This document was written to explain the science of chiropractic. Most of the physiology discussed was prepared by Dr. James L. Chestnut B.Ed., M.Sc., D.C., C.C.W.P.
You have 24 movable bones in your spine called vertebrae. Whenever two of these vertebrae bones come together at an articulation or joint, there can be movement. There can be too little movement or too much. Since joints in your spine are so close to your spinal cord and nerve roots, too much or too little joint motion can have serious effects. This aberrant motion is called a subluxation.
The key to comprehending the global pathological effects of the subluxation complex lies in understanding that the structural component (decreased or aberrant motion and/or slight static or dynamic facet joint misalignment – Kinesiopathology) results in both increased nociceptive input into the Central Nervous System (most of which is subconscious or asymptomatic) and decreased proprioceptive (mechanoreceptor) input into the CNS (afferent neuropathology) that also occurs subconsciously or asymptomatically. A facet joint is an articulation between vertebrae where most of the stress or load bearing weight is applied.
Once it is established that both symptomatic and asymptomatic subluxation complex result in increased nociception and decreased proprioception and that these changes contribute to a chronic increased stress response and a state of chronic catabolism in the host (pathophysiology – allostasis), the concept of subluxation complex leading to or contributing to global physiological changes that make the host more susceptible to disease and illness becomes scientifically sound.
The aberrant motion and alignment (kinesiopathology) associated with the subluxation complex also leads to joint and muscle degeneration(myopathology, connective tissue pathology and biochemical changes) and motor control errors in the vestibulospinal tract (efferent neuropathology), resulting in decreased strength, balance, and coordination, which in turn lead to increased susceptibility to both injury and degeneration.
Increased nociception can lead to sensitization of the nociceptive pathways both peripherally and centrally via the process of synaptogenesis or neuroplasticity. This sensitization process results in lowered firing thresholds and has been documented to lead to allodynia (non-noxious stimulus like light touch resulting in pain). Again, it is important to understand that an increase in nociception does not necessarily mean an increased in conscious pain. Pain is the cortical, emotional response to nociceptive information that reaches the cortex and there can be a great deal on nociceptive input that does not reach the conscious brain. Nociception is the detection of noxious stimuli or stressors and the body responds accordingly by increasing the stress response and associated stress hormones, such as catecholamines(epinephrine/norepinephrine) and cortisol. The metabolically compromising effects of a chronic increased stress response have already been documented. Thus, subconscious or asymptomatic as well as symptomatic subluxation complex metabolically compromise the host and lead to decreased physiological function and concomitant decreased disease resistance and increased disease susceptibility.
The key to comprehending that subluxation complex can be eliciting metabolically compromising changes in the host without symptoms lies in understanding that the nociception, muscle spasm, vasoconstriction, and decreased proprioception associated with the subluxation complex are physiological processes and do not always reach the cortex and provide conscious awareness. This is why individuals can present with an initial bout of back pain and an x-ray examination reveals severe spinal degenerative changes that have been taking place without pain or any other conscious symptoms for years. Based on physiological, biomechanical and histological research we know that a joint that does not have proper motion and alignment is often asymptomatic. The key to joint health and to proper proprioceptive and nociceptive neurology is proper joint motion and alignment. This simply cannot be accurately determined by the presence or absence of symptoms alone.
Chiropractic is now scientifically proven; proper structure of the spine is required for proper function of the nervous system as it relates to the control and regulation of global physiology and health. Have a nice day.