It would be an understatement to call the debate on the risks posed by chiropractic neck manipulations "lively" – it is a heated discussion, and every time I write about this subject, my inbox fills with hate mail.
Well over 500 cases have been documented where a patient has suffered a stroke after getting his or her neck manipulated and many have died subsequently. What seems to happen is that certain manipulations carried out by chiropractors - particularly those that involve forceful rotation of the neck to one side - may over-stretch an artery that runs along the spine. If that happens this vessel can dissect or disintegrate, resulting in a blockage of blood flow to the brain, ie. a stroke.
Most chiropractors adamantly deny that their treatment is to blame. Strokes happen all the time, they rightly say. Lots of patients who suffer strokes haven't been anywhere near a chiropractor. This is undeniably true, so the decisive question is this: do patients who consult chiropractors have more strokes than patients who do not?
Annoyingly, sound data to resolve this dispute is very hard to come by. The evidence so far is not entirely straightforward and, depending which study we select, support can be found for both sides. This is why every new piece of information on this topic is important and a recent article by US neurosurgeons is more than welcome.
They analysed a database of patients who had experienced a stroke to identify those who had chiropractic treatment prior to the event. They found 13 such patients within a three-year period who initially presented with head and neck pain, typically hours or days after receiving chiropractic treatment. In all these cases, the neurosurgeons found damage to arteries that are located close to the upper vertebrae and supply part of the brain with blood and oxygen.
All the patients were treated either with drugs or surgery. Three had permanent neurological deficits as a result of the damage and one died of a massive stroke. The remaining nine patients made complete recoveries.
According to the neurosurgeons, the analysis suggests that such events are much more frequent than previously assumed: "In all likelihood, a substantial number of cases are not reported either because the injury is not severe or is asymptomatic." I think this is a reasonable assumption and I can add some own data in support.
In 2001, we surveyed all UK neurologists asking them to report cases referred to them of neurological complications occurring within 24 hours of cervical spine manipulation over a 12-month period. The response rate was 74% and they reported a total of 35 patients suffering severe adverse events suspected to be caused by this treatment within one year.
This number may look small, but the really important finding of our survey was that none of these complications had ever been reported anywhere. Which means that the extent of under-reporting was exactly 100%.
The conclusions of the American neurosurgeons in their recent paper speak for themselves:
Chiropractic manipulation of the cervical spine can produce dissections of the cranial and cervical segments of the vertebral and carotid arteries. Given the popularity of chiropractic treatment, the incidence of this phenomenon is most likely underreported. These arterial injuries can be severe, producing adverse neurological sequelae and even death (including 31% of patients in this series). Consequently, aggressive endovascular and surgical techniques may be required to restore vessel patency and to preserve neurological function."
[Woman getting spine adjustment via Lisa F. Young / Shutterstock]