Chronic pain conditions after herniorrhaphy decrease with time, but slowly
Article Outline
Persistent postoperative pain (PPP) is not a novel pain problem, but recently there has been renewed interest in this type of pain both in terms of epidemiology, pathophysiology and management. Persistent postoperative pain is now a recognized and well-documented sequelae following a series of surgical procedures such as herniorrhaphy, thoracotomy, mastectomy, amputation, etc. (Kehlet et al., 2006). The prevalence of chronic pain following surgery varies, but in general it has been reported to be a major problem in approximately 5% and sometimes up to 10% of cases after surgery. Pain following herniorrhaphy is one of those condition that has been most investigated.
In this issue of SJP, Sandblom et al. (2010) report their results from a questionnaire study carried out in the county of Uppsala, Sweden, where 1744 answered a questionnaire about pain (response rate 72%). Pain was common with approximately 25% having pain in the early postoperative phase but decreasing considerably with time. So although pain is not uncommon with 14% still reporting pain 7 years after surgery, it is not a permanent problem in all patients.
The mechanisms underlying these pains are not known. Nerve injury is one factor that has been studied as a potential risk factor (Kehlet et al., 2006, Aasvang et al., 2008). The illioinguinal, genitofemoral or illiohypgastric nerves are the nerves most at risk of being damaged, and indeed studies confirm that damage to these nerves, e.g., nerve cut or crush and entrapment by mesh, is a potential mechanism (Aasvang and Kehlet, 2009). Other factors such as preoperative pain, inflammation and genetic mechanisms may also contribute. In the study by Sandblom et al. (2010), a multifactorial analysis suggested that age, postoperative complications and operative procedure might also be risk factors. The problem is to identify the patients that are at risk for development of these pains. This question, is not unique to postoperative pain but equally important for all other pain conditions where chronicity is a risk. In this respect, the surgical model represents an ideal condition for identifying such patients because the surgical procedure can be planned and pre-, per- and postoperative factors can be studied in a standardized fashion.
One important lesson from Sandblom et al. (2010) in their prolonged follow-up of almost 2000 adult patients after inguinal herniorrhaphy is that the number of patients with chronic pain decreases significantly with time. This is an argument against the temptation to reoperate. It is natural that the patients think there must be something wrong with the scar tissue and they are often adamant in their pressure on the surgeon to “fix” what is causing the pain by exploring the scar tissues.
Reoperation is, however, documented to increase the risk of chronic pain (Kehlet et al., 2006, Stubhaug and Breivik, 2007). Occasionally, the surgeon will find an entrapped nerve, entrapped by a mesh or an unfortunate suture, that can be released and pain may improve (Aasvang and Kehlet, 2009). This, however, is rare. Evaluation of chronic postherniorrhaphy pain for possible exploratory reoperation should be performed by highly qualified, skilled and experienced surgeons (Aasvang and Kehlet, 2009). Too often we see patients in the pain clinics who have had up to several reoperations with unchanged or increasing pain after each such recurrence of nerve damage in the inguinal area.
Hopefully, lessons learned from the postsurgical pain field can be transferred to other conditions and assist in elucidating the enigma of the transition from acute to chronic pain.
References
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PII: S1877-8860(09)00012-3
doi:10.1016/j.sjpain.2009.09.011
© 2009 Scandinavian Association for the Study of Pain. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Natural course of long-term postherniorrhaphy pain in a population-based cohort
