What is pain?

Pain is a complex experience common to all human beings and yet unique to each of us. The International Association for the Study of Pain (ISAP) defines pain: “as an unpleasant sensory and emotional experience, associated with actual or potential tissue damage, or expressed in such terms. Pain is always subjective¹.” That is a mouthful of a definition! But, perhaps if we look at it step by step, it will help gain some understanding about the complexities  of pain and its treatment.

The definition starts with the statement that pain is an unpleasant sensory and emotional experience. No one would dispute that pain is unpleasant, but have you considered that it is always sensory and emotional? No matter whether the pain is caused by a broken bone or a broken heart, we always experience it in our bodies (sensory) and in our emotions.

As human beings, we are embodied. Every thought and emotion, or feeling is the result of a series of chemical reactions in our brains. And these reactions, which result in our thoughts and feelings, also affect our bodies and arise in sensations. This part of the definition points us to the critical fact that pain is a construct of the brain, not of the body.

Pain is 100% from the brain². Pain is theorised to be the brain’s response to threat. Whether that threat is physical or emotional doesn’t matter, when you are threatened and your brain produces pain, you pay attention and do something about it. Pain gets your attention and you change your behaviour to try and reduce the threat – perhaps by taking your hand off the hot stove to stop it burning, or by crying so that someone comes and gives you a hug, or by going to a doctor so that you know what’s wrong and what to do about it. All of these behaviours might be useful at different times and you use them to reduce the threat that has produced pain. You might not like pain, but it serves an important purpose.

Recognising that pain is in the brain, helps us to understand how it is possible to damage the body and not feel pain; we’ve all had that bruise or cut which we didn’t feel at the time and later wondered what happened. It is possible for things to happen in the body, and for nerves to send messages to the brain, and for some reason (or numerous reasons) for the brain to ignore those messages and not produce pain – probably because the brain has judged that what has happened isn’t that dangerous really.

Recognising that pain is in the brain also helps us to understand that pain is an experience (as it says in the definition), and so sometimes pain will feel better or worse depending on the context of the experience.

We’ve all stubbed our toes at some point in our lives, and it’s extremely painful. But think about the day when you stub your toe after you’ve just had a fight with someone you love, or you’ve failed an exam and you don’t know how you’re going to pay the bills. How bad is the pain then? So much worse, isn’t it? That’s because our brains produce pain not just based on the information from the stubbed toe but also from all the other information it is getting at the time. If the threat from all the information is high, the pain is also going to be high! But if you stub your toe while on holiday, with friends when you are in a good mood then it’s not bad at all. It is all about threat in the brain!

So, if pain is in the brain, what can we do about it? You can treat the nerves that carry the messages to the brain and you can treat the nerves in the brain too. Your choices are multiple; while medicines play a part, there is so much more you can do for yourself, ranging from ice and heat to exercise and mindfulness practice. One of the most effective ways to treat pain is through exercise³.

Exercise treats pain because it helps our bodies to be fit and strong in order to cope with challenges. Exercise also helps your brain, by stimulating it to release chemicals which make you feel good (the runner’s high is a real thing). Exercise makes the brain more efficient in producing painkilling chemicals; it distracts us and makes us happy, and it helps to reduce all the worries and negative emotions, which contribute to the brain feeling threatened.

Remember, pain is the brain’s response to threat. As a human being, you’re designed to move and exercise is medicine for pain⁴. So, if you have pain, now is the time to start exercisng, it doesn’t matter what kind of exercise you do, just get out there and start doing it!

References:

1. Merskey H, Bogduk N: Classification of Chronic Pain. Second Edition edition. Seattle, WA: IASP Press; 2002.
2. Nijs J, Lluch Girbes E, Lundberg M, Malfliet A, Sterling M: Exercise therapy for chronic musculoskeletal pain: Innovation by altering pain memories. Man Ther 2015, 20(1):216-220.
3. Law LF, Sluka KA: How does physical activity modulate pain? Pain 2017, 158(3):369-370.
4. Kohl HW, 3rd, Craig CL, Lambert EV, Inoue S, Alkandari JR, Leetongin G, Kahlmeier S: The pandemic of physical inactivity: global action for public health. The Lancet, 380(9838):294-305.
   

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MEET OUR EXPERT  – ROMY PARKER

Romy Parker is an Associate Professor and Director of the Pain Management Unit in the Department of Anaesthesia and Perioperative Medicine at the University of Cape Town. She is an experienced clinician working in chronic pain management as part of the Chronic Pain Management interdisciplinary team of Groote Schuur Hospital. Her research all focusses on the area of pain with emphasis on developing and testing treatments relevant to a South African context.