Symptoms: Pain or numbness involving the area between the legs, including the genitals and occasionally some of the inside of the thigh. Often only one side is affected. The pain may be aggravated by sitting.

Diagnosis: The diagnosis is based on matching the affected area to the areas supplied by the Pudendal nerve. MR Neurography imaging can identify entrapments. Injections can confirm the diagnosis and can help.

What causes the problem? There are four common sites of nerve entrapment that can cause a pudendal nerve syndrome. The nerve may be entrapped as it:

• passes under the piriformis muscle
• crosses the sacrospinous ligament and dives under the sacrotuberous ligament
• travels across the obturator foramen within the Alcox canal
  upon exit from Alcox canal and branching in the perineal area (between the legs)

Another cause is entrapment or irritation of the Impar ganglion on the internal surface of the coccyx.

How can it be treated? At the Institute for Nerve Medicine, Dr. Aaron Filler uses open MRI image guidance to inject anesthetic, steroid or anti-scarring materials at the various possible entrapment points. In some cases, injections such as these help relieve symptoms, but most often the injections serve to confirm the diagnosis and pinpoint the cause.

Dr. Filler has also developedinimal access surgical treatments that are directed at releasing the nerve entrapments. In some patients, this involves cutting or trimming the piriformis muscle. In other patients, the sacrotuberous or sacrospinous ligaments must be cut or trimmed. Others require dilation of the Alcox canal.

Overall, the surgical treatments for pudendal nerve entrapment syndrome at INM are new and quite different than those offered elsewhere. Dr. Filler’s success rates are 85-90% good to excellent – far exceeding the uncertain outcomes of older types of pudendal nerve surgery. Many patients can expect significant or complete relief of symptoms from effective treatment – often within days of the surgery.