Vertebral artery dissections (VAD) are a rare but important cause of ischemic stroke, especially in younger patients. Many etiologies have been identified, including motor vehicle accidents, cervical fractures, falls, physical exercise, and, as I have often discussed on this blog, cervical chiropractic manipulation. The goal of this study was to investigate the subgroup of patients who suffered a chiropractor-associated injury and determine how their prognosis compared to other-cause VAD.

The researchers, neurosurgeons from Chicago, conducted a retrospective chart review of 310 patients with vertebral artery dissections who presented at their institution between January 2004 and December 2018. Variables included demographic data, event characteristics, treatment, radiographic outcomes, and clinical outcomes measured using the modified Rankin Scale.

Overall, 34 out of our 310 patients suffered a chiropractor-associated injury. These patients tended to be younger (p = 0.01), female (p = 0.003), and have fewer comorbidities (p = 0.005) compared to patients with other-cause VADs. The characteristics of the injuries were similar, but chiropractor-associated injuries appeared to be milder at discharge and at follow-up. A higher proportion of the chiropractor-associated group had injuries in the 0-2 mRS range at discharge and at 3 months (p = 0.05, p = 0.04) and no patients suffered severe long-term neurologic consequences or death (0% vs. 9.8%, p = 0.05). However, when a multivariate binomial regression was performed, these effects dissipated and the only independent predictor of a worse injury at discharge was the presence of a cervical spine fracture (p < 0.001).

The authors concluded that chiropractor-associated injuries are similar to VADs of other causes, and apparent differences in the severity of the injury are likely due to demographic differences between the two populations.

The authors of the present paper are clear: “chiropractic manipulations are a risk factor for vertebral artery dissections.” This fact is further supported by a host of other investigations. For instance, the Canadian Stroke Consortium found that 28% of strokes following cervical artery dissection were preceded by chiropractic neck manipulation. Dziewas et al. obtained a similar rate in patients with vertebral artery dissections. Many chiropractors are in denial; however, this is merely due to their overt conflicts of interest.

My conclusions from the accumulated evidence are this:

Spinal manipulations of the upper spine should not be routinely used for any condition. Patients who nevertheless insist on having them must be made aware of the risks and give informed consent.

28 Responses to Chiropractic manipulations are a risk factor for vertebral artery dissections

  • Still doesn’t establish that the spinal manipulation caused the VAD. What this does suggest is that those with milder cases of a VAD may first go to a chiropractor.

    • @DC

      And when a young person with a miild case of VAD goes to a chiropractor first, what happens then?

      • Same as if they went to their PCP…do a history and an exam.

        • @ DC

          Re “do a history or an exam”, given that there are no *reliable* screening methods available to chiropractors to determine who might be predisposed to injury, how can an exam be of any use?

          • BW…to determine who might be predisposed to injury,

            If they present with milder symptoms of VAD and exited with milder symptoms of a VAD, where is the injury? Did the spinal manipulation cause a mild injury to an existing mild-symptom VAD?

            “The characteristics of the injuries were similar, but chiropractor-associated injuries appeared to be milder at discharge and at follow-up.”

            Of course this is just one “what if…”. There may be other explanations.

            But it makes sense that those with more severe symptoms would seek urgent care and not a chiropractor.

            BTW…read the question that Bjorn asked.

  • Ok. Since i am apparently a meatball can someone explain this to me.

    How could they determine cSMT is a risk factor if they did not establish that the VAD didn’t exist prior to the cSMT?

    There are other concerns with this paper but lets start with this question.

    • Look at the paper. It probably discusses how they concluded that manipulating people’s necks is a risk factor for VAD.

      You can get an idea from this:
      “Overall, 34 out of our 310 patients suffered a chiropractor-associated injury. These patients tended to be younger (p = 0.01), female (p = 0.003), and have fewer comorbidities (p = 0.005) compared to patients with other-cause VADs. ”
      They’re saying that the people who saw chiropractors and were diagnosed with VAD shortly after, are less likely to have other risk factors for VAD.
      They could calculate the risk of VAD that those people who’d had their necks manipulated would have had if they hadn’t seen a chiropractor shortly before, and see if an excess number were diagnosed with VAD.

      Similarly, the CDC estimates the efficacy of the flu vaccine by comparing the percentage of people in general who got the flu vaccine, vs the percentage of people who’ve been lab-diagnosed with flu, who had been vaccinated for it.

      • I have read the paper. I will look again but i dont recall the authors saying their study demostrated cSMT is a risk factor for VAD, only an association.

        Also, the paper is vague regarding the two groups. It doesnt mention if the chiropractic group did not have a history of “all other trauma” prior to cSMT.

        Since incidents as falls and MVAs, for example, are common reasons to seek chiropractic care, and can be a cause of VAD, it is crucial to know if these events occurred in the chiropractic group as a reason for seeking care.

        I am actually surprised it was published as is, well, maybe not.

        • >It doesnt mention if the chiropractic group did not have a history of “all other trauma” prior to cSMT.

          They analyzed the chirorpractic group in other ways:

          Overall, 34 out of our 310 patients suffered a chiropractor-associated injury. These patients tended to be younger (p = 0.01), female (p = 0.003), and have fewer comorbidities (p = 0.005) compared to patients with other-cause VADs.

          It would have been weird if they didn’t check “all other trauma”.

          Blake “fished for fancies” but hopefully they weren’t fanciful excuses.

          The paper isn’t available on sci-hub, so I can’t check your statement about the “all other trauma”.

          • It’s weird they didn’t mention other trauma in the chiropractic group, either being present or absent.

            At least a two week history prior to cSMT needed to be done, checking for any other possible causes of VAD. Presenting symptoms needed to be considered as possible signs of an existing VAD. The areas that were adjusted needed to be disclosed. Overall, a sloppy study that didn’t add much to what we already know.

            As far as associated:

            “.. the association merely suggests a hypothesis, such as a common cause, but does not offer proof. In addition, when many variables in complex systems are studied, spurious associations can arise. Thus, association does not imply causation.”


      • A LTE was just published. It points out some issues and suggestings they have with the study.

        Basically, the study failed to demonstrate what they set out to do.

  • “Spinal manipulations of the upper spine should not be routinely used for any condition. ”

    This is a risk vs. benefit issue, so something about a lack of benefits is necessary here.

    • you can find dozens of posts on this issue on this blog

      • Dr. Ernst,
        If you have written about the lack of benefits of neck manipulation, a link to some info about that could substantiate the implied claim about the lack of benefit to compensate for the risk of maybe having an artery torn.

          • Thanks!

            >The effect of chiropractic spinal manipulative therapy is probably due to a placebo response.

            Physical therapists also sometimes manipulate people’s necks, even sometimes using high-velocity manipulative techniques, at least according to this: That site looks like it’s about physical therapy, not chiropractic.

            Are they doing it differently than chiropractors do, and does it have benefits when they do it? That page discusses precautions.

          • chiros claim they do it best

          • >chiros claim they do it best

            So the chiropractors are doing something different from what the PT’s do, with neck manipulations? According to that site, high-velocity techniques “have proven efficacy in the management of some patients with neck pain disorders”.
            But I also saw an article in a physical therapy journal, which said that

            “Manipulation of the cervical spine (MCS) is used in the treatment of people with neck pain and muscle-tension headache. The purposes of this article are to review previously reported cases in which injuries were attributed to MCS, to identify cases of injury involving treatment by physical therapists, and to describe the risks and benefits of MCS. One hundred seventy-seven published cases of injury reported in 116 articles were reviewed. The cases were published between 1925 and 1997. The most frequently reported injuries involved arterial dissection or spasm, and lesions of the brain stem. Death occurred in 32 (18%) of the cases. Physical therapists were involved in less than 2% of the cases, and no deaths have been attributed to MCS provided by physical therapists. Although the risk of injury associated with MCS appears to be small, this type of therapy has the potential to expose patients to vertebral artery damage that can be avoided with the use of mobilization (nonthrust passive movements). The literature does not demonstrate that the benefits of MCS outweigh the risks. Several recommendations for future studies and for the practice of MCS are discussed.”

            From that, it sounds like what the chiropractors are doing might be a lot more risky; and physical therapists might not generally consider MCS to be worth the added risk.

          • This is another reason to think that chiros are causing VADs, not the other way around, where having symptoms in that area would cause someone to see a chiropactor.
            Lots of people would see a PT if they had neck symptoms, not a chiropractor. But it’s far less common for people to be diagnosed with VAD soon after they’ve seen a PT, than soon after they’re seen a chiropractor.

          • Not a fair comparison.

            Neck pain is the second most common reason to seek chiropractic care. I highly doubt that is true for physical therapists.

            Often MDs are the first line for neck pain with a referral to PT, if indicated. Thus they are typically screened for pathology first. As more PTs become entry level it will be interesting to see if any changes occur.

            Only around half the states in the USA allow PTs to do spinal manipulation. In those states, PTs only do around 5% of all spinal manipulations. Thus, just looking at raw numbers, it can be deceiving.

            Cervical spinal manipulation is still in the clinical guidelines for PTs for someconditions.

            No PT national organization has called for a ban on cervical manipulations.

    • The paper attempted to look at risk. Looking at any possible benefit wasn’t part of the research design.

  • So when people are diagnosed with a VAD right after having their neck manipulated by a chiropractor, is the chiropractor in any danger of losing their license?
    Chiropractors could claim that a rogue chiropractor did this, but is the de-factor position of the chiropractic regulatory board that “no no, a chiropractor wouldn’t do that, a chiropractor doesn’t cause VAD”?
    Would that be a strange implied claim? The vertebral artery looks awfully vulnerable.

  • ps Have experiments been done on animals, say, to see what level of force is necessary to cause a VAD? Or investigated it in other ways?
    It’s a pretty grim thought to do this to an animal, predators probably often cause a VAD when they bite an animal on the neck.

    • Most studies used a cadaver. They found that the greatest strain on the VA does not occur during cSMT but within normal ROM. Herzog did much of that research.

      One animal study looked to see if cSMT had a negative effect on an existing “VAD” in dogs. It did not. Interestingly, the study above seems to indicate that as well, if they presented to a chiropractor with a pre-existing VAD (mild symptoms on exit). Of course additional research is needed to know this.

  • Ernst failed to link to this review…

    “Cervical manipulation for acute/subacute neck pain was more effective than varied combinations of analgesics, muscle relaxants and non-steroidal anti-inflammatory drugs for improving pain and function at up to long-term follow-up.”

    Of course we could go into the comparative benefits vs risks of the pharmaceutical approach, but apparently that is trolling.

    • @ DC

      Professor Ernst has already looked at that paper here:


      “In my view, these analyses show that the quality of most studies is wanting and the evidence is weak – much weaker than chiropractors and osteopaths try to make us believe. It seems to me that no truly effective treatments for neck pain have been discovered and that therefore manipulation/mobilisation techniques are as good or as bad as most other options. In such a situation, it might be prudent to first investigate the causes of neck pain in greater detail and subsequently determine the optimal therapies for each of them. Neck pain is a SYMPTOM, not a disease! And it is always best to treat the cause of a symptom rather than pretending we know the cause as chiropractors and osteopaths often do…The call for further research is, of course, of no help for patients who are suffering from neck pain today. What would I recommend to them? My advice is to be cautious:

      Consult your doctor and try to get a detailed diagnosis.

      See a physiotherapist and ask to be shown exercises aimed at reducing the pain and preventing future episodes.
      Do these exercises regularly, even when you have no pain.

      Make sure you do whatever else might be needed in terms of life-style changes (ergonomic work place, correct sleeping arrangements, etc.).

      If you are keen on seeing an alternative practitioner for manual therapy, consult a osteopath rather than a chiropractor; the former tend to employ techniques which are less risky than the latter.

      Avoid both chiropractors and long-term medication for neck pain.”

      • “In my view…”? Ernst struggles knowing the difference between spinal manipulation and chiropractic. Heck, he didn’t even title this blog accurately (risk factor?)

        Also note that most chiropractors also look at and recommend exercise, ergonomic work place, correct sleeping arrangements, etc.

        The main question is…does SMT have an additive or synergistic effect when combined with exercise, for example?

        Current evidence suggests yes, a combined approach is better for some people for some conditions.

        Are there risks with cSMT? Sure, it appears, based upon case reports, mostly if it is done on those with contraindications to the procedure and/or delivering an improper technique. Well, duh.

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