Headaches and neck pain are not easy to live with and many of us seek out chiropractors to help ease symptoms. However, mild side effects of the treatment are surprisingly frequent and, more seriously, the arterial wall can break, which usually causes a stroke.
The brain is supplied with oxygen via arteries that run very close to the bones in our neck. In some places, the proximity is such that extreme movements can significantly affect these fragile blood vessels. This can happen, for instance, in a car accident, during contact sports or even when bending the head back over the washbasin at the hairdresser. It also occurs with depressing regularity when chiropractors or other healthcare professionals manipulate the neck. Because chiropractic is so popular, it is essential to define its risks precisely.
Symptoms such as a slight increase in pain are experienced by about half of all patients but rarely last longer than 24 hours. Serious complications are much less frequent, but do exist. In a worst-case scenario, an artery in the upper spine is overstretched during a particular type of manipulation of the neck. Typically, such treatment would involve an abrupt movement where the chiropractor rotates the neck and simultaneously bends it backwards.
A recent US investigation confirmed that there were serious risks of complications after this type of therapy. In 2003 alone, more than 100 complications following upper-spinal manipulation were published in medical literature. Chiropractors are adamant that this is a tiny number compared to the thousands of manipulations administered during that period - they estimate that only one in three million patients will experience a serious complication. If true, the therapy would be very safe indeed.
Our own research, however, casts considerable doubt on some of these assumptions. We asked all UK neurologists about cases of serious adverse effects after spinal manipulation. Over 12 months, these doctors witnessed 35 such cases. Undoubtedly, chiropractors would argue that this figure is not high yet the important finding of our survey was not the number but the fact that none of these 35 cases had previously been reported. They had been on the records of the neurologists but unvailable for anyone else researching this subject.
In other words, under-reporting was precisely 100%. If under-reporting is that high, estimates about the frequency of such problems simply do not make sense. All we can truthfully say is that we presently do not know how often serious complications occur. This message, understandably, is not at all popular with chiropractors.
There are further reasons to doubt that the frequency of serious adverse effects is only one in three million patients. A group of US neurologists recently described 22 cases; most related to nerve injuries after manipulation of the neck. The neurologists then obtained estimates of the frequency of such therapy in their area. Their findings suggested the frequency to be about one in 850 patients undergoing a series of upper-spinal manipulations. This figure may be little more than a wild guess, but the fact that one group estimates the rate at one in three million, while another team believes it is one in several hundred, is disquieting, to say the least. When it comes to serious risks of medical interventions, this level of uncertainty is unacceptable.
Perhaps it was considerations like these which recently led the government of Ontario to announce that it will no longer insure chiropractic services. A similar step was taken by the government of British Columbia last year. Meanwhile a group of UK chiropractors have laudably started a large investigation into adverse effects of spinal manipulation which, for the first time in the history of chiropractic, might generate reliable information on this vital subject.
So what is my advice for people suffering from neck pain? Luckily there are other options to treat such complaints which are virtually free of unwanted effects - and I recommend consulting a good physiotherapist. He or she will probably design a set of simple exercises which can be performed at home at virtually no cost - leaving you in total control of your condition. Chiropractic treatment, it seems, is not the best solution.
· Edzard Ernst is professor of complementary medicine at the Peninsula Medical School at the Universities of Exeter and Plymouth.