Strokes Linked to Chiropractic Treatment

Feb. 8, 2002 -- Can a common chiropractic adjustment kill? An ongoing study presented at a meeting of stroke experts says it could, but the level of risk to patients remains unclear.

The study is taking place in Canada against the backdrop of lawsuits contending that chiropractic adjustments caused the deaths of two women. At the center of the storm is study leader John W. Norris, MD, professor of neurology and director of the University of Toronto's stroke research unit.

"Quite a number of strokes are associated with chiropractic manipulations," Norris tells WebMD. "It's not generally known by patients or doctors or chiropractors how common it is."

Norris did not set out to study chiropractic medicine. His research team became interested in trying to find out how often relatively young people suffer strokes -- and why. They began to collect stroke data from every Canadian province. The study is still ongoing.

The data collected so far show that one of the leading causes of stroke before age 45 is something called dissection of the cervical artery. That's when one of the two arteries that wind through the back of the neck to the brain gets twisted too much. The lining of the artery bleeds and forms a blood clot. This clot can easily enter the brain and cause a fatal stroke.

Doctors used to think this was a very rare event -- but now that they know to look for it, they are finding it is a more common than they had thought. What's striking about Norris's study is that one in four people who died from stroke after cervical dissection -- 42 out of 173 cases -- had recently seen a chiropractor. A common chiropractic manipulation is to "crack" the neck with an abrupt twist.

"God did not mean for you to twist the neck like that. The artery is stretched beyond its capacity," Norris says. "We think 100 patients per year in Canada alone have chiropractic-associated cervical dissections -- and there must be 1,000 a year in the U.S.," Norris says.

Not so, says neurologist and chiropractor Scott Haldeman, DC, PhD, MD. Haldeman is clinical professor of neurology at the University of California, Irvine. He's also adjunct professor at Southern California University for Health Sciences (formerly Los Angeles Chiropractic College).

Haldeman has analyzed the Norris team's data and says that the researchers have jumped to a conclusion.

"Where the incorrect jump is made is that if someone has a chiropractic manipulation and then has a stroke, they say that the manipulation caused stroke," Haldeman tells WebMD. "They don't ask what the patient was like before he went to the chiropractors office. A substantial number of them probably went to the chiropractor because their stroke already was evolving. This type of stroke starts off as neck pain and headaches -- a main reason people go to a chiropractor."