Pudendal nerve entrapment is a rare and hard-to-diagnose but important cause of chronic pelvic pain. It is also known as Alcock’s Canal Syndrome. Pudendal nerve entrapment refers to a pathological and very severe pain that arises when the pudendal nerve is compressed along its anatomical course. Most often it can be compressed while passing between the ligaments (the sacrospinous and the sacrotuberous ligament); if it is compressed while passing through Alcock’s Canal, also called the pudendal canal, this is known as Alcock’s Canal Syndrome.
It Leads to Painful Sexual Intercourse
This pain is seen in the areas supplied by the pudendal nerve or its branches. In women these areas are the clitoris, the mons pubis (the area with genital hair), the vulva, the lower third of the vagina and the labia. However, although the pain is usually one-sided, it may be felt throughout the pelvic bone. Symptoms may begin suddenly or may appear gradually, increasing over time. Typically the pain increases steadily through the day and gets worse with sitting. Depending on which nerve branches are affected, the pain may be one-sided or two-sided. In the clinic, however, it is usually in the form of one-sided somatic pain. In these areas the skin may also be overly sensitive to touch and pressure. Possible symptoms include burning, numbness, tenderness, pain like an electric shock or a stabbing knife, a sensation of a foreign body or a lump in the vagina and the rectum, a twisting or squeezing sensation, constipation, pain during bowel movements, burning while passing urine, pain during sexual intercourse, sexual dysfunction and loss of sensation. Among the causes one may count repeated mechanical trauma in the pelvic region (sitting for long periods continuously, cycling for many years, lifting weights), a difficult pregnancy, a difficult birth, inflammatory or autoimmune disease, endometriosis, repeated infection, and accidents, falls or surgery affecting the pelvic region. However, it may also occur without any clear clinical history.
How Is the Diagnosis Made?
There is no test that gives a definite diagnosis of pudendal nerve entrapment. The diagnosis is made from the patient’s history, the symptoms, the identification of the situations that reduce and increase the pain, and a thorough neuropelveological examination. There are very few doctors in the world who have received this training. In the examination, the affected nerve root is examined in terms of pain and loss of function. The functions of the nerves throughout the pelvic region and the presence of a mass that could cause pressure on the nerve can be investigated with MRI and CT. Today the most important imaging method used in the diagnosis is imaging taken as 3 Tesla MRI and tractography. PNMLT (pudendal nerve motor latency test) is similar to EMG and is a test that helps in assessing the nerve. Using a very fine and long needle, local anaesthesia is applied around the nerve, so that the pain arising from the nerve being under pressure is numbed and reduced. The block is usually applied through the vaginal route to the region of the ischial spine, where the nerve is compressed between the sacrospinous ligament and the sacrotuberous ligament, and for this the area is checked with the finger and the local anaesthetic substance is given. If the pain disappears or decreases for as long as the local anaesthetic is effective, this suggests that there is entrapment at one level of the pudendal nerve. A pudendal nerve block is a very safe procedure in experienced hands. It must be performed by people who have received this training.