Chiropractic Strokes Again: An Update

The risk of stroke with neck manipulation has been addressed on SBM before by Dr. Crislip, by myself, by chiropractor Samuel Homola, and by Jann Bellamy. I have listed the links at the end of this article for the convenience of interested readers. Recent studies merit a followup.

A case report published in the Annals of Internal Medicine July 17, 2012, describes a 37 year old nurse who had a history of chronic neck pain. She had been getting neck manipulations from her chiropractor once a month for 12-15 years! (One can only conclude that the manipulations had not accomplished much.) She developed a new symptom (pain when turning her head up and to the right), and at her 4th visit in a week, during neck manipulation, she heard a loud pop and immediately had the sensation that the room was spinning. She developed visual disturbances, vomited, and had a loss of balance, persistently falling to the left. The chiropractor failed to recognize her symptoms as signs of a stroke. Instead of rushing her to the ER, he performed an  “occipital adjustment” in an attempt to relieve her symptoms. She went to the ER 1.5 hours after the event and was found to have a cervical artery dissection. She was discharged from the hospital after 48 hours but has residual symptoms. The authors’ conclusion:

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 patients with neck pain.

Another case report published in the Journal of Neuroimaging  on July 20, 2012, describes a 63 year old man with a history of surgery for carotid artery disease who sought chiropractic care for neck pain. He developed clumsiness in one hand with impaired touch sensation shortly after neck manipulation. Diagnostic studies revealed an acute ischemic stroke that was attributed to an embolus from disruption of carotid artery calcifications. They concluded that it suggested a causal association, especially in the absence of any other predisposing events. They recommended that patients with extensive carotid artery calcifications be advised against neck manipulations.
In December 2011 a study appeared in the Journal of Neurosurgery under the title “Craniocervical arterial dissections as sequelae of chiropractic manipulation: patterns of injury and management.”  It used a database of patients with endovascular disease to identify 13 patients who experienced cervical artery dissections following neck manipulation. It begins with a review of the literature with a long list of references supporting a causal association between high-velocity, low amplitude (HVLA) maneuvers and strokes. It describes a probable mechanism: a tear is produced in the artery wall (a dissection) and either a clot is propagated from the area of dissection or the dissection narrows the artery enough to impair blood flow.

The treatment of choice for these arterial injuries has been anticoagulation therapy. Because of the severity of the dissections in some of their patients, these authors used a more aggressive approach with stent placement and craniotomy to relieve brainstem compression. They describe the outcomes.

They describe two of their cases in detail. One, a 30 year old man, noted pain immediately after neck manipulation. He had a dissection that almost completely obstructed a neck artery. After a complicated hospital course and rehabilitation, he has residual paralysis and difficulty with speech, is unable to work, and depends on his wife for care.

In another case, a 54-year-old presented the day after neck manipulation with headache, incoordination, and difficulty walking. After intensive treatment for arterial dissection and thrombosis, he recovered completely.

Of 13 patients in their series, 9 recovered completely, 3 were permanently disabled, and one died.

They go on to point out:

Patients often visit the chiropractor complaining of head or neck pain, and a certain percentage may have preexisting arterial dissections. Nonetheless, as demonstrated in this series, patients can present within hours to days of chiropractic manipulation with new objective neurological deficits or more severe neurologic complaints. This temporal relationship suggests that either the arterial injury was produced de novo or made worse as a result of manipulation. Worsening of the patient’s complaint or the manifestation of a new neurological deficit after cervical manipulation should prompt urgent medical evaluation.

This undermines the speculations of the Cassidy study, which is often cited by chiropractic apologists. It argued that strokes are not caused by chiropractors but that a stroke is already in progress and is causing neck pain and that is the reason patients consult a chiropractor. Dr. Crislip did a good job of demolishing that study.

Chiropractors always object to being singled out because the culprit is neck manipulation and that is also practiced by other providers.  Nevertheless, chiropractors perform the vast majority of neck manipulations and have claimed manipulation therapy as their raison d’etre. In every case in these new articles, the manipulation was performed by a chiropractor. And in at least one case, the chiropractor was clearly negligent: he failed to recognize stroke symptoms as an emergency and tried to treat the symptoms with more manipulation.

In an earlier study, patients under 45 who suffered a vertebrobasilar stroke were 5 times more likely than controls to have had neck manipulations in the previous week. The actual magnitude of the risk is impossible to quantify, and perceptions differ.  There is reason to believe that many cases are not recognized or reported. Typically, a single chiropractor was aware of each case of manipulation-related dissection while 3-4 neurologists were involved in the patient’s treatment. 1 out of every 48 chiropractors and 1 of 2 neurologists were aware of a case over their lifetime.
Despite some loud protestations, chiropractors do acknowledge the risk. Provocative testing before cervical manipulation is widely recommended in the chiropractic literature. The validity of such testing is questionable, and at any rate the HVLA maneuver is not part of the provocative test and it is the likely culprit. Regardless of the magnitude of risk, the existence of a risk is undeniable and patients should know there is a risk before they agree to treatment. The Association of Chiropractic Colleges suggests informed consent but does not mandate it. Even  knowing about the risk won’t protect patients entirely. I know of one case where a patient fully intended to avoid neck manipulation, yet the chiropractor manipulated her neck without any warning and she suffered an immediate stroke on the table. And there wasn’t even any indication for neck manipulation: she was being treated for shoulder pain, not neck pain.

It’s been said before, but I’ll say it again: any degree of risk is unacceptable when there is no benefit. A Cochrane systematic review has shown that HVLA manipulations are no more effective for neck pain than gentle mobilization and that neither is effective unless used in conjunction with an exercise program. And there is even less evidence for benefit in non-neck-related conditions. NUCCA practitioners and other chiropractors who manipulate necks for almost any complaint are clearly out of line.

Related SBM articles

And there’s more chiropractic posts listed on SBM’s Chiropractic page.

This article was originally published in the Science-Based Medicine blog.

Dr. Hall is a contributing editor to both Skeptic magazine and the Skeptical Inquirer. She is a weekly contributor to the Science-Based Medicine Blog and is one of its editors. She has also contributed to Quackwatch and to a number of other respected journals and publications. She is the author of Women Aren’t Supposed to Fly: The Memoirs of a Female Flight Surgeon and co-author of the textbook, Consumer Health: A Guide to Intelligent Decisions.

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