What alternative health

practitioners might not tell you



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Adverse events associated with spinal manipulation. Regarding neck manipulation, the risk/benefit ratio for the procedure appears to be in question due to the availability of safer options.

NOTE: In the UK, there appears to be no publicised national system for reporting adverse events related to chiropractic treatment. Furthermore, the UK General Chiropractic Council's current promotional literature appears to make no mention of serious risks.


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Safe for children?

Sandra Nette v. Stiles et al

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Researchers found 14 significant injuries, 9 of which were serious, and 2 children died. In one of the fatal cases, the child died from a brain hemorrhage after receiving a neck manipulation; in the other, the child died after a suspected neck fracture. Some children suffered paralysis, while others had less serious or minor problems, such as severe headache and back pain. A chiropractor performed the adjustments in most cases. The reviewers commented that despite the fact that spinal manipulation is widely used on children, paediatric safety data are virtually non-existent. [NOTE: The article did not consider harmful aspects of chiropractic care that are far more common than the reported events. These include (a) decreased use of immunisation due to misinformation given to parents, (b) psychologic harm related to unnecessary treatment, (c) psychologic harm caused by exposure to false chiropractic beliefs about "subluxations," and (d) financial harm due to unnecessary treatment.] Sunita Vohra, MD, FRCPC, MSc, Bradley C. Johnston, ND, Kristie Cramer, MSc and Kim Humphreys, DC, PhD, Pediatrics (January 2007)

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Includes the Jury's recommendations regarding neck manipulation. Chirobase (January 2004) NOTE: Although many chiropractors claim that the jury's verdict of 'accidental' was indecisive. Tim Danson lawyer for the CMCC said of the verdict: "It represents a massive miscarriage of justice". Chiropractic services have now been delisted by the governments of British Columbia(Canadian Memorial Chiropractic College) and the CCA (Canadian Chiropractic Association) Ontario and Alberta.

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Bearing in mind that the requirement to explain risks to patients has the potential to affect a chiropractor's income, it is interesting to note a revealing comment which was made at an inquest in Canada which involved a chiropractor who had allegedly caused a patient to suffer a stroke through neck manipulation. When pressed as to why he wasn't telling his patients about the 'potentially catastrophic injuries and death' which may result from neck manipulation, he said that if he were to tell patients that "I can kill you", then "half of them would walk out". (Chirowatch) [Use 'Edit' then 'Find on This Page' to locate quote]

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"On September 12, 1996, four days after her 45th birthday, Ontario resident Lana Dale Lewis died after suffering a stroke….. Dr. John Deck, neuropathologist from the Office of the Chief Coroner, Toronto, blamed the death on chiropractic manipulation. Deck said that there was no significant doubt in his mind that the chiropractic manipulation was the cause of the fatal stroke. His findings were certified by Dr. Robert Huxter, Regional Coroner for Ontario and by another Ontario coroner, Dr. Murray Naiberg." John Burdett (Skeptics Canada)

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"Conclusions: Spinal manipulation, particularly when performed on the upper spine, is frequently associated with mild to moderate adverse effects. It can also result in serious complications such as vertebral artery dissection followed by stroke. Currently, the incidence of such events is not known. In the interest of patient safety we should reconsider our policy towards the routine use of spinal manipulation." Edzard Ernst, Journal of the Royal Society of Medicine (July 2007) (J R Soc Med 2007;100:06-0100.1-9)

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"In this case, the artery that dissected was a vertebral artery, which is more likely to be prone to dissection because of anatomy and the action of the neck manipulation. The personal injury was present within 9 days of treatment. Other than tension headaches, there is no reliable evidence to identify any underlying disease that would be implicated in the dissection of the artery. On balance, the personal injury is determined to have been caused by the neck manipulation performed on 09/11/2007."

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"Spinal manipulative therapy is a frequently applied therapy for back and neck pain. Carotid and vertebral artery trauma, cerebellar and brainstem stroke, fracture of odontoid process, and atlantoaxial dislocation due to chiropractic manipulation have been reported in the literature. We report an occurrence of quadriparesis after chiropractic manipulation...We believe that the manipulation in this patient led to the para central C6-C7 disc protrusion and subsequent quadriparesis due to temporal association with the maneuver, clinical plausibility, and lack of alternate explanation.  Although the absolute risk due to neck manipulation is small, the risk-to-benefit ratio of manipulation for neck pain and prolapsed disc is unacceptably high."  American Journal of Medicine (November 2009) [FULL TEXT]

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"While manipulation of any kind has the potential to cause injury, stroke caused by neck manipulation is of greatest concern. Risk must always be weighed against benefit when upper neck manipulation is considered. Risk of stroke caused by neck manipulation is statistically low, but the risk is serious enough to outweigh benefit in all but a few rare, carefully selected cases…When the RAND (Research and Development) organization published its review of the literature on cervical spine manipulation and mobilization in 1996, it concluded that only about 11.1% of reported indications for cervical spine manipulation were appropriate...Since about 90% of manipulation in the United States is done by chiropractors who use spinal manipulation as a primary treatment for a variety of health problems, neck manipulation is more problematic among chiropractors than among physical therapists and other practitioners who use manipulation only occasionally in the treatment of selected musculoskeletal problems...All things considered, manual rotation of the cervical spine beyond its normal range of movement is rarely justified. The neck should never be manipulated to correct an asymptomatic "chiropractic subluxation" or an undetectable "vertebral subluxation complex" for the alleged purpose of restoring or maintaining health or to relieve symptoms not located or originating in the neck. There is no evidence that such subluxations exist." Article by Sam Homola, DC, Science Based Medicine (27th August 2009)

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"There is a very good chance that you will feel worse after seeing a chiropractor. According to a new systematic review [see link immediately below], serious complications of spinal manipulation are rare, but 33-60% of patients experience milder short-term adverse effects such as increased pain, radiation of pain, headaches, vertigo and even loss of consciousness." Article by Harriet Hall MD, Science Based Medicine (2nd June 2009)

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"Table 3 has the smoking gun..…My conclusion, from reading the paper in its entirety, rather than the abstract, is that a population that should not have a stroke, the young, has a marked increase association with stroke 24 hours after visiting a chiropractor…..In real medicine, it takes less data than this to bring a drug under scrutiny to decide if the benefits are worth the potential risks of a therapy." Evaluation by Mark Crislip, MD, Science Based Medicine (17th July 2008)

The evaluation also notes the following regarding neck manipulation force: “…in a good hanging, the victim should not strangle to death (1). A good hanging should be set up such that there is a fall just far enough so that the first and second vertebral bodies are separated, breaking the neck and quickly killing the victim. You do not want them to fall too far, as the head may come clean off and that is aesthetically unpleasant. Most people who die these days from hanging do not get a ‘good’ hanging; they suffocate at the end of a rope, a particularly gruesome way to die. The vertebral artery is often damaged in suicidal hanging (2); “The vertebral artery was shown to be injured quite frequently (rupture, intimal tear, sub-intimal hemorrhage), namely in one quarter of all cases, and indeed in more than half taking into account the perivascular bleeding.” This easy injury is in part due to mechanical reasons “The vertebral arteries appear to be particularly susceptible to injury in trauma of the cervical spine because of their close anatomical relationship to the spine” (3). 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 (8)”. 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."

FULL TEXT of the Cassidy paper [pdf]

PREFACE: Neck Pain and the Decade of the Bone and Joint 2000–2010

FULL TEXT of all papers contained in Neck Pain and the Decade of the Bone and Joint 2000–2010



I have a copy of the paper. If I am interpreting it correctly, a figure that stands out is that patients with VAD who are <45 are 12 times more likely than non-VAD persons to have attended a chiropractor within the previous 24 hours 95% CI (1.25-115.36). For chiropractic attendance within three days the figure is 3.33 (1.02-10.92), and the association remains up to 30 days Odds ratio 3.13 (1.48-6.63). There is NO such association for the over 45 age group -- 0.55 (0.16-1.85) for having seen a chiropractor within 24 hours.

This in accord with what the observational evidence suggests --- strokes coming on immediately, or within a day or so after neck manipulation in young persons.

The big "however", and the only new thing that the Cassidy paper contributes, is that there is at least an equally strong association with doctor attendances -- here there is an Odds ratio of 11.21 (3.59-35.03) for 0-1 days and 9.53 (3.96-22.97) for 0-3 days. And, interestingly, there does remain a strong association of VAD with doctor visits in the previous 24 hours with an OR of 6.65 (4.18-10.58) in the over 45s.

What can it all mean? I have always accepted that some patients may have attended a chiropractor because of neck pain that is actually due to a stroke in progress, but this is definitely NOT an adequate answer for all cases. Many have had no preceding relevant symptoms, or have been treated for more chronic complaints.

May the answer lie in a source of bias that is not considered in the paper's discussion? I have little personal experience in neurology but I suspect that most patients with early VAD will also have worrying neurological symptoms and that this draws the majority of patients with VAD towards medical doctors rather than chiropractors for any medical attendances that occur prior to hospital admission.

And medical attendances is all that is being measured here. It is not a direct assessment of the effects of neck manipulation.


The study itself did not report the presenting complaint or whether neck manipulation was performed, so it was really meaningless. What if patients with early stroke symptoms are more likely to see a medical doctor than a chiropractor and what if some of the patients had no pre-existing symptoms but saw a chiropractor for health maintenance and had strokes as a result? The data would look the same. The author's speculation that patients who saw chiropractors were already having a stroke is in no way supported by the data. And of course, chiropractors seeing a patient with stroke symptoms should have recognized them and sent the patient to a hospital. If they can't recognize stroke symptoms, they are likely doing neck manipulations on these already vulnerable patients, which can't be good.

The really pitiful thing is that chiropractors could so easily keep a register of presenting complaints, type of manipulations, and follow-ups to see if stroke was later diagnosed. If they kept good records, they could either SHOW us that there was no association between neck manipulation and stroke, or they could show that there was a tiny risk and they could have quantified it and maybe figured out which patients were at greatest risk. If a similar risk was even remotely suspected for a scientific medical treatment, you can bet physicians would have done that kind of research by now.

We have plenty of smoking gun cases where a patient with no headache or neck pain got neck manipulation and collapsed on the table with torn vertebral arteries. Chiropractors would have us believe that they would have collapsed anyway without manipulation, but they can't offer any supporting data. The very fact that they try to defend these cases with rationalizations and speculations rather than data just shows how far they are from science-based thinking.


Cassidy was very adamant in pointing out, entirely correctly, that a statistical association does not equal causality…One might have wanted to ask about the "association" between peoples' recovering health after a visit to the chiropractor and primary care physician, respectively. I mean, they do base their whole so-called profession on the faith in causality between chiropractic "care" and beneficial health outcomes, don't they?

DCs like to "point out" that all reports of adverse effects of chiropractic, including stroke and death, are only "case reports" and "anecdotes" and thus meaningless, because there are no control groups. They seem to have learnt the lesson from the critique by the medical science side that anecdotes don't count as data. But they are missing the whole thing, the difference between an experimental study and reports of adverse effects, that aren't of course experimental and can't have control groups. I have never heard of a real medical doctor dismissing any "anecdotic" reports of adverse effects of drugs or other medical treatments -- and neither do the DCs in that context!! On the contrary, they almost always end up in tu quoque arguments against NSAIDs in their pathetic attempts at justifying chiropractic.

This stubborn denial of any possible inkling of a thought of a suspicion of causality between neck manipulation and the frequent smoke-gun-reported adverse effects is a terrible disgrace to Cassidy and the chiropractors as fellow human beings as well as professional health care providers. But I think I understand them, because -- please tell me if I am correct or incorrect in believing this -- that if they admitted that there might be an ever-so-small causal relationship between neck manipulation and stroke, they would risk lots of litigation processes where they would lose and have to pay huge amounts of money to the victims? That might explain why they so strongly object to even having a form for written consent, since such a piece of paper would count as admitting the risk, or?

The only really interesting piece of information is that Cassidy has conceded that he once had a patient who got a stroke on his manipulation table after neck manipulation. Cassidy did think, at the time, that the manipulation caused the stroke, but that he does not think so now any more, thanks to his study. This opens up for the suspicion that he was heavily biased in architecting the study...Unlike most medical articles nowadays, the Cassidy report has no "Disclosure statement" or "Declaration of potential bias". Maybe purposely omitted?

When a stroke occurs in a chiropractor's office during or immediately following a neck manipulation, especially in the case of a healthy young person, there is good reason to suspect a temporal or causative association with neck manipulation. In many cases, however, a stroke caused by neck manipulation may occur days later when a damaged vertebral or carotid artery releases a blood clot or an embolus that travels to the brain stem or to the brain. When these patients develop symptoms of stroke, they will go to the emergency room or seek medical care rather than go to a chiropractor’s office. The patient may not report the neck manipulation he or she had at the chiropractor’s office and the physician may be unaware that the patient had such treatment (most often for conditions or reasons other than head or neck pain), thus relieving the chiropractor of any blame and jacking up the number of stroke victims seeking primary care. For this reason, it may be misleading to say that the incidence of stroke associated with chiropractic care is the same as that associated with primary care, as reported in the Cassidy study.


One of my greatest concerns is that they seem *not* to have included those who died or otherwise were not *discharged*. They do not even mention them, so we do not know the number of exclusions. The text is not clear on this matter (except that recently dead persons or long-term care residents were excluded from the *controls*). I may be seriously wrong on this issue, because I don't understand exactly what "discharge abstract" is in this context…I learned that Canada has specially trained "abstractors", but nobody asked if they were medically trained persons or clerical staff, or what.


The Cassidy study confirmed previous findings of an association between vertebrobasilar artery stroke and chiropractic visits in those under 45 years of age.

The odds ratio for PCPs is a separate issue and we don’t know what it means. The assumption that patients sought care for pre-existing symptoms of stroke was not justified by the data. The data collection method did not permit any conclusions about that or even about neck manipulation.

So far no study has directly assessed the relationship between presenting symptoms, neck manipulation vs. other interventions, and stroke. That is the kind of study we need. Chiropractors themselves have been concerned about the stroke/neck manipulation connection, but they haven’t yet studied it in any meaningful way.

In the recent hearings in Connecticut Cassidy testified that he had once thought he was responsible for a stroke that his patient suffered after neck manipulation, but he changed his mind after the Cassidy study. I don’t think he was justified in changing his mind based on those inadequate data.

What we really want to know is whether neck manipulation is a risk factor for stroke. The data from several studies, the many “smoking gun” case histories, and the presence of a credible mechanism suggest that it is. If previous visits with PCPs are associated with stroke, that is an entirely separate question. If pre-existing neck pain predicts these strokes and prompts visits to any provider, that would be useful to know, but this study doesn’t illuminate us. The study didn’t even address neck manipulation, only visits to chiropractors – which might have involved activator or other treatments without manipulation. And for all we know, a few of the visits to PCPs could have involved neck manipulation, particularly if the PCP was a DO.

The study may serve a psychological function for chiropractors by reinforcing their beliefs but it is really useless as far as helping us understand what is going on. It certainly does not show that neck manipulation can’t cause strokes. I think most chiropractors would hesitate to manipulate the neck of someone who was having a stroke in progress; and if there is no reliable way to differentiate those patients from patients with musculoskeletal neck pain, doesn’t that mean that chiropractors ought to be reluctant to manipulate any patient with neck pain?

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"Sometimes the damage is immediate and the patient collapses on the chiropractor's table. Sometimes mild symptoms start immediately and progress after the patient leaves the chiropractor's office. Sometimes the tear is a small one and it clots over; then days later the clot breaks loose, travels to the brain and causes a delayed stroke. By this time, the patient may not connect his sudden collapse to the previous visit to the chiropractor..…How often can a stroke be attributed to neck manipulation? We really don't know. Estimates have varied from one in ten million manipulations to one in 40,000. I should clarify that only one specific type of stroke, basilar stroke, has been linked to chiropractic. It has been estimated that about 20% of all basilar strokes are due to spinal manipulations. This would work out to about 1300 a year in the U.S. But we just don't know, because it has not been properly studied. Carotid artery strokes have also been reported after chiropractic treatments. Chiropractors do not follow up on every patient. Patients who have delayed strokes may never see their chiropractor again, so chiropractors would naturally tend to underestimate the risk. Many of these diagnoses are missed because the vertebral arteries are not typically examined on autopsy." Article by Harriet Hall MD, Science Based Medicine (29th April 2008)

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"We report three cases of serious neurological adverse events in patients treated with chiropractic manipulation. The first case is a 41 years old woman who developed a vertebro-basilar stroke 48h after cervical manipulation. The second case represents a 68 years old woman who presented a neuropraxic injury of both radial nerves after three sessions of spinal manipulation. The last case is a 34 years old man who developed a cervical epidural haematoma after a chiropractic treatment for neck pain. In all three cases there were criteria to consider a causality relation between the neurological adverse events and the chiropractic manipulation. The described serious adverse events promptly recommend the implementation of a risk alert system." Clinical Neurology and Neurosurgery (December 2007)