What is Chronic Pain?

Introduction:

Chronic pain is often dismissed because it is a medical condition frequently misunderstood.  The lack of understanding of the mechanisms by which chronic pain exists in the patient’s body has stark consequences.  Chronic pain patients are
often told by medical practitioners that if their pain persists for 6 months or
longer that they are experiencing some sort of psychological pathology commonly
interpreted as separate and distinct from the patients’ pain.  The other common scenario that pain patients encounter is being labeled as exhibiting “drug seeking behavior” especially if patients seek out different specialists for relief.  This entry is my attempt to define chronic pain.  Chronic pain is a complicated physiological process that will require, at times, the use of scientific language.  It is important, however, for patients to understand the mechanisms by which they are experiencing pain not
just for the purpose of legitimacy—to be able to say that the severity by which
they are suffering correlates to a problem within the body—but to gain
knowledge of the disease which altered their life so dramatically.  But in defining chronic pain I want to show that clinicians and researchers have yet to fully understand pain, even in acute situations, and treating a mystery is nearly impossible.

There is a quote that I was given by a pain psychologist: “the reign of pain falls
mainly on the brain” and it certainly does, but not in the way we habitually
encounter and think about pain.   Under acute pain situations, an injury or noxious stimulation causes specialized nerve fibers called nociceptors, to trigger pain.  Noxious stimulation in its simplest terms is anything that that the body senses could potentially cause tissue damage (e.g., extreme temperatures and loud noises).
Therefore, pain has its own receptor, nociceptors, that respond to either tissue damage or a threat to tissue damage.  From an acute standpoint, pain is evolutionarily necessary, beneficial, adaptive, one of the most important senses, and normal.  As a result, the body is
accordingly prepared for pain; and has established nociceptors located densely
in the skin and mucous membranes (the lining of passageways that are open to
the exterior environment: digestive, respiratory, urinary, and reproductive
tracts), in practically every organ of the body, in the meninges (membranes
that lie between the nervous tissue and bone) of the brain, but not in the
brain itself.  The damaged tissue release chemicals that stimulate the nociceptors that then trigger pain.

If there is an input into our bodies’ system that triggers specialized pain receptors,
such as an injury, our bodies’ eventually restores the system back to normal.   Under chronic pain conditions, this recuperative process becomes disordered where the body is no longer following the process of injury and, therefore, pain.  This chaos in the bodies of chronic pain sufferers is most likely due to ongoing nociceptive feedback where the
receptors are continuously stimulated or the intensity of the injury and pain
within the body.  What is often made unclear to patients experiencing pain both chronic and acute is that the pathway of pain is often difficult for clinicians and researchers to locate because pain travels through varied and complex routes and the sensation can
originate anywhere along these routes before arriving at the brain.  When the brain receives the pain signals it relays these signals to two parts of the brain via neurons (third order).  For the purpose of this essay, let’s consider neurons to be communicators of the nervous system that are excitable meaning they respond to environmental stimuli, conductors that produce electrical signals to other cells in distant locations, and neurons secrete neurotransmitters that stimulate the next cell. The science of chronic pain was in the past explained by what is commonly referred to as “a miss-firing of the synapses” within the stimulation process.  When a nerve signal reaches the end of an axon and cannot go further, it triggers neurotransmitters that stimulate electrical or chemical impulses in the next cell by way of a synapse.  This is how neurons “communicate” with one another.  However, research recently highlighted that synapse may not alone release signals to the other neurons to fire but axons transmit important messages to other neurons as well.  What is clear about chronic pain seems to be that its persistence and existence in the body remains unclear.  What chronic pain is not is a symptom of physiological or psychological weakness in an individual.  It is not a symptom of
hypochondria nor can an individual positive-think themselves out of pain.  Inadequate understandings of the complex mechanisms of chronic pain or even the basic tenants of chronic pain in the medical community are therefore translated into patients and their families understanding of pain and into the very management that should provide
relief.  A closer look at the theories ofthe causes of chronic pain will be explored in my next blog.

Photo courtesy of Society for Neuroscience