Pudendal Nerve BlocksIn the context of PNE, a nerve block involves injecting a liquid at a precise location near a nerve. For a small nerve like the pudendal that takes slightly different paths in different people, this requires more than just studying a person's body and deciding where to insert the needle, at what angle, and how deep. It requires imaging of some type, such as Xray (fluoroscope) or CT. Without the accuracy these imaging systems provide, it is difficult or impossible to know if the needle tip is located correctly. If incorrectly located, the nerve can be damaged or the injected liquid will be too far away to have its intended effect. Dr. Bensignor says the needle tip must be within one millimeter of the target. There are two main types of injected liquids: a local anesthetic and slow-release steroids. The local is a short term diagnostic tool. If the pain goes away and stays gone for the short term, the location was correct and the nerve can be suspected of being a contributor or the sole source of pain. The steroids are a long term therapeutic attempt. In some cases they will cause the nerve, if it is irritated, to get better. This can take days or weeks, and improvement may be temporary or permanent. This delay explains why physicians prefer a delay of several weeks between nerve blocks with steroids. If the nerve is not irritated, the steroids have no effect. The local anesthetic is usually lidocaine and heparin. The long term anesthetic is usually cortisone. Although, sometimes the doctors will mix different anesthetics for different people. Two main locations are used. The ischial spine block is done by injecting into the sacrospinous ligament. Alcock's canal block is done by injecting into the sacrotuberous ligament. These are not the same as the blocks carried out for childbirth pain. In some cases the blocks may worsen the pain a little but this should last only a few days. It appears that steroids have less than a 5% chance of curing PNE. Of the many nerve blocks that Dr. Ken Renney's team has done, they have "cured" only one patient with nerve blocks alone. This was a 17 year old male football player who had had the condition for only 3 weeks. After two injections he returned to football with "no discomfort." As Ken wrote to me on 10/1/2003:
This agrees with the generally low percentage rate seen in PN patients as a whole on the discussion forums. We were all scratching our heads. No one seemed to know anyone who had been cured by nerve blocks alone, though a few had seen a reduction in pain. For a few people that have undergone the nerve blocks, there have been some that have seen a permanent worsening of symptoms. When the nerve block is conducted under guidance, they usually have the patient lay down in the prone position. The doctor will put in an anesthetic, to make the buttocks numb, so that you can't feel the needle as much as it is trying to find it's target, the pudendal nerve. When the doctor is able to find the pudendal nerve, he will then inject either the local aneesthetic or the long term steroid. The procedure itself lasts approximately 30 minutes. This is done on an outpatient basis. No overnight stay is required. If you feel no pain, it means that you had a positive response to the nerve block and the pudendal nerve is the probable culprit. If you still have pain after the block, it concludes one of two things. 1. The pain is not as a result of the pudendal nerve or 2. The physician did not get close enough to the nerve to feel any effects. Usually the physican might order another block to make sure that they can entirely rule out pudendal neuralgia, by trying to see if they can get close enough to the nerve again.
Below are some great pictures of what to expect when receiving a nerve block. The following picture is a CT guided photo shows the optimum placement of where the needle to be, in this particular person.
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