Overview
Pudendal Neuralgia occurs when the pudendal nerve is injured, irritated, or compressed. Symptoms include burning pain (often unilateral), tingling, or numbness in any of the following areas: buttocks, genitals, or perineum (the area between the buttocks and genitals). Symptoms are typically present when a person is sitting but often go away when the person is standing or lying down. The pain tends to increase as the day progresses. Additional symptoms include pain during sex and needing to urinate frequently and/or urgently. Damage to the pudendal nerve can result from surgical procedures, childbirth, trauma, spasms of the pelvic floor muscles, or tumors. Pudendal neuralgia may also result from certain infections (such as herpes simplex infections) or certain activities (such as cycling and squatting exercises). There are no imaging studies that diagnose pudendal neuralgia; however, MRI and CT may help to exclude other causes of the pain. Physical therapy is often the first line of treatment.
Commonly Associated With
Pudendal Neuralgia; Cyclist’s Syndrome
Cause
Possible causes include:
• compression of the pudendal nerve by nearby muscles or tissue – sometimes called pudendal nerve entrapment or Alcock canal syndrome
• prolonged sitting, cycling, horse riding, or constipation (usually for months or years) – this can cause repeated minor damage to the pelvic area
• surgery to the pelvic area
• a broken bone in the pelvis
• damage to the pudendal nerve during childbirth – this may improve after a few months
• a non-cancerous or cancerous growth pressing on the pudendal nerve
In some cases, a specific cause is not found.
Symptoms
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
9. A normal result on electrophysiological tests
Diagnostic tests:
The following tests can help in the diagnosis:
1. Diagnostic blocks: In females, the unguided block can be performed vaginally and in males transperineally. If there is pain relief following the procedure, it indicates that pudendal nerve pathology is the likely cause of pain. The absence of pain relief doesn’t necessarily mean that the patient doesn’t have the condition as it can be because of operative error as well. Image-guided blocks (use of fluoroscopy, ultrasound, CT scan ) increases the efficiency of performance.
2. Quantitative sensory threshold testing works on the principle that compressed nerves cannot detect and transmit changes in vibration and temperature sensation. Thus patients with nerve injury are unable to detect gradual changes in temperature.
3. High-frequency ultrasonography is helpful in the detection of the site of compression. Compressed nerves appear flat, whereas inflamed nerves appear edematous.
4. Doppler ultrasound has a role in the diagnosis of PNE. As the pudendal nerve and vessels course together in a neurovascular bundle, the assumption can be if there is nerve compression, it would also cause vein compression as well, which is diagnosable with a doppler ultrasound.
5. MRI (magnetic resonance imaging) can help in ruling out other causes of chronic pain. The advancement of MRI techniques in evaluating peripheral nerves provides a detailed description of the anatomy, fascicular details, the blood supply of nerve, and 3-D anatomy. It also helps in localizing the site of entrapment. Functional MRI assesses nerve integrity based on their biological properties. Currently, it is considered experimental and inconclusive.
There are no specific and consistent radiological findings in patients with PNE, and further research is necessary.
If the patient fulfills Nantes criteria, no further investigation is needed to make the diagnosis. However, if the patient lacks any of the criteria, further evaluation should be pursued. MRI helps to rule out other causes of chronic pain in such cases.
Treatment
The treatment options are as below:
1. Conservative: Avoidance of painful stimulus is one of the most important parts of the treatment. For instance, if cycling causes pain, then either the patient should use proper padding or cease the activity. Similarly, patients who present with pain on prolonged sitting should adopt lifestyle modifications to minimize sitting.
2. Physical therapy: Pelvic floor physical therapy works best for patients in whom pain results from muscle spasms. Physical therapy helps in the relaxation of pelvic floor muscles by releasing spasms and also helps in muscle lengthening.
3. Pharmacologic therapy: The drugs used are analgesics, muscle relaxants, and anticonvulsants (including gabapentin and pregabalin). There are no randomized trials to study and evaluate the efficacy of these drugs.
4. Pudendal nerve block: The other treatment modality is infiltration with local anesthetic or steroid in an area encircling the pudendal nerve. The block can be given unguided or with the aid of ultrasonography, fluoroscopy, or computed tomography (CT) scan. The most consistent technique is with the use of CT scan.
5. Surgical decompression is considered the best treatment for PNE. The four different approaches are transperineal, transgluteal, transischiorectal, and laparoscopy. All methods destroy nerve fibers. It helps in removing the cause of the compression. Erdogru described a new technique (Istanbul technique) of laparoscopy using the omental flap in 27 patients. The outcome measurement was in terms of pain scores and quality of life. Approximately 81% of patients had more than 80% reduction in pain after six months. Laparoscopy has the advantage of a better surgical field, but it has a learning curve.
6. Neuromodulation: This latest treatment includes the use of peripheral nerve stimulator which causes stimulation of the pudendal nerve in the ischioanal fossa. The first case report of this technique by Valovska mentioned the successful management of a patient with pudendal neuralgia with minimally invasive transforaminal sacral neurostimulation. A prospective trial of 27 patients with refractory pudendal neuralgia showed promising results with the use of stimulation of conus medullaris, in which twenty out of 27 patients responded, and out of those twenty patients, all had long-term relief.
7. Pulsed radiofrequency: Pulsed radiofrequency is a relatively new neuromodulation technique and is considered safer than continuous radiofrequency ablation. Current literature suggests that it involves the use of electromagnetic radiation to cause neuromodulation. It is useful for chronic refractory neuropathic pudendal neuralgia.
8. Lipofilling: This is a relatively new technique for the treatment of pudendal neuralgia. Venturi described this technique in fifteen female patients. It requires an autologous injection of adipose tissue along with stem cells in the pudendal canal. The results of ten patients showed decreased pain and a better quality of life at the end of six months. Since this study was of small sample size, and there was no control group, further research in this area is necessary for a more comprehensive application
Other
Evaluation
Pudendal nerve entrapment is a potentially challenging condition to diagnose because there are no specific diagnostic tests. The clinician needs to realize that it is exceedingly mandatory to get a thorough history and perform a detailed physical examination to reach a diagnosis.
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 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 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
Source
https://rarediseases.info.nih.gov/diseases/10713/pudendal-neuralgia//
https://www.ncbi.nlm.nih.gov/books/NBK544272/
