Chiropractic Spinal Adjustments,
Changes in Organ Systems
& Treatment of Disease
A literature review and report on the positive effects of chiropractic on the autonomic nervous system, heart function and the circulatory system
A report on the scientific literature
By: Mark Studin DC, FASBE(C), DAAPM, DAAMLP
William Owens DC, DAAMLP
Citation: Studin M., Owens W., (2015) Chiropractic Spinal Adjustments, Changes in Organ Systems and Treatment of Disease, The American Chiropractor, 38(11) 20, 22-25
A report on the scientific literature
The autonomic nervous system is the part of the nervous system that supplies the internal organs, including the blood vessels, stomach, intestine, liver, kidneys, bladder, genitals, lungs, pupils, heart, and sweat, salivary, and digestive glands.
The autonomic nervous system has two main divisions:
After the autonomic nervous system receives information about the body and external environment, it responds by stimulating body processes, usually through the sympathetic division, or inhibiting them, primarily through the parasympathetic division. The autonomic nerve pathway involves two nerve cells. One cell is located in the brain stem or spinal cord and is connected by nerve fibers to the other cell, which is located in a cluster of nerve cells (called an autonomic ganglion). Nerve fibers from these ganglia connect with internal organs. Most of the ganglia for the sympathetic division are located just outside the spinal cord on both sides of it. The ganglia for the parasympathetic division are located near or in the organs they connect with.
The autonomic nervous system controls many internal body processes such as the following:
Many organs are controlled primarily by either the sympathetic or the parasympathetic division. Sometimes the two divisions have opposite effects on the same organ. For example, the sympathetic division increases blood pressure, and the parasympathetic division decreases it. Overall, the two divisions work together to ensure that the body responds appropriately to different situations. (Low, 2015, http://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/autonomic-nervous-system-disorders/overview-of-the-autonomic-nervous-system)
As you can see by the above definition, the human body is in large part controlled by autonomic or automatic nerves, the kind that function without your control. The question that has arisen throughout the years in chiropractic is, “Can the chiropractic spinal adjustment have an effect on those nerves and with that, can disease process or pathology be influenced? The question of the chiropractic spinal adjustment positively effecting pain through the brain connection (central nervous system) has already been conclusively established.
As reported these authors in 2015, the chiropractic adjustment produces direct and measureable effects on the central nervous system across multiple regions which is responsible for the processing of emotion (cingulate cortex, aka limbic cortex) and the insular cortex, which is also responsible for regulating emotion as well as homeostasis. The motor cortex is involved in the planning and execution of voluntary movements, the amygdala’s primary function is memory and decision making (also part of the limbic system), the somatosensory cortex is involved in processing the sense of touch (remember the homunculus) and, finally, the periaqueductal gray is responsible for descending pain modulation (the brain regulating the processing of painful stimuli).
The next question then becomes, “Can the chiropractic adjustment cause the central nervous system to effectuate changes in those systems that regulate our organs through the autonomic nervous system?” When studying the autonomic nervous system, according to Welch and Boone (2008), “Because of the proximity of the upper cervical vertebrae to the brainstem, parasympathetic influences dominate these segmental levels; and therefore, a cervical adjustment could likely result in a parasympathetic response (slowing down of heart beat, lowering of BP, constriction of pupils). In those spinal regions where sympathetic innervation is substantial (upper thoracic and upper lumbar), a chiropractic adjustment could elicit a sympathetic response (stimulation of heart beat, raising of BP, dilation of pupils” (p. 87).
In this study, the findings after a cervical adjustment were linked to an increase in parasympathetic dominance. This was apparent when observing the changes occurring in pre- to post-adjustment HRV [heart rate variability] total power that reflects the balance between LF [low frequency] (ie, sympathetic tone) and HF [high frequency] (e, parasympathetic tone). It was evident that, in each patient, the pre- to post-adjustment decrease in LF/HF [low frequency/high frequency] was due to either a larger increase in parasympathetic activity or a lesser decrease in parasympathetic activity when compared with sympathetic activity. These findings are consistent with other studies that have linked upper cervical chiropractic adjustments to parasympathetic mediated regulatory systems.
Among those individuals receiving thoracic adjustments, the findings indicated that the responses were sympathetic in nature…Heart rate variability data revealed that total power, which is a measure of total autonomic signal, decreased substantially post-adjustment. When considering the balance between parasympathetic/sympathetic activity (LH/HF) [low frequency/ high frequency], it was evident that, in each patient, the pre- to post-adjustment decrease in LH/HF [low frequency/high frequency] was due to either a larger increase in sympathetic activity or a lesser decrease in sympathetic activity when compared with parasympathetic activity. These findings are consistent with other studies that have linked thoracic chiropractic adjustments to sympathetic mediated regulatory systems.” (p. 90-91).
Budgell and Hirano (2001) reported, “…authentic spinal manipulation was associated with changes in heart rate and heart-rate variability, which could not be duplicated with sham manipulation. The distinguishing features of the authentic manipulation are the high-velocity, low-amplitude thrust applied to and resulting in cavitation of an intervertebral joint. The authentic manipulative procedure employed in this study has been widely used in clinical trials of the effects of spinal manipulation on headache and biomechanical disorders of the neck” (p. 98).
Budgell and Polus reported in The Journal of Manipulative and Physiological Therapeutics (2006) that chiropractic adjustments of the thoracic spine were associated with significant heart rate values and influenced the autonomic output of the heart, meaning that the heart rate generally lowers with the chiropractic adjustment because of the shift in the neurological communication of the autonomic nervous system (to the parasympathetic nerves) causing the heart to slow or normalize. This study by Budgell and Polus offers potential answers to many as to why patients' heart rates spike for no apparent reason. The spine, although a great influence to the nervous system, has often been overlooked in the clinical arena as the prime cause for cardiac issues. The authors of this article want to emphasize that chiropractic care has a positive effect for many conditions, including cardiac, and should be consideredin conjunction with necessary treatment from all other health care specialists, as clinically indicated, in order to make a conclusive diagnosis to rule out life-threatening illnesses.
Ward, Coats, Tyer, Weigand, and Williams (2013), found that in an upper thoracic manipulation (mobilization) of the thoracic spine, “There was no statistically significant or clinically relevant difference found between groups for any of the cardiovascular measurements at any time point” (p. 107). This study would appear to overturn the previous findings of autonomic change as a sequella to a chiropractic adjustment. However, if you look carefully at the study limitations, you will realize that this study strongly suggests that chiropractic has perhaps the “only solution” to effect autonomic changes.
Ward et al. (2013) included the following points under the heading “Study Limitations.” “The population that we sampled was composed of chiropractic students who regularly receive spinal manipulation. It is possible that the general public who do not receive regular chiropractic manipulation may react differently than individuals who receive spinal manipulation more frequently. In our design, we did not attempt to exclusively manipulate fixated segments of the upper thoracic spine. It may be argued that, if a patient had a painful fixated spinal segment that was manipulated, the results of this study may have been different…Last, our study participants were young and relatively normotensive” (p. 108-109).
The limitations also suggest that the treatment rendered was a joint mobilization, similar to what physical therapy is designed to do and not a chiropractic spinal adjustment. There were no fixations, and a as result, no negative neurological sequelae. In addition, this study was performed on young, healthy chiropractic students who have been getting chiropractic adjustments on a regular basis, probably removing any aberrant neurological issues prior to this study. It is highly unlikely there were significant biomechanical alterations in this study population again, due to age and frequency of chiropractic care.
Additionally, the lead author of this article, over the course of 5 years in private practice, did pre- and post-extremity Doppler studies on a “sick” population that was not receiving any chiropractic care and observed the same results as Welch and Boone stated above. In addition, Ward et al. (2013) appear to have validated why a chiropractic adjustment on a historical “chiropractic subluxated” region must be “adjusted chiropractically” to have the benefit of autonomic changes. It is the chiropractic “diagnosis” of the functional spinal biomechanical abnormality that is the expertise of the doctor of chiropractic, not simply the act of the therapeutic adjustment to treat neuromuscular negatively affected regions and not simply mobilize segments.
Chronic pain patients were studied by Kang, Chen, Chen and Jaw (2012). Their focus was on the following: sleep disorders, pain scales, pressure pain thresholds, disability indexes and heart rate variability analysis. Although these authors have touched on many areas that have been reported to have a positive influence by chiropractic care, for the purpose of this review we are focusing on heart rate variability. Kang et al. (2012) reported, “Heart rate variability (HRV) analysis, initially developed to evaluate the prognosis of cardiac diseases, has been utilized to assess autonomic functions in chronic pain conditions…The autonomic nervous system plays an important role in the pathogenesis of chronic muscle pain. The autonomic dysfunction in fibromyalgia is characterized by persistent autonomic hyperactivity at rest and hypo-reactivity during stress. In addition, HRV analysis in patients with chronic low back pain has shown that a greater level of disability is associated with a lower HRV” (p. 797). They continued, “Our results are similar to a previous study demonstrating that in participants with chronic low back pain, decreased HRV is significantly associated with a higher index of perceived disability but not with pain intensity itself…It has long been postulated that autonomic regulatory dysfunction is involved in the pathogenesis of several chronic pain conditions” (Kang et al., 2012, p. 801). They concluded, “…reduced HRV was associated with subjective disability in patients with chronic neck pain” (Kang et al., 2012, p. 802).
Kang et al. (2012) stated, “The pathologic mechanism of chronic neck pain is still not understood and is a multifactorial disease… Chronic neck pain is difficult to treat. Treatment options must include multimodal, interventions combining physical agents, oral medications, local injections, and adequate exercise” (p. 800). This prevailing message perpetuates previous reports in the literature and further solidifies that allopathy has no solutions for mechanical cervical spine chronic pain. Apkarian ET. Al. (2004) reported that “Ten percent of adults suffer from severe chronic pain. Back problems constitute 25% of all disabling occupational injuries and are the fifth most common reason for visits to the clinic; in 85% of such conditions, no definitive diagnosis can be made.” (pg. 10410) Apkarian, Hashmi, and Baliki (2011) reported “Clinically, the most relevant conditions in which human brain imaging can have a substantial impact are chronic conditions, as they remain most poorly understood and minimally treatable by existing [medical] therapies” (p. S53).” In essence, what these authors are stating is that although many people suffer from chronic spine pain, very few of them are actually diagnosed with a “medical condition,” aka an “anatomical” lesion. The chiropractic profession has long professed the lesion is actually functional and based on aberrant spinal biomechanics (subluxation) or mechanical spine pain (no fracture, tumor or infection). That, in fact, is what places chiropractic in the unique role in the diagnosis and management of biomechanical spine pain. When we lead with “chiropractic spinal assessment,” we have no competition in medicine or rehabilitation.
Peterson, Bolton, and Humphreys (2012) “…investigate[d] outcomes and prognostic factors in patients with acute or chronic low back pain (LBP) undergoing chiropractic treatment” (p. 525). In chronic LBP, recent studies indicate that significant improvement is often fairly rapid, usually by the fourth visit, and that patients initially receiving treatment 3 to 4 times a week have better outcomes” (Peterson et al., 2012, p. 526). “Patients with chronic and acute back pain both reported good outcomes, and most patients with radiculopathy (neurogenic) also improved” (Peterson et al., 2012, p. 525). “At 3 months…69% of patients with chronic pain stated that they were either much better or better” (Peterson et al., 2012, p. 538). This is unlikely to be due to the natural history of low back pain because these patients have already passed the period when natural history occurs.
A study by Tamcan et al. (2010) was the only population-based study of the so called “natural history” of lower back pain and the authors found the “natural history” of chronic lower back pain was not ending in resolution of symptoms, but instead they documented patients moving “in and out” of a level of pain they could tolerate. Based on the only population-based study of chronic lower back pain, the idea that the natural history of lower back pain ends with a resolution of symptoms is completely false and something that is merely perpetuated by our present healthcare system.
Lawrence et al. (2008) reported, “Existing research evidence regarding the usefulness of spinal adjusting… indicates the following…1. As much or more evidence exists for the use of SMT [spinal manipulation] to reduce symptoms and improve function in patients with chronic LBP as for use in acute and subacute LBP” (p. 670). “…the manual therapy group showed significantly greater improvements than did the exercise group for all outcomes. Results were consistent for both the short-term and the long-term” (Lawrence et al., 2008, p. 663). We see in this study, as in others, that biomechanical alterations in the human spine, aka spinal subluxation, must be diagnosed and treated. They cannot simply be exercised or mobilized away. This is the unique domain of the doctor of chiropractic.
Dunn, Green, Formolo, and Chicoine (2011) reported, “The clinical outcomes achieved for this sample should be considered within the context of this veteran patient base, which is typically represented by older, white males with multiple comorbidities. A high percentage of overall service-connected disability was noted, with only a small percentage associated with the low back region. Considerable psychological comorbidity was found, with a high prevalence of PTSD [post-traumatic stress disorder] and depression diagnoses. PTSD and chronic pain tend to co-occur and may interact in a way that can negatively affect either disorder. A previous retrospective study of chiropractic management for neck and back pain demonstrated less improvement among those with PTSD. These points are significant because severe comorbidities and psychosocial factors lessen the likelihood of obtaining positive outcomes with conservative measures, including SMT [chiropractic adjustments], for chronic LBP [low back pain]. Mean percentages of clinical improvement exceeded the MCID [minimum clinically important difference], despite the levels of service-connected disability and comorbidity among this sample of veteran patients” (pg. 930). They went on to conclude that in spite of significant comorbidities that historically compromise positive results, 60.2% of patients met or exceeded the minimum clinically important difference for improvement.
The above studies verify that allopathy cannot conclude an accurate diagnosis for chronic back or neck pain while chiropractic reportedly helps resolve these issues 69% of the time as reported in the literature. The authors of this paper have currently practiced for a combined 52 years and can confirm, based upon our observations in the private practice setting, that the percentage is closer to 95% for resolving mechanical spine pain. Although this is an observation and could appear unusually high, that is an accurate accounting of both our experience and that of many other practicing chiropractors who we have informally polled.
Therefore, the above studies, excluding Ward et al. (2013), strongly, suggest that the autonomic nervous system has a direct cause and effect relationship with the chiropractic spinal adjustment and verifies another central nervous system connection. They also verify that chiropractic has demonstrated solutions in today’s healthcare system that can help prevent autonomic aberrant effects of chronic pain on heart rate variability and other related disabilities where allopathy has failed.
When we consider disease care, it is critical to consider the autonomic connection and the effect of chiropractic care as that is part of the equation for scientifically validating many observational conclusions that doctors of chiropractic have realized in their offices over the last century. In addition, this and other central nervous system connection show promising results as the foundation for determining how organs and disease react to the chiropractic spinal adjustment. Although the literature does confirm this hypothesis, it is based on millions getting well observationally and science simply needed time to catch up. Although we now are beginning to realize many answers there is still quite a way to go in our understanding… but we are just that much closer with understating more of the adjustment-central nervous system-autonomic nervous system-disease connection.
1. Low, P. (2015). Overview of the autonomic nervous system. Merck Manual Consumer Version, Retrieved from http://www.merckmanuals.com/home/brain-spinal-cord-and-nerve-disorders/autonomic-nervous-system-disorders/overview-of-the-autonomic-nervous-system
2. Studin, M., & Owens W. (2015). Research proves chiropractic adjustments effect emotions, learning, memory, consciousness, motivation, homeostasis, perception, motor control, self-awareness, cognitive function, voluntary movement, decision making, touch and pain: BRAIN CONNECTION. US Chiropractic Directory. Retrieved from http://uschirodirectory.com/research/item/744-research-proves-chiropractic-adjustments-effect-emotions,-learning,-memory,-consciousness,-motivation,-homeostasis,-perception,-motor-control,-self-awareness,-cognitive-function,-voluntary-movement,-decision-making,-touch-and-pain.html
3. Welch, A., & Boone, R. (2008). Sympathetic and parasympathetic responses to specific diversified adjustments to chiropractic vertebral subluxations of the cervical and thoracic spine. Journal of Chiropractic Medicine, 7(3), 86-93.
4. Budgell, B., & Hirano, F. (2001). Innocuous mechanical stimulation of the neck and alteration in heart-rate variability in healthy young adults. Autonomic Neuroscience: Basic and Clinical 91(1-2), 96-99.
5. Budgell, B., & Polus, B. (2006). The effects of thoracic manipulation on heart rate variability: A controlled crossover trial.Journal of Manipulative and Physiological Therapeutics, 29(8), 603-610.
6. Ward, J., Coats J., Tyer, K., Weigand, S., Williams, G. (2013). Immediate effects of anterior upper thoracic spine manipulation on cardiovascular response. Journal of Manipulative and Physiological Therapeutics, 36(2), 101-110.
7 Kang, J. H., Chen, H. S., Chen, S. C., & Jaw, F. S. (2012). Disability in patients with chronic neck pain, Heart rate variability analysis and cluster analysis. Clinical Journal of Pain, 28(9), 797-803.
8. Apkarian V., Sosa Y., Sonty S., Levy R., Harden N., Parrish T., Gitelman D., (2004) Chronic Back Pain Is Associated with Decreased Prefrontal and Thalamic Gray Matter Density, The Journal of Neuroscience, 24(46) 10410-10415
Apkarian, A. V., Hashmi, J. A., & Baliki, M. N. (2011). Pain and the brain: Specificity and plasticity of the brain in clinical chronic pain. Pain, 152(Suppl. 3), S49-S64.
9. Peterson, C. K., Bolton, J., & Humphreys, B. K. (2012). Predictors of improvement in patients with acute and chronic low back pain undergoing chiropractic treatment. Journal of Manipulative and Physiological Therapeutics, 35(7) 525-533.
10. Tamcan, O., Mannion, A. F., Eisenring, C., Horisberger, B., Elfering, A., & Müller, U. (2010). The course of chronic and recurrent low back pain in the general population. Pain, 150(3), 451-457.
11. Lawrence, D. J., Meeker, W., Branson, R., Bronford, G., Cates, J. R., Haas, M., Hawk, C. (2008). Chiropractic management of low back pain and low back-related leg complaints: A literature synthesis. Journal of Manipulative and Physiological Therapeutics, 31(9), 659-674.
12. Dunn, A. S., Green, B. N., Formolo, L. R., & Chicoine, D. (2011). Retrospective case series of clinical outcomes associated with chiropractic management for veterans with low back pain. Journal of Rehabilitation Research & Development, 48(8), 927-934.