By Martha Kerr

NEW YORK (Reuters Health) – A study presented last week at the American Stroke Association's 27th International Stroke Conference in San Antonio showed a link between chiropractic neck manipulation and cervical artery dissection leading to stroke in young people. The study has prompted a strong reaction from the American Chiropractic Association, which believes the study conclusions are not valid.

The study was conducted by Dr. John W. Norris, of the University of Toronto, and members of the Canadian Stroke Consortium. In a retrospective analysis of data collected on stroke in persons less than 45 years of age, Dr. Norris and colleagues reported finding 158 cases of cervical artery dissection as a cause of the stroke. In 24% of those cases, chiropractic neck manipulation preceded the stroke.

"At best, [the Canadian Stroke Consortium] can draw the conclusion that there is some temporal association between neck manipulation and stroke," Dr. William Lauretti told Reuters Health. Dr. Lauretti, in private practice in Bethesda, is the Maryland delegate to the American Chiropractic Association.

"I don't see any criteria [in the study] that shows that chiropractic treatment was the cause of stroke," Dr. Lauretti asserts.

Dr. Lauretti called the statistics cited in the Canadian study "outrageous." He cites a 5-year retrospective study published last year in Stroke: Journal of the American Heart Association by Rothwell et al. that indicated the number of vertebrobasilar strokes in young people were approximately the same in those who underwent chiropractic manipulation in the week before the event and those who did not.

The American Chiropractic Association has issued a statement that calls the Canadian study "junk science."

When asked for his reaction, Dr. Norris told Reuters Health that "there is no doubt that chiropractic treatment can improve symptoms," but added that "I don't believe in high velocity manipulation of the neck." He said that is the technique that is most likely to cause arterial dissection.

Dr. Norris said that in all cases his team has reviewed, dissection occurs at C1, where the artery enters the skull. He added that dissection can be caused by any sort of trauma, not necessarily chiropractic manipulation.

Dr. Norris commented that a petition, signed by 60 neurologists to-date, is being circulated to ban the practice of chiropractic neck manipulation. Dr. Lauretti says he has been practicing for 12 years and has performed 12,000 to 15,000 neck manipulations with no adverse effects. "It's a lot safer than the most conservative medical treatment," which is nonsteroidal anti-inflammatory therapy. "NSAIDs are associated with a much higher risk of death than neck manipulation," Dr. Lauretti asserts.