Pudendal neuralgia is condition causes by an injury to the pudendal nerve. It is a condition analogous to the carpal tunnel syndrome where nerves supplying a hand are compressed between the ligaments going to fingers. The pudendal nerve, one of the major nerves in the pelvic, innervates the pelvic floor and external genitalia. In women, injury to the nerve causes pain in rectum, perineum (area between rectum and vulva), vulva, labia, vagina and clitoris. In men, pain is in the rectum, perineum (area between the rectum and scrotum), scrotum (not testicles) and penis. Most often patients with pudendal neuralgia will experience a severe burning, tingling pain in the area of the nerve. Sometimes the entire area is affected, and sometimes patients may have isolated rectal, vulvar (scrotal) or clitoral (penile pain). In approximately 70% of patients, pain is only on one side of the body (one nerve is affected) and in the remaining 30%, pain is on both sides. A very characteristic feature of pudendal neuropathy is that pain is most severe when the patient is sitting, especially on a soft chair. When lying down or standing, pain is less. Usually pain is better in the morning and becomes progressively worse towards the evening. Interestingly, pain is less when sitting on the toilet than on a chair. Patients with pudendal neuralgia may have symptoms other than pain. This includes pain with urination or bowel movement, frequency of urination, pain with intercourse or orgasm and sometimes persistent sexual arousal. In many patients, the reason for the injury of the pudendal nerve is not know. Some of known causes of pudendal nerve injury are: trauma to pelvic area, gynecologic surgery (hysterectomy, repair of falling bladder, surgery for incontinence), childbirth and prolonged sitting. In cases of surgical injury, onset of pain is usually sudden. In other cases it may be slow over many months or years. In patients who develop pudendal neuralgia and have no treatment, pain usually progresses over the years.
Diagnosis
Diagnosis of pudendal neuralgia is made based on history, physical exam and additional tests. In our practice we use Nantes criteria to diagnose pudendal neuralgia. They are:
- Pain in the anatomical territory of the pudendal nerve.
- Worsened by sitting.
- The patient is not woken at night by the pain.
- No objective sensory loss on clinical examination.
- Positive anesthetic pudendal nerve block.
Pudendal nerve block done under guidance of CT scanner is the most important diagnostic procedure in patients with pudendal neuralgia. In patients in whom other reasons for pelvic pain were ruled out temporary relief of pain with pudendal block is considered a positive diagnostic test. This injection may also be therapeutic. Steroid injected together with local anesthetic is a powerful anti-inflammatory agent. Some patients within one week of injection may feel a decrease in pain because of decrease of inflammation and swelling around the nerve.
Treatment
Treatment of pudendal neuralgia consists of conservative measures, medications, injections and surgery. First line treatment is avoidance of nerve re-injury. Patients are asked to stop all the activities which aggravate pain, such as prolonged sitting. If there is no improvement in pain the next step is physical therapy. This is best performed by a therapist knowledgeable in pelvic floor dysfunction. To find a therapist in your area, visit pelvicpain.org. Together with physical therapy, medications like Neurontin or Lyrica are used to facilitate regeneration of the nerve and decrease pain. If those treatment modalities are not successful, patients are offered a series of 3 CT guided injections 6 weeks apart. Please see instructions for patients undergoing CT guided injection. If there is no long term relief of pain, patients are offered surgery.
Surgery
Surgery designed to decompress the injured pudendal nerve is done through 3-4 inch incision on the buttocks. This is called transgluteal pudendal neurolysis. There are three other surgical approaches to decompress the nerve: through the vagina, through the incision around anus and laparoscopic, but at the Arizona Center for Chronic Pelvic Pain we strongly feel that the transgluteal approach gives the best visualization of the nerve. It also allows placement of cover around the nerve which protects against scar tissue and placement of pain pump catheter which delivers steady dose of local anesthetic around the nerve for 10 days after surgery. The transgluteal approach to pudendal nerve decompression was originally described by Professor Roger Robert in Nantes, France. Procedures done at the Arizona Center for Chronic Pelvic Pain is a modification of the original Robert procedure. The most significant difference is that the sacrotuberous ligament cut during this surgery to gain access to the nerve is repaired toward the end of the procedure using cadaveric tendon. We feel that repairing this ligament may decrease the risk of instability of sacroiliac joint. Another modification is use of On-Q pain pump. During the surgery a thin catheter is placed next to the nerve. Bupivacaine (Marcaine) or a different anesthetic is dripped on the nerve for 10 days after the procedure. This provides excellent postoperative pain control. It may also help reverse a process called central sensitization. In this process, the central nervous system becomes sensitized by painful stimuli from injured nerve. Even if the nerve is decompressed, pain continues because the central nervous system is already sensitized. Blocking the nerve for some time after surgery may decrease central sensitization and speed up recovery. After surgery, it is important to continue use of medications and physical therapy for at least one year. Please see the post-operation instructions.
Outcomes
Outcomes from pudendal nerve decompression surgery depend on multiple factors such as length, degree and cause of nerve injury. Approximately 40% of patients who undergo transgluteal pudendal decompression have significant improvement in pain, 30 % of patients have some improvement in pain, 30 % have no change in pain and 1% may get worse. It is important to remember that improvement is usually felt 4-6 months from surgery and maximum improvement is 12-18 months from surgery.
