Chronic Pain

What is chronic pain?

Everyone feels pain differently and nobody can know what somebody else's pain is like. This can make it difficult to define and describe pain.

The definition of pain devised by the International Association for the Study of Pain (IASP) is 'pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage'. This is a widely used and accepted definition of both short-term acute pain and chronic pain.

Dr Macrae, a Consultant Anaesthetist and Pain Specialist explained that acute pain is the body's warning system which tells the body to move away from danger and to protect itself from further injury, and that with chronic pain there are changes in the nervous system and brain so that the pain system no longer functions as a warning system.

The word chronic, however, refers to the persistence of pain. The IASP defines chronic pain as 'pain which has persisted beyond normal tissue healing time'. Although there is no formally accepted time for this, any pain lasting for more three months is generally considered to be chronic pain. Most people's experience of chronic pain though will have lasted longer than three months.

The information about pain occurring in the body is carried in nerves from all parts of the body through the spinal cord to the brain. There are at least two main pathways that carry information to the brain, one which goes to an area of the brain that tells us how much pain and where it is coming from (the sensory cortex) and another which goes to the emotional areas of the brain.

When the body is injured chemicals are released that make the pain system more sensitive and, as the injury heals, this sensitisation normally switches off. Dr Macrae explains that with chronic pain the sensitisation is not switched off and can actually become more sensitive.

People can develop chronic pain following a wide variety of injuries and illnesses. We talked to people that had chronic pain following an accident, nerve damage (following surgery), arthritis, Lupus, Multiple Sclerosis and ME (chronic fatigue syndrome). These are only some of the causes of chronic pain. 

Sometimes it is not easy to identify how the pain started and what caused it. For example, we talked to several people who had unexplained pelvic or abdominal pain. It is often difficult for people to understand why they are still experiencing pain.

Some of the people we talked to suspected that there was ongoing damage in their bodies. However, others had been told that their injuries had healed. Dr Macrae explains some of the different processes that occur with chronic pain from arthritis, pain from nerve injury or disease that affect the nerves and pain where there has been an injury to a disc in the spinal cord.

Most of the people that we talked to were aware that the level of pain they experienced could be influenced by how they were feeling emotionally, for example whether they were happy, angry or anxious. There is some evidence that psychological distress can lead to developing chronic pain as well as making it worse. A doctor explains how the pain messages can be altered by what we think and feel.

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(See 'Coping with the emotional impact of pain', 'Learning about pain management', 'NHS pain management programmes' and 'Sleep, stress and environmental factors').

Last reviewed August 2018.

Last updated May 2015.


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