Critique of the Canadian Stroke Consortium's Spontaneous vs. Traumatic Arterial Dissection Study

Journal of the American Chiropractic Association, May 2004 by Haneline, Michael T, Lewkovich, Gary

With findings that run so contrary to the existing scientific evidence in this area, it wouLd seem incumbent upon the CSC authors to take all necessary steps to assure the accuracy of the data used to generate their conclusions. Unfortunately, this was not the case. According to Dr. Beletsky, there was no independent attempt to verify the veracity of the submitted information.

Instances of inaccurate citations of medical literature were evident in the 2000 paper by Noms et al. They incorrectly attributed the first report of ICA dissection in the literature to a 1947 paper by Pratt-Thomas and Berger, which actually involved the VA.29 They also indicated that the ICA is tethered adjacent to C2, which is only partially true. It only becomes tethered, or fixed in place, when the head and neck are positioned in hyperextension and lateral flexion or rotation to the opposite side.30 Otherwise, the ICA is freely moveable within its cervical pathway, and only becomes fixed to the surface of the bone as it enters the carotid canal above the atlas.31 The ICA can be stretched over the upper cervical vertebrae when the neck is positioned as mentioned above.30 This forces the ICA against the upper cervical vertebrae and, accordingly, if accompanied by a sudden and usually severe stretch, the ICA becomes susceptible to injury.

The CSC, in particular John Norn's, MD, has made a number of anti-cervical manipulation comments, and has been successful in realizing sizeable press coverage as a result of these statements. To quote from the 2000 CMAJ paper: ". . . neck manipulation should probably be avoided in patients with recent acute neck pain, especially if it follows closely upon an accidental injury, because a fragile clot formed over an otherwise asymptomatic arterial tear is easily dislodged by abrupt head movement, especially rotation."1 This statement is without foundation, since it has never been established in the medical literature that persons who have sustained head or neck injury are any more susceptible to developing a post-manipulation CAD than the general population.

Dr. Norris appears to be of the opinion that there is an indisputable causal relationship that exists between neck manipulation and CAD. As was written in one of his CMAJ Letters, ". . . the research question is not whether neck manipulation can result in dissection of a cervical artery, for it surely can . . ."' At this time, the relationship between neck manipulation and CAD is not supported by any literature that is capable of demonstrating a causeand-effect relationship. Where the ICA is concerned, this relationship is even more tentative.32 The only medical evidence that is currently available on this issue is Class III (i.e., case reports and case series), which is the least persuasive evidence and cannot be used to assign cause-andeffect relationships. When careful, scientific research is performed in this area, such as a population-based case controlled study done by Rothwell et al.,6 responsible authors are quick to point out that no cause-and-effect relationship could be drawn from their data. Serious researchers realize that some patients with neck pain may consult a doctor of chiropractic with an already established CAD and the occurrence of a temporally related manipulation may have nothing to do with the subsequent manifestation of CAD symptoms.33