. Urologic evaluations could not reveal the cause of the pain.

Received: June 16, 2014. The patient was referred to our pain clinic. A US-guided Revised: July 11, 2014. pudendal nerve block was carried out using 5 ml of 1% Accepted: July 31, 2014. lidocaine with triamcinolone acetonide 5 mg. The patient was Corresponding author: Dong Eon Moon, M.D., Department of Anesthe- siology and Pain Medicine, The Catholic University of Korea, Seoul placed in the prone position with a pillow beneath the pelvic St.Mary's Hospital, 505, Banpo-dong, Seocho-gu, Seoul 137-040, Korea. area. The skin from the left lower gluteal line to the iliac Tel: 82-2-2258-2236, Fax: 82-2-537-1951, E-mail: [email protected] crest was draped with a sterile technique. After the block, the

250 Seong Min Han, et al：Effective treatment of pudendal neuralgia 251 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏

Fig. 1. Ultrasound-guided pudendal nerve radiofrequency. The transducer is placed transversely over the ischial spine. The needle electrode is advanced laterally with the in-plane approach. Fig. 3. The location of the needle tip checked by fluoroscopy. FH: femoral head, IS: ischial spine.

tracing the US transducer caudally from ilium, the ischium became progressively straighter as it transformed into the ischial spine. The transducer was positioned in the supposed position of the sacrospinous ligament. At this level, we identified the internal pudendal artery and the pudendal nerve (Fig. 1). A 22-gauge, 10 cm long, 10 mm active tip radiofrequency (RF) needle (Radionics Inc., Burlington, MA, USA) was moved near to the left pudendal nerve (Fig. 2). The sensory stimulation at 50 Hz and 0.4 V produced paresthesia in the innervation of the pudendal nerve. The US-guided PRF was performed at 42oC for 120 seconds. The curved RF Fig. 2. Doppler image showing the internal pudendal artery at the level needle was turned by 90 degrees clockwise from the initial of the ischial spine. The open arrow indicates the internal pudendal artery, the closed arrow indicates the pudendal nerve. The arrowheads target lesion and the PRF was then performed again. In the indicate the needle. SSL: sacrospinous ligament, STL: sacrotuberous same manner, the PRFs were repeated until the entire 360 ligament, IS: ischial spine, GM: gluteus maximus. degree area had been covered. The position of the needle tip was checked under fluoroscopy (Fig. 3). perineoscrotal pain improved to a NRS of 3/10 for four hours. After the procedure, the pain decreased to NRS of 0/10. For pain management, a 37.5 mg tramadol/375 mg acetamino- The pain relief was continued for 6 months and the patient is phen combination tablet three times a day, 5 mg nortriptyline currently being monitored as part of follow-up. twice a day and 400 mg gabapentin three times a day were Case 2 administered for 2 weeks. A second diagnostic US-guided left pudendal nerve block with 5 ml of 0.25% bupivacaine was The second patient was a 34-year-old male experiencing pain performed 2 weeks later. The patient experienced significant in the glans penis and the external urethral orifice. His penile pain relief again for 6 hours. Therefore, a US-guided PRF of pain had been expressed as a burning sensation with a NRS the left pudendal nerve was performed for treatment. of 6/10 for 5 years. He visited the urology department to The patient lay in the prone position. A US-guided PRF of evaluate the cause of the pain but there was no specific the left pudendal nerve was performed using a 5–12 MHz finding. The symptoms progressively worsened and turned into curved transducer (SonoSite Inc., Bothell, WA, USA). By a lancinating, burning and penetrating pain in a sitting 252 Anesth Pain Med Vol. 9, No. 4, 2014 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏

Urinary incontinence is a significant complication of retropubic radical prostatectomy, and a sling operation is sometimes needed [4]. Senechal et al. [7] demonstrated the origin, course and termination of the perineal nerve as a branch of the pudendal nerve derived from the second, third and fourth anterior sacral rami. Pudendal nerve branches are located in the zone of lateral dissection towards the ischiopubic rami. The pudendal nerve innervates to the penis, clitoris, bulbospon- giosus muscle, ischiocavernosus muscles, scrotum, and anus. The pain can occur from pudendal nerve entrapment or damage. Some studies reported pudendal nerve block as an effective treatment for urinary urgency, hesitancy, and male pelvic pain [8,9]. Pudendal neuralgia may occur without a Fig. 4. Ultrasound image of pudendal nerve radiofrequency. The needle specific provoking factor. Patients with pudendal neuralgia is advanced near the pudendal nerve. The open arrow indicates the internal pudendal artery, the closed arrow indicates the pudendal nerve. experience disturbance in their daily life activities, such as The arrowheads indicate the needle. SSL: sacrospinous ligament, STL: working at a desk, studying in school, and driving a car. sacrotuberous ligament, IS: ischial spine, GM: gluteus maximus. However, definite treatment guidelines have not been established for pudendal neuralgia [10]. Pudendal nerve block position. He took 150 mg pregabalin, and 10 mg amitriptyline, is a possible method for diagnosis and treatment. 10 mg oxycodone three times a day for 2 years, but the Although multiple techniques of pudendal nerve block have effects were minimal. Differential diagnostic blocks of the been demonstrated [6,10], the success rate of US-guided pudendal nerve were performed twice under US guidance. As pudendal nerve block is comparable with that of fluoroscopy a result, the patient’s NRS significantly decreased from 6/10 to guided block [5]. A computed tomography (CT)-guided puden- 3/10 for six hours. We decided to perform a PRF under US dal nerve block technique has been reported in previous guidance. The procedure was carried out in using the same studies. The use of CT images to guide the pudendal nerve technique as in case 1. The patient’s NRS was maintained as block adds to the level of accuracy of the procedure. 3/10 for two years after the procedure. However, the physician becomes exposed to radiation. Ultrasound scanning in the transverse plane was used to find Case 3 the ischial spine, sacrotuberous ligament, sacrospinous ligament, The third patient was a 61-year-old female referred to the and internal pudendal artery. A low frequency transducer was pain clinic for intractable vagina, vulva, and perineal pain. She located at the level of the ilium, and was caudally moved. was diagnosed with atrophic vaginitis and was treated The ischium became progressively straighter. Bellingham et al. conservative care in gynecology for 10 months. However, the [5] reported that the time needed to perform the US-guided patient’s symptoms had gradually worsened. The pain was technique was 3.5 minutes longer than in the fluoroscopic rated as NRS 8/10 and was aggravated in a sitting position. approach, despite the theoretical advantage of the visualization Furthermore, she had side effect of opioid and anticonvulsant of the interligamentous plane, ischial spine, internal pudendal such as nausea, vomiting, and dizziness. An US-guided artery, and pudendal nerve. They showed that patients in the pudendal nerve block was performed using 5 ml of 2% US-guided group had a lower incidence of sciatic numbness lidocaine, and resulted in gradual improvement of the perineal than in the fluoroscopy-guided group. Furthermore, the real pain. We performed a US-guided pudendal nerve PRF in the challenge was to direct the needle near the pudendal nerve same fashion as in cases 1 and 2 (Fig. 4). As a result, the with the in-plane approach. The nerve block with US-guidance patient’s pain decreased to NRS 0/10 for one year. present several advantages, such as being less hazardous than a fluoroscopy-guided nerve block and requiring a relatively small DISCUSSION amount of local anesthetics due to visualization of the target nerve [11]. If a US-guided PRF is to be performed, accurate In the first case, the symptoms occurred after sling-surgery. visualization of the target nerve may be a weighty factor. Seong Min Han, et al：Effective treatment of pudendal neuralgia 253 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏

Fluoroscopy-guided pudendal nerve block is also available. However, fluoroscopy finds a shortcoming in radiation REFERENCES exposure. A sensory test should be performed in the fluoroscopy guidance. Tagliafico et al. [12] reported that US can 1. Robert R, Prat-Pradal D, Labat JJ, Bensignor M, Raoul S, Rebai identify all the terminal branches of the pudendal nerve by up R, et al. Anatomic basis of chronic perineal pain: role of the pudendal nerve. Surg Radiol Anat 1998; 20: 93-8. to 75% with a high-frequency transducer. Furthermore, in 2. Labat JJ, Riant T, Robert R, Amarenco G, Lefaucheur JP, Rigaud young female patients of reproductive age, US-guided nerve J. Diagnostic criteria for pudendal neuralgia by pudendal nerve block can be performed more safely than fluoroscopy-guided entrapment (Nantes criteria). Neurourol Urodyn 2008; 27: 306-10. block. 3. Benson JT, Griffis K. Pudendal neuralgia, a severe pain syndrome. RF has been a generally popular treatment modality since Am J Obstet Gynecol 2005; 192: 1663-8. the 1950s. Unfortunately, the long-term outcomes of pudendal 4. Hollabaugh RS Jr, Dmochowski RR, Kneib TG, Steiner MS. Preservation of putative continence nerves during radical nerve blocks have been worse than expected for pudendal retropubic prostatectomy leads to more rapid return of urinary neuralgia [3]. Therefore, it is believed that the long-term continence. Urology 1998; 51: 960-7. therapeutic effect from RF treats the underlying peripheral 5. Bellingham GA, Bhatia A, Chan CW, Peng PW. Randomized lesion. RF lesioning is clinically used in two ways [13]. The controlled trial comparing pudendal nerve block under ultrasound conventional method uses a constant output of high-frequency and fluoroscopic guidance. Reg Anesth Pain Med 2012; 37: 262-6. current and produces heat over 45oC, whereas the PRF 6.Rhame EE, Levey KA, Gharibo CG. Successful treatment of refractory pudendal neuralgia with pulsed radiofrequency. Pain temperature generally does not exceed 42oC [13]. Conventional Physician 2009; 12: 633-8. RF can cause permanent nerve damage by neuroablative 7. Senechal C, Limani K, Djeffal C, Paul A, Saint F, Petit J. thermocoagulation. PRF produces the same voltage fluctuations Perineoscrotal pain after InVance suburethral sling: Cadavre in the lesion of the treatment target without thermocoagulation. anatomical study. Prog Urol 2008; 18: 456-61. Unlike in conventional RF neurotomy, the therapeutic effect of 8. Brouwer R, Duthie G. Sacral nerve neuromodulation is effective treatment for fecal incontinence in the presence of a sphincter PRF is obtained from the delivery of an electromagnetic field defect, pudendal neuropathy, or previous sphincter repair. Dis and the dissolution of heat between pulses instead. Numerous Colon Rectum 2010; 53: 273-8. case reports of PRF for the treatment of intractable pain can 9. Bui C, Pangarkar S, Zeitlin SI. Relief of urinary urgency, be found, and significant clinical results are found with PRF hesitancy, and male pelvic pain with pulse radiofrequency ablation of the pudendal [6], femoral, obturator, supraorbital [14], and of the pudendal nerve: a case presentation. Case Rep Urol 2013; third occipital nerve [15]. Importantly, PRF is safe and there 2013: 125703. 10. Calvillo O, Skaribas IM, Rockett C. Computed tomography-guided are few reports of adverse effects. To get a successful pudendal nerve block. A new diagnostic approach to long-term outcome from PRF, multiple cycles should be performed. anoperineal pain: a report of two cases. Reg Anesth Pain Med Besides, there are several small branches of the pudendal nerve 2000; 25: 420-3. [6]. In order to successfully perform a US-guided pudendal 11. Marhofer P, Harrop-Griffiths W, Kettner SC, Kirchmair L. Fifteen PRF, the acquisition of the ultrasound anatomy around the years of ultrasound guidance in regional anaesthesia: part 1. Br J Anaesth 2010; 104: 538-46. pudendal nerve and of the scanning techniques is required. 12. Tagliafico A, Perez MM, Martinoli C. High-Resolution ultrasound In this report, we presented a case series of successful of the pudendal nerve: normal anatomy. Muscle Nerve 2013; 47: US-guided pudendal PRFs. We suggest that US-guided puden- 403-8. dal PRF is one of the management methods for intractable 13. Racz GB, Ruiz-Lopez R. Radiofrequency procedures. Pain Pract pudendal neuralgia. 2006; 6: 46-50. 14. Lee JY, Sim WS, Kim DK, Park HJ, Oh MS, Lee JE. Ultrasound-guided pulsed radiofrequency treatment for posther- petic neuralgia of supraorbital nerve. Anesth Pain Med 2014; 9: 103-5. 15. Kim ED, Kim YH, Park CM, Kwak JA, Moon DE. Ultra- sound-guided pulsed radiofrequency of the third occipital nerve. Korean J Pain 2013; 26: 186-90.