Pain is a very common experience for us all and the causes of pain would seem obvious. Even so, most experts who know a lot about the science of pain agree that pain is complex and consider it a part of a sophisticated body protection mechanism. Pain actually comes from the brain in response to the communication between the nervous and immune systems about danger to the body. Both systems have complex methods of detecting and evaluating everything that is going on inside and outside the body.
What causes pain?
Pain actually comes from the brain in response to the communication between the nervous and immune systems about danger to the body. Both systems have complex methods of detecting and evaluating everything that is going on inside and outside the body. The brain assesses all this information (things such as past experiences, the current injury and the situation), and then decides whether pain is a necessary and purposeful response (eg, detecting potentially harmful heat from a hotplate or scanning for sharp objects sticking into our feet as we walk along a path). Pain results when these evaluations suggest we need to change behaviour to protect ourselves.
What is the purpose of pain?
The purpose of pain is easy to understand in situations where there is obvious tissue injury, such as a sprained ankle, when stopping activity will protect the ankle from further injury. Even so, it is also easy to imagine that you may not experience pain immediately if you were involved in something exciting, such as kicking the winning goal as you went over on your ankle. When you are focused on winning the game, stopping and protecting the ankle injury may be considered by the brain to be less important at that time, and so pain would not serve a useful purpose.
Pain that lasts for more than the time expected for healing to occur is often called chronic pain or persistent pain. In some people, pain persists past the acute inflammatory phase. The reasons for this are currently unknown, but most tissues in the body will heal within three months. By this time after an injury, tissue damage is less likely and so the purpose of pain is more complicated than simply protecting against further injury. As we learn more about persistent pain, the more it is becoming apparent that there may be increased activity in the protection systems of the body contributing to the ongoing experience of pain. Sometimes it seems as though the body’s alarm system has increased its sensitivity and pain is triggered with even the slightest threat, even when there is no actual risk of damaging tissue. It could be said that the body’s protection system is working really well but it is not working very purposefully. Importantly, this can also occur in ongoing conditions that don’t follow normal healing timeframes, like osteoarthritis.
Is pain proportional to injury?
Put simply, pain is not always proportional to injury. In our day to day lives, we’ve all had brief pains that just occur at odd moments for no reason. A paper cut can hurt quite a lot, even though there is little damage. Conversely, many heroic feats of action that result in obvious injury that have been recorded on YouTube and other media often hurt less than expected (eg, the young man who released his arm that was trapped in a rock crevice by cutting it off and said that the worst sensation he had was a ‘zing’ when he cut through the nerve).
There is also a whole lot of research that shows that many of the tissue changes that we see on MRI scans are not proportional or even related to the pain that is felt by the person who has had the scan. Many of the changes that we see on scans are actually normal variations that occur as our body gets older—like getting grey hair or wrinkles.
Why does pain persist?
While we still do not have all the answers for this, there is an incredible amount of research being conducted trying to answer the question of, ‘Why does pain sometimes persist, even though it seems that the body has healed?’ There is increasing evidence that sometimes the nervous and immune systems adapt in unhelpful ways, and those adaptations make the nervous system ‘primed’ or ‘sensitised’ to create pain. What this means is that there is increased activity in certain parts of the body’s protection system, leading to increased experiences of pain. We know some of the factors that can ‘prime’ the nervous and immune system. For example, we know if we are anxious or stressed, we release a lot of chemicals into our body that can contribute to increasing pain intensity—you probably notice this yourself at times.
How common is chronic pain?
Around one in five people experience pain that lasts for more than about three months, certainly after an injury might have been expected to heal, and this is called chronic or persistent pain. Chronic pain affects people across all age groups and genders. Many people can function very well despite the ongoing pain, while others find the pain very limiting. Chronic pain imposes a very large burden on the individual and on our society: there are physical and mental health care costs, loss of work productivity and associated financial problems, challenges to social and interpersonal relationships and changes in mood and emotional responses. Indeed, according to World Health Organisation Global Burden of Disease data, chronic pain is one of the leading causes of disability in adults throughout the world.
How do we treat and manage pain?
As noted above, pain is experienced once the nervous and immune systems make sense of what is happening inside and outside the body. Therefore, the assessment and treatment of pain needs to reflect these multiple factors. The biopsychosocial model provides an evidence-based framework for clinicians to use in the clinic. This model encourages clinicians to evaluate the biological, psychological and social contributors to the pain experience and provide management for each factor that might play a role. For example, in the early stages of an acute sprained ankle, it may be that reducing the process of inflammation in the local tissues and strapping to reduce load is the most valid treatment approach (mostly intervening with biological factors). Some education and reassurance that the ankle is not fractured (which is a psychological intervention) will also help turn down the body’s protection systems. When pain persists, the biological factors may not be the predominant focus and treatment is more effective when other contributors are identified and addressed.
Pain management may involve a team of healthcare providers, including GPs, physiotherapists, nurses and other allied health practitioners, such as clinical psychologists. Most importantly, pain management works best when everybody involved in managing the pain (including the person with pain) regularly communicates and has an agreed understanding of how treatment should proceed. It is also essential that treatment goals and strategies are planned and understood by all involved and that there is a clear understanding of the contributions that each team member will make. Coordinated care is often difficult to achieve, whether in the public or private system, but it should be the goal of all practitioners.
Given that chronic pain is often related to adaptations in the nervous and immune systems, effective treatment is often associated with attempts to reverse those adaptations. There is substantial evidence that increased knowledge about pain allows individuals to gain more control over their pain experience. Also, one of the most valuable things individuals in pain can do is learn how to move despite being in pain.
What role does physiotherapy play?
Physiotherapists with a special interest in managing pain are well-placed to provide education on the complexities of pain and how the nervous and immune systems work. They also play a key role in developing an activity plan for regaining function. They may use techniques such as taping and exercises to facilitate muscle use and regain fitness, or use a brace or splint to support healing tissue in an acute situation. They assess and manage sensory and movement changes that might occur in association with pain, and they may teach pain management techniques that might include distraction, mindfulness, positive thinking and reconceptualisation of the pain experience (often in conjunction with other treating practitioners).
The following may have a role in the management of pain once a thorough assessment has been completed:
Education has been shown to have an important role in reducing fear associated with pain. Education allows the person with pain to better understand the contributors to and purpose of the pain, empowering them to take more control of their situation. Education needs to be delivered thoughtfully, with regards to the amount of information, the level of detail and the format of education sessions. Your physiotherapist will have a range of resources to draw on in order to help you learn in the best way.
Exercise has a range of benefits. It is used as a strategy to resume function. It may assist in restoring strength, mobility and fitness levels. In some pain conditions, exercise may reduce the pain itself. Exercise can also be unsuccessful if you have not got the starting point right. Your physiotherapist will be able to guide you in the process of determining where to start and how to steadily and consistently reintroduce you to the activities that are part of everyday life. It is important to set goals and work in a paced manner towards achieving them.
Medications are often used successfully to reduce pain in the acute stage. When pain persists, however, their effectiveness as a single treatment strategy is limited, and evaluation of side effects is essential. Use of any medication should be strictly and regularly evaluated by your GP and done in conjunction with other pain management strategies, like exercise.
The input of your clinical psychologist with an interest in chronic pain is often beneficial to deal with the consequences of pain. Issues such as generalised anxiety, depression, post-traumatic stress and fear of movement are all potential targets to address.
Pain, whether short-term or of longer duration, may have many contributing factors and consequences. Therefore, it is reasonable to expect that a multidimensional approach to managing it will be much more effective than a single approach, especially when pain persists.