VIDEO : PAIN. IS IT ALL JUST IN YOUR MIND?
Professor Lorimer Moseley – University of South Australia
A definition of pain
Pain is defined as: “An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” (International Association of the Study of Pain, 2011). Generally pain gets a bad press, but we need pain to indicate that our tissues are being stressed and we need to change behaviour. This is entirely normal with acute pain as tissue damage is related to the pain experienced (acute pain will be influenced by circumstance, for example consider a person I saw who had his hip fractured and dislocated by a charging bull, but still managed to run and roll 60 meters and jump over a fence. He didn’t experience pain until he reached the other side of the fence! The brain decides when we can feel pain). It is the body’s response to a perceived threat and we have evolved to focus on pain. Pain that does not stop after several months is different from this acute pain and 1 in 7 people in the UK suffer from chronic pain.
The onset of the problem
As an example, you twist or fall and injure some part of your body. The pain is intense for two days but gradually it improves. Initially you limp or hobble and activity is reduced. Simple analgesics seem to help and gradually you return to full pain free movement within a few weeks. But what happens if you still experience pain after 6 months and you continue to limp? Simple medication no longer seems as effective and you are prescribed stronger medication that helps a bit, but they produce unpleasant side effects. Your sleep is disturbed and you have difficulty working or returning to normal sports or pastimes. Your GP sends you for an x-ray or scan and all the results are normal. Various treatments have failed and hope of improvement diminishes. As you spend longer resting you become anxious that you will not improve and the future seems bleak. Some pain just starts spontaneously and no specific injury or event triggers it. Approximately, 50 percent of all the patients we see at the clinic cannot recall a specific injury that triggered their problem and often they just woke up one morning with pain.
Why we continue to limp
Unfortunately, in the above scenario, you have chronic pain (pain lasting longer than 3 months) and this problem is increasing rapidly in the UK and worldwide. You are not alone. Why the pain continues, many years after the injured tissue has repaired is complicated, but we know it is a combination of different factors. Some problems continue as we learn to stress tissues to compensate for the initial injury. As we limp we learn to walk differently and our brain continues to use this abnormal movement pattern. Unless we move it differently, we will continue to ‘limp’ and compensate for pain and we make the situation worse.
The relationship between tissue damage and pain
The longer the pain continues the relationship between tissue damage and pain diminishes. It is possible to have no tissue damage, but still experience excruciating pain. This is seen with patients who report ‘phantom limb’ pain in areas of their body that have been amputated. Their pain is ‘real’ and it is often as a result of the brain remembering the mechanism of the injury or pain in the area before the amputation. The brain and the nerves that supply each part of our body have the ability to increase the sensitivity to the pain and the brain can actually change in response to ongoing pain.
Pain and the brain
All pain is experienced in the brain and pain is produced by the brain. That does not mean that pain is ‘in you head’. It is not imaginary and it is very real, but pain is influenced by how we think or feel. If we have chronic pain and we are been followed by someone who looks menacing and carrying a large club our brain does not produce pain. We focus on getting out of the situation and our brain has an ability to reduce pain by releasing natural painkillers (endogenous opiates). This is an important protective mechanism and our brain is constantly making decisions and that can be to reduce pain to help us survive. However pain can also be intensified, for example, if we are anxious or depressed the pain increases (not everyone with chronic pain in depressed or anxious, but it is important to recognise those people).
Professor Moseley explains why things hurt.
Pain and context
The context and the environment in which we experience pain influences pain levels. What happens to your pain level if you are at a party and laughing with friends? Why is the pain worse at night when you have nothing to distract your pain? Pain is closely related to our thoughts and beliefs and this is why psychological interventions can be effective with some people with chronic pain.
Where is the pain coming from?
If we have been told we have a ‘degenerative’ joint or a damaged/prolapsed disc in our spine we will assume, not surprisingly, that the pain is a direct result of the damaged structure, but in many cases this is incorrect. The x-ray or scan might show changes which we assume are the source of the pain, but often similar findings are seen in people who have never had pain. Therefore, treatment aimed only at the ‘damaged’ area might prove unsuccessful and leave you thinking your problem is so ‘severe’ that even surgery or injections have failed to help. It is only by understanding the consequences of pain and how your body can be sensitised to the pain can you fully understand how local treatment is not the only answer. These events are normal and by recognising the physiological changes your body undergoes it is possible to reduce the ‘fear of pain’ and start changing beliefs (this will be discussed in the section on rehabilitation).
Pain and movement
Our body produces pain to warn us that tissue is under threat and we must take action and change behaviour. This is prefectly normal and we need pain to prevent further damage. In some rare cases people are born without pain, but they suffer damage to their body as they continue walking when they have fractured their leg or have a piece of gravel in their shoe. Pain is an early warning system that indicates that we must change, but if this system goes wrong we can be left with chronic pain.
In the chronic pain state the body over protects the painful area and usually we rest the painful part. With time we lose muscle bulk and the normal joint loading that is required for healthy joints is diminished. The adage: ‘use it or lose it’ is highly relevant in chronic pain as it is with our increasingly sedentary lives. Once we start to believe pain means more damage the vicious cycle continues.
The fear of movement is a key determinant of future function and many people with chronic pain can be frightened by the emotive terms that health professionals use. For example, ‘degenerative joints’, ‘crumbling discs’, and ‘unstable’ pelvic joints. These terms are often used, but research suggests that many of these are inaccurate and many people have joint changes as seen on imaging and never have pain. I always tell patients that our body changes with age,for example grey hair, this is not a pathology but a reflection of how hair changes with time. Similar changes are seen with our joints on x-rays and scans. These are normal changes seen in many of us but they do not necessarily mean we will experience pain.
Nerves provide another challenge when they are involved. The nervous system is highly complex and it transmits pain signals (nociceptive free nerve endings) from our body to the brain via the spinal cord. Nerves have considerable blood flow and this is reflected in their high metabolic rate. Following nerve injury pain is usually higher that other type of problems. Consider the difference between low back pain and the extreme pain experienced when the nerve in the back of the leg is affected (‘sciatica’).
Nerve pain is often associated with altered sensation in the body and nerve that normally transmit sensation can start to produce pain. Consider touching the small hairs on you arm but instead of feeling the hairs move you experience pain. This happens in some people with chronic pain and is called allodynia.
Nerve pain is also easily ‘remembered’ by the brain and spinal cord so other centres away from the original injury site are activated and become ‘sensitised’ so even light touch or movement produce pain. This leads to the characteristic ‘ramping up’ of the pain experience and also reporting pain spreading from the original site. For example, 50 percent of people with chronic low back pain also complain of neck pain. Unfortunately, the more pain we have, the more we can get.
As pain is experienced with small movements or light touch, it is only too easy to begin believing that pain means ‘harm’. If we believe we are causing more tissue damage it is natural for our body to prevent movement and we rest for longer. This produces a vicious cycle as we experience more pain and the rest periods increase. This leads to the high levels of disability seen in chronic pain and we lose social contact, stop activities and rely on a range of powerful medications to help reduce the pain.