There was an interesting conference at the Royal Society of Medicine on November the 19th about chronic pain. The meeting was about the different factors which affect our perception of pain and the different ways in which we respond to an episode of acute pain. Whether, after the acute episode is over, the pain subsides and disappears or whether the pain continues to be experienced long after the initial episode has resolved. Some 20% of people seem to be at risk of developing chronic, long term pain after an acute episode. The conference was not specifically about sickle cell pain, but it was clear that the discussion applied just as much to sickle cell as to any other painful condition.
The sensation of pain is universal; we all experience pain at one time or another. However, although the sensation of pain is always related to some damaging insult to the body, what we actually feel is also critically dependent on how the brain processes that information. We are all familiar with how sometimes severe pain can be tolerated and even ignored because there are more important issues to deal with at the time and conversely how sometimes a trivial headache can seem to dominate our consciousness so that we are not able to do anything else at all. These are examples of where the emotional content of the moment has a profound impact on our experience of pain. Higher areas of the brain are able to modulate or change the experience of pain either by up-regulating or down-regulating the flow of pain impulses to the brain. The factors which can alter this central processing of pain are many and various but some of them will be very familiar to you.
Anxiety and depression are key factors in up-regulating pain perception and it is one of the reasons why, if you have sickle cell disease, and you are psychologically strong and resilient, you are more likely to manage painful crises successfully.
Distraction, or taking your mind off of the pain, is also a well known way of down-regulating pain impulses, and familiar to everyone with sickle cell. All of you will have different distraction strategies to help you manage painful episodes.
The opposite of distraction is attention. Here, the more you attend to the pain, the more importance and significance you give the pain, the more you will feel it. Put another way, over attention to a pain will up-regulate and increase the intensity of the pain experience.
Another factor is expectation, in other words the more you are on the alert for pain, or constantly monitoring yourself for the beginning of a painful crisis, the more likely it will happen and the more severe the pain will be when it arrives. This sort of constant scanning of the body for pain or danger is called hyper-vigilance. Being in a persistent state of hyper-vigilance is exhausting and results in pain being associated with feelings of threat and fear. It is easy to see how under those circumstances the sensation of pain is heightened and made more severe. Hyper-vigilance is also associated with catastrophising, another way in which pain is up-regulated, which is described below.
Attention and expectation are, I think, closely related; the more focus there is on pain the more severely this will be experienced. Now there is a conflict here for those with sickle cell, because your doctors will tell you to watch out for pain, treat it quickly and monitor the effects of your treatment. But this sort of attention, whilst important, will tend to up-regulate and amplify the pain you experience. So, it is a question of balance; think about pain and how you will manage it for definite, but make sure that you are not too concentrated on pain behaviour, don’t over attend to the pain you experience or become obsessed with managing every fluctuation in pain severity. This will only make matters worse.
Catastrophising is another key factor in pain perception. If you like, it describes the situation where you lose psychological control of the pain. Where a trivial, non-serious pain assumes gigantic proportions, you feel it is the end of the world and that you cannot possibly survive this onslaught a moment longer. Now, some pains are truly terrible and overwhelming and some pains are associated with serious, maybe even life threatening complications, and in those situations it is appropriate to feel vulnerable and to be frightened. But the majority of crisis pains are not like that, they are less severe, restricted to a specific part of the body, time limited and usually manageable with simple pain killers. In these situations it is important to remain in control and keep the pain in proportion, don’t allow it to expand, overwhelm and dominate you. Catastrophising is surprisingly common and we will all have had difficulty at some point in time in keeping the experience of pain in proportion.
Finally, there is the issue of sensitisation. This can happen in the periphery, in the skin or bones, where the nerve endings, which are sensitive to pain, are located and as a result the nerve endings become even more sensitive than usual. Or sensitisation can happen in the brain where pain signals are routinely amplified, or up-regulated so that minor pain is experienced as severe pain and even normal sensations, like touch, trigger the experience of excruciating pain. For patients with sickle cell there are two important issues here.
There is some evidence that brain sensitisation is more likely to happen in patients who have repeated episodes of pain which are poorly managed and treated. This has obvious implications in sickle cell and implies that inadequately treated painful crises actually result in a deterioration in pain perception, making the pain of future crises more severe than it needs to be. This is a powerful argument for ensuring that all crises are treated effectively and as quickly as possible, so that no patient has to experience unnecessary pain, with the risk that this may result in alterations in the brain making future crises more difficult to manage. There is however a conflict here, because the same sort of sensitisation also appears to result from excessive use of opiates, the most powerful class of pain killing drugs, including morphine and diamorphine. This is known as “opiate induced hyperalgesia”.
It looks like a catch 22 situation; don’t use the powerful pain killing drugs and risk sensitisation due to inadequately treated pain, or use the drugs to control the pain, but risk the same sensitisation occurring as a result of exposure to opiates. Again, the answer is probably one of balance. It is important to treat pain effectively BUT only to use the strongest pain killers when there is no other alternative. This is one of the reasons why your doctor may be reluctant to consider the routine use of strong pain killing medication until all other options have been tried and failed.
Many of the issues discussed in this blog; anxiety, depression, distraction, attention or hyper-vigilance, expectation, catastrophising and sensitisation are amenable to help. If you think that any of these factors apply to you, then they maybe making your painful crises more difficult to manage than they need to be. You should take steps to remedy the situation. The best way is to speak to the psychologist attached to your sickle cell service, who will be able to start a course of treatment, which will modify or limit the operation of these factors and make you pain easier to manage.