This article aims to provide some insight into the nature of pain and is not meant to be prescriptive. If you suffer from chronic pain, it is recommended that you visit your physician for treatment options and/or a referral to a pain clinic.
Pain has been defined as:
an unpleasant sensory and emotional experience associated with actual or potential tissue damage – International Association for the Study of Pain
Pain is most commonly triggered by a noxious physical, chemical, or electrical stimulus. While most pain usually resolves once the noxious stimulus is removed and the body has healed, in many cases pain persists after both events have happened. Pain that continues for more than three months defines chronic pain.
Astoundingly, almost one in three people live with some form of chronic pain. Understanding of the mechanisms of pain signals and how the brain modulates them may provide insight on strategies for deflecting some of pain’s misery.
The types of pain can be grouped into 3 classes:
1. Nociceptive pain, triggered by sensory nerve fibers in the skin called nociceptors. The types of nociceptors are categorized by what activates them: mechanical (pressure, tearing, crushing); thermal (heat or cold); chemical (salt, histamine released from damaged tissue), and some respond to more than one stimuli type and are called polymodal. Nociceptive pain can also be categorized as to its depth within the body: superficial somatic, deep somatic or visceral.
Superficial somatic pain is sensed by nociceptors in the skin or subcutaneous tissue, and is sharp, clearly defined and easily located, e.g. minor cuts or burns.
Deep somatic pain comes from nociceptors in muscles, tendons, ligaments, connective tissue, blood vessels or bones, and is dull, aching and poorly localized, e.g. sprains.
Visceral pain comes from nociceptors in organs deep in the body that respond to inflammation, stretch and ischemia but not so much to cutting or burning. Visceral pain is vague, hard to locate and the sensation is sometimes sent by nerves to or near the surface of the body such as the skin. Visceral pain may present with nausea, vomiting, or a dull, deep squeezing feeling, e.g. ischemic heart pain can be felt as pain in the jaw, left arm or other places, and often comes with nausea and chest pressure.
2. Inflammatory pain (associated with tissue damage and the infiltration of immune cells into the damaged tissues);
3. Pathological pain (related to a disease state that damages the nervous system or causes its abnormal function - e.g. fibromyalgia, tension headache, or peripheral neuropathy). Peripheral neuropathic pain (often experienced by diabetics) can feel like burning, tingling, stabbing, electrical shocks or pins and needles.
Once stimulated, nociceptors send electrochemical signals along their nerve fibers to the spinal cord into a complex multi-branched path that is modulated at various points along the way and is fed into many different parts of the brain with the result that what you feel depends upon how exactly the brain has processed the signal.
Interestingly, if a nerve pathway is severed between a painful body part and the brain, there will be no feeling of pain, indeed, no feeling at all. This is why quadriplegics for example, do not feel sensory stimuli below the level of the damaged area of their spinal cord.
Once stimulated, sensory receptors such as nociceptors send electrochemical signals along nerve fibers to the spinal cord.
Pain signals going to the brain are similar in that you have some degree of control over how the signals are interpreted, although you need to learn a special technique to help you turn down the volume on your pain or to adjust its colour. I’ll talk more about these techniques in Part II at a later date.
While pain medications such as opioids are generally effective for dealing with acute pain, they are much less effective at diminishing chronic pain. This medical reality can lead to frustration and disappointment in chronic pain sufferers who don’t understand this fact and visit many doctors, trying many different drugs in search of the “magic bullet” which doesn’t exist.
Tolerance to opioid drugs builds up quickly after using them for a number of weeks, requiring ever increasing doses to achieve the same result. Physical dependence occurs, making it seem like there is no alternative for combatting the pain. Dangerously, opioids have the side-effect of depressing respiration, and with higher doses can stop breathing completely, as we are seeing with the current opioid crisis and high death toll. It has become apparent that opioids are not the sole answer for chronic pain.
The key point I want to make is that pain signals are modulated by many different areas of the brain, causing the experience to vary with situational, social, gender and cultural factors, and the nature of the attention you give to it. Soldiers in battle, for example, can sometimes suffer grievous injuries yet not feel pain . While this is partly because the body releases endorphins that are the body's natural "opioids", a more significant factor seems to be that their attention is focused on what is going on around them rather than on their bodies.
Science has shown that it is possible for some people, experienced meditators for example, to train their mind to channel their attention to a painful stimulus, acknowledge it, and then to divert their attention to something else such as their breathing, diminishing or eliminating their experience of pain. While meditation may or may not turn out to be helpful for you, the key point here is that we do have some conscious control over our brain's "attention channel", and there are several types of therapies that are based upon this principle. Watch for my next article in which I will explore these ideas in greater detail.
Sometimes it is not possible to eliminate pain completely, and you will always have a certain level of background pain. However, knowing that there are ways that you can modify how your brain interprets pain signals can open up opportunities to explore ways of doing this, reducing or eliminating your need for pain medications.
As a chronic pain sufferer, I have come to this realization, and while it is not ideal, I have more or less figured out what activities I can and cannot do within my limitations. This allows me to pursue some of the things that give me the greatest enjoyment in life, and I hope to share more with you in a future article. In the meantime, for more information about the nature of pain, I recommend the Wikipedia article on pain.