One cause of pain that tends to be predominantly on one side of the perineum (the area that would be in contact when sitting on a saddle) may be irritation to or entrapment of the nerves that supply that area. These are called the pudendal nerves, and this pain condition is called pudendal neuralgia.
The pelvic pain is worsened by sitting and lying, and can include prickling, stabbing, burning, numbness, and the sense of a foreign object in the urethra, penis or vagina, and rectum. In addition to pain, sexual dysfunction, impotence, faecal and urinary incontinence can be a problem.
The pudendal nerves pass through the floor of the pelvis and can be affected by various factors to cause pain. The commonest of these is local pressure by factors such as cycling or horseriding, as well as by trauma or surgery. In addition pressure from a baby's head in labour and other causes may lead to pudendal nerve pain.
Diagnosis is mostly clinical and from the results on examination. There are no absolute diagnostic (pathognomic) criteria, but various clinical features can be suggestive of the diagnosis. Sometimes assessment of the results of electrical stimulation of the nerves can be helpful, and sometimes an MRI scan may be used to exclude other causes of pain in this area. In some cases benefit (and clarification of diagnosis) may be gained from local anaesthetic and steroid injection of the nerves.
A considerable amount of work on this condition has been done by a team in Nantes in France, and one of the tools used in the diagnosis of Pudendal neuralgia is the Nantes Criteria. These include five essential diagnostic criteria:
- 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.
Other clinical criteria can provide additional arguments in favor of the diagnosis of pudendal neuralgia.
Some criteria may also exclude the diagnosis - pain that is purely in the coccyx, the buttock or base of the abdomen (hypogastric), exclusively paroxysmal, exclusively itch rather than pain, and presence of imaging abnormalities able to explain the symptoms.
The Nantes Criteria are discussed in greater detail, primarily for medical professionals, on this linked page, and the original paper can be accessed here.
Several sites have a very good range of further information both for patients and medical professionals on this condition. These include the Society for Pudendal Neuralgia site and the Pudendal Hope site.
Pelvic Pain Support Network pages
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 15/02/2016