A report by the American Heart Association (AHA) suggesting a possible link between adjustments of the neck — whether by a chiropractor or osteopathic doctor — and stroke has created intense debate.
The study’s author, Jose Biller, chair of neurology at Loyola University Chicago Stritch School of Medicine, states that thrusts and rotations sometimes used in neck manipulation may cause a small tear in the artery walls in the neck. Biller says such a tear “occurs with a sudden movement that can hyperextend or rotate the neck, such as one you may see with whiplash or sporting events, or even violent coughing or vomiting. The techniques for cervical manipulation, even though they vary among health professionals, include a rotation of the neck and sometimes a forceful thrust.”
However, the paper also goes on to note the evidence does not prove that the practice can directly cause strokes.
Keith Overland, former president of the American Chiropractic Association, (ACA) says, “Two studies that have come out recently said that there is no evidence that the force or direction utilized in cervical manipulation reaches the threshold of stretching the arteries to the point that they can be damaged.” Overland also points out that practitioners who perform neck adjustments apply force that is “no greater than what people can do in activities of daily life.”
In response to the AHA report, the International Chiropractors Association (ICA) is reviewing the scientific and clinical literature regarding the safety record and effectiveness of chiropractic adjustment procedures.
ICA President Michael S. McLean explains, “Medical researchers frequently misunderstand the critical differences between specific chiropractic adjustments and cervical manipulation. Doctors of chiropractic are highly trained in the use of the adjustment, which is the specific and scientific application of directional force to facilitate the reduction of nerve interference. Manipulation is the forceful passive movement of a joint beyond its active limit of motion. Since manipulation doesn’t imply the use of precision, specificity, or the correction of nerve interference, it is not synonymous with chiropractic adjustment.”
For example, a literature review published in the September 2013 issue of the International Journal of Clinical Practice looked at whether spinal manipulative therapy (SMT) was a causative or associative factor in stroke. Although long anecdotal, there was no statistical evidence. After examining the literature, the study’s author determined the incidence of stroke after a neck adjustment occurred between one case out of every 400,000 to one in 5.6 million. The conclusion was that prejudice by some in the medical community toward chiropractic have created distorted perceptions.
The review also noted that 60 percent of strokes occur due to an abnormal amount of lipids (cholesterol and/or fat) in the blood and that smoking, hypertension, obesity, cardiovascular disease, and diabetes are considered significant risk factors for stroke. Chiropractic adjustments or SMTs are not, leading the author to conclude, “The evidence for causality of vertebral artery dissection from chiropractic is weak.”
The Canadian Medical Association Journal (2001) reviewed the malpractice data from between 1988 and 1997. Paul Carey, president of the Canadian Chemical Producers’ Association, adds: “This most recent study establishes such an extremely low degree of risk that patients can feel confident about the safety of neck manipulations performed by chiropractors.”
Another study published in the Journal of the Canadian Chiropractic Association concluded there was a one per 3 million risk of stroke after neck adjustments. Lastly, not a single case of vertebral artery stroke was found after reviewing approximately 5 million cervical manipulations from 1965 to 1980 at the National College of Chiropractic Clinic in Chicago.
The bottom line is chiropractic adjustments administered by qualified, licensed doctors of chiropractic pose no demonstrable, significant risk of stroke.