“Life threatening therapists”

On 17 January 2010, the Dutch broadcasting company Vara screened a documentary entitled “Life threatening therapists”.1 Two cases were presented: the first case described a 42-year-old male who suffered a bilateral vertebral artery dissection in a chiropractic office2; the second case was that of a 3-month-old girl who died during a treatment from a craniosacral therapist.3 Several people were interviewed including the chiropractic patient; the parents of the dead infant; professor of alternative medicine E. Ernst; former minister of Public Health, E. Borst; a neurologist F. van Kooten; and paediatricians P. Brand and C. Verlaat. The NCA (the Dutch Chiropractic Association) offered to have Prof. van Tulder respond to the first case but the directors refused the contribution.

The articles and the programme claim that both cases were clearly caused by the practitioners and that cervical manipulation and craniosacral technique should be banned. Over 100,000 people have watched the Zembla documentary1; meanwhile, questions have been raised to the representative ministers in the Dutch House of Commons. This commentary aims to present a more balanced picture of the evidence regarding adverse events following chiropractic cervical manipulation.

Since the beginning of chiropractic, allopathic medicine has been trying to tackle this alternative branch in several ways, often because it was seen as a competitive threat. In order to exist, chiropractic in the United States had to deliberately choose the ‘alternative’ pathway to distinguish itself. When chiropractic came to Europe, more emphasis was placed on research, reflecting the drive towards an evidence-based practice. When in the 1990s two Canadian patients died after chiropractic treatment, the media gave the deaths so much attention that neurologists demanded a total avoidance of cervical manipulation. This also induced the need for the different disciplines (neurology, angiology, epidemiology, chiropractic, manual therapy and osteopathy) to research the possible link between cervical manipulation and vertebral artery dissection.

Based on a 2-year retrospective survey of 486 neurologists of California, 55 post-manipulative strokes were reported by 177 neurologists.4 This was followed by a 10-year retrospective study of Danish chiropractors, which estimated an incidence of 1 case per 1.3 million cervical manipulations.5 As illustrated by these two examples, there was a large discrepancy in the estimated incidence of this complication, depending on the profession doing the reporting.

Although a number of studies identified a temporal relationship between cervical manipulation and stroke,6, 7, 8 recent epidemiological investigation indicates no increased risk of stroke following a visit to a chiropractor compared to other primary care physicians.9 The temporal relationship is now thought to represent the tendency of patients with prodromal stroke to seek chiropractic care for the symptoms of head and neck pain and that the stroke then proceeds regardless of the chiropractor's actions.9

The precise incidence of vertebral artery dissection is unknown. The estimate of symptomatic vertebral artery dissections in the general population ranges from 0.97 per 100,00010 to 4 per 100,000.11 These figures are similar to the estimated incidence of serious complications following cervical manipulation.12

Cadaveric studies13 suggest that the manipulative impulse cannot be the causative agent, since the mechanical forces it generates are proportionally very low compared to the strain required to produce mechanical failure in a healthy vertebral artery.14 In a recent study on cadaveric rabbit arterial tissue similar to the human vertebral artery no microstructural damage could be detected after an exposure of repeated strains equal to 1000 manipulations when compared to the control group.15 The important factor appears to be the position or movement (extension and rotation) to which the neck is subjected.16, 17 For example, looking into the air for a long time (at a hairdressers, when painting the ceiling, attending a dentist,18 attending an air show, having a facial massage19) will increase the risk of having this kind of stroke if predisposed. To reduce this potential risk, cervical extension is avoided in the pre-manipulative position of a chiropractic manipulation.

In the last 20 years, the research into the safety and effectiveness of chiropractic treatment has increased its acceptance and chiropractic is increasingly valued as a part of integrated medicine instead of ‘complementary and alternative’ medicine. Chiropractic is beginning to be included in evidence-based national guidelines worldwide. The position and role of the chiropractor in the future healthcare system will need to be determined and established through research, education and debate.

It is of course important to describe serious complications associated with cervical manipulation and a number of national incident reporting systems now exist as well as the traditional case report. It is ironic that these reports are often used as ‘proof’ of chiropractic harm by the same authorities who are quickest to point out, correctly, that case reports of benefit from treatment are no more than temporal association and do not constitute cause and effect.

Biomechanically, the relationship between the treatment and the bilateral dissection reported on TV is dubious; it appears likely the patient was suffering from an underlying occult arteriopathy. Even though the second case did not involve a chiropractor, some chiropractors integrate craniosacral therapy into their practice and the TV programme implied the safety concerns naturally raised by the tragic death should be extended to chiropractic. In reality, the profession can boast an excellent safety record for treatment of the paediatric population. Minor, reversible or self resolving adverse events (irritability, soreness, headache) associated with paediatric spinal manipulative therapy have been reported in 0.5% of paediatric cases in general chiropractic practice20 and 1% in a chiropractic teaching clinic.21 Even though the highlighted cases are serious, the exaggerated, one-sided conclusions of the contributors, authors and directors should not be taken as scientific evidence allowed to affect treatment protocols, much less statutory legislation.