Chronic pain after inguinal hernia or sports hernia surgery occurs in approximately 2-4% of all patients who undergo the procedure. There are several reasons for chronic pain, but the most likely source is an injury, kinking, or scarring to the sensory nerves in the inguinal canal. This usually occurs in the setting of a mesh repair, but can even occur with a no mesh technique as well.
The type of pain often changes when there is a nerve problem after hernia surgery. The patient will often describe the pain as severe, sharp, electrical, and stabbing. The pain is usually localized to a specific area on the inguinal area, and certain motions can make the pain much worse. In men, the pain can even radiate to the testicle in some cases.
This problem arises when the nerve adheres to the mesh following the initial repair. The mesh is placed to bridge the defect in the inguinal floor or to plug the internal ring. The effectiveness of mesh occurs several weeks later as the mesh incorporates to the tissues of the inguinal floor with scar tissue, which is essentially the body’s natural glue to allow tissues to heal together or in this case the mesh. Ideally, the mesh only comes in contact to the muscles, conjoint tendon, or the inguinal ligament, which would create a strong construct to reinforce the weakened inguinal floor. However, just as the mesh adheres to the muscles, tendon, and ligament, it can adhere to blood vessels, bowel, nerves, and any other structure in the area. In most, cases this adherence is not symptomatic; however, when the nerves are involved, this can result in severe pain as described earlier. The nerves should be able to glide freely in the inguinal canal, but when there are stuck to the mesh, every time the person moves in a certain direction, the nerve sends signal to the brain which represents the pain. These symptoms usually do not present for several weeks after the surgery since the it takes several weeks for the scar tissue to form.
In some case, the pain can improve as the nerve frees from the scar tissue with increase most, but the reality is that most the time it does not since the reaction to the mesh can create more scar than a suture only repair. In these cases, the nerves should be approached from an external (open) approach to allow the surgeon to identify and inspect the damaged or scarred nerves. On occasion, the nerves can be spared and freed from the mesh, but the majority of the time, then nerves need to be cut and placed in the muscle to remove them as a source of pain. When this is done the pain reduction is immediate, but the patient is trading permanent numbness for the lack of pain. This always needs to be considered before doing groin denervation.
It is important to mention, then even when all three inguinal nerves are removed, this does not affect sensation to the genitals. The area of numbness will be localized in the inguinal crease and in some cases the upper inner thigh for most people. In general, the vast majority of patients experiencing several post-hernia groin pain, the numbness is welcomed because they have been experiencing such debilitating pain.