Stroking for a Fight

What is going on in Canada? That beautiful land to the north, known for its respectable and good-natured citizens, has recently become home to a dirty little propaganda war against the chiropractic profession that has been executed with all the grace and civility of a bloody, tooth-spitting hockey brawl.

The controversy reached a peak in February of this year, when a group of 60 Canadian neurologists issued a press release warning of the “perils” of chiropractic neck manipulation. The news release said neck manipulation is one of the leading causes of stroke in people under 45.

The National Post, a daily newspaper that is a Canadian version of USA Today, picked up the story. A banner headline in the February 7, 2002 issue screamed, “MDs Warn of Chiropractic Peril.” While the story noted that the chiropractic profession says the risk of stroke is minute—about one in 1 million neck manipulations—it went on to offer an astounding quote from Calgary neurologist Brad Stewart, MD, “The latest figures have put it a little closer to one in 5,000 [manipulations]. That’s a big change. Chiropractors refuse to acknowledge this, and they carry on.”

So, are Canadian chiropractors really wiping out patients at an alarming rate? I seriously doubt it, and I think the evidence clearly demonstrates the inherent safety of chiropractic treatment, both in the United States and in Canada. The evidence also shows that the Canadian neurologists’ campaign is more like a propaganda war than a public education initiative.

First, let us look at the problem of stroke occurring after a neck manipulation. There is little question that, in extremely rare cases, a neck adjustment may result in an injury to the posterior cerebral circulation. Even minor trauma to the vertebral artery may cause a dissection or tearing of the inner artery wall, resulting in ischemia to the brainstem—a type of stroke known as a vertebrobasilar accident (VBA).

Recent evidence suggests that certain individuals have a predisposition to this type of injury.¹ For example, several inheritable connective tissue disorders are associated with an increased risk of vertebral artery dissection. Other recent studies have suggested a role for an infectious trigger in cervical artery dissections.²

All well-designed studies indicate that the risk of a patient suffering a VBA from a neck adjustment is minute. A recent Canadian study,³ based on malpractice statistics, found the likelihood that a chiropractor will be made aware of an arterial dissection following cervical manipulation is approximately 1 in 8.06 million office visits, 1 in 5.85 million cervical manipulations, 1 in 1,430 chiropractic practice years, and 1 in 48 chiropractic practice careers.

Other recent studies have drawn similar conclusions, but have been misinterpreted by critics. For example, a study in the journal Stroke4 found that VBA patients in the Canadian providence of Ontario who were younger than 45 were five times more likely than controls to have visited a chiropractor within a week of the event. They found no statistical correlation between VBA and chiropractic treatment in patients older than age 45. However, a closer analysis of the data presented in this study shows that any conclusions relating cervical manipulation to an increased incidence of VBA was based on fewer than five individual stroke cases that occurred over the study’s 5-year time frame.

Basically, this study found that the 11.5 million people had about 50 million chiropractic visits during a 5-year period, some 15 to 20 million of which presumably involved at least one cervical manipulation. Among this population there were about five incidences of VBA stroke that were statistically related to cervical manipulation.

These figures contrast sharply with the alarmist claims made by the Canadian chiropractic critics. They point to another ongoing survey by the Canadian Stroke Consortium (www.strokecon sortium.ca). This group is collecting data from a survey of neurologists who treated VBA patients. They have claimed that “stroke resulting from neck manipulation”⁵ occurred in as many as 28% of their cases, and there may be as many as 200 cases a year in Canada. However, the criteria for inferring this claimed relationship—much less their basis for presuming causality—have never been adequately described. Moreover, the survey contains no control group, and no apparent protocol to determine which patients are included.

Despite the propaganda, chiropractors should not be complacent about the issue of risk. It is vital that all practicing chiropractors be familiar with the red flags suggesting patients who are at higher risk of suffering this tragic complication. Chiropractic researchers have published dozens of studies in recent years that will help chiropractors better identify the rare patients who have risk factors, and leaders in the profession will continue to work to clarify this complex issue.

The efforts of the chiropractic profession to safely and effectively serve the public are hindered by the sort of cynical and alarmist activities in which some members of the Canadian medical profession have recently engaged. Astute Canadians should have learned two valuable lessons this past February: 1) don’t believe everything French judges say about Canadian figure skaters, and 2) don’t believe everything neurologists say about chiropractors.

William J. Lauretti, DC, practices in Gaithersburg and Bethesda, Md. His chapter, “The Comparative Safety of Chiropractic” will appear in Fundamentals of Chiropractic, a new textbook that will be published by Churchill Livingstone this fall.

References
1. Schievink WI. The treatment of spontaneous carotid and vertebral artery dissections. Curr Opin Cardiol. 2000;15:316.
2. Grau AJ, Brandt T, Buggle F, et al. Association of cervical artery dissection with recent infection. Arch Neurol. 1999;56:851.
3. Haldeman S, Carey P, Townsend M, Papadopoulos C. Arterial dissections following cervical manipulation: the chiropractic experience. CMAJ. 2001;165:905.
4. Rothwell DM, Bondy SJ, William JI. Chiropractic manipulation and stroke: a population-based case-control study. Stroke. 2001;32:1054.
5. Norris, JW, Beletsky V, Nadareishvili ZG. Canadian Stroke Consortium. Sudden neck movement and cervical artery dissection. CMAJ. 2000;163:38.