Update from the Canadian Stroke Consortium

In July 2000 CMAJ published a brief commentary by us on behalf of the Canadian Stroke Consortium concerning our current national study of stroke following cervical arterial dissection.1 The goal of the study was, and still is, to determine the relationship of extreme head movements and other forms of head and neck trauma to dissection of the neck arteries and stroke. Therapeutic neck manipulation, performed usually for the relief of neck pain and mostly by chiropractors, is associated with only 20% of the cases of dissection and stroke in our study.

We quickly received a large volume of email messages and faxes, mainly hostile and mainly from chiropractors. Trial by radio, television and print media was also swift, but the press coverage was generally favourable. However, “sides” were clearly declared. The study was vilified for not having “controls” and for being unscientific in general, and we were criticized for publishing results prematurely.

We have repeatedly protested that this is a collaborative national study (not a “Toronto study”) conducted to collect basic descriptive data on this underreported cause of stroke in young people. Data from the consortium and from centres in other countries consistently confirm dissection of neck arteries to be the major cause of stroke in young people.2^,3 After our commentary was published, a case–control study showed that patients below 45 years of age with vertebrobasilar stroke were 5 times more likely than controls who had not had a stroke to have visited a chiropractor in the week before the event.4

Compared with a retrospective study design, the prospective nature of our study allows much more accurate evaluation of the role of trivial trauma in the occurrence of stroke and determination of the frequency of stroke recurrence in the acute phase, which may facilitate development of better therapies. We post data on our Web site as we accumulate it so that it is accessible to all.

Collaboration with our chiropractic colleagues is crucial to understanding and resolving the association between sudden neck movement and stroke. Blanket denial or distortion of our data from various quarters can only delay discovery of the necessary facts at the expense of the well-being of patients.