Vertebral subluxation

The vertebral column seen from the side

Vertebral subluxation is a chiropractic term that is used to describe a myriad of signs and symptoms (syndrome) thought to occur as a result of a misaligned or dysfunctional spinal segment. The chiropractic subluxation complex is a functional biomechanical spinal lesion with purported altered neurological function that can result in neuromusculoskeletal and visceral disorders. Officially, the WHO definition of the chiropractic vertebral subluxation is: "A lesion or dysfunction in a joint or motion segment in which alignment, movement integrity and/or physiological function are altered, although contact between joint surfaces remains intact. It is essentially a functional entity, which may influence biomechanical and neural integrity." This is in contrast to the medical definition of spinal subluxation which, according to the WHO, is a "significant structural displacement, and therefore visible on static imaging studies."

The chiropractic vertebral subluxation complex has been a source of controversy and confusion since its inception in 1895 with critics both inside and outside the profession due to its metaphysical origins and claims of far reaching effects. Although research into the significance of the chiropractic vertebral subluxation is ongoing, it generally does not have the support of mainstream medicine.

Components of vertebral subluxation complex

Traditionally there have been 5 components that form the chiropractic subluxation. The vertebral subluxation complex is differentiated by the fifth component, general systemic disturbances secondary to the spinal misalignment (vertebral subluxation).

1. Spinal Kinesiopathology
2. Neuropathophysiology/Neuropathology
3. Myopathology
4. Histopathology
5. Pathophysiology/Pathology

Examination

Historically, the detection of spinal misalignments (subluxations) by the chiropractic profession has relied on X-ray findings and physical examination. At least 2 of the following 4 physical signs and/or symptoms must be documented to qualify for reimbursement:

• Pain and tenderness
• Asymmetry/misalignment
• Range of motion abnormality
• Tissue/tone changes

Background

It has been proposed that a vertebral subluxation can negatively affect general health by altering the neurological communication between the brain, spinal cord and peripheral nervous system. Although individuals may not always be symptomatic, straight chiropractors believe that the presence of vertebral subluxation is in itself justification for correction via spinal adjustment.

Chiropractic treatment of vertebral subluxation focuses on delivering a chiropractic adjustment which is a high velocity low amplitude (HVLA) thrust to the dysfunctional spinal segments to help correct the chiropractic subluxation complex. Spinal manipulation is the primary procedure used by chiropractors in the adjustment. Manipulation has been shown to help with low back pain, neck pain and tension type headaches, but further studies are inconclusive on the use of spinal manipulation outside the treatment of neuromusculoskeletal disorders.

Rationale

According to the founder of Chiropractic, D.D. Palmer:

"Physiologists divide nerve-fibers, which form the nerves, into two classes, afferent and efferent. Impressions are made on the peripheral afferent fiber-endings; these create sensations which are transmitted to the center of the nervous system. Efferent nerve-fibers carry impulses out from the center to their endings. Most of these go to muscles and are therefore called motor impulses; some are secretory and enter glands; a portion are inhibitory their function being to restrain secretion. Thus, nerves carry impulses outward and sensations inward. The activity of these nerves, or rather their fibers, may become excited or allayed by impingement, the result being a modification of functionating — too much or not enough action — which is disease."

Chiropractors use and have used various terms to express this concept: subluxation, vertebral subluxation (VS), vertebral subluxation complex (VSC), and have varying opinions on its philosophical and clinical relevancy.

Functional theories

Spinal nerve roots
The formation of the spinal nerve from the dorsal and ventral roots
A spinal nerve with its anterior and posterior roots.
Details
Identifiers
Latin	radix posterior
Anatomical terminology

V. Strang, D.C., describes several hypotheses on how a misaligned vertebra may cause interference to the nervous system in his book, Essential Principles of Chiropractic.

• Nerve compression hypothesis: suggests that when the vertebrae are out of alignment, the nerve roots and/or spinal cord can become pinched or irritated. While the most commonly referenced hypothesis, and easiest for a patient to understand, it may be the least likely to occur.
• Proprioceptive insult hypothesis: focuses on articular alterations causing hyperactivity of the sensory nerve fibers.
• Somatosympathetic reflex hypothesis: all the visceral organ functions can be reflexly affected by cutaneous or muscular stimulation.
• Somatosomatic reflex hypothesis: afferent impulses from one part of the body can result in reflex activity in other parts of the body.
• Viscerosomatic reflex hypothesis: visceral afferent fibers cause reflex somatic problems.
• Somatopsychic hypothesis: the effects of a subluxation on the ascending paths of the reticular activating system.
• Neurodystrophic hypothesis: focuses on lowered tissue resistance that results from abnormal innervation.
• Dentate ligament-cord distortion hypothesis: upper cervical misalignments can cause the dentate ligaments to put a stress on the spinal cord.
• Psychogenic hypothesis: emotions, such as stress, causing contraction in skeletal muscles.

The vertebral subluxation has been described as a syndrome with signs and symptoms which include: altered alignment; aberrant motion; palpable soft tissue changes; localized/referred pain; muscle contraction or imbalance; altered physiological function; reversible with adjustment/manipulation; focal tenderness.

Scientific investigation

The investigation of vertebral subluxation has been ongoing since it was first postulated in 1895. The early practitioners used palpation and the anatomy of the nervous system as a guide (meric system). In their efforts to be more specific, they seized the newly discovered X-ray technology and introduced the neurocalometer (a heat sensing device). It was during those early years that the medical establishment first criticized the chiropractic profession, saying that the conditions that those early chiropractors were treating were only psychophysiologic disorders. To prove that chiropractic patients had real conditions, BJ Palmer opened a research clinic as a part of the Palmer College of Chiropractic. When a patient entered the clinic, they were first examined by medical doctors and a diagnosis was formulated. They were then sent to the chiropractic part of the clinic, treated, and sent back to the medical doctors for evaluation. Since then, chiropractors have sought a greater understanding of the mechanisms and effects of the vertebral subluxation. Today we see motion x-rays, surface EMG, and digital thermography though none of these methods have been proven to be reliable or valid in the detection of vertebral subluxations.

As research projects are able to employ new techniques and technologies to evaluate nervous system function and effects, further support for chiropractic principles has surfaced. Chiropractors have long suggested that spinal joint fixation that results from subluxation will result in degenerative effects that compromise the spinal joints. A 2004 research team at the National University of Health Sciences evaluated changes of the lumbar vertebral column following fixation (immobility) by surgically fusing spinal joints in experimental rats. The fixated joints showed significant degeneration compared to the mobile joints, confirming that surgical fixation results in time-dependent degenerative changes of the zygapophysial joints.

Autonomic Nervous System
Blue = parasympathetic
Red = sympathetic

Chiropractic also asserts that spinal health and function are directly related to general health and well-being. Preliminary research concerning the intricate functioning of the nervous system suggests that this speculation may have some support. David Seaman, DC, MS reviewed the work of several researchers concerning autonomic nervous system relationship to the somatic tissues of the spine. He noted that Feinstein et al. were the first to clearly describe some symptoms associated with noxious irritation of spinal tissues. They injected hypertonic saline into interspinous tissues and paraspinal muscles of normal volunteers for the purpose of characterizing local and referred pain patterns that might develop. His observations included:

"The pain elicited from muscles was accompanied by a characteristic group of phenomena which indicated involvement of other than segmental somatic mechanisms. . . . The manifestations were pallor, sweating bradycardia, fall in blood pressure, subjective faintness, and nausea, but vomiting was not observed. Syncope occurred in two early procedures in the series of paravertebral injections and was subsequently avoided by quickly depressing the subject's head or by having him lie down at the first sign of faintness. These features were not proportional to the severity of or to the extent of radiation; on the contrary, they seemed to dominate the experience of subjects who complained of little pain, but who were overwhelmed by this distressing complex of symptoms."

Feinstein referred to these symptoms as autonomic concomitants. It is likely that these autonomic concomitants were caused by nociceptive stimulation of autonomic centers in the brainstem, particularly the medulla. Feinstein indicated that "this is an example of the ability of deep noxious stimulation to activate generalized autonomic responses independently of the relay of pain to conscious levels." In other words, pain may not be the symptomatic outcome of nociceptive stimulation of spinal structures. Such a conclusion has profound implications for the chiropractic profession. Clearly, patients do not need to be in pain to be candidates for spinal adjustments.

The efficacy and validity of spinal manipulation to address visceral disorders systems remains and is a source of controversy within the chiropractic and medical communities. Though research is ongoing on this topic, conclusions that support or refute the usefulness of spinal manipulation on organic disorders remains to be seen. Additionally, to complicate matters, chiropractic professors and researchers, Nansel and Szlazak, found that:

"the proper differential diagnosis of somatic (musculoskeletal) vs. visceral (organ) dysfunction represents a challenge for both the medical and chiropractic physician. The afferent convergence mechanisms, which can create signs and symptoms that are virtually indistinguishable with respect to their somatic vs. visceral etiologies, suggest it is not unreasonable that this somatic visceral-disease mimicry could very well account for the "cures" of presumed organ disease that have been observed over the years in response to various somatic therapies (e.g., spinal manipulation, acupuncture, Rolfing, Qi Gong, etc.) and may represent a common phenomenon that has led to "holistic" health care claims on the part of such clinical disciplines." Considering this phenomenon, Seaman suggests that the chiropractic concept of joint complex (somatic) dysfunction should be incorporated into the differential diagnosis of pain and visceral symptoms because these dysfunctions often generate symptoms similar to those produced by true visceral disease and notes that this mimicry leads to unnecessary surgical procedures and medications.

Other chiropractic researchers have also questioned some of the claimed effects of vertebral subluxation:

"The literature supports the existence of somatovisceral and viscerosomatic reflexes, but there is little or no evidence to support the notion that the spinal derangements (often referred to as subluxations by chiropractors) can cause prolonged aberrant discharge of these reflexes. Equally unsupported in the literature is the notion that the prolonged activation of these reflexes will manifest into pathological state of tissues, and most relevantly, that the application of spinal manipulative therapy can alter the prolonged reflex discharge or be associated with a reversal of the pathological degeneration of the affected reflexes or tissues. The evidence that has been amassed is largely anecdotal or case report based and it has attracted much intra disciplinary debate because of its frequent association with certain approaches to management (largely described as being traditional or "philosophical" in nature)."

Researchers at the RMIT University-Japan, Tokyo studied reflex effects of vertebral subluxation with regards to the autonomic nervous system. They found that "recent neuroscience research supports a neurophysiologic rationale for the concept that aberrant stimulation of spinal or paraspinal structures may lead to segmentally organized reflex responses of the autonomic nervous system, which in turn may alter visceral function."

Professor Philip S. Bolton of the School of Biomedical Sciences at University of Newcastle, Australia writes in Journal of Manipulative and Physiological Therapeutics, "The traditional chiropractic vertebral subluxation hypothesis proposes that vertebral misalignment cause illness, disease, or both. This hypothesis remains controversial." His objective was, "To briefly review and update experimental evidence concerning reflex effects of vertebral subluxations, particularly concerning peripheral nervous system responses to vertebral subluxations. Data source: Information was obtained from chiropractic or, scientific peer-reviewed literature concerning human or animal studies of neural responses to vertebral subluxation, vertebral displacement or movement, or both." He concluded, "Animal models suggest that vertebral displacements and putative vertebral subluxations may modulate activity in group I to IV afferent nerves. However, it is not clear whether these afferent nerves are modulated during normal day-to-day activities of living and, if so, what segmental or whole-body reflex effects they may have."

Conclusions: Monitoring mixed-nerve root discharges in response to spinal manipulative thrusts in vivo in human subjects undergoing lumbar surgery is feasible. Neurophysiologic responses appeared sensitive to the contact point and applied force vector of the spinal manipulative thrust. Further study of the neurophysiologic mechanisms of spinal manipulation in humans and animals is needed to more precisely identify the mechanisms and neural pathways involved.

Researchers at the Department of Physiology, University College London studied the effects of compression upon conduction in myelinated axons. Using pneumatic pressure of varying degrees on the sciatic nerves of frog specimens, the studied supported the idea of nerve conduction failure as a result of compression.

Critiques

An area of debate among chiropractors is whether "vertebral subluxation" is a metaphysical concept (as posited in B. J. Palmer's philosophy of chiropractic) or a real phenomenon.

In an article on vertebral subluxation, the chiropractic authors wrote:

"There is nothing inherently dogmatic or anti-scientific in the notion that an articular lesion may have health consequences, or that correction of joint dysfunction may relieve symptoms and/or improve health. Neither does our current inability to predict the effects (if any) of subluxation and/or the benefits of subluxation-correction relegate this hypothetical construct to the dustbin of clinical theories. Indeed, it would be just as inappropriate to dispose of this largely untested theory without data as it is to proclaim its meaningfulness without adequate evidence. On the other hand, as Carl Sagan suggested, extraordinary claims will require extraordinary evidence. With respect to the supposed mechanisms of adjusting, Haldeman reminds us that "What must be avoided... is the unreasonable extrapolation of current knowledge into speculation and presentation of theory as fact." Given the current deficiency of empirical data, the only sound scientific-epistemological position that we can conceive of is to acknowledge our ignorance: we don't know if subluxation is clinically meaningful or not. We suggest that this is a requisite first step toward greater wisdom concerning subluxation."

Since its inception, the concept of vertebral subluxation has been a source of definitional debate. Tedd Koren, DC offers this explanation as a possible cause of the confusion:

The vertebral subluxation cannot be precisely defined because it is an abstraction, an intellectual construct used by chiropractors, chiropractic researchers, educators and others to explain the success of the chiropractic adjustment.

This is not a unique state of affairs, abstract entities populate many branches of science...

Subluxations, genes, gravity, the ego and life are all heuristic devices, "useful fictions" that are used to explain phenomenon that are far larger than our understanding. We use them as long as they work for us and discard or limit their application when they become unwieldy or unable to account for new observations...

Critics of chiropractic have incorrectly assumed that chiropractic is based on the theory or principle that vertebral subluxations cause "pinched" nerves that cause disease. They have it backwards. Chiropractic is based on the success of the spinal adjustment. The theory attempting to explain the success of the adjustment (nerve impingement, disease, subluxations) followed its clinical discovery.

Examples of such erroneous criticisms based on this straw man argument abound in the medical literature. Some examples: "The teachers, research workers and practitioners of medicine reject the so-called principle on which chiropractic is based and correctly and bluntly label it a fraud and hoax on the human race." "The basis of chiropractic is completely unscientific." The theory on which chiropractic is based [is false], namely that a "subluxation" of a spinal vertebra presses on a nerve interfering with the passage of energy down that nerve causing disease to organs supplied by that nerve, and that chiropractic "adjustments" can alleviate the pressure thereby treating or preventing such disease. There is no scientific evidence for the validity of this theory."

To be fair, statements by some chiropractors have tended to perpetuate this misunderstanding: "Pressure on nerves causes irritation and tension with deranged functions as a result."

When chiropractors declare that "pinched nerves" "nerve impingement" "spinal fixations" or others mechanisms of action explain how subluxations affect the person and how chiropractic works they are making the same mistake medical critics make - assuming chiropractic is based on theory. Mechanisms and theories are useful tools, but their limitations should always be kept in mind.

External links

• Vertebral Subluxation in Chiropractic Practice - Council on Chiropractic Practice
• Models of Vertebral Subluxation:A Review - Christopher Kent, DC
• Journal of Vertebral Subluxation Research - A Peer-Reviewed Scientific Journal
• Chiropractic's Elusive Subluxation - Stephen Barrett, M.D.
• Does the Vertebral Subluxation Exist? - Tedd Koren, DC
• Subluxation - The Silent Killer - Ronald Carter, DC, MA, Past President, Canadian Chiropractic Association