My reaction to reading the paper discussed herein, were I a handsome Spaniard.

My reaction to reading the paper discussed herein, were I a handsome Spaniard.

Bleh. I turned from a short trip to the city of angles with a bad man cold that just isn’t going away. Those who do primary care all tell me that whatever is going around lasts 2-3 weeks. Great. I am not sick enough to get out of work but I am not well enough to have any enthusiasm to do anything. I look at the key board and sigh. I just want to binge watch something mindless.

I know Harriet covered “Systematic Review and Meta-analysis of Chiropractic Care and Cervical Artery Dissection: No Evidence for Causation” last week. But it is one thing to read the evaluation of a paper and quite another to evaluate a paper on your own. It is the latter process where you, and by you I mean me, actually learn something. I write mostly for my edification, not yours. Sorry. It is all about me. I will likely read Harriet’s post this weekend.

The issue at hand is whether chiropractic manipulation can cause a stroke.


The basic theory and practice of chiropractic, as pulled out of thin air in 1895 by DD Palmer, is complete, utter, 100% nonsense. The is no subluxation complex, there is no inane, er, I mean, innate, intelligence (I think my spell check has become conscious) , no disease caused by misaligned vertebrae that is fixed by having the spine adjusted by a chiropractor.

If a patient is seeking care for neck pain and receiving diagnosis and treatment based on chiropractic, they are receiving pure, unadulterated pseudo-science.

Now part of chiropractic practice is manipulation of the patient, in both senses of the word. So while prior plausibility would suggest treatment based on chiropractic principles should do nothing, it is possible that the physical neck manipulation inflicted on the patient by chiropractor could have effects independent of the underling chiropractic bunk.

Only it doesn’t.

Meta-analyses suggest:

None of the 4 trials convincingly demonstrated the superiority of CSM (Chiropractic spinal manipulation) over control interventions. In conclusion, the notion that CSM is more effective than conventional exercise treatment in the treatment of neck pain was not supported by rigorous trial data.


There has been scant investigative research into the treatment of acute neck pain with chiropractic manipulation.


Acute NP: There are few studies, and the evidence is currently inconclusive. Chronic NP: There is moderate evidence that SMT/MOB is superior to general practitioner management for short-term pain reduction but that SMT offers at most similar pain relief to high-technology rehabilitative exercise in the short and long term. Mix of acute and chronic NP: The overall evidence is not clear. There is moderate evidence that MOB is superior to physical therapy and family physician care, and similar to SMT in both the short and long term. There is limited evidence that SMT, in both the short and long term, is inferior to physical therapy.

And for headache?

Despite claims that spinal manipulation is an effective treatment for headache, the data available to date do not support such definitive conclusions. It is unclear to what extent the observed treatment effects can be explained by manipulation or by nonspecific factors (e.g. of personal attention, patient expectation).

So an intervention that is based on fantasy and has no good clinical support for efficacy should not be used at all based on general principles. Certainly no antibiotic would be prescribed that had no activity against any organisms and whose purported mechanism of action was based on interfering with the flow of bacterial innate intelligence.

It is interesting to consider the symptoms that occurs after chiropractic neck manipulation. 31% had a symptomatic reactions,

a new complaint not present at baseline or a worsening of the presenting complaint by >30%

These SR’s were:

1) neck pain and/or stiffness/soreness, 2) radiating (arm or leg) pain/discomfort, 3) arm or leg weakness, 4) tiredness/fatigue, 5) headache, 6) dizziness/imbalance, 7) nausea/vomiting, 8) ringing in the ears, 9) blurred or impaired vision, 10) confusion or disorientation, 11) depression or anxiety, 12) fainting, 13) low back discomfort/soreness

Many of these are the same symptoms that occur with a cerebral vascular event. It is a list that gives one pause, that one being me. Not if you are a chiropractor:

It should be noted that several of the side effects reported in our study have been found in previous studies with patients taking medication. Headaches, fatigue, dizziness, and nausea are among the most common drug-related adverse reactions, and these have been reported by people not taking any medication.

What defines chiropractic, indeed all pseudo-medicines, is the inability to recognize that their interventions can harm and to look instead for alternative explanations to hand wave away any complications as due to some other cause. Frank Drebin is the chiropractic role model.

I know. Applying reality and rational thought to a pseudo-medicine. As if that is going to work. But an intervention that is based on fantasy and has no good clinical support for efficacy should have not even the hint of a suggestion of a possibility of a complication, much less a catastrophic complication like an arterial tear and stoke. Medicine is about risk-benefit and an intervention that has zero benefit should have zero risk.

The paper

The authors of the study at hand were concerned that the joint Position Paper published in Stroke by the American Heart Association/American Stroke Association, “Cervical Arterial Dissections and Association With Cervical Manipulative Therapy,” which suggested an association between stroke and spine manipulation,

did not include a meta-analysis, nor did it seek to classify studies and grade the body of evidence.

They sought to remedy that situation.

They searched the literature and found.

253 articles. Seventy-seven were judged by all reviewers to be non-relevant. Four articles were judged to be class III studies, and two were rated class II.

And all of them showed an association between chiropractic and stoke.


Let me repeat.

It showed an association between stroke and chiropractic.

For a useless procedure that should give one pause.

But the quality of the studies was judged to be poor and at risk for bias.

So? All the arrows point the same direction. Again, for a useless therapy based on fictions, the results, as mentioned in the first line of the discussion

The results of our systematic review and meta-analysis suggest a small association between chiropractic care and CAD.

Very concerning.

But then it gets weird as they then rationalize away the results. And these are neurosurgeons, not chiropractors.

They go from:

Our analysis shows a small association between chiropractic neck manipulation and cervical artery dissection.


This relationship may be explained by the high risk of bias and confounding in the available studies, and in particular by the known association of neck pain with CAD and with chiropractic manipulation.


There is no convincing evidence to support a causal link between chiropractic manipulation and CAD.


Belief in a causal link may have significant negative consequences such as numerous episodes of litigation.

But if all the data points the same way, a lack of belief that chiropractic manipulation would lead to the utilization of a dangerous and useless therapy, with subsequent strokes in people who might not have otherwise had one.

What is a more significant negative consequence? Litigation because patient had a stroke associated with chiropractic or chiropractors no longer using a useless intervention because it might hurt people. As if THAT will ever happen. These authors evidently think litigation is worse than a stroke. That perhaps says something about the nature of medical litigation.

Hill’s criteria

The authors differentiate between association and causation, and as we all know, the former does mean the latter. So they then apply Hill’s criteria. But. It appears they apply Hill’s criteria only based on the five studies they reviewed, not on the entire literature.

Of course, I find the case reports where patients suffer a stroke after cervical manipulation to be particularly compelling, especially combined with the preponderance of literature as noted in the Stroke Position Paper.

Looking beyond the few studies these authors evaluated, I would apply Hill’s differently.

Strength of the association: Strong. Especially with the case reports. Rare, but strong.

Consistence: Strong. Most studies and case reports show an association.

Outcome specific to exposure. They say “As seen in Cassidy et al., exposure to a primary care doctor and exposure to a chiropractor are equally likely to result in CAD. In this case the outcome is not specific.”

But the question is not exposure to an MD versus a DC, but whether they had spine manipulation or not, and in the sub group of the young, who should not be having strokes, visiting a DC was associated with a stroke. While we do not know, I suppose the DC’s may not have done any spinal manipulation in those patients and instead suggested rest and Tylenol.

Yeah. Right. Usually the saying “Go to Midas, get a muffler” is a reasonable assumption.

When the literature as a whole is considered, the outcome specific to the exposure is good.

Temporal relationship? Good as well.

Biologic gradient? Agree, no data. Maybe. See below.

Plausibility and coherence? I would say strong.

Chiropractic physics

A Newton, big N, is the measure of force.

It is named after a famous fig cookie…no, sorry, a bit of misunderstanding. It is named after Isaac Newton from the second law of motion. Force equal mass time acceleration.

Pictured: Serious business.

Pictured: Serious business.

How much force does chiropractic generate with its high-velocity-low-amplitude manipulations?

They aim for about 400 to 600 Newtons when teaching chiropractic students, although this force only lasts for about 135 milliseconds.

But just how many cookies does 400–500 Newtons represent? Minimum of 2,680 cookies. That is a lot of cookies hitting a neck all at once, especially with the force concentrated at a point, even if for 135 milliseconds.

A kilogram of mass is 9.8 Newtons.

A 70 kg human? 686 Newtons. That is the force measured on the bottom of the feet as you stand on the ground.

Move the force measurement to the neck. If you were to suspend a body by the neck with a noose, the force measured at spine and surrounding soft tissues would also be 686 Newtons.

For a brief period of time, chiropractic applies 58% to 87% of the force of a suspended hanging.

A judicial hanging has drop, and this leads to a force of around 1200 N, “sufficient to produce a subluxation of C2 and C3 vertebra.”

Pictured: Subtlety.

Pictured: Subtlety.

I suspect that would be a subluxation refractory to chiropractic.

Is there any other similar injury to chiropractic? Perhaps whiplash, where a sudden force is applied to a relaxed neck.

Postmortem studies have shown that vertebral artery lesions are found in about one third of fatally injured road traffic accident victims with vertebral atlas injury. In previous reports, neurological deficits or death have followed posterior neck injuries by up to 8 days after the accident.

Although the measured forces I have found in whiplash are higher. As one chiropractic paper noted:

While neck manipulation loads are slower to develop and displacements smaller, they may reach peak amplitudes on maximum effort comparable to those seen in low-velocity collision experiments.

And like a good chiropractic paper, it denied the similarities and that chiropractic could cause injury. Because that is what chiropractors do:

Perceived causation of reported cases of cervical artery dissection is more frequently attributed to chiropractic manipulative therapy procedures than to motor vehicle collision related injuries, even though the comparative biomechanical evidence makes such causation unlikely.

Chiropractic manipulation, hanging and whiplash are on a continuum of forces, with a continuum of injuries.

Take home? Don’t F with the ma.

Analogous to proven association? They say:

While severe trauma most certainly causes dissection, it may be debated whether the situation in chiropractic care is analogous.

Yeah, it could be debated, but again, looking at the literature as a whole? Not much of a debate.

Is there proof that chiropractic causes stroke and cervical artery dissection? Nope. But the association and supportive data is very worrisome and I would recommend it no more than I would a noose.

If chiropractic neck manipulation were a medication? Based on the severity of the potential reaction it would have a black box warning in the PDR. If side effects were combined with efficacy, chiropractic would never be approved, much less make it out of clinical trials.

Not that chiropractors care about patient safely. Or any pseudo-medical provider for that matter. Chiropractors love to point out the dangers of NSAIDs while aggressively denying any risk from their useless pseudo-medicine. With the exception of disposable acupuncture needles, no pseudo-medicine has ever been altered or abandoned because of concerns of patient safety. Ever.

The precautionary principle (or precautionary approach) to risk management states that if an action or policy has a suspected risk of causing harm to the public, or to the environment, in the absence of scientific consensus (that the action or policy is not harmful), the burden of proof that it is not harmful falls on those taking an action that may or may not be a risk.

Ignored by chiropractic since 1895.

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  • Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, from 1990 to 2023. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His multi-media empire can be found at

Posted by Mark Crislip

Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, from 1990 to 2023. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His multi-media empire can be found at