Spinal manipulation.....is the hallmark treatment of chiropractors.....For conditions other than back pain, there is no good evidence for the effectiveness of spinal manipulation.5
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The retrospective case series (Table 3) confirm that spinal manipulation is associated with risks such as vascular accidents and non-vascular complications. Such adverse effects are being reported from several countries and often have serious consequences. The therapists involved are mostly chiropractors; this predominance is probably due to the fact that these therapists use spinal manipulation more frequently than other practitioners. Most of the incidents reported in case series or surveys had not been previously reported, indicating that under-reporting may frequently be high.
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Consequently, the frequency of serious adverse effects is currently unknown. Estimates by chiropractors vary (e.g. 6.4 per 10 million manipulations of the upper spine and 1 per 100 million manipulations of the lower spine).53 These figures, however, may be over-optimistic.
Retrospective investigations have repeatedly shown that under-reporting is close to 100%.13,52 This level of under-reporting would render such estimates nonsensical. At present, there is no sufficiently large and rigorous prospective study to generate reliable incidence figures; previous studies have failed to investigate those patients which were lost at follow-up. This could be the subgroup which has been harmed. It is therefore essential that future studies follow up close to 100% of the initial patient sample.
The effectiveness of spinal manipulation for most indications is less than convincing.5 A risk-benefit evaluation is therefore unlikely to generate positive results: with uncertain effectiveness and finite risks, the balance cannot be positive.
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The chiropractic profession tends to downplay the risks: ‘chiropractic services are safe’;60 ‘the healthy vertebral artery is not at risk from properly performed chiropractic manipulative procedures.’61 Others argue that ‘the occurrence of cerebrovascular accidents in the chiropractic population is 0.000008%’,62 that causality is not proven or even unlikely,61,63-66 that other interventions are more risky (see below),67 that the mechanical forces employed for spinal manipulation are too low to cause injury,68 or that there is a ploy from the medical establishment to sideline chiropractors.69-71 In the light of the evidence summarized above, such attitudes do not seem to be in the best interest of patients.
It is, of course, important to present any risk-benefit assessment fairly and in the context of similar evaluations of alternative therapeutic options. One such option is drug therapy. The drugs in question—non-steroidal anti-inflammatory drugs (NSAIDs)—cause considerable problems, for example gastrointestinal and cardiovascular complications.72,73 Thus spinal manipulation could be preferable to drug therapy. But there are problems with this line of argument: the efficacy of NSAIDs is undoubted but that of spinal manipulation is not, and moreover,
the adverse effects of NSAIDs are subject to post-marketing surveillance while those of spinal manipulation are not. Thus we are certain about the risks and benefits of the former and uncertain about those of the latter. Finally, it should be mentioned that other therapeutic options (e.g. exercise therapy or massage) have not been associated with significant risks at all.
Ernst E. Adverse effects of spinal manipulation: a systematic review.
J R Soc Med 2007;100:330-338
http://jrsm.rsmjournals.com/cgi/content/full/100/7/330
