Hang 'em High: Cervical Manipulation and Stoke

Hang 'em High: Cervical Manipulation and Stoke

I learned early in my career that even simple interactions can lead to harm. I had a patient as an intern who had an out of hospital cardiac arrest. In the field they placed an IV for resuscitation. The IV site became infected, she became bacteremic, the Staph went to her aortic valve, which blew out acutely and she died.

It is why I roll my eyes when people say the first rule of medicine is do no harm. Everything you do in medicine has the potential for harm, including doing nothing. All actions and all inactions can have bad consequences.

The real rule of medicine is that the odds of providing benefit should be greater than the odds of doing harm. But there is also a fudge factor for the disease being treated. I once took care of a patient who died of acute liver failure due to medication she was taking for toenail fungus. I always mention this to patients when they ask for terbinafine. There is a low likelihood of death to treat a trivial problem but most people find the risk/benefit unacceptable when I mention my case. And there are other, less toxic, therapies.


If the disease, like leukemia, offers certain death, patients are more likely to accept the risk of serious complications from a bone marrow transplant since the potential payoff, life, is worth it. It is a variable and complex calculous not done justice by the simplistic phrase 'Do no harm.'

The issue with most of the pseudo-medicines is they do nothing and so should have no side effects. Homeopathy is one of the pseudo-medicines that meets that criteria (excluding the real potential harm by not using real medicine).

Cervical Manipulative Therapy has little real proven indication, especially if being used to fix mythical subluxations. Chiropractors are remarkably adamant that their adjustments are safe and do not cause stroke, often from vertebral artery dissection (VBD). They point to Risk of Vertebrobasilar Stroke and Chiropractic Care Results of a Population-Based Case-Control and Case-Crossover Study, as evidence that chiropractic is safe and suggest patients are seeking chiropractic care for their prior VBD. In point of fact the study confirms the risk of stoke following CMA.

I noted at SBM

A passive hanging (no drop) gives about 686 Newton’s of force around the neck for a 70 kg human. In chiropractic, “the mean force of all manual applications (is) 264 Newton’s and the mean force duration (is) 145 milliseconds”. So a chiropractic neck manipulation, for a short period of time, can provide 38% the force of a hanging. And a bad hanging at that.

Neck injuries are not that frequent because the muscles of the neck prevent injury by preventing sudden, disastrous, movement. If you want to increase the chance of injury from relatively minor trauma, have the person relax. If the muscles are relaxed because the person is not expecting the trauma, the chance of injury goes up. It is why whiplash can occur after minor injuries. Chiropractors often have their patients relax just before the coup de grâce , I mean manipulation, helping to maximize the chance of injury despite having less force applied to the neck than a noose and gravity.

Given the above, to claim that the VBA occurred before the patient had chiropractic neck manipulation is like saying the hanging victim had a broken neck, but it occurred on the steps up to the scaffold.

There is now a position paper Cervical Arterial Dissections and Association With Cervical Manipulative Therapy from the American Heart Association/American Stroke Association.

They review the literature and anatomy/physiology of stroke and CMA. The money quote:

Although current biomechanical evidence is insufficient to establish the claim that CMT causes CD, clinical reports suggest that mechanical forces play a role in a considerable number of CDs and most population controlled studies have found an association between CMT and VAD stroke in young patients. Although the incidence of CMT-associated CD in patients who have previously received CMT is not well established, and probably low, practitioners should strongly consider the possibility of CD as a presenting symptom, and patients should be informed of the statistical association between CD and CMT prior to undergoing manipulation of the cervical spine.

The preponderance of data points to CMT as a risk for dissection and stroke and there is certainly plausibility for what is fortunately a rare event.

I have spent a significant part of my career in infection control and quality, where we strive apply the literature to maximize patient safety and to good effect.

To date the only pseudo-medical quality initiative that led to an increase in patient safety of which I am aware is the use of sterile disposable acupuncture needles, an intervention they work hard to subvert by ignoring all other infection control interventions like gloves. A hallmark of pseudo-medicines is they do no change because of data.

In real medicine we recognize the potential for harm and strive to reduce it. In my institutions we try to always put patient safety first. The question is the response by the chiropractic community to this paper. I predict denial rather than changes in practice to increase the safety of their clients.

Well what do you know? From the American Chiropractic Association

"The largest and most credible study, Cassidy et al., found that a patient is as likely to have seen a primary care medical doctor as a doctor of chiropractic prior to experiencing a cervical arterial dissection (CD).

"Neck manipulation is a safe, conservative treatment option for neck pain and headache. The evidence presented in the AHA paper fails to show that neck manipulation is a significant risk factor in CD. In addition, the paper fails to put into context risks associated with other neck pain treatments such as neck surgery, steroid injections and prescription drugs.

If you care about patients, you err on the side of their safety even, or espcially, when there is uncertainty about the risk, espcially when the risk is as catastrophic as a stroke.  Their statement suggests the ACA has other interests than patient safety.  So the occasional  preventable stokes will continue.

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Points of Interest 8/8/2014