form the chiropractic subluxation. spinal kinesiopathology neuropathophysiology/neuropathology myopathology histopathology biochemical changes diagnosis historically, the detection of spinal misalignment (subluxations) by the chiropractic profession has relied on x-ray findings and physical examination. at least two of the following four physical signs and/or symptoms must be documented to qualify for reimbursement : pain and tenderness asymmetry/misalignment range of motion abnormality tissue/tone changes rationale 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. 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 misalignment 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. procedure 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 adjustment is the primary procedure used by chiropractors in the adjustment. disagreement amongst practitioners the chiropractic subluxation is the heart of the split between "straight" and "mixer" chiropractors. straight chiropractors continue to follow palmer's vitalistic tradition, claiming that subluxation has considerable health effects and also adding a visceral component to the definition, while mixers, as exemplified by the united kingdom's general chiropractic council, consider it a historical concept with no evidence identifying it as the cause of disease. some chiropractors have described the disagreements within the profession about the concept, and have written skeptically about boop as an antiquated idea. in 1992 one wrote: "the main problem we often run into is the bone out of place (boop) concept. it seems we somehow step on toes when we describe the spine as a functioning entity instead of a stack of bones that can be shifted back and forth into the ideal configuration. the boop concept will eventually fade, and we are grateful for its contribution to chiropractic. for many decades, it offered a model to work from. this model has been updated by the rest of the healing profession, but chiropractors have been hesitant to let this antiquated model go. some within our profession hold onto this model with a religious fervor. the chiropractic profession has moved into a new age. the boop concept has been updated and science is ever upon us in the 90s. let's start asking questions again and drive the chiropractic profession kicking and screaming into the 21st century." chiropractor david seaman wrote in 1994 about the "brutal civil war": "according to various gossip columnists in chiropractic, our profession appears to be currently enmeshed in a brutal civil war between boop (bone-out-of-place) practitioners and low back pain practitioners. it should be known that the boopers incorrectly call themselves subluxation-based practitioners. my experience has demonstrated that the boopers do not know enough about subluxation to call themselves subluxation-based chiropractors. we would all do well to not be subluxation-based in the boop sense. it should also be known that this so-called war is really an over-dramatized skirmish between vocal boopers and a theoretical group of anti-chiropractic dcs. i have yet to meet any of these anti-chiropractic dcs. unfortunately, the boopers seem to think that those who do not embrace the totality of boop philosophy are merely non-boopers who are still very pro-chiropractic and appreciate the philosophy of chiropractic from a contemporary and nondogmatic perspective." in an article written in 2004, seaman openly disparaged the idea still propounded by "modern-day advocates of this concept": "... it is essentially impossible to have nerve interference. to summarize, nerve interference is described, by modern-day advocates of this concept, as a reduction of neural or mental impulses, which occurs in response to a bone-out-of-place (boop) subluxation... clearly, the boop subluxation model fails miserably when considered in the light of basic neuroscience facts... boop subluxationists become angry and defensive when the boop model of subluxation is criticized... the reactionary nature of certain boop subluxationists is to accuse those who don't buy into the boop model of being anti-chiropractic – an astonishing leap of ignorance, to say the least. furthermore, anyone who does not buy into the model is trying to "medicalize chiropractic" - another example of low-iq thinking. and if tears do not well up in your eyes when you hear the phrase, "the power that made the body, heals the body," you are accused of having no passion for chiropractic – still another example of depressed, frontal-lobe activity. even worse, if you don't buy into every bizarre, new age, tree-hugging notion that comes down the pike and is circularly attached to subluxation, you will be accused of being an atheist – an excellent example of the need for psychiatrists and the drugs they prescribe." evidence of condition believers within the chiropractic tradition assert that spinal health and function are directly related to general health and well-being, including visceral disorders, but the efficacy and validity of spinal manipulation to address visceral disorders systems remains a source of controversy within the chiropractic profession. although research is ongoing on this topic, conclusions that support the usefulness of spinal manipulation for 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). still other chiropractic researchers stated quite directly: ... early chiropractic philosophy ... considered disease the result of spinal nerve dysfunction caused by misplaced (subluxated) vertebrae. although rejected by medical science, this concept is still accepted by a minority of chiropractors. ... indeed, many progressive chiropractors have rejected the historical concept of the chiropractic subluxation in favor of ones that more accurately describe the nature of the complex joint disfunctions they treat." 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." edzard ernst has stated that the "core concepts of chiropractic, subluxation and spinal manipulation, are not based on sound science." 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: subluxation syndrome is a legitimate, potentially testable, theoretical construct for which there is little experimental evidence. acceptable as hypothesis, the widespread assertion of the clinical meaningfulness of this notion brings ridicule from the scientific and health care communities and confusion within the chiropractic profession. we believe that an evidence-orientation among chiropractors requires that we distinguish between subluxation dogma vs. subluxation as the potential focus of clinical research. we lament efforts to generate unity within the profession through consensus statements concerning subluxation dogma, and believe that cultural authority will continue to elude us so long as we assert dogma as though it were validated clinical theory. other chiropractors have declared its unproven status as an area that needs reform: some may suggest that chiropractors should promote themselves as the experts in "correcting vertebral subluxation." however, the scientific literature has failed to demonstrate the very existence of the subluxation. until and unless sound research published in credible journals demonstrates the existence and reliable identification of vertebral subluxation, and vertebral subluxation is found to be an important public health problem, society at large will not care about its correction. thus, "subluxation correction" alone is not a viable option for chiropractic's future. a beth israel deaconess medical center article describes the mainstream understanding of vertebral subluxation theory: since its origin, chiropractic theory has based itself on "subluxations," or vertebrae that have shifted position in the spine. these subluxations are said to impede nerve outflow and cause disease in various organs. a chiropractic treatment is supposed to "put back in" these "popped out" vertebrae. for this reason, it is called an "adjustment." however, no real evidence has ever been presented showing that a given chiropractic treatment alters the position of any vertebrae. in addition, there is as yet no real evidence that impairment of nerve outflow is a major contributor to common illnesses, or that spinal manipulation changes nerve outflow in such a way as to affect organ function. in 2009, four scholarly chiropractors concluded that epidemiologic evidence does not support chiropractic's most fundamental theory. since its inception, the vast majority of chiropractors have postulated that "subluxations" (misalignments) are the cause or underlying cause of ill health and can be corrected with spinal "adjustments." after searching the scientific literature, the chiropractic authors concluded: no supportive evidence