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Can neck massage stimulate the vagus nerve? For better or worse? (Member Post)

 •  • by Paul Ingraham
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Carotid artery massage, anyone? In theory, you would do this to relax you with a potent reflex, via stimulation of the mighty vagus nerve. Vagal stimulation by any means is touted as a kind of relaxation hack, and not just any relaxation but the best kind: full-blown recovery mode (significant “parasympathetic activation”), like you might get from really nailing a good meditation session.

That’s the hope.

Paradoxically, people also legitimately wonder and worry if the same trick might be harmful. “With great power…”

But vagal stimulation is the least of your worries — or therapeutic opportunities — for massage on the side of the neck and throat. As always, your friendly neighbourhood salamander brings the sobering perspective (and the interesting physiology).

Detailed but stylized silhouette image of the brain and vagus nerve in glowing blue, as though electrified.

The sprawling vagus nerve. Notice that the many vagal branches almost create a partial map of the viscera, especially the GI tract. Also notice how it’s very clearly a pair of nerves descending from the brain, not “the” (singular) vagus nerve.

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There is a lot of hype about the vagus nerve and its role in our health, probably because it’s a mighty nerve. The vagus nerve is ginormous, long and complex, and almost entirely dedicated to critical physiology, things like blood pressure, respiration, and digestion. It emerges from the bottom of the brain and passes through the neck and into the trunk, branching out from there to connect to … well, almost everything (most of the organs).

You do not want anything to go wrong with this nerve. True vagal neuropathy exists, and it’s no joke.12345 But it’s also rare. The medical literature is notably lacking in case studies of injury to the vagus nerve, other than the ones caused by surgery! This is not an easy nerve to injure without a scalpel, and you’re not likely to do it with massage unless you get quite vicious with pressure in an area where that is obviously a Bad Idea. Any massage intense enough to even annoy the vagus nerve would also be risking other kinds of injury, some of them worse:

  • ⚠️ Damaging other more delicate nerves (like the brachial plexus).
  • ⚠️ Tearing the carotid artery, or causing or dislodging a clot or some artery gunk (plaque).
  • ⚠️ Triggering the carotid sinus reflex strongly, which is mostly harmless but could cause an uncomfortable drop in blood pressure in some people, and fainting in a few.

So the vagus nerve is really the least of your worries in this area.

An example of vagus neuropathy due to overgrowth of the weird styloid process (highlighted), which causes mostly neck & throat pain, but can also get weirder. Case courtesy of Dr. Ammar Haouimi, Radiopaedia.org case rID: 81953.

The carotid sinus reflex: vagal or not?

Carotid sinus massage and carotid sinus hypersensitivity trigger the carotid sinus reflex, which is a blood-pressure lowering reflex. Baroreceptors (pressure detectors) are clustered in the carotid sinus, a bulge in the artery where it forks (beside the Adam’s apple). This pesky reflex is probably a major reason why some people are concerned about vagal stimulation from neck massage… and all the more so because it seems to have a hair trigger in some people. Carotid sinus hypersensitivity is actually common, but mostly so mild that people don’t even know they have it. So it’s unusual for it to cause dizzying blood pressure drops or fainting. But it is a thing, and people might be well aware of their tendency to feel weird or gross when this area is rubbed or stretched.

A few people who have this self-awareness probably attribute it to “vagus nerve stimulation” — because the carotid sinus reflex is widely seen as vagal thing. Except… it’s not a vagal thing. Some readers might be quick to try to contradict me on this. “But Paul!” they will say, “Carotid sinus massage is a ‘vagal manoeuvre.’ So it’s obviously vagal stimulation!”

Not so fast.

The “vagal” manoeuvre is not very vagal

The vagal manoeuvre is all about triggering a reflex, exactly the same in spirit as tapping the knee with a rubber hammer to make the knee jerk — except it’s massaging the neck to reduce blood pressure. But this allegedly “vagal” sorcery is not clearly vagal in two main ways:

  1. The vagal manoeuvre just triggers a reflex… which is not really what people mean by “stimulates the vagus nerve,” any more than you can illuminate a whole office building by turning on the lights in the lobby.7
  2. That reflex is not technically mediated by the vagus nerve! Surprise! The vagus nerve is all about parasympathetic regulation, but the baroreflex actually works its blood-pressure-reducing magic by dialing back sympathetic stimulation — and the vagus nerve doesn’t do sympathetic.8
  1. There’s the mirror image aortic arch baroreflex. It does the same thing as the carotid baroreflex, but it actually does use the vagus nerve (see last footnote). But I don’t recommend trying to stimulate the aorta with your bare hands. That would get ugly.
  2. And then there’s vasovagal syncope, which is another kind of reflex syncope (fainting). Triggering the carotid baroreflex may also be called the vagal manoeuvre because its effect is so similar to “vasovagal syncope,” which refers specifically to fainting (syncope) triggered by seeing blood, stress, and prolonged standing. (I once experienced vasovagal syncope because of all three of those: I got exhausted and sunburned hunting oysters, and then plunged a screwdriver into my palm trying to shuck one. Out like a light! I felt like a robot shutting down, and then very slowly rebooting.) Vasovagal syncope and the vagal manoeuvre are distinct causes of reflex syncope, and definitely not the same phenomenon … but their kinship is probably why pushing the baroreflex button gets called a “vagal” manoeuvre.

Don’t try to massage the vagus: it won't help, and you might hurt something else

With great power comes great responsibility, and so some people who believe in the power of vagal stimulation are also afraid of the “power” of vagus stimulation. This is unnecessary, because there is no such power to abuse. You cannot “stimulate the vagus nerve” dangerously or significantly with any ordinary massage any more than you can “stimulate” the ulnar nerve to do what the ulnar nerve does, or the sciatic nerve, or any nerve. It’s like trying to turn on a light by massaging the cord (hat tip to reader Mark O. for that excellent analogy).

Therapeutic vagus stimulation with electricity is a real thing, albeit only half-baked. But there is no other known way to meaningfully stimulate the vagus nerve — for good or ill — and certainly not with any neck massage. Not one you’d want to receive, anyway. Or deliver.

There are good reasons to avoid massage of the side of the throat and neck, or to do it only slowly and gently and cautiously. But vagus stimulation is not the reason why.

Notes

  1. Badhey A, Jategaonkar A, Anglin Kovacs AJ, et al. Eagle syndrome: A comprehensive review. Clin Neurol Neurosurg. 2017 Aug;159:34–38. PubMed 28527976 ❐
  2. Klein TAL, Ridley MB. An old flame reignites: vagal neuropathy secondary to neurosyphilis. J Voice. 2014 Mar;28(2):255–7. PubMed 24315656 ❐
  3. Rees CJ, Henderson AH, Belafsky PC. Postviral vagal neuropathy. Ann Otol Rhinol Laryngol. 2009 Apr;118(4):247–52. PubMed 19462843 ❐
  4. An Y, Park K, Lee S. The First Case Report of Bilateral Vagal Neuropathy Presenting With Dysphonia Following COVID-19 Infection. Ear Nose Throat J. 2022 Feb:1455613221075222. PubMed 35164601 ❐ PainSci Bibliography 51343 ❐
  5. Tan ET, Johnson RH, Lambie DG, Whiteside EA. Alcoholic vagal neuropathy: recovery following prolonged abstinence. J Neurol Neurosurg Psychiatry. 1984 Dec;47(12):1335–7. PubMed 6512554 ❐ PainSci Bibliography 51339 ❐
  6. Lacerda GdC, Lorenzo ARd, Tura BR, et al. Long-Term Mortality in Cardioinhibitory Carotid Sinus Hypersensitivity Patient Cohort. Arq Bras Cardiol. 2020 02;114(2):245–253. PubMed 32215492 ❐ PainSci Bibliography 51342 ❐
  7. A reflex arc is precise: it does only one thing, and it’s pathway is just one “lane” of the huge multi-lane highways of nerves. The vagus nerve is particularly large, and mediates several reflexes and much else. When people talk about “vagal stimulation,” they are not talking about triggering a single reflex: they are (very optimistically) talking about stimulating all of its functions … which would induce deep relaxation. Triggering your baroreflex doesn’t do that.
  8. “The” baroreflex has two batches of pressure sensitive nerve endings, one in the aortic arch in the chest, and the other in the carotid artery in the neck. But the baroreceptors in the carotid sinus are wired to the CNS by the glossopharyngeal nerve, not the vagus. The aortic arch baroreceptor axons travel within the vagus nerve, but that’s not what the vagal manoeuvre stimulates!

    Weirdly, the vagal manoeuvre is actually kind of the opposite of vagal stimulation. Blood pressure can be reduced either by decreasing sympathetic stimulation, or increasing parasympathetic. These two divisions of the autonomic nervous system are very yin and yang. Blood pressure can be boosted by sympathetic or tamed by parasympathetic … but you can also just remove the boosting, and that is in fact how the baroreflex works. It slows the flow of the signals that raise blood pressure, rather than squirting out more of the signals that lower it!

    The aortic arch part of the baroreflex does exactly the opposite, and does use the vagus to lower blood pressure with parasympathetic nerve impulses. Mirror image functionality! It’s quite interesting that we have redundant reflexes that tackle the same problem using opposite approaches.

    It’s all fiendishly complex, and I am not going to definitively say that the vagus nerve is completely uninvolved in the carotid sinus baroreflex. For instance, there is evidence that the vagus nerve does contain sympathetic fibres, and so there may be vagus involvement in the sensory half of the carotid baroreflex arc. But it’s clearly mostly a sympathetic result.

    Like I said above, the devil is in the details… and there are a lot of details here. It took me a long time to write and fact-check this explanation.

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