Chronic post-surgical pain – 10 years on
Dr William Macrae, Consultant in Pain Medicine, Ninewells Hospital,
Dundee.
Biography
Bill Macrae is a Consultant Anaesthetist, in the department of Clinical
Neurosciences at Ninewells Hospital, Dundee. He works in the Chronic Pain
Service, the Acute Pain Team and the Hospice. His work interests include
Palliative Care, and Chronic Pain after Surgery.
In cooperation with Iain
Crombie, Huw Davies and members of the North British Pain Association he has
undertaken several studies on the Epidemiology of Pain.
Abstract
Introduction
The role of surgery in the development of chronic pain was first recognised 10
years ago. Surgery was found to contribute to pain in over 20% of patients
attending pain clinics (1). Since that time there have been several reviews of the
topic (2-6). The problem is now recognised by those working in the field of Pain
Medicine, but many other health professionals are not aware that there is a
problem. Surgical textbooks often ignore the topic. It is clear that chronic postsurgical pain (CPSP) is a major health issue that affects many people and has a
significant effect on people’s quality of life (7). Treating chronic post-surgical
pain can be difficult and unrewarding, so prevention is important.
Our
understanding of mechanisms and risk factors is still incomplete. There are
clearly factors that show an association but this must not be confused with
cause. It is important to appreciate that any injury causes a reaction in the
nervous system, and may result in a hyperalgesic state (8). Most chronic pain
syndromes represent such a hyperalgesic pain syndrome, and it is inappropriate
to assume that something has gone wrong, or that it is necessarily the surgeon’s
fault.
The problems
This talk will review the problems that emerge after ten years of research and
publications, these are:
Definitions. Problems exist in defining operations as well as defining CPSP itself.
The nature of the studies on CPSP. Most are large population based surveys,
using questionnaires, and the validity of these studies is open to question.
Understanding the mechanisms.
CPSP is complex and has several
mechanisms. Nerve injury has been assumed to be important, but there is no
simple relationship between nerve injury during surgery and chronic pain. This
raises three important questions:
1. What level of nerve injury is needed to induce the changes that result in
neuropathic pain?
2. Can damage to tissues other than nerves cause neuropathic pain?
3. What is the relative contribution of central and peripheral changes in the
nervous system?
Risk factors. This is complex and includes patient factors such as genotype,
medical history, past experiences and psychosocial factors, and medical factors,
such as the nature of the operation, the anaesthetic, perioperative analgesia and
other treatments given.
Prevention. Two strategies emerge as worthwhile:
1. Optimise perioperative analgesia.
2. Minimise unnecessary surgery.
References
1. Crombie IK, Davies HTO, Macrae WA. Cut and thrust: antecedent surgery
andtrauma among patients attending a chronic pain clinic. Pain 76: 167171, 1998.
2. Kehlet H, Jensen TS, Woolf C. Persistent postsurgical pain: risk factors
and prevention. Lancet 367: 1618-25, 2006.
3. Macrae WA. Can we prevent chronic pain after surgery? In: Shorten G,
Carr DB, Harmon D, Puig MM, Browne J, eds. Postoperative pain
management. Philadelphia: Saunders Elsevier, pp. 259-64, 2006.
4. Macrae WA. Chronic pain after surgery. British Journal of Anaesthesia 87
(1): 88-98, 2001.
5. Macrae WA. Chronic post-surgical pain: 10 years on. Br J Anaesth 101
(1): 77-86, 2008.
6. Macrae WA, Davies HTO. Chronic Postsurgical pain. In: Crombie IK,
Linton S, Croft P, Von Korff M, LeResche L, eds. Epidemiology of pain.
Seattle: International Association for the Study of Pain, pp. 125-142, 1999.
7. Smith BH, Torrance N, Bennett MI, Lee AJ. Health and quality of life
associated with chronic pain of predominantly neuropathic origin in the
community. Clinical Journal of Pain 23: 143-9, 2007.
8. Villanueva L, Dickenson AH, Ollat H. The pain system in normal and
pathological states. Seattle: IASP Press, 2004.
w.a.macrae@dundee.ac.uk