Chiropractic Tied to Rare Strokes

Study says practice can rupture arteries

Adam Marcus

Adam Marcus

Published on May 12, 2003

MONDAY, May 12, 2003 (HealthDayNews) -- Letting a chiropractor near your neck could be asking for serious trouble.

A new study adds to evidence that people who undergo manipulation -- or "adjustment" -- of the high spine put themselves at risk of ruptured arteries that can lead to strokes.

The study found that stroke patients with torn arteries in the neck were six times more likely to have been to a chiropractor for an adjustment in the preceding month than those whose strokes happened for other reasons. A report on the findings appears in the May 13 issue of Neurology.

"There is a strong association between" neck manipulation and stroke, says study author Dr. Wade S. Smith, a neurologist at the University of California, San Francisco. "It's probably rare, but it's there."

Smith says he and his colleagues aren't saying people shouldn't go to chiropractors, or even that they should avoid neck manipulations entirely. The procedure probably accounts for at most one in every 1 million strokes among young people. "We're not looking at an epidemic problem here or a major scourge," Smith says.

However, many chiropractors fail to warn their patients about the possible complication, and neurologists don't always consider the link, either.

Dr. William Lauretti, a chiropractor and a delegate to the American Chiropractic Association, says he and his colleagues don't typically address the risk of strokes because it's so low and, from their perspective, unproved.

Lauretti says recent research on cadavers found the forces spinal manipulation puts on the neck arteries are weaker than those that accompany normal movement of the head, and much less than required to stretch the vessel. "A normal artery is really very tough and resilient," he says.

Splits, or dissections, of the neck arteries are believed to cause up to a fifth of all strokes in young people, or about two to three cases per 100,000.

Previous studies have suggested manipulation of the cervical spine (the seven highest vertebrae) can cause dissections.

In the new study, Smith's group looked for the link between spinal manipulation and strokes in men and women under age 60. They interviewed 51 who had suffered either a major stroke or a transient ischemic attack -- a form of "small" stroke -- following a split artery.

Seven of these patients, or 14 percent, said they'd been to a chiropractor the month before suffering their stroke. On the other hand, three of 100 men and women stroke patients who hadn't had a vessel rupture had seen a chiropractic recently.

Neck pain often precedes a dissection, and it's a main reason people go to a chiropractor -- raising the possibility that manipulations are unfairly blamed for the vessel damage.

But even after accounting for neck pain, the risk of dissection following spinal manipulation persisted. And more than half of the people who'd suffered a dissection after seeing a chiropractor said their neck pain had appeared or worsened during or after the spinal procedure.

Interestingly, Smith says, although previous studies have linked spinal manipulation with tears of the carotid arteries -- the main vessel in the head and neck -- his research didn't support that connection. All of the risk appeared to involve the vertebral artery, which threads up the spine and into the skull. That makes sense, he adds, because the vessel's walls are bent by twisting and turning of the head.

In addition to neck pain and spinal manipulation, infections also appeared to raise the risk of dissection, according to the study. Certain viruses may weaken blood vessels, making them vulnerable to tears, Smith says.

Dr. Vadim Beletsky, a stroke expert at the University of Western Ontario who has looked at the risks of chiropractic manipulation, believes the practice "may be dangerous and yes, it can cause a devastating stroke or death. However, we can't just forbid this method of treatment since some people are benefiting from it and regardless of stroke risks will continue to do so for decades."

As a middle measure, he says, "informed consent must be mandatory" when patients visit a chiropractor. "We have no right to interfere, but it is our duty to warn."

More information

For more on strokes, try the National Stroke Association. For more on chiropractic, try the American Chiropractic Association.

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