Pudendal nerve entrapment is a rare and painful condition.  

Pudendal neuralgia by pudendal nerve entrapment is described as severe, sharp pain along the course of the pudendal nerve.  Genital numbness and erectile dysfunction are two of the major symptoms and the prevalence has been reported to be 50–91% and 13–24% respectively.  This can be caused by trauma, infection, tumour, child birth, iatrogenic injury, surgery and/or microtrauma from cycling.  It has been reported that 7–8% of cyclists on long-distance multiday rides experience pudendal neuralgia.  Diagnosis of pudendal nerve entrapment is often delayed or misdiagnosed, causing people to suffer with this for 2–10 years.  It is important to understand the clinical presentation and diagnostic criteria to allow early diagnosis and appropriate treatment. 

Pudendal nerve entrapment syndrome

Symptoms and signs:

• Constant penis pain and a dull ache in the perineum 

• Pain management

Patient must fulfil all Nantes and at least 1 complementary criteria. 

Nantes Criteria

Inclusion criteria:

1. Pain co-relates with the anatomical distribution of pudendal nerve: Pudendal nerve supplies external genitalia. The pain can be superficial or deep in the vulvovaginal, anorectal, and distal urethra.

2. Pain predominantly in sitting position: This symptom favors nerve compression because if there is a decrease in mobility of the nerve, it makes the nerves vulnerable to compression against hard ligamentous structures. This aspect of pain is dynamic as the pain results from compression and not by sitting position. 

3. The patient does not get up with pain at night, although many patients may experience difficulty going to sleep because of pain.

4. There is no sensory loss: The presence of superficial perineal sensory impairment indicates a sacral root-lesion rather than PNE.

5. Relief of pain with pudendal nerve block: This essential criterion is not specific as any perineal disease other than entrapment can cause pain in the anatomic region of the pudendal nerve.  A negative block also doesn’t exclude the diagnosis if there is a lack of precision or when performed too distally.

Complementary diagnostic criteria:

1. Pain is of a burning, shooting, or stabbing nature and associated with numbness.

2. Allodynia or hyperpathia

3. Foreign body sensation or heaviness in rectum or vagina.

4. The pain progressively increases and peaks in the evening and stops when the patient sleeps.

5. Pain is more on one side.

6. Pain is more prominent posteriorly and is triggered minutes or hours after defecation.

7. Tenderness that is felt around the ischial spine during a digital vaginal or rectal examination.

8. An abnormal result on neurophysiological tests

Exclusion criteria:

1. Pain exclusively in the territory not served by the pudendal nerve. It can be in the hypogastrium, coccyx, pubis, or gluteus.

2. Pain is associated with pruritus (more suggestive of a skin lesion).

3. Pain entirely paroxysmal in nature.

4. An imaging abnormality can justify the cause of the pain.

Associated signs:

1. Pain in the buttock 

2. Referred sciatic pain

3. Pain in the medial thigh (indicates obturator nerve)

4. Pain in the suprapubic region

5. Increased frequency of urine or pain with a full bladder

6. Pain after ejaculation

7. Pain worsens hours after sexual intercourse. 

8. Erectile dysfunction

9. A normal result on electrophysiological tests

http://eknygos.lsmuni.lt/springer/600/105-109.pdf

https://obgyn.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1600-0412.1997.tb07986.x

https://www.spesmedica.com/en/emg/pudendal-electrode-2/

https://www.spesmedica.com/wp-content/uploads/2022/04/TDS-PUDENDAL-ELECTRODE.pdf

https://spesmedicausa.com/shop/ols/products/pudendal-electrode

https://abdominalkey.com/electrophysiological-study-of-the-pelvic-floor/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498251/pdf/main.pdf

https://fascrs.org/patients/diseases-and-conditions/a-z/pelvic-floor-dysfunction-expanded-version

https://www.ncbi.nlm.nih.gov/books/NBK559246/

https://www.ajronline.org/doi/10.2214/AJR.09.3670

http://www.brazjurol.com.br/november_december_2006/Cavalcanti_ing_705_712.htm

Pudendal motor conduction studies, the amplitude is measured baseline-to-peak, the latency reported is the distal onset latency. Stimulation was done on each side via St Mark's disposable electrode, via transrectal approach. There was chaperone present for the study and patient consented. 

Pudendal motor nerve conduction studies was performed on each side using St. Mark's disposable electrode, via transrectal approach. The patient in left lateral position with the hips and knees flexed.  The electrode mounted on the examiners gloved index fingers inserted in the rectum. The stimulation is transrectally performed with the electrode located at the ischial spine and stimulation of the pudendal nerve was performed at this point.  Contraction of the external anal sphincter was felt on stimulation of the pudendal nerve and the response is recorded at the base of the examiner’s finger.  The amplitude is measured baseline-to-peak.  The latency of the external anal sphincter muscle is measured from the onset of the stimulation artefact to the onset of the motor response. The examination was repeated with the patient in the supine position with knees and hips flexed.

100 Hz (low-pass) and 10 kHz (high-pass)

20 Hertz (Hz) and 10 Kilohertz (KHz) for low and high frequency, respectively. 

Current duration: 0.2 ms.

We started from an initial sensitivity of 50 microvolts per division (μV/div) and adjusted it as necessary. We used a base time of 50 ms (5 ms/div)

The latency of a normal pudendal nerve is 2.1 ± 0.2msec, with a normal range of 2.5msec; however, the latency increases with age.

An abnormal result of PNTML test indicates that the pudendal nerve is affected, but it is not specific for pudendal neuralgia. Conversely, a normal reading does not rule out pudendal neuralgia because only the motor nerves are being evaluated. 

PNTML= pudendal nerve terminal motor latency, transrectal approach. 

Swash M, Snooks SJ.Motor nerve conduction studies of the pelvic floor innervation. In: Henry MM, Swash M, eds. Coloproctology and the Pelvic Floor. Oxford: Butterworth-Heinemann, 1992:196–206

Tetzschner T, Sorensen M, Johnson L, Lose G, Christiansen J. Delivery and pudendal nerve function. Acta Obstet Gynecol Scand 1997;76:324–331, with permission from Blackwell Publishing

Kiff es, Swash M.  Slowed conduction in the pudendal nerves and idiopathic neurogenic fecal incontinence.  Br J Surgery.  1984;71:614-61 6.

Lefaucheur J, Yiou R, Thomas C. Pudendal nerve terminal motor latency: age effects and technical considerations. Clin Neurophysiol. 2001 Mar;112(3):472-6. Doi: 10.1016/s1388-2457(01)00464-3. PMID: 11222969.

In the 1rst series, PNTML ranged from 1.8 to 5.6 ms. The mean +- SD value of the right PNTML was 2.82 +- 1.08 ms and that of the left PNTML was 3.06 +- 1.09 ms. A side difference was found between the right and left PNTML values (P . 0:01, Wilcoxon signed rank test). The averaged PNTML (2.94 +- 0.8 ms) correlated significantly with the age of the subjects (r . 0:4, P. 0:01, Spearman test). A significant difference in the averaged PNTML values was found between subjects under 50 years and those over 50 years (2.5 +- 0.8 vs. 3.5 +- 0.4 ms; P . 0:02, Mann±Whitney U test).

 Int J Colorectal Dis . 1997;12(5):280-4. doi: 10.1007/s003840050106. Reliability of pudendal nerve terminal motor latency T Tetzschner 1, M Sørensen, O O Rasmussen, G Lose, J Christiansen