Invited commentary: persistent pain after inguinal hernia repair: what do we know and what do we need to know?

Although the international definition of persistent postsurgical pain has been pain 2–3 months postoperatively, this should probably be extended to 6 months in hernia surgery, to allow the mesh-related inflammatory responses to decrease. The assessment of pain-related influence on daily activities has been emphasised repeatedly and in future trials we need to agree and implement a uniform assessment with details on the functional consequences [2, 3, 4, 5]. In this context, a more specific assessment of pain-related sexual dysfunction including dysejaculation needs to be addressed [6, 7]. In addition, testicular pain (orchialgia) should be differentiated from inguinal pain or scrotal skin pain and is probably even more difficult to treat. Too often in the past, chronic pain has been insufficiently reported as “yes” or “no”. Many authorities believe that nerve damage is the most important pathological mechanism for post herniorrhaphy groin pain. Nevertheless, the previously proposed classification of pain syndromes into “neuropathic” vs “nociceptive pain” [8] has limited practical significance, since we have no reproducible diagnostic methods to differentiate the two [9, 10, 11]. We have to take into account that in every open groin hernia operation branches or sub-branches of the inguinal nerves are damaged. So far, the specificity and sensitivity of nerve damage assessed by quantitative sensory testing is limited [9, 10, 11]. Furthermore, the relative role of an intra-operative nerve damage vs later inflammatory-mediated “neuropathy” remains unknown, as is the specific role of mechanical or fibrotic responses of scar tissue formation. Finally, there is a need for clarification of the relative role of peripheral vs central neural mechanisms of pain perception [12].