Professor Edzard Ernst looks at the evidence surrounding the risks of upper spinal manipulation
For the last 16 years, I have been researching the risks of spinal manipulation1, in particular the question of whether manipulation of the upper spine can cause vascular accidents. Despite the fact that several hundred such cases have been reported, chiropractors have remained keen to deny a causal relationship.
Recently, support came from by a case-control study by the Canadian chiropractor Cassidy2. It suggested that the relationship is not causal but coincidental. This article is now frequently cited to support the notion that chiropractic is free of serious risks.
However, based on the totality of the best evidence available to date, there can be little doubt that the formal criteria for causality are, in fact, fulfilled3, and that upper spinal manipulation is the cause of vascular accidents. Moreover, the Cassidy study2 is seriously, some would say fatally, flawed(eg 4). Finally, there are several case-control studies that contradict its findings; so the totality of the evidence from case-control studies does suggest that upper spinal manipulation is risky4.
Even if one conceded that there is still reasonable doubt about this question, responsible and ethical healthcare professionals have to subscribe to the precautionary principle. Neck manipulation is not of proven therapeutic value for any condition5. Therefore, we have to err on the safe side.
Put bluntly, this means that, until the matter is settled, we should not routinely use or recommend upper spinal manipulation. At the very minimum, we should only do so after fully informed consent.Professor Edzard Ernst Professor Edzard Ernst