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Study Looks at Chiropractic Treatment, Stroke Risk

Mon May 12, 2003

By Alison McCook

NEW YORK (Reuters Health) - People who undergo chiropractic neck and spine adjustments may be at higher risk of having a stroke as a result of tiny tears in their arteries, researchers said Monday.

However, experts said the risk of such a problem is rare at best and that chiropractic manipulations are safe overall.

Previous research has suggested that certain "high velocity" neck manipulations used by chiropractors can lead to a stroke-inducing condition called artery dissection, in which the inside wall of an artery becomes torn.

These findings, however, have been sharply criticized by representatives from the American Chiropractic Association, claiming that the research does not demonstrate that the manipulation is the cause of stroke.

In the newest study to suggest a link between chiropractic treatment and stroke, researchers found that people under age 60 who experienced stroke as a result of dissection were almost seven times more likely to have undergone a spine and neck adjustment 30 days before their stroke than other patients.

During the study, Dr. Wade S. Smith of the University of California, San Francisco, and colleagues interviewed 51 people who had experienced stroke as a result of arterial dissection and compared their chiropractic history to that of 100 patients who had a stroke as a result of other causes.

Their findings appear in the journal Neurology.

In an interview with Reuters Health, Smith said the results suggest that chiropractic manipulations can either cause the dissection to occur, or worsen a pre-existing dissection, causing stroke, he said.

He noted that more than half of the people whose stroke resulted from dissection reported a severe worsening of pain after their manipulations, a phenomenon not reported by any people who suffered stroke from other causes.

Smith noted, however, that he believed that the chance of stroke after neck manipulations was very small, and that chiropractic medicine was, overall, safe.

That said, Smith added that patients probably deserve to know that certain manipulations carry that risk. "I think that patients deserve the right to be informed about it ... to hear that this can cause injury, although it's probably rare."

However, Dr. Linda S. Williams of the Health Services Research and Development Service in Indianapolis, Indiana, who wrote an accompanying editorial, said she disagrees.

"I personally haven't felt consent for the procedure is something that definitely needs to be done," she told Reuters Health.

She explained that Smith and his colleagues did not determine which chiropractic manipulations were performed during patient visits and so cannot say that patients who developed dissections even received the potentially dangerous neck manipulation.

Moreover, the authors tried to determine if people developed dissection before or after their chiropractic manipulation by asking them if they felt neck pain before or after visiting a practitioner, a technique that is notoriously unreliable, Williams said. As such, errors in patients' abilities to recall when their pain occurred may have influenced the findings, she noted.

Dr. William Lauretti, a chiropractor in private practice in Bethesda, Maryland, and a spokesperson for the American Chiropractic Association, told Reuters Health that the study does not clearly establish that stroke-causing dissections are linked to chiropractic medicine.

He explained that previous research has shown that the neck manipulations featured in the study may not stress arteries enough to cause dissection.

Moreover, even if the procedure does increase the risk of dissection and stroke, Lauretti noted that the risk is so small that patients may have just as high a risk of dying in a car accident on the way to the appointment, but chiropractors are not required to warn them of that.

As evidence, Lauretti added that he has been in practice for 12 years and has performed around 15,000 head and neck treatments. "I've never seen any sort of a significant complication from it."

SOURCE: Neurology 2003;60:1424-1428,1408-1409.

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