Stroke Risks From Spinal Manipulation Unknown

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May 22, 2000 -- Could going to the chiropractor for a spinal adjustment increase your risk for a stroke? The chiropractic industry has been under fire over the past few years due to an untold number of strokes -- and in some cases deaths -- blamed on spinal manipulation. One specific procedure performed by chiropractors, known as extension rotation and torque, is under attack.

In one case, a 20-year-old Canadian named Laurie Jean Mathiason died in 1998 after she received a spinal manipulation, from a chiropractor, for treatment for an injury she received after falling down stairs. She complained of sudden neck pain after her last treatment, passed out, and then died within a few days, without regaining consciousness.

Critics say this incident is only one of many similar incidents. "The problem is, nobody knows how common it is," long-time chiropractic critic Stephen Barrett, MD, tells WebMD. "The chiropractic profession either does not keep track of, or won't reveal, the actual figures. Their largest malpractice insurer will not give out the figures despite numerous attempts to obtain them."

The chiropractic profession says the risks are very well known -- and they're small. Jerome F. McAndrews, national spokesman for the American Chiropractic Association and a member of the board of directors of the profession's leading malpractice insurance company, tells WebMD there have been only 130 incidents of manipulation-caused stroke in history. McAndrews says of those, 46% were done by nonchiropractors such as osteopaths, orthopaedic surgeons, and physical therapists -- even though chiropractors perform 94% of all manipulations.

"By comparison, your odds of dying in an accredited American medical hospital from medical mistakes, are 5,000 in one million," says McAndrews.

Greg Tinker, a medical litigator in Seattle for 26 years, calls the numbers used by the chiropractic industry "phony statistics and faulty analysis." Tinker tells WebMD, "their numbers are based on some bizarre estimates based on reported cases and the reported cases are only the ones admitted by the chiropractors' insurance companies. I'm certain it is only the tip of the iceberg."

Tinker has represented three women who have suffered strokes after chiropractic treatments. "All involved strokes of young women with no other stroke risk factors other than chiropractic cervical manipulation."


McAndrews says during his 44-year chiropractic career, similar charges are made periodically "by those who would like to continue hurting our profession using these accusations that are simply not accurate. Spinal manipulation is, in fact, perhaps the safest health care procedure in recorded history."

Here is what is at the core of the issue: There are four arteries involved in the neck. Two carotid arteries are in the front of the neck and two vertebral arteries in the back of the neck. The two vertebral arteries are the most vulnerable, since they wind around the bones of the neck.

A stroke occurs when a blood vessel bringing oxygen and nutrients to the brain bursts or is clogged by a blood clot or by thickening of the artery wall. Because of this rupture or blockage, part of the brain doesn't get the oxygenated blood flow it needs. Without oxygen, nerve cells in the affected area of the brain stop functioning within minutes.

These manipulations are thought to cause strokes mainly by arterial "dissections," which occurs when the artery is stretched, producing a tear of the delicate internal lining. Blood spills under the artery's lining, either blocking the artery or producing a clot, which then dislodges and is carried upstream to the brain, causing a stroke.

In 1999, the Canadian Stroke Consortium (CSC) did a retrospective survey of arterial dissection in Canada over the past few years, and 15 centers reported 63 cases. The CSC is a network of stroke centers in various hospitals across Canada. These preliminary results show:

  • Of the stroke cases, 70% were due to neck trauma, and 30% were "spontaneous."
  • Of the traumatic cases, 50% were caused by neck manipulation. In some cases, arteries on both sides of the neck were damaged.
  • In the 50% that occurred without manipulation, minor neck trauma included swinging a golf club, vigorous drying after a shower, and bouts of violent coughing.
  • The great majority of traumatic dissections involved the vertebral artery.
  • 90% of the dissections occurred within hours of the trauma, but some cases were weeks later and in a few, months later.


McAndrews disagrees with the CSC findings. "These are just false figures. I don't think they're conducting a scientific study at all," he says.

McAndrews says sometimes people -- not chiropractors -- take the chin with their left hand and place their right hand on top of the skull and rotate the head rapidly. "That's when you get all kinds of pops in the neck the way you would get if you popped your knuckles. That procedure is not used in chiropractic [clinics]."

Barrett disagrees, saying that procedure, and other faulty techniques, are indeed used in chiropractic clinics. The problem, he says, is no one wants to admit to a faulty technique. "They've issued some bulletins, and when those bulletins were made public, they became very unhappy. What do you think would happen if they did do something that would establish a potential standard of care? That could be used to hang the chiropractors and admit they were wrong."

McAndrews says the ACA does issue periodic bulletins to its members to ensure safe treatment. In the ACA's Policies on Public Health and Related Matters, obtained by WebMD, under the heading Manipulative Qualifications, the ACA agrees to warn the American public of the inherent dangers in the misuse of the manipulative adjustment "by persons other than those adequately trained and qualified by due educational and examination process," or "by persons with less training than those required in the core curriculum of approved chiropractic."

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