SaveYourself.ca • Sensible advice for aches, pains & injuries
published 10/08/10, updated 3/21/12
Jump to the Mar 2012 update, “The sympathetic rebuttal.”
Are the little bundles of nerves that exit your spine the wellspring of all visceral vitality? Will your organs wilt like neglected house plants if those nerve roots are slightly impinged? This is what many chiropractors believe, and would like their customers to believe.
It’s a pre-scientific idea, born and promoted over a century ago well before the relevant anatomy and physiology was understood, before the foundations of modern neurology were built. For a long time I’ve understood that the idea was generally wrong because “health” is mostly determined by systems and organs that are not regulated much or at all by signals passing through spinal nerve roots. Also, it’s obvious that victims of serious spinal injuries are not afflicted with organ failure. Logic! Furthermore, there are many reasons to believe that nerve roots are actually quite difficult to “pinch” to any meaningful degree in the first place. And so on.
Nevertheless, my understanding was not complete enough for the decisive, witty rebuttal I would need to drive the point home in a dinner party argument after a couple glasses of red wine. The lightbulb went on while I was editing a ScienceBasedMedicine.org article by Sam Homola, DC (see Chiropractic Vertebral Subluxations). It wasn’t really new information for me, but it was stated in a particularly clear manner that put an end to many years of not quite understanding this in the best way …
It’s not merely that visceral tissues do not rely on the life-giving sauce of spinal nerve root signals — they don’t depend on them at all. The big bundles of nerves that pass between vertebrae only transmit nerve messages for musculoskeletal structures such as bones, muscles and skin. (Yes, there is an exception, which will be discussed below. I’m glossing over it here because it doesn’t change the punch line.) They do not send or receive signals from your “guts.” Cut a nerve root completely, and you’ll certainly paralyze something … but not an organ.
So what nerves do hook up to organs? Sam Homola:
The body’s organs are supplied primarily by autonomic nerve ganglia and plexuses located outside the spinal column and by cranial and sacral nerves that pass through solid bony openings, providing overlapping nerve supply independent of any one spinal nerve that passes between two vertebrae.
Spines are just generally remarkably unimportant in terms of keeping a sack of bones and organs running smoothly.Organs pretty much run themselves, with just a little bit of signalling from non-spinal nerves (and this is why they can be transplanted without hooking them up to any 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. In fact, spines are just generally remarkably unimportant in terms of keeping a sack of bones and organs running smoothly.
So there.
This is unambiguous biology and anatomy, and that’s the point … but of course that doesn’t stop some chiropractors from flatly contradicting it. I have received a number of criticisms of this simple article. I will now turn to those objections … and spend more time with them than with the original, basic point.
One reader offered the half-right rebuttal 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 my post was bollocks.
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 equinae syndrome, and you really don’t want it to happen to you.
So that’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. 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.
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. 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.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.
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 clearly 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. Incontinence is awful, but totally irrelevant to the classic, general chiropractic claim that spinal manipulation has anything to do with general health. Next time you suffer from a little incontinence, try going to a chiropractor to get it treated, and see how well that goes.
Your health is not determined by your bladder! And your bladder health is not determined by your spine.
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 musculoskeletal and peripheral structures that the nerve supplies.
But not other structures, as far as anyone knows. Just the tissues the spinal nerves 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. Such a phenomenon is remotely plausible — it could 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.
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 any nerve impingement, and so it is only tangentially related to the classic claim that impinged spinal nerves affect organ health. We can certainly safely assume that any spinal joint actually pinching a spinal nerve is probably also irritated, but it is quite possible (much more likely, in fact) to have a joint that is irritated without any nerve impingement. 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, there is no 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. 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.
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 very far: they deliver signals 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 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 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 outside the spinal column, sympathetic signals are even routed past nerve root lesions to some extent. Cutting the spinal cord completely destroys motor and sensory function below that level, but organs carry on without any trouble, for decades, and quadriplegics do not die of organ failure. They might die of an infected bed sore, like actor Christopher Reeves (Superman), but not of organ failure.
As mentioned above, organs mostly run themselves. Their health and function is simply not dependent on those signals. This why, in a very general sense, organ transplantation works: organs need a blood supply to survive in a new body, but they do just fine without hooking up any nerves (and a good thing, 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 and anatomical connection that is critical to muscular action and sensation. The sympathetic nerves have an indirect and non-critical functional connection. Thus in early versions of this article I saw it as a complex but ultimately irrelevant tangent.
