Pain is a sensation that is experienced by all of us at some time or another.  Understanding more about the biology and psychology of pain will help you to understand your pain and the approach taken here in Pain Clinic. 

 The International Association for the Study of Pain (IASP) defines pain as:

"An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage".

The IASP definition is useful since it stresses two aspects of pain.  Pain is something that you feel physically - your body senses it. We know a great deal about the physical aspects of pain.  However, as well as this, pain is also something you feel emotionally. Pain is subjective, affected by your current and past experiences, your individual bodily response to pain and what the pain means to you. It is also affected by psychological factors from day to day. For example, on days that you are feeling down, you may notice pain more than on days when you are feeling happy.  We also all notice times when we can distract ourselves from pain and notice it less.  So it can sometimes be hard for doctors to understand exactly what you are feeling with your pain.

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Pain can be described as Acute and Chronic, depending on its duration. Acute pain is of short duration and normally resolves when the body heals itself, for instance after injuries or operations.  Pain can become chronic or long-lasting, this may persist after the body has healed so is often not a useful sensation.

Acute pain is your body's way of saying that something is or might become damaging to you. Acute pain is generally sudden in onset, and lasts a relatively short time. It is often a warning sign so for example if you turn on a tap and put your hands under it, and the water that comes out is painfully hot, you will immediately pull your hands away. The pain warned you that if you continued to keep your hands in the water, they would probably get badly burned. As another example, your shoe may rub against your foot, causing you pain but no injury. If you ignore this warning sign, you can end up with a blister - damaged tissue - as well as pain. Acute pain generally disappears when the injury heals or the illness goes away (either of its own accord, or after successful treatment), or the body can no longer detect the source of the pain (for example, your rubbing shoe).

We know that damaged tissue for example from an injury does not always lead to pain, and the amount of pain doesn't always correspond to the amount of injury (so a paper cut can be very painful, and sometimes people don't notice that they've had a serious injury). This is because the danger sensors in the skin and soft tissues  (nociceptors) send messages to your spine which are then relayed to your head - your brain decides on the basis of other sensation, stress level, knowledge and previous experience whether those signals are dangerous and should be painful, or not.

Sometimes pain can become chronic, or persistent. It is said to be chronic when it is present to at least some degree for long periods of time (typically after 3-6 months).  Chronic pain may remain constant, or it can come and go, like the pain of migraines. It sometimes indicates a long-lasting health problem, which may or may not be serious and may or may not be treatable.  Chronic pain may be due to causes such as wear and tear of joints: this is called nociceptive pain.  Sometimes changes in the nervous system can themselves lead to pain: this is called neuropathic pain.  Indeed, sometimes pain itself can cause changes in the nervous system that lead to an increase in and maintenance of pain sensation (sometimes called 'sensitization' or 'pain wind-up').  Persistent pain can prevent the completion of daily tasks or certain movements and impacts upon all aspects of life including for example ability to concentrate, sleep, lowering ones mood, and decreasing social contact.

One way to understand pain sensitization is in terms of your home burglar alarm: normally the burglar alarm goes off loudly alerting you that someone is breaking into your house; but if a spider chooses to make its web over a detector then insignificant movements by that spider may be interpreted by the burglar alarm as being danger signals thus setting off the alarm. When someone has a nervous system sensitized to pain (the burglar alarm above) then sensations that would normally be interpreted as being harmless are interpreted by their brain as dangerous thus triggering a pain signal. An example of sensitization is having a hot shower when you have a sunburnt neck - normally this would be a nice hot shower, but the sunburn means that the sensation of hot water on your neck is felt as painful so you turn down the temperature and have a tepid shower. Some persistent pain conditions (for example fibromyalgia) seem to be partially due to the central nervous system (the brain and spinal cord) being sensitized to overreact to small danger signals (nociception) from the body, sensations that wouldn't normally cause pain. 

A strange feature of chronic (persistent) pain is that it may persist even after the injury that caused it has healed. So when you see a doctor in Pain clinic they will check you carefully to see if there are any treatable causes of your pain or other painkillers that could be tried. If your pain persists despite these treatments the doctor may refer you for pain management advice as we know that pain tends to affect us in various ways. For example, pain tends to restrict our movements (thus over time soft tissues shrink and movement becomes more painful and difficult), pain also tends to lower ones mood and often makes us withdraw socially. Pain management aims to keep you active, to keep you doing fun things and to promote social contact and thus challenge the downward spiral that may come with chronic pain.

We know that chronic pain is stressful: typically our bodies respond to stress with a fight / flight / freeze response and we have raised levels of stress hormones in our blood. These stress hormones have a range of effects on us including making it harder for us to sleep, and may lead us to want to withdraw to a place of safety such as the bedroom. One aspect of pain management is to try to find techniques or strategies that are helpful in relaxing you.

We know that the sensation of pain may not be an accurate reflection of the degree of tissue damage. Some people for example have pain in limbs that have been removed (this is called 'phantom limb pain'), because although the pain feels as if it is in the limb it is really in our brain (central nervous system). We also know it is important to keep active, to find a baseline of activity you can do on good and bad days otherwise you may find yourself doing less and less over time. It's important that you understand your pain condition to reassure yourself that movement really is safe for your body so please ask your healthcare team any questions you may have, and then set yourself a small exercise goal. As the pain sensation you get is not a good guide about how much to exercise to do it is good to increase your exercise very gradually - aim to start by establishing a baseline of exercise and activity that you can do even when you are having a bad day.

Our thoughts can influence our mood so it can sometimes be helpful to notice those thoughts and reflect upon them, as pain can make us perceive situations in a negative light. For some people a chance to reflect upon their experience with a pain psychologist can help them find strategies to get their life back on track. It may also be helpful to share your experience of living with chronic pain with other people: knowing that you are not alone, and hearing how other people manage certain situations with chronic pain can often be useful for sufferers. Certainly, ongoing pain tends to make people feel low and withdraw from social situations so a part of ongoing pain management is to get back to doing more fun and social things - what did you enjoy doing, and how can we help you get back to that?

An animated video from Australia (Brainman) gives an excellent five-minute overview of chronic pain and some of its issues, and here is a UK animation about chronic pain management.

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