What is chronic pain?
Chronic pain is defined as continuous, long-term pain that has lasted for more than six months, or that prolongs after the time that healing would have been thought to have occurred.1 Chronic pain can also occur when no obvious cause for it can be found; this is thought to be due to changes in the body’s nervous system.2 Chronic pain does not appear to have a useful function; it can persist for months or even years and is very difficult to treat.3
Types of chronic pain
Chronic pain can be divided into two classes: nociceptive and neuropathic.4 All people will experience nociceptive pain at some point and it includes such things like cutting yourself, a burn or an injury. Conversely, neuropathic pain is caused by a problem with nerve pathways, which means the way that the nerve sends pain messages to the brain is affected.5
Neuropathic pain is often described as numbness, tingling or like an electric shock.4
It is a debilitating condition and although the exact number of people suffering from this (the so-called prevalence) is unknown, some European based studies have estimated it at anywhere between seven to 37 per cent.5
It is often under-diagnosed and under-treated.5
Causes of chronic pain
Chronic pain can occur anywhere in the body. It may follow an illness or an injury that appears to have healed or may develop for no apparent reason. Common types of chronic pain include back pain, headaches, arthritis, cancer pain and neuropathic pain. Chronic pain is thought to be one of the most common conditions for which people seek medical attention.4
In Europe, backache is the most commonly reported location for chronic pain.6 The causes of back pain can be very complex and it is difficult to obtain an accurate diagnosis. The pain may be a result of earlier injury or trauma or may be caused by arthritis or spinal disc abnormalities. Some patients have Failed Back Surgery Syndrome (FBSS), which is persistent low back and leg pain in those who have not achieved a successful outcome with back or spine surgery. However, in many cases the cause of the pain cannot be determined.
Diagnosis of chronic pain
Neuropathic pain is one of the more poorly understood types of chronic pain. It is often under-diagnosed and under-treated.5 It is caused by damage to the nervous system and often occurs in association with diseases such as diabetes. It can also occur after a spinal injury or limb amputation. Neuropathic pain can also manifest as a distinct syndrome such as complex regional pain syndrome, which affects one of the arms, legs, hands, or feet and often spreads to affect the entire arm or leg.
Electrophysiological studies can be performed to measure how well the nerves and muscles are functioning, and x-rays, MRI and CT scans can be used to pinpoint problems in the bones or deep tissues. However, these tests may fail to find an anatomical reason for chronic pain.3 To date there seems to be no diagnostic tests that can either measure the intensity of pain or pinpoint its location. Although patients can rate their pain subjectively on a pain rating scale, these scales would be of limited value diagnostically because pain tolerance varies greatly from person to person. As a result, diagnosis is difficult and relies on the patient’s description.3
- Hornberger et al. Rechargeable Spinal Cord Stimulation Versus Nonrechargeable System for Patients With Failed Back Surgery Syndrome: A Cost-Consequences Analysis Clin J Pain 2008;24:244-252
- Policy Connect. About Chronic Pain. http://www.policyconnect.org.uk/cppc/about-chronic-pain Accessed March 2012
- Brunton S. Approach to assessment and diagnosis of chronic pain. J Fam Pract. 2004;53(10 Suppl):S3-10.
- Galluzi. Management of neuropathic pain. Journal of the American Osteopathic Association. 2005;sup 4 (105):S12-S19
- International Association for the Study of Pain. Pain Clinical Updates. 2010; Vol. XVIII, Issue 7: 1-6
- Breivik H et al. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Eur J Pain 2006;10:287–333