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.

This page was updated on 11th September 2013.

Related links


Safe for children?

Sandra Nette v. Stiles et al

Chiropractors and Medical Malpractice Lawsuits

According to the U.S. National Practitioner Data Bank, between September 1, 1990 and January 29, 2012, a total of 5,796 chiropractic medical malpractice reports were filed.  Common reasons for the lawsuits were strokes and other injuries.  

[Video] Chiropractic Neck Manipulation: Dangers and Death

Video (49:54 mins) produced by Canadian Victims of Chiropractic Neck Manipulation: "This video is not a high priced production. The tragedies are felt at home, so this is where the stories are told. It is the best these families can do. They don't have millions of dollars to spend as the chiropractors did in the inquest into the death of Lana Dale Lewis. Yet, with less than one percent of the resources, the truth did again prevail. Chiropractic neck manipulation does cause death."

US: Chiropractic groups sued by stroke victims

Victims of Chiropractic Abuse, Inc. (VOCA) has initiated a class-action lawsuit charging the Connecticut Chiropractic Council, the Connecticut Chiropractic Association, and their members with knowing that neck manipulations are associated with strokes and can cause stroke but refusing to inform patients of the risks in order to maximize profits. The suit also accuses the chiropractors of employing a strategy of misrepresentations or omissions designed to mislead patients by violating state laws that require they clearly identify themselves as chiropractors in advertising and marketing materials when using the title of "Doctor". VOCA is seeking financial damages; an injunction forbidding the use of the deceptive tactics; and other equitable relief, including but not limited to an order requiring chiropractors who have engaged in these deceptive tactics to pay appropriate fines. The suit was filed immediately after the Connecticut State Board of Chiropractic Examiners refused to grant VOCA's request to order chiropractors to warn patients that neck manipulation entails a risk of stroke. 

Evidence for a causal link between chiropractic treatment and adverse effects

"So far, we know for sure that mild to moderate as well as serious complications, including deaths, do occur after chiropractic spinal manipulations, particularly those of the upper spine. What we cannot say with absolute certainty is whether they are caused by the treatment or whether they happened coincidentally. Our knowledge in this area relies mostly on case-reports and surveys which, by their very nature, do not allow causal inferences. Therefore chiropractors have, in the past, been able to argue that a causal link remains unproven. A brand-new blinded parallel group RCT might fill this gap in our knowledge and might reject or establish the notion of causality once and for all...what does this new study tell us? In my view, it is strong evidence to suggest a causal kink between chiropractic treatment and mild to moderate adverse effects." Edzard Ernst's blog (27th June 2013)

More on the risks of spinal manipulation

"Australian researchers have just...[published] a systematic review aimed at systematically reviewing all reports of serious adverse events following lumbo-pelvic SMT...The authors' conclusion was that this systematic review describes case details from published articles that describe serious adverse events that have been reported to occur following SMT of the lumbo-pelvic region. The anecdotal nature of these cases does not allow for causal inferences between SMT and the events identified in this review...The authors make a strong point about the fact that case reports never allow causal inference. One can only agree with this notion. However, the precautionary principle in medicine also means that, if case reports provide reasonable suspicion that an intervention might led to adverse-effects, we need to be careful and should warn patients of this possibility. It also means that it is up to the users of SMT to demonstrate beyond reasonable doubt that SMT is safe." Edzard Ernst (23rd June 2013)

How chiropractors put patients at risk

"A team of Swiss and UK chiropractors just published a survey to determine which management options their colleagues would choose in response to several clinical case scenarios...In my view, the findings of this survey are deeply worrying and the interpretation of the authors is not far from an attempt to 'white-wash' the results. Like with most investigations of this nature, the results are wide open to selection bias; particularlythe dismal UK response rate begs many questions. In all likelihood, reality is much worse than implied by the results of this investigation. And these results clearly show that, even with a fairly dramatic safety incident, chiropractors fail to respond adequately. There is no doubt in my mind: chiropractors put patients at risk." Edzard Ernst (10th June 2013)

Chiropractic Manipulation of the Neck and Cervical Artery Dissection

“Although incidence of cervical artery dissection precipitated by chiropractic neck manipulation is unknown, it is an important risk. Given that risk, physical therapy exercises may be a safer option than spinal manipulation for treating patients with neck pain.” Conclusion of a letter from Raymond E. Bertino, MD, Arun V. Talkad, MD, Jeffrey R. DeSanto, MD, Jane H. Maksimovic, DO, and Shyam G. Patel, MD. Ann Intern Med. (17th July 2012)

Spinal cord injury following chiropractic manipulation to the neck

“This case report describes a 50-year-old man who developed neurological symptoms a few hours after manipulation (high velocity low amplitude [HVLA] technique) of the cervical spine. Magnetic resonance (MR) imaging of the cervical spine revealed intramedullary high signal at the C2/3 level of the right side of the cervical cord on the T2-weighted images. The potential mechanism of injury and causes of the radiological appearance are discussed.” Source: Clinical Radiology, University Hospital of Wales, Cardiff. Acta Radiol. (24th October 2011)

Craniocervical arterial dissections as sequelae of chiropractic manipulation: patterns of injury and management

This authoritative study finds that chiropractic manipulation of the cervical spine is a known cause of craniocervical arterial dissections: “These injuries can be severe, requiring endovascular stenting and cranial surgery. In this patient series, a significant percentage (31%, 4/13) of patients were left permanently disabled or died as a result of their arterial injuries.” Journal of Neurosurgery (16th September 2011)

Risk factors and clinical features of craniocervical arterial dissection

“Craniocervical arterial dissection is one of the most common causes of ischaemic stroke in young people and is occasionally associated with neck manipulation. Identification of individuals at risk will guide risk management…Mild mechanical trauma to the head and neck was significantly associated with craniocervical arterial dissection (OR 23.53). Cardiovascular risk factors for stroke were less evident in the dissection group (3)”. Manual Therapy (August 2011)

Cauda equina syndrome and spine manipulation: case report and review of the literature

“We observed and treated a 42-year-old patient who complained a rapid onset of saddle hypoparesthesia and urine retention only a few hours after the spinal manipulation performed for L5-S1 herniated disc. The comparison of the two following MRIs performed before and after the manipulations seems to prove a close pathogenetic relationship.” Tamburrelli FC, Genitiempo M, Logroscino CA. European Spine Journal (15th March 2011)

Acute spinal epidural haematoma causing cord compression after chiropractic neck manipulation: an under-recognised serious hazard?

“Spinal manipulative therapy performed by chiropractors is increasingly common in the United Kingdom. Spinal epidural haematoma is a rare complication of such physical therapy but when identified represents a neurological emergency. We describe the case of a 64 year-old man who presented with a dense hemiplegia due to a spinal epidural haematoma following cervical spine manipulation performed for acute neck pain. The clinical features and surgical management of the case are discussed and we stress the importance of recognition of chiropractic manipulation as a potential cause of neurological sequelae and discuss the potential pitfalls of such therapy as it becomes more widespread.”  J R Army Med Corps (December 2010)

Vertebral Artery Dissection After Iatrogenic Cervical Subcutaneous Emphysema

“VADs are associated with a variety of minor traumatic mechanisms including painting a ceiling, yoga, chiropractic manipulation of the spine, and driving. These events cause injury to the vessel wall either by shearing forces secondary to rotational injuries or direct trauma to the vessel wall on bony prominences, especially the transverse processes of the cervical vertebrae.” J Card Surg. (14th November 2010)

Withdrawal rates as a consequence of disclosure of risk associated with manipulation of the cervical spine: a survey

Only 45% of chiropractic respondents in this study indicated they always discussed risk with patients in need of cervical manipulation. When asked whether they believed discussing the possibility of a serious adverse reaction to cervical manipulation could increase patient anxiety to the extent there was a strong possibility the patient would refuse treatment, 46% said they believed this could happen. Jennifer Langworthy and Lianne Forrest, Chiropractic & Osteopathy (October 2010)

Bilateral Vertebral Artery Dissection After Chiropractic Maneuver

“Clinical evidence strongly supports the notion that the dissection occurred during the maneuver since an MRI scan prior to the manipulation showed a protruded intervertebral disk and intact cervical vessels.” Clinical Neuroradiology (20th October 2010) [FULL TEXT - pdf]

Serious adverse events after spinal manipulation: a systematic review of the Korean literature

“It is concluded that adverse effects after spinal manipulation are not specific to chiropractic but occur with most types of spinal manipulation. Incidence figures can, however, not be derived from the data available to date.” Byung-Cheul Shin, Myeong Soo Lee, Tae-Yong Park, and Edzard Ernst, Focus on Alternative and Complementary Therapies (Volume 15, Issue 3, pages 198–201, September 2010)

Does upper spinal manipulation cause vascular accidents?

“…based on the totality of the best evidence available to date, there can be little doubt that the formal criteria for causality are, in fact, fulfilled, and that upper spinal manipulation is the cause of vascular accidents. Moreover, the Cassidy study is seriously, some would say fatally, flawed. Finally, there are several case-control studies that contradict its findings; so the totality of the evidence from case-control studies does suggest that upper spinal manipulation is risky.  Even if one conceded that there is still reasonable doubt about this question, responsible and ethical healthcare professionals have to subscribe to the precautionary principle. Neck manipulation is not of proven therapeutic value for any condition. Therefore, we have to err on the safe side. Put bluntly, this means that, until the matter is settled, we should not routinely use or recommend upper spinal manipulation. At the very minimum, we should only do so after fully informed consent.”  Edzard Ernst, Pulse (27th July 2010) [Free registration] 

Deaths after chiropractic: a review of published cases (FULL TEXT)

"Twenty six fatalities were published in the medical literature and many more might have remained unpublished. The alleged pathology usually was a vascular accident involving the dissection of a vertebral artery. Conclusion: Numerous deaths have occurred after chiropractic manipulations. The risks of this treatment by far outweigh its benefit. Edzard Ernst, Int. Journal of Clinical Practice, Vol. 64 Issue 8, Pages 1162-1165 (16th June 2010) [pdf]

Deaths after chiropractic spinal manipulations: a reply [Prof. E. Ernst Int J Clin Pract. July 2011]

To the Editor: "This response (1) confirms that many chiropractors find it impossible to accept the key messages regarding spinal manipulation therapy (SMT), namely that this therapy lacks a plausible rationale (2) and its risks outweigh its benefits (3). The risks are, of course, far greater than the relatively few deaths seem to imply. Several hundred cases of severe but non-fatal adverse events are on record (e.g. 4,5). The benefits of SMT have, so far, not been demonstrated; even the many chiropractors who criticised my review (6–12), have not produced convincing evidence for such benefit. Why? The answer is simple: there is none! In the most recent Cochrane review of SMT for chronic low back pain, the main indication for chiropractors, concluded that ‘there is no clinically relevant difference between SMT and other interventions for reducing pain’ (13). For all other conditions, the evidence is even more squarely negative (14). If we focus on the bigger picture, we are confronted with balancing little benefit with considerable risks. The result of such an evaluation can never be positive – no matter how we turn and twist the complex details of this debate.” 

References: (1 ) Haynes MJ. Deaths after chiropractic: a comment. Int J Clin Pract; 65: 817. (2) Homola S. Real orthopaedic subluxations versus imaginary chiropractic subluxations. FACT 2010;15(4): 284–7. (3) Ernst E. Chiropractic: a critical evaluation. J Pain Sympt Man 2008; 35(5): 544–62. (4) Shin BC, Lee MS, Park T-Y, Ernst E. Serious adverse events after spinal manipulation: a systematic review of the Korean literature. FACT 2010; 15(3): 198–201. (5) Terrett AGJ. Current Concepts in Verebrobasilar Complications Following Spinal Manipulation. Iowa, IA: NCMIC Chiropractic Solutions, 2001. (6) Ernst E. Deaths after chiropractic: a review of published cases. Int J Clin Pract 2010; 64: 1162–5. (7) Wenban AB, Bennet M. Critique of review of deaths after chiropractic, 1. Int J Clin Pract 2011; 65: 102. (8) Poelsma C, Owen D. Critique of review of deaths after chiropractic, 2. Int J Clin Pract 2011; 65: 103. (9) Dokos C, Tragiannidis A. Critique of review of deaths after chiropractic, 3. Int J Clin Pract 2011; 65: 103–4. (10) Perle SM, French S, Haas M. Critique of review of deaths after chiropractic, 4. Int J Clin Pract 2011;65: 104–5. (11) Whedon JM, Bove GM, Davis MA. Critique of review of deaths after chiropractic, 5. Int J Clin Pract 2011; 65: 105. (12) Ernst E. Response to critiques of review of deaths after chiropractic. Int J Clin Pract 2011; 65: 106. (13) Rubinstein SM, van Middelkoop M, Assendelft WJ, de Boer MR, van Tulder MW. Spinal manipulative therapy for chronic low-back pain. Cochrane Database Syst Rev 2011; 2: CD008112. (14) Ernst E, Canter PH. A systematic review of systematic reviews of spinal manipulation. J R Soc Med 2006; 99: 192–6.

Acute paraplegia after chiropraxis

“We describe the case of a 45-year-old woman who suffered complete paraplegia shortly after a chiropractic maneuver in the thoracic spine. Dorsal CT showed a calcified disc herniation at the T8-T9 level and MRI revealed a diffuse spinal cord ischemia from T6 to the conus medullaris without spinal cord compression at the level of herniation. Despite a normal arteriography, authors suggest a vascular injury as the cause of the deficit.” European Spine Journal (16th June 2010)

Cervical Artery Dissection: Emerging Risk Factors

“Cervical artery dissection (CAD) represents an increasingly recognized cause of stroke and the most common cause of ischemic stroke in young adults…known risks factors for CAD are major head/neck trauma like chiropractic maneuver…” Open Neurol J. (June 2010)

Letter from Britt Harwe, President, Chiropractic Stroke Awareness Group (CSAG)

“… the National Quality Forum lists 28 ‘never events’ healthcare mistakes that should never happen and need to be reported. Death or serious disability from spinal manipulation is listed as no. 16. But chiropractors do not have to report this because they have a loophole. The National Quality Forum demands it of clinics and hospitals but no reporting is mandated for individual doctor’s offices where 99% of spinal manipulation is done. Chiropractors generally do not practise in hospitals or clinics. Therefore, there is no accurate reporting for injuries that occur as a result of spinal manipulation. Yet we have hundreds of victims who have suffered needless injuries due to a stroke as a direct result of a chiropractic manipulation, and they are horrible, permanent injuries and they happen to mostly young healthy people under the age of 45 years.” Focus on Alternative and Complementary Therapies (March 2010)

Cervical intradural disc herniation after spinal manipulation therapy in a patient with ossification of posterior longitudinal ligament: a case report and review of the literature

“Spinal manipulation therapy (SMT) is often used by people with neck pain or discomfort as an alternative therapy due to its claimed less invasiveness and comparable efficacy. However, excessive manipulations are reported to cause rare but serious complications such as tetraplegia, vertebral artery dissection, epidural hematoma, and phrenic nerve injury.” Spine (March 2010)

Vascular accidents after chiropractic spinal manipulation: Myth or reality?

"The association between chiropractic neck manipulation and vascular accidents is well established. A recent case control study, however, casts doubt on the notion that the association is caused by nature. A detailed critique of that study reveals several weaknesses. Therefore the balance of probabilities seems to indicate that the association, in fact, is causal."  Professor Edzard Ernst, review and opinion published in Perfusion (February 2010) [pdf]

Professor Ernst defends himself against accusations of bias, particularly relating to his critical assessments of chiropractic, in this January 2011 interview with On The Other Hand podcast host and chiropractor, Brett Kinsler. [Transcript.]

Catastrophic complication of chiropractic manipulation: A report of quadriparesis

"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]

Neck Manipulation: Risk vs. Benefit

"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)

Adverse Effects of Chiropractic

"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)

Safety of chiropractic interventions: a systematic review

CONCLUSION: There is no robust data concerning the incidence or prevalence of adverse reactions after chiropractic. Further investigations are urgently needed to assess definite conclusions regarding this issue. Spine. 2009 May 15;34(11):E405-13

Chiropractic and Stroke: Evaluation of the paper 'Risk of Vertebrobasilar Stroke and Chiropractic Care: Results of a Population-Based Case-Control and Case-Crossover Study', Spine: 2008 Feb 15;33(4 Suppl):S176-83; Cassidy JD, Boyle E, Côté P, He Y, Hogg-J

"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?

Chiropractic and stroke

"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)

Does cervical manipulative therapy cause vertebral artery dissection and stroke?

“Weak to moderately strong evidence exists to support causation between Cervical Manipulative Therapy (CMT) and Vertebral Arterial Dissection and associated stroke. Ultimately, the acceptable level of risk associated with a therapeutic intervention like CMT must be balanced against evidence of therapeutic efficacy. Further research, employing prospective cohort study designs, is indicated to uncover both the benefits and the harms associated with CMT.” The Neurologist (January 2008) [PDF]

Chiropractic manipulation: Reasons for concern?

"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)

Spinal manipulation: are the benefits worth the risks?

"In conclusion, spinal manipulation is based on questionable pathological concepts and therefore lacks biological plausibility. Its risks may be considerable and its benefits have not been convincingly demonstrated in rigorous trials. What follows is sobering: the benefits of spinal manipulation do not seem worth the potential risks." Edzard Ernst, Expert Review of Neurotherapeutics, Vol. 7, No. 11, Pages 1451-1452 (November 2007) Full text available via this link.

Report of a young mother who suffered a stroke at the hands of a New Zealand chiropractor

"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."

Adverse effects of spinal manipulation: a systematic review

"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)

Adverse Events Associated With Pediatric Spinal Manipulation: A Systematic Review

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)

Vertebral artery dissections after chiropractic neck manipulation in Germany over three years

36 patients (mean age 40+11 years) with vertebral artery dissections associated with chiropractic neck manipulation were identified in neurological departments at university hospitals in Germany. 90% of patients admitted to hospital showed focal neurological deficits and among these 11% had a reduced level of consciousness. 50% of subjects were discharged after 20+/-14 hospital days with focal neurological deficits, one patient died and one was in a persistent vegetative state. Risk factors associated with artery dissections (e.g. fibromuscular dysplasia) were present in only 25% of subjects. Reuter U, Hamling M, Kavuk I, Einhaupl K M, Schielke E; for the German vertebral artery dissection study group. Journal of Neurology (March 2006) [pdf]

Pain in the neck

"…the best options for neck pain are fairly simple and inexpensive. Adding spinal manipulation to the regimen not only does not improve the situation, it may be detrimental." Edzard Ernst, The Guardian (9th August 2005)

Frequency and clinical predictors of adverse reactions to chiropractic care in the UCLA neck pain study

Concludes: "Our results suggest that adverse reactions to chiropractic care for neck pain are common and that despite somewhat imprecise estimation, adverse reactions appear more likely to follow cervical spine manipulation than mobilization. GIven the possible higher risk of adverse reactions and lack of demonstrated effectiveness of manipulation over mobilization, chiropractors should consider a conservative approach for applying manipulation to their patients, especially those with severe neck pain". Spine (1st July 2005)

Dangers of alternative medicine

Irish television programme which contains a 22-minute segment (commencing after 12 minutes) about the dangers of chiropractic neck manipulation: "The attempts to minimise this by the chiropractic profession are astonishing and, to be frank, rather disgusting" — Brad Stewart, Canadian neurologist. The rebuttals made by Hagan McQuaid, International Vice-President of the Chiropractic Association of Ireland, are wholly unconvincing. The programme concludes by questioning the effectiveness of statutory regulation. Prime Time, RTE (5th May 2005)

Cerebrovascular Complications Associated with Spinal Manipulation

Concludes that serious cerebrovascular complications of spinal manipulation continue to be reported. Their incidence is unknown. Large and rigorous prospective studies are necessary in order to define the risks of spinal manipulation accurately. E. Ernst, Physical Therapy Reviews (March 2004) [The Full Text version of this article has recently become subscription-only. In the Case Reports section (Table 1) of the Full Text version, 11 cases are listed where a chiropractor was the therapist involved in administering cervical spine manipulation in which the CAUSALITY of the adverse event is listed as 'CERTAIN'. In two of these cases (Corazzo 1998 and Siegel 2001), the adverse event was vertebral artery dissection and stroke].

Coroner's Jury Concludes That Neck Manipulation Killed Canadian Woman

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.

Amani Oakley's closing in the Lana Dale Lewis Inquest

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]

Fatal chiropractic: The Lana Dale Lewis case

"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)

Stroke and Spinal Manipulation

"The preponderance of the scientific literature supports a direct cause-and-effect mechanism between spinal manipulation and stroke. The therapeutic benefit of spinal manipulation in acute neck pain remains unproven. The [American] public deserves to be provided a thorough informed consent by practitioners of spinal manipulation prior to any treatment being rendered. Further research into informed consent, stroke caused by spinal manipulation, and the therapeutic benefit of the procedure, if any, needs further investigation." Article by Preston Long, PhD, Journal of Quality Healthcare (2004) [pdf]

The medial medullary infarction (Dejerine syndrome) following chiropractic neck manipulation

"A-38-year-old man suddenly developed nausea, vomiting and vertigo during chiropractic neck manipulation. This was followed by right hemiplegia, right deep sensory disturbance and left hypoglossal nerve palsy, consistent with the medial medullary infarction (Dejerine syndrome). The MRI revealed infarction at left medial part of the medulla. The vertebral angiogram and MRA showed marked narrowing of the left vertebral artery. X-rays of the cervical spine showed no spondylosis, dislocation nor osteolysis of the odontoid process….. The mechanism was suggested that rotation and tilting of the neck stretches and compresses the vertebral artery at the cervical joint causing injury to the vessel, with an intimal tearing, dissection, and pseudoaneurysm formation. Consequently, the present case may be caused by injury to the left vertebral artery with an intimal tearing during neck manipulation sufficient to cause disection and subsequent infarction of the brain stem." No To Shinkei (February 2003) [Japanese article]

A Prevention of the Vertebrobasilar Accidents Following Cervical Thrust Manipulations

"It is now a well established fact that cervical thrust manipulations can harm the vertebral artery…This problem is now better known. It is no longer attributed to atherosclerosis (and ageing process) but to a dissection of a vertebral artery, a clinical entity observed in younger patients (20-45 years)." Recommendations of The French Society of Orthopaedic and Osteopathic Manual Medicine (SOFMMOO) (2003)

Complications following vertebral manipulation — a survey of French region physicians

In a survey among 240 neurologists, neurosurgeons, rheumatologists and physicians aimed at estimating the frequency and the incidence of strokes, myelopathies, radiculopathies or osteoarticular accidents linked to spinal manipulation during the preceding two years, the incidence of vertebro-basilar accidents was 30 times higher than in published series. Annales de Readapatation et de Medecine Physique (2003)

Intracranial hypotension after chiropractic manipulation

German neurologists report the case of a 40-year-old woman who had a chiropractic upper spinal manipulation and immediately afterwards suffered increasingly severe symptoms of intracranial hypotension, e.g. headache, nausea and vomiting. After considerable diagnostic confusion a dural tear was found at the level of C1-C2. There were no other causes for the leak of cerebro-spinal fluid. The authors are thus certain that this is the first well-documented case of intracranial hypotension caused by chiropractic. They also speculate that a substantial amount of cases of 'spontaneous' intracranial hypotension may be related to upper spinal manipulation. Journal of Neurology, Neurosurgery and Psychiatry (2003)

Complications of cervical spine manipulation therapy: 5-year retrospective study in a single-group

Conclusions: Cervical spinal manipulation therapy may worsen preexisting cervical disc herniation or cause disc herniation resulting in radiculopathy, myelopathy, or VA compression. In cases of cervical spondylosis, CSMT may also worsen preexisting myelopathy or radiculopathy. Manipulation of the cervical spine may also be associated with higher complication rates than previously reported. Neurosurgical Focus (December 2002) [pdf]

Stroke, cerebral artery dissection, and cervical spine manipulation therapy

"The results of this study suggest that stroke, particularly vertebrobasilar dissection, should be considered a random and unpredictable complication of any neck movement including cervical manipulation. They may occur at any point in the course of treatment with virtually any method of cervical manipulation." Journal of Neurology (August 2002)

Spinal Manipulation: Its safety is uncertain

"Specific risk factors for vascular accidents related to spinal manipulation have not been identified, which means that any patient may be at risk, particularly those below 45 years of age." Edzard Ernst, Canadian Medical Association Journal (2002)

Canadian Neurologists Warn Against Neck Manipulation

Includes a statement of concern to the Canadian public from Canadian neurologists regarding the debilitating and fatal damage manipulation of the neck may cause to the nervous system. Concern No.5 strongly recommends "the immediate banning of all spinal manipulation of infants and children". Brad Stewart, MD, Chirobase (2002)

Life-Threatening Complications of Spinal Manipulation

"….one must consider underreporting: if a patient suffers a serious complication after spinal manipulation, her chiropractor is unlikely to see her again, and the physicians who do might not think of a link between manipulation and the adverse effect. And even if they consider an association, are they likely to publish this as a case report? Moreover, none of the prospective studies available to date have enough power to detect events that occur less frequently than 1 in approximately 500 patients." E. Ernst, Stroke (2001)

Chiropractic Manipulation and Stroke

"Practitioners of this technique (cervical spine manipulation) should be called on to demonstrate the evidence-based benefit of this procedure and to define the specific indications for which the benefits of intervention outweigh the risk." Stroke (2001)

Brown-Sequard syndrome of the cervical spinal cord after chiropractic manipulation

This case report describes a 58-year-old woman who was treated by a chiropractor with neck manipulation (high-velocity thrust) for neck pain. Immediately after the third session, the patient experienced neurolgical symptoms. She saw a neurologist and was admitted to hospital 3 days later. The diagnosis was confirmed by magnetic resonance imaging (MRI). American Journal of Neuroradiology (August 1998)

Radiculomedullary complications of cervical spinal manipulation

"This report describes four patients with cervical myelopathy and/or radiculopathy caused or aggravated by spinal manipulation. In one patient, magnetic resonance scans before and after chiropractic treatment strongly suggests that the disc prolapse syndrome experienced by the patient was provoked by the spinal manipulation." Spinal Cord. (August 1996)

Complications of spinal manipulation: a comprehensive review of the literature

An authoritative systematic review: "It is difficult to estimate the incidence of SMT (spinal manipulative therapy) complications, as they are probably underreported in the literature…Referral for SMT should not be made to practitioners applying rotatory cervical manipulation." Journal of Family Practice (May 1996)

Complications of chiropractic treatment for back pain

Although chiropractic treatment is a popular alternative, its long-term effect is questionable and the medical literature contains numerous reports of patients whose condition worsened as a result of it. Postgraduate Medicine (May 1988)

Complications of Cervical Manipulation: A Case Report of Fatal Brainstem Infarct with Review of the Mechanisms and Predisposing Factors

"Medical and surgical complications of chiropractic manipulation occur infrequently in relation to the number of procedures performed. These complications include intracranial hemorrhage, spinal cord injuries, trauma to the carotid and vertebral arteries, and vertebral-basilar distribution infarction. This is a report of a case of vertebrobasilar infarction following chiropractic manipulation leading to a comatose state within 1 h following the manipulative procedure. This case report should alert the forensic pathologist to the possibility of cervical manipulation as a cause of acute brainstem infarction, and the mechanism and the predisposing factors to injury should be reviewed. The importance of careful autopsy technique and use of postmortem arteriographic techniques are emphasized." Journal of Forensic Sciences (July 1987)