Are the little bundles of nerves that exit your spine the wellspring of visceral vitality? Will your organs wilt like neglected house plants if your nerve roots are slightly impinged? This is what many chiropractors would like their customers to believe1 — while others speak out against it. In journals, even.2
The subluxation theory of chiropractic is a pre-scientific idea with a strong streak of vitalism. It was born and promoted over a century ago well before the relevant anatomy and physiology was known, before the foundations of modern neurology were built.
There are many ways of arguing that organ health is not dependent on spinal nerve supply. For instance, nerve roots are quite difficult to “pinch” to any meaningful degree in the first place. But the main point of this article is that …
There is no exclusive or essential neurological connection between spines and organs
It’s not just that visceral tissues don’t benefit much from the life-giving sauce of spinal nerve root signals — they don’t depend on them at all. Only musculoskeletal structures do. Bones, muscles, and skin are completely at the mercy of the big bundles of nerves that pass between vertebrae. Pinch them hard enough and there’s trouble for sure … but not with an organ. Cut a nerve root completely, and you’ll certainly paralyze something … but not an organ.
Spinal nerve roots do not directly “hook up” to organs with a single direct and exclusive connection. Those connections are somewhat indirect and highly redundant — much like the blood supply to most tissues — and the neural supply the organs do get is weirdly unimportant, kind of like your tonsils.3 In fact, organs can be transplanted without hooking them up to any nerves at all!
Critics have been pointing the problems out for a century.
The fundamental dogma of chiropractic, that disease is caused by dislocation or subluxation of the bones of the spinal column, pressing on nerves, is simply a complete misrepresentation of the demonstrated facts.
So how are organs attached to the nervous system?
The body’s organs are innervated primarily by autonomic nerve ganglia and plexuses located outside the spinal column, supplied largely by autonomic cranial and sacral nerves that pass through solid bony openings and by preganglionic spinal cord fibers. The very important vagus nerves traverse openings in the base of the skull and travel down to supply thoracic and abdominal organs. Overlapping autonomic nerve supply from many directions and sources, along with chemical, hormonal, and circulatory factors, assures function of the body’s organs, unaffected by a segmental dysfunction (subluxation) and independent of spinal nerves that are designed primarily to supply musculoskeletal structures.
Organs pretty much run themselves, with just a little bit of optional signalling from mostly non-spinal nerves. Our general health is also regulated (in a big way) by hormone signalling through the fluids of the body, which is also entirely independent of spinal nerve function.
Spines and their nerves are remarkably unimportant in terms of keeping a sack of organs running smoothly.
This is unambiguous biology and anatomy fact, but of course that doesn’t stop some chiropractors from contradicting it. I have received many angry e-mails about this point. I will now turn to those objections … and spend more time with them than with the original point, which is really quite straightforward.
The paralysis rebuttal: the fate of organs after trauma doesn’t mean they depend on spinal nerves
People who suffer serious spinal injuries — paraplegics and quadraplegics — are vulnerable to serious organ dysfunction and systemic health problems over time.6789 Interestingly, the effect on mortality is about the same as a smoking habit.10 This fascinating and terrible phenomenon has been well-documented in medical journals only relatively recently (although patients and doctors were likely aware of it all along).
Surely this means that organs are dependent on (spinal) nerve supply after all? Actually, it almost demonstrates the opposite: it shows how organs are mainly regulated by the autonomic nervous system and not via pathways through the spinal nerves. After complete loss of spinal nerve supply, organs continue to function quite well in the short term, even as movement and sensation are destroyed (paralysis). But the irritation to the spinal cord causes autonomic dysregulation over time, slowly wreaking havoc on organ function.
In other words, organs don’t depend on the spinal cord, but they do partially depend on smooth operation of the autonomic nervous system … and the ANS gets twitchy in response to an injured spinal cord.
Many experts have argued that organ function must not depend on spinal nerves, because they supposedly do not fail in paralyzed patients.11 But they do! A good argument based on a bad premise. Although the true fate of organs in paralyzed patients is important (and scary), it doesn’t actually undermine the main point of this article, just one of the classic arguments for it. There are others!
The bladder rebuttal: one-quarter right and not important
One half-right rebuttal is that incontinence is a well-known symptom of serious spinal nerve root injuries. The bladder is an organ and it can fail with spinal nerve root injury, ergo spinal nerves hook up to organs, ergo chiropractic spinal adjustment can affect organs and general health, ergo this article is wrong.
Actually, I’m not sure that rebuttal is even half right. Maybe one third? One quarter? Let’s clear this up.
The part that’s right: Urinary and fecal incontinence are indeed symptoms of trauma to the lower end of the spine. In this one limited sense, which has pretty much nothing to do with chiropractic adjustments, spinal nerve roots do indeed “hook up” to the bladder and lower bowel. When those nerves are damaged it’s called cauda equina syndrome, and you really don’t want it to happen to you.
So that part’s right. But from that one bit of rightness came a whole bunch of wrong.
The sphincter factor: However, the spinal nerve roots that do this are not causing “organ failure” but “sphincter failure” — failure of the ring-shaped muscles that keep people from leaking.12
The sacral fortress: Furthermore, the nerve roots involved are too low to be affected by any kind of “spinal adjustment.” They emerge from a row of holes in the sacrum, the large wedge of bone between your butt cheeks. 13
Third-class organs: Let’s face it, the bladder and lower bowel barely qualify as organs anyway. I wouldn’t want to live without them, but they are not in the same league as a liver or a kidney. They aren’t “vital” organs. So even if spinal nerve roots were actually critical to bladder health, and even if they could be helped by spinal adjustment, it would hardly be a big win for chiropractic.14 Your health is not determined by your bladder!
And your bladder health is not determined by your spine.
The referral rebuttal
Another common rebuttal to this article is that irritated spinal joints “send” their dysfunction to neighbouring structures. This is much like the well-documented phenomenon of “referred pain” — pain felt at a location other than the source, such as shoulder and arm pain caused by a heart attack. But pain isn’t the only thing that can be referred. For instance, we know that spinal joint pain can affect sympathetic nervous system functions in the structures that the nerve supplies.
But not other structures, as far as anyone knows. Just the tissues the spinal nerves actually connect to directly. Not organs. Or the nerve ganglia that supply them. There is no significant referral effect that might cause organ failure or even suboptimal performance.15
This rebuttal is also not quite relevant to the physiology of impinged spinal nerves, but the physiology of any irritated spinal joint — with or without a nerve pinch — and so it is only tangentially related to the main claim that organ health is compromised by spinal nerve impingement.16 And so the referral rebuttal actually has nothing to do directly with “pinched nerves.” Even if the pinch was real, and even if it could be relieved, it’s hardly a guarantee that the joint itself would not still be seriously cranky.
The referral rebuttal is an explanation in search of a phenomenon. Frank visceral disease simply does not correlate at all with spinal injury and dysfunction, and there is extensive evidence of absence of any therapeutic effect derived from such a relationship.17
The sympathetic rebuttal
There is an indirect neurological connection between spinal nerves and some organs, and some readers have called foul on me for not acknowledging it. So I will now acknowledge it … and explain why it doesn’t really matter.
Yes, there is indeed a type of nerve (sympathetic) that comes out of the spine through the nerve roots (ventral horn), and they do “sort of” affect organs. However, it’s not a direct connection or a strong effect.
After leaving the spine, these nerves do not go far: they deliver one kind of regulatory signal to nerve bundles (ganglia) just outside the spine, and that’s the end of the line for them. The ganglia are like wee tiny little brains, free to make “decisions” to pass those signals on to organs … or not. It’s like getting off at a giant airport and maybe getting on another plane. Maybe.
This isn’t just an academic distinction. The transfer of those signals from spine to organ is not inevitable. It really is a “maybe,” determined by a number of other factors. It is a “connection,” but it’s a very different sort of connection.
There is nothing vital to the vital organs in those nerve fibers. They deliver their signals to complex junctions that continue to do their thing just fine with or without input from the CNS. Even if the flow of information from the CNS is completely interrupted, the ganglia (and the organs) still get most of the information they need from other sources. Because the ganglia are vertically connected by fibres mainly outside the spinal column, sympathetic signals are actually partially routed around nerve root lesions.
As mentioned above, organs mostly run themselves. Their health and function is just not dependent on those signals. This is why, in a general way, organ transplantation is an option: organs need a blood supply to survive in a new body, but they do just fine without hooking up any nerves … and lucky for us, because we don’t have the technology for that.
So this is the difference: motor and sensory neurons span the full distance from tissue to spinal cord — a continuous anatomical connection that is unambiguously critical to muscular action and sensation. The sympathetic nerves have an indirect and definitely non-critical functional connection to organs.
In early versions of this article I felt it was a complex but ultimately irrelevant tangent, that might make my point seem weaker without actually being weaker. However, I got too many irritating complaints from chiropractors who believed I was ignorant of the biology that I decided to publicly explain: not only am I aware of the biology, I am aware that it doesn’t actually support their point, and doesn’t matter in the end.
And what about the parasympathetic?
The autonomic nervous system has two major divisions, the sympathetic nervous system (SNS) and the parasympathetic (PNS), which are responsible for revving things up and calming them down respectively. While the SNS gets more buzz, the benefits of wiggling spinal joints have been attributed to acute effects on both the SNS and PNS. Many chiropractors believe they are “stimulating the parasympathetic nervous system”… which is synonymous with saying that adjustment is “relaxing,” because that’s what the PNS does: when those nerves start firing, we get mellower. Being touched and handled professionally and warmly is usually reassuring and relaxing… but probably not as much as you get from a hot bath or a nice meal with good friends.
The evidence does not support any clinically significant effect on autonomic function, sympathetic or parasympathetic. The results of Picchiottino et al, as summarized in an editorial in a chiropractic journal in 2019:18
Regarding the current state of the knowledge, our main conclusion for manual therapists is that the use of spinal manipulation to obtain specific acute effects on the autonomic nervous system is not supported by scientific evidence.
The straw man rebuttal
Many allegedly reasonable chiropractors have (angrily) asserted to me that this article is bogus because no good modern chiropractor actually believes in subluxation as a spookily powerful tool for broad spectrum healing. But their profession is very much still “clinging to the theory that gave it birth and independence.”19
Despite the controversies and paucity of evidence the term subluxation is still found often within the chiropractic curricula of most North American chiropractic programs.
Funk et al, 2018, Chiropr Man Therap20
I have no doubt that belief in subluxation as the cause of almost any disease is probably on the wane, and there are certainly some progressive chiropractors who explictly reject subluxation — but less than 20% of Canadian chiropractors,21 for example. That’s not nearly enough improvement that the chiropractic profession can claim to be free of that legacy. Criticism of the belief is still warranted and relevant.
Did you find this article useful? Interesting? Maybe notice how there’s not much content like this on the internet? That’s because it’s crazy hard to make it pay. Please support (very) independent science journalism with a one-time donation or RECURRING donation.
See the donation page for more information & options. Exclusive content for patrons coming mid-2021.
About Paul Ingraham
I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter.
What’s new in this article?
2019 — Science update — Discussed acute effects of SMT on the parasympathetic nervous system, and cited Picchiottino et al on the lack of clinically significant effects.
2019 — Added a small section responding to the criticism that this article is attacking a straw man, a belief that modern chiropractors don’t really have. (They really do, actually. In substantial numbers.)
2017 — Important update about autonomic dysregulation of organs after spinal trauma.
2010 — Publication.
- Swain MS, Gliedt JA, de Luca K, Newell D, Holmes M. Chiropractic students' cognitive dissonance to statements about professional identity, role, setting and future: international perspectives from a secondary analysis of pooled data. Chiropr Man Therap. 2021 Feb;29(1):5. PubMed #33526067 ❐ PainSci #51712 ❐
An analysis of survey data from almost 2400 chiropractic students showed that 45% embrace subluxation-based or “straight” chiropractic, strongly emphasizing that this view of chiropractic continues to define the profession well into the 21st Century. Specifically, they agreed that it is important for chiropractors to hold strongly to the traditional chiropractic theory that adjusting the spine corrects “dis-ease.”
- Mirtz TA, Morgan L, Wyatt LH, Greene L. An epidemiological examination of the subluxation construct using Hill's criteria of causation. Chiropractic & Osteopathy. 2009 Dec;17(1):13. PubMed #19954544 ❐ PainSci #55783 ❐
This landmark paper penned by four chiropractors is a strong indictment of a philosophical pillar of their own profession. Although a bit of a moving target over the years, subluxation theory generally refers to the idea that spinal joint dysfunctions have broad health significance, which has been a major component of chiropractic thought since the founding of the profession. The authors analyze and condemn it:
No supportive evidence is found for the chiropractic subluxation being associated with any disease process or of creating suboptimal health conditions requiring intervention. Regardless of popular appeal this leaves the subluxation construct in the realm of unsupported speculation.
And yet it’s been there for more than a century, I’d like to add.
Dr. Harriet Hall explained the significance of the paper in an article for ScienceBasedMedicine.org, The End of Chiropractic.
- Someone’s going to protest that tonsils do matter, that they must have some biological value to us or they wouldn’t be there. Not necessarily, no: evolution is funny that way. It’s true that the benefit of tonsillectomy, especially in adults, is still unclear. However, there seems to be good evidence of absence of any systemic harm from tonsillectomy. For example: “It is reasonable to say that there is enough evidence to conclude that tonsillectomy has no clinically significant negative effect on the immune system.” There are several studies like that one.
- “The Basis of Chiropractic.” Fads and Quackery in Healing: An Analysis of the Foibles of the Healing Cults with Essays on Various Other Peculiar Notions in the Health Field. Blue Ribbon Books. New York, 1932.
- ScienceBasedMedicine.org [Internet]. Homola S. Following the Guidelines of Science: A Chiropractic Dilemma; 2012 Oct 26 [cited 16 Mar 10].
- Stein DM, Menaker J, McQuillan K, et al. Risk factors for organ dysfunction and failure in patients with acute traumatic cervical spinal cord injury. Neurocrit Care. 2010 Aug;13(1):29–39. PubMed #20407933 ❐
- Sezer N, Akkuş S, Uğurlu FG. Chronic complications of spinal cord injury. World J Orthop. 2015 Jan;6(1):24–33. PubMed #25621208 ❐ PainSci #53557 ❐
- Hagen EM. Acute complications of spinal cord injuries. World J Orthop. 2015 Jan;6(1):17–23. PubMed #25621207 ❐ PainSci #53562 ❐
- Hou S, Rabchevsky AG. Autonomic consequences of spinal cord injury. Compr Physiol. 2014 Oct;4(4):1419–53. PubMed #25428850 ❐
- Smoking shortens lives by about ten years (Jha), or about 85% of a normal lifespan — which is almost exactly the same as the life expectancy of a paraplegic. According to Yeo, lifespan is 84% of normal for paraplegia (and 70% for quadraplegics).
- For example, in previous versions of this article, I quoted Dr. Steven Novella, neurologist, from Chiropractic: A Brief Overview:
Another source of evidence that the chiropractic theory of subluxations and innate intelligence is completely false comes from the unfortunate victims of spinal trauma. There are many victims of complete transection, or disruption, of the cervical spinal cord in the neck. Such a complete injury leaves its victim quadraplegic, unable to move the arms or legs. If the injury is high enough in the spinal cord the victim may not even be able to breath on their own. In such victims no impulses from the brain are able to travel below the spinal cord in the neck, and therefore most of the communication between the brain and the body is interrupted. Certainly, this is a much more dramatic and complete interference of nerve flow than that of an impinged spinal nerve.
Yet, in these patients, the organs continue to work without difficulty and diseases do not develop at any higher rate than those without such an injury. Of course, there are some effects from the disruption of the autonomic nervous system, that part of the nervous system which regulates the bladder, the degree of bowel motility, and other functions. But all effects of spinal cord damage are caused by known neurological injury. If subluxation theory were correct, then patients with high spinal cord injuries would be ravaged by every conceivable disease.
Dr. Novella is a extremely credible expert on this topic and many others, but he got this wrong when he wrote that, likely for the same reason almost everyone else did for a long time: organ failure aft\er spinal lesions was not documented, and as a clinical phenomenon it was undoubtedly overshadowed by the drama of paralysis.
- That is, the effect of sacral nerve root lesions on bowel and bladder control is due to paralysis of voluntary muscles — just as with other spinal nerve root lesions — and not due to any impact on the health of the actual bladder and bowel.
- Those holes are like holes in the walls of a fortress and cannot be changed by anything short of violent trauma. Not even chiropractors claim to be able to do it. Sacral nerve roots, regardless of their function, are thus not only irrelevant to organ function, but also impossible to affect with any kind of spinal adjustment.
- Incontinence is awful, but irrelevant to the classic chiropractic claim that spinal manipulation has anything to do with general visceral vitality. Next time you suffer from a little incontinence, try going to a chiropractor to get it treated, and see how well that goes.
- Such a phenomenon is plausible — it might exist — but there isn’t any particularly good reason to believe that it happens. Indeed, there are good reasons to believe that it doesn’t, or that it’s trivial.
- We can certainly safely assume that any spinal joint that is actually clamping down on a spinal nerve is probably also generally irritated, but it is quite possible (much more likely, in fact) to have a joint that is irritated without any pressure on a nerve.
- Sure, the possibility of subtle neurological interactions between joints and organs exists, but unless it's a clinically significant interaction, I can't work up any interest in it.
- Picchiottino M, Leboeuf-Yde C, Gagey O, Hallman DM. The acute effects of joint manipulative techniques on markers of autonomic nervous system activity: a systematic review and meta-analysis of randomized sham-controlled trials. Chiropr Man Therap. 2019;27:17. PubMed #30911373 ❐ PainSci #52239 ❐
- Sciencebasedmedicine.org [Internet]. Homola S. Opposing Chiropractic: Persecution or Justified Criticism? – Science-Based Medicine; 2015 Feb 1 [cited 19 Oct 24].
Clinging to the theory that gave it birth and independence, the chiropractic profession continues to define chiropractic as a method of removing nerve interference or correcting vertebral subluxations to restore and maintain health. State laws using vertebral subluxation theory to define and license chiropractors remain unchallenged. According to the National Board of Chiropractic Examiners in the United States:
The specific focus of chiropractic practice is known as the chiropractic subluxation or joint dysfunction. A subluxation is a health concern that manifests in the skeletal joints, and through complex anatomical and physiological relationships, affects the nervous system and may lead to reduced function, disability, or illness. (Christensen MG, et al. Practice Analysis of Chiropractic. National Board of Chiropractic Examiners. Greeley, Colorado. May 2010.)
- Funk MF, Frisina-Deyo AJ, Mirtz TA, Perle SM. The prevalence of the term subluxation in chiropractic degree program curricula throughout the world. Chiropr Man Therap. 2018;26:24. PubMed #29988608 ❐ PainSci #53049 ❐
- Biggs L, Hay D, Mierau D. Canadian chiropractors’ attitudes towards chiropractic philosophy and scope of practice: implications for the implementation of clinical practice guidelines. J Can Chiropr Assoc. 1997;41(3):145–154. PainSci #57174 ❐
From the abstract: “We found that 18.6% of [chiropractors] held conservative views .... Conservative chiropractic philosophy rejects traditional chiropractic philosophy as espoused by D.D. and B.J. Palmer, and emphasizes the scientific validation of chiropractic concepts and methods.” That’s a scandalously low number of chiropractors rejecting Palmer and emphasizing science.