So is it true that neck manipulations at the chiropractor's office can cause someone to have a stroke? Based on the available evidence it seems extremely likely that they can! This is no joke. There are certain abrupt and not so abrupt movements of the neck which have been associated with strokes caused by vertebral artery dissection, an injury to large arteries that run on each side of the neck, and which bring blood to the posterior parts of the brain. For instance, bending the neck backwards during hair washing at the hair salon, or while painting a ceiling have been associated with a similar injury to the vertebral arteries.
What could cause this to happen? Rapid abrupt movements or manipulations of the neck can stretch the vertebral arteries as they ascend towards the skull, and cause their walls to tear, or rupture. This can either cause a blood clot to form inside the damaged artery, or a significant amount of bleeding to occur. Either of these situations is extremely dangerous as it has the potential to decrease or completely stop blood flow to the most vital parts of the brain. Relatively speaking, this is not such a rare event, estimated to occur as often as 1 in every 20,000 neck manipulations performed by chiropractors.
Some have argued that people who are susceptible to vertebral artery dissection in the first place are the only people who actually become injured by the chiropractic manipulation. This is possible, I suppose, although it is also reasonable to expect that a rapid, and abrupt rotation of a person's neck could accidentally cause even normal arteries to become injured.
What do the studies show? They show a mixture of results. Some for instance have reported that even when controlling for people with neck pain, chiropractic neck manipulation is an independent risk factor for vertebral artery dissection. Others have reported that chiropractic neck manipulation is not a risk factor for stroke at all. Who is right? Your guess is as good as mine. The whole subject seems almost impossible to study, for obvious, (or maybe not so obvious) reasons.
If you are convinced that neck manipulation is the best treatment for your pain, but you suspect that your vertebral arteries might become injured as a result of the abrupt, rapid, rotation of your neck, talk to your doctor about the subject before you start your sessions with the chiropractor.