Pain is a complex and still imperfectly understood phenomenon. The International Association for the Study of Pain defines pain as ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’. Pain is thus not a simple sensory phenomenon, but also has an emotional component. Importantly, our experience of pain is not only determined by our body physiology (i.e. the pain messages produced by our tissues), but also by our mental state, education and culture. These indeed all have an influence on the complex pathways that our nervous system uses to regulate pain.
Acute pain usually occurs in response to tissue injury. Tissue injury activates peripheral pain receptors, which send impulses along sensory nerves to our central nervous system. Acute pain serves a very important purpose – informing us about injury or potential injury. Without pain, we would for example not have the reflex to take our hand off a hot plate and might experience significant tissue damage as a result. Acute pain is one of the essential mechanisms that we have evolved to preserve the integrity of our body.
Chronic pain is quite different in that it may, or not, be related to ongoing tissue injury. Diseases like cancer or injuries like disk herniations can cause long-lasting pain. In some cases, however, pain persists beyond the time required to repair an initial, self-limited injury. Pain then starts a life of its own, existing in the absence of ongoing painful stimuli. This is due to the sensitisation (or activation) of nerves and other elements of the nervous system by repetitive stimuli. In other cases, chronic pain arises due to damage to the pain system itself (this is called neuropathic pain). A typical example is the nerve damage occurring in uncontrolled diabetes. Unlike acute pain, pain that exists in the absence of painful stimuli doesn’t protect us from any danger and thus doesn’t serve any evolutionary purpose.
Chronic pain is often associated with psychological distress, depression and anxiety, which can contribute to make the pain worse. Whereas the treatment of acute pain will focus on physical aspects (i.e. addressing the causative injury), the treatment of chronic pain requires a more multidimensional approach, also addressing the psychological aspects of the condition. This is all the more important as psychological factors are significant modulators of pain. In this context, mind-body therapies such as relaxation and meditation may have an essential role to play.
Originally written by Nicolas Roost for LiveBeingFit (www.livebeingfit.com)