Study Eyes Strokes
During Chiropractic
Neck Adjustments

Chiropractic manipulation is safely done millions of times a year in Canada to treat back and neck pain and other ailments.
When the neck is rotated sharply, a major blood vessel can tear on the inside, causing a clot to form. Both doctors and chiropractors alike say sometimes the treatment can lead to strokes; if the neck is rotated improperly, a blood vessel can tear, causing a clot to form.
Most experts think the incidence of strokes extremely rare. But a new study says it may be more frequent.
CBC News has obtained a summary of an unpublished study by a group which calls itself the Canadian Stroke Consortium. Its study looked at some 60 cases of stroke and concluded 21 were due to neck manipulation.
Although some occurred during physiotherapy, researchers say most were caused by chiropractors.
Toronto neurologist Dr. John Norris says stroke experts see two new cases a month.
"That's probably just the tip of the iceberg," Norris says. "I think there are many more out there."
But Dr. Howard Vernon, director of research at the Canadian Memorial Chiropractic College, cautions the study is too preliminary to draw any conclusions.
"Right now, the best estimates that we have are that it (strokes caused by chiropractic manipulation) is extremely rare. In the order of the same frequency, perhaps, as being struck by lightning."
Details of the study are to be released at a news conference Tuesday.
But the stroke consortium isn't expected to have its study published for several months.