Pain is a subjective sensory and emotional experience that occurs in the brain, typically caused by actual or potential tissue injury. Although it may be ‘all in our head’, it is a very real sensation that our body experiences. These signals are our nervous system’s way of warning us of danger or potential danger. It is a protective mechanism that acts as our body’s alarm system.
Acute pain is pain that typically lasts less than three months, and often, it is a direct response to an injury or illness. It is normally resolved with pharmacological and physical interventions, with only some psychosocial involvement. For example, when you drop a hammer on your toe, receptors at the injury site are activated and send signals up to pain receptors in the brain. Your brain then assesses the current danger-safety balance and decides whether to sound the alarm. This is why you may feel a papercut at home but not the sharp tree branches cutting into you when running away from a bear.
Chronic pain typically lasts longer than three months and is not necessarily linked to tissue damage. There is often more psychosocial involvement in chronic pain, as ongoing pain leads to changes in daily routine, mood, and motivation. These symptoms, in turn, will likely exacerbate the pain experience further. This seemingly endless pain cycle acts as a negative feedback loop, and often prevents participation in meaningful activities, leading to a pain-centred life. As such, the treatment of chronic pain is more involved, requiring multidisciplinary expertise in order to desensitize the hypervigilant nervous system.
The nervous system is neuroplastic; meaning that it is capable of change over time and will accommodate to meet the body’s demands. Although normally an adaptive and helpful response, neuroplasticity can lead to pain exacerbation in a chronic setting. Persistent pain can trick the brain to perceive that there is more damage at the tissue than there actually is. In response to this, the brain generates a larger output in order to respond to this perceived danger. This leads to a hypersensitive nervous system which can cause previously painful stimuli to be even more painful (hyperalgesia), or previously harmless stimuli to now be painful (allodynia). However, not all hope is lost! Neuroplasticity can go both ways. Just as the nervous system learned to be more sensitive, there are therapeutic strategies to calm the nervous system and teach it to be less sensitive.
Now, we’ve talked a lot about the physiological side of pain, but pain is not all physical. It is what is termed biopsychosocial. This means that physical, psychological, and social-environmental factors have an effect on pain experiences. Have you ever had a bad day and everything feels much worse? This is why the most effective pain treatments today take an interdisciplinary approach in order to address all biopsychosocial factors. Treatment often involves pharmacological and non-pharmacological therapy, physical therapy, pain education, setting expectations/goals, and addressing other disruptions to daily functioning such as sleep and work difficulties. By working together with pain, rehabilitation, and counselling specialists, the hope is to transition from a pain-centred life to a function-centred life.
To learn more about chronic pain, check out this short video: https://www.youtube.com/watch?v=ikUzvSph7Z4