Pudendal neuralgia (PN) results from irritation of the sacral nerve roots or compression injury of the nerve along its course to the distal portions of the genitals and pelvic floor. The pudendal nerve arises from the sacral nerve roots of S2-S4 and relays sensory information from the genitals, provides motor innervation for the bulbocavernosus and ischiocavernosus muscles, and maintains sympathetic and parasympathetic innervation to the pelvic floor musculature.1
The pudendal nerve is most often affected by compression at the greater sciatic notch, within the pudendal (Alcock’s) canal, deep to the obturator internus muscle, and by compression at the terminal branches which supply sensation to the genitals and anus.2,3 This complex course of the pudendal nerve allows multiple opportunities for neural injury.
SYMPTOMS AND PREVALENCE
Symptoms of PN may include sharp pain or numbness in the genitals and perineum, erectile dysfunction in males, and impotence in both males and females with chronic nerve irritation.4,5 The nature of cycling for long distances in a fixed position creates an ideal situation for compression of the pudendal nerve.
Long-term compression of neurovascular structures often results in increased pain or loss of sensation in the distal branches of the nerve similarly seen in piriformis syndrome.6 In a study of 100 male cyclists with weekly training distances over 400 km, Leibovitch and Mor estimated the prevalence of genital numbness and erectile dysfunction to be 61% and 24%, respectively.1
An increased incidence of genital numbness and erectile dysfunction has also been reported in male cyclists over the age of 50 with increased body weight, a history of 10 years of cycling, and high intensity level of training.7 A 2016 systematic review concluded that between 34% and 63% of competitive and recreational cyclists experience genital numbness; furthermore, 19% of competitive female cyclists reported difficulty with urination.8
DIAGNOSIS OF PUDENDAL NEURALGIA
The clinical diagnosis of PN is most often a diagnosis of exclusion. Differential diagnosis for PN requires one to rule out lumbosacral nerve root compression, primary hip pathology, iliopsoas dysfunction, and gluteus maximus involvement masquerading as low back pain.2 The most current criteria used to clinically identify PN are the Nantes criteria.3,9,10 The Nantes criteria are as follows:
- Pain expressed in the perineum and genitals (specifically the vulva, vagina, clitoris, glans penis, scrotum, and rectum)
- Pain aggravated by sustained periods of sitting
- Patient denies being awakened due to nocturnal perineal pain
- No objective sensory loss
- Positive response to an anesthetic block
Additionally, Magnetic Resonance Imaging (MRI), and Magnetic Resonance Neurography (MRN) have been efficacious in identifying intrapelvic neural irritation.11 However, Magnetic Resonance Tractography (MRT) has shown recent promise in identifying compromise to the lumbosacral plexus and its branches within the intrapelvic girdle when compared against MRN.11 Use of MRT as an early diagnostic tool may decrease reliance on intraoperative examination when assessing issues of the intrapelvic neural entrapments.
CURRENT INTERVENTIONS
Current non-surgical interventions for treating PN include: botulinum toxin A injections, nerve blocks, pulsed radiofrequency stimulation, behavior modification, and pelvic floor physical therapy.10,12,13 Additionally, there is considerable evidence to support the use of electroacupuncture (EA) in the management of various pelvic floor conditions.
EA has been reported useful for urinary incontinence in women after radical hysterectomy,14 improving bowel and bladder function after spinal cord injury,15 decreasing pain in chronic prostatitis and chronic pelvic pain syndrome in men,16 and reducing idiopathic pain in the pudendal nerve distribution.11
Other forms of acupuncture have been supported for the treatment of neural compression injuries as well. Yang et al identifies the use of manual acupuncture compared to steroid use in order to address carpal tunnel syndrome; the acupuncture treatment improved long-term outcomes in pain and distal nerve conduction of the median nerve.17 A 2015 systematic review and meta-analysis concluded that acupuncture was more effective than medication at reducing pain intensity and increasing pain threshold in individuals with sciatica.18
ELECTRICAL DRY NEEDLING TO THE SACRAL NERVE ROOTS
The sacral nerves and pelvic floor musculature correlate closely with several acupuncture points in the bladder channel (BL32 to BL34 – i.e., within the S2, S3 and S4 sacral foramina); moreover, elicitation of the deqi response at these points has been shown to stimulate the sacral spinal nerve roots and attenuate hyperactivity of the bladder.15,16,19–21 It is thought that stimulation of the sacral nerve roots using EDN may alleviate pudendal nerve irritation with resultant analgesic effects throughout the distal branches.22 EDN may promote analgesia through opioid controlled channels via activation of endogenous cannabinoids in the sympathetic nervous system, and non-opioid pain relief mediated in the brain stem by production of serotonin and norepinephrine.23
EDN has been found to stimulate the reduction in inflammatory cytokines centrally via stimulation of the hypothalamic-pituitary-adrenal axis, and locally via inhibition of cox-2 production by stimulation of the corticotropin releasing hormone-proopiomelanocortin-corticosteroid axis.23 Specifically, increased cortisol assists cox-2 production in prolonging endogenous anandamide conservation, thereby prolonging the anti-inflammatory and analgesic effects of the endocannabinoid system.23
Further, EDN has been shown to reduce pain and disability in patients being treated for enthesopathy.24 Thus, the use of EDN at the sacral nerve roots, and perhaps the ischial tuberosities, may provide an analgesic effect to the pudendal nerve distribution via peripherally altering opioid receptors and centrally mediating cellular inflammation responses.15,16,19–23
The selection of the EDN electrical protocol can have significant physiological effects based on the frequency of the electrical current. For instance, 2-Hz has been found to be effective in decreasing edema after trauma.25 Similarly, a 2-Hz EDN protocol has been found to increase the release of endomorphins, β-endorphins, and enkephalins which bind to µ and δ opioid receptors.26
A 5-Hz protocol has been found to improve arteriolar vasodilation and increase nitric-oxide production in geniculate vasculature.27 The use of 100-Hz has been associated with decreased neural sensitivity to itch sensation by reducing the expression of gastrin-releasing peptide receptors in the spinal dorsal horns.28
The combination of 2-Hz and 100-Hz frequencies has been suggested to optimally stimulate enkephalin production at low frequency and dynorphin response at high frequency in order to provide a maximally driven analgesic response via the effects of opioid peptides and their respective receptor sites.29
Therefore, perhaps an amateur cyclist reporting perineal pain upon initiation of a novel training program may benefit from a low frequency treatment in order to decrease the localized inflammation and improve peripheral analgesic response, whereas, a cyclist with chronic PN may benefit from a combination of low- and high-frequency stimulation in order to improve vasodilation and nitric oxide release to the pelvic floor musculature, in addition to stimulation of the opioid receptors and reduction in inflammatory cytokines.
CONCLUSIONS
Given the nature of long-distance cycling and prolonged compression of the pudendal nerve along the ischial rami against the saddle, EDN targeting the sacral nerve roots may be a useful option in the management of PN. Notably, compared to the potential risk of puncturing the bladder, rectum, vagina or prostate with needling directly to some of the pelvic floor muscles, EDN targeting the sacral nerve roots within the sacral foramina is likely a much safer procedure due to the boney backdrop during deep needle insertions.
AUTHORS
Nathan Wrzesinski, DPT, Cert. DN
Fellow-in-Training, AAMT Fellowship in Orthopaedic Manual Physical Therapy
Physical Therapist, Parkview Therapy Services, Fort Wayne, IN
Clint Serafino, DPT, FAAOMPT, Dip. Osteopractic
Assistant Director, AAMT Fellowship in Orthopaedic Manual Physical Therapy
Senior Instructor, Dry Needling Institute
James Dunning, PhD, DPT, MSc, FAAOMPT, Dip. Osteopractic
President, American Academy of Manipulative Therapy
Director, AAMT Fellowship in Orthopaedic Manual Physical Therapy
Owner, Montgomery Osteopractic Physical Therapy & Acupuncture, Montgomery, AL
REFERENCES
1. Leibovitch I, Mor Y. The Vicious Cycling: Bicycling Related Urogenital Disorders. Eur Urol. 2005;47(3):277-287. doi:10.1016/j.eururo.2004.10.024
2. Filler AG. Diagnosis and treatment of pudendal nerve entrapment syndrome subtypes: imaging, injections, and minimal access surgery. Neurosurg Focus. 2009;26(2):E9. doi:10.3171/FOC.2009.26.2.E9
3. Khoder W, Hale D. Pudendal Neuralgia. Obstet Gynecol Clin North Am. 2014;41(3):443-452. doi:10.1016/j.ogc.2014.04.002
4. Chiaramonte R, Pavone P, Vecchio M. Diagnosis, Rehabilitation and Preventive Strategies for Pudendal Neuropathy in Cyclists, A Systematic Review. J Funct Morphol Kinesiol. 2021;6(2):42. doi:10.3390/jfmk6020042
5. Hibner M, Desai N, Robertson LJ, Nour M. Pudendal Neuralgia. J Minim Invasive Gynecol. 2010;17(2):148-153. doi:10.1016/j.jmig.2009.11.003
6. Fishman LM, Dombi GW, Michaelsen C, et al. Piriformis syndrome: Diagnosis, treatment, and outcome—a 10-year study. Arch Phys Med Rehabil. 2002;83(3):295-301. doi:10.1053/apmr.2002.30622
7. Kennedy J. Neurologic Injuries in Cycling and Bike Riding. Neurol Clin. 2008;26(1):271-279. doi:10.1016/j.ncl.2007.11.001
8. Trofaier ML, Schneidinger C, Marschalek J, Hanzal E, Umek W. Pelvic floor symptoms in female cyclists and possible remedies: a narrative review. Int Urogynecology J. 2016;27(4):513-519. doi:10.1007/s00192-015-2803-9
9. Labat JJ, Riant T, Robert R, Amarenco G, Lefaucheur JP, Rigaud J. Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria). Neurourol Urodyn. 2008;27(4):306-310. doi:10.1002/nau.20505
10. Pérez-López FR, Hita-Contreras F. Management of pudendal neuralgia. Climacteric. 2014;17(6):654-656. doi:10.3109/13697137.2014.912263
11. Lemos N, Melo HJF, Sermer C, et al. Lumbosacral plexus MR tractography: A novel diagnostic tool for extraspinal sciatica and pudendal neuralgia? Magn Reson Imaging. 2021;83:107-113. doi:10.1016/j.mri.2021.08.003
12. Echols K, Rich J. Non-venous Pelvic Pain and Roles for Pelvic Floor PT or Pudendal Nerve Blocks. Tech Vasc Interv Radiol. 2021;24(1):100735. doi:10.1016/j.tvir.2021.100735
13. Chang MC. Efficacy of Pulsed Radiofrequency Stimulationin Patients with Peripheral Neuropathic Pain: ANarrative Review. Pain Physician. 2018;1(21;1):E225-E234. doi:10.36076/ppj.2018.3.E225
14. Yi W min, Chen Q, Liu C hao, Hou J yun, Chen L dan, Wu W kang. Acupuncture for Preventing Complications after Radical Hysterectomy: A Randomized Controlled Clinical Trial. Evid Based Complement Alternat Med. 2014;2014:1-6. doi:10.1155/2014/802134
15. Liu Z, Wang W, Wu J, Zhou K, Liu B. Electroacupuncture Improves Bladder and Bowel Function in Patients with Traumatic Spinal Cord Injury: Results from a Prospective Observational Study. Evid Based Complement Alternat Med. 2013;2013:1-9. doi:10.1155/2013/543174
16. Zhou M, Yang M, Chen L, et al. The effectiveness of long-needle acupuncture at acupoints BL30 and BL35 for CP/CPPS: a randomized controlled pilot study. BMC Complement Altern Med. 2017;17(1):263. doi:10.1186/s12906-017-1768-2
17. Yang CP, Hsieh CL, Wang NH, et al. Acupuncture in Patients With Carpal Tunnel Syndrome: A Randomized Controlled Trial. Clin J Pain. 2009;25(4):327-333. doi:10.1097/AJP.0b013e318190511c
18. Ji M, Wang X, Chen M, Shen Y, Zhang X, Yang J. The Efficacy of Acupuncture for the Treatment of Sciatica: A Systematic Review and Meta-Analysis. Evid Based Complement Alternat Med. 2015;2015:1-12. doi:10.1155/2015/192808
19. Oliveira e Lemos M, Cummings M. An Alternative Approach to Pudendal Nerve Stimulation. Acupunct Med. 2018;36(6):423-424. doi:10.1136/acupmed-2018-011751
20. Chen S, Wang S, Xuan L, Xu F, Lu H, Lu J. Sacral electroacupuncture as a treatment for urge urinary incontinence: a prospective case series. Acupunct Med. 2021;39(5):522-528. doi:10.1177/0964528420968846
21. Xu H, Liu B, Wu J, et al. A Pilot Randomized Placebo Controlled Trial of Electroacupuncture for Women with Pure Stress Urinary Incontinence. Baak JPA, ed. PLOS ONE. 2016;11(3):e0150821. doi:10.1371/journal.pone.0150821
22. Langevin HM, Schnyer R, MacPherson H, et al. Manual and Electrical Needle Stimulation in Acupuncture Research: Pitfalls and Challenges of Heterogeneity. J Altern Complement Med. 2015;21(3):113-128. doi:10.1089/acm.2014.0186
23. Butts R, Dunning J. Peripheral and Spinal Mechanisms of Pain and Dry Needling Mediated Analgesia: A Clinical Resource Guide for Health Care Professionals. Int J Phys Med Rehabil. 2016;04(02). doi:10.4172/2329-9096.1000327
24. Dunning J, Butts R, Henry N, et al. Electrical dry needling as an adjunct to exercise, manual therapy and ultrasound for plantar fasciitis: A multi-center randomized clinical trial. Baur H, ed. PLOS ONE. 2018;13(10):e0205405. doi:10.1371/journal.pone.0205405
25. Hahm TS. The Effect of 2 Hz and 100 Hz Electrical Stimulation of Acupoint on Ankle Sprain in Rats. J Korean Med Sci. 2007;22(2):347. doi:10.3346/jkms.2007.22.2.347
26. Napadow V, Makris N, Liu J, Kettner NW, Kwong KK, Hui KKS. Effects of electroacupuncture versus manual acupuncture on the human brain as measured by fMRI. Hum Brain Mapp. 2005;24(3):193-205. doi:10.1002/hbm.20081
27. Loaiza LA, Yamaguchi S, Ito M, Ohshima N. Electro-acupuncture stimulation to muscle afferents in anesthetized rats modulates the blood flow to the knee joint through autonomic reflexes and nitric oxide. Auton Neurosci. 2002;97(2):103-109. doi:10.1016/S1566-0702(02)00051-6
28. Li HP, Wang XY, Chen C, et al. 100 Hz Electroacupuncture Alleviated Chronic Itch and GRPR Expression Through Activation of Kappa Opioid Receptors in Spinal Dorsal Horn. Front Neurosci. 2021;15:625471. doi:10.3389/fnins.2021.625471
29. Han JS. Acupuncture: neuropeptide release produced by electrical stimulation of different frequencies. Trends Neurosci. 2003;26(1):17-22. doi:10.1016/S0166-2236(02)00006-1
OSTEOPRACTIC 