A recent study shows that patients who have their necks and spines adjusted by a chiropractor have an increased risk of stroke. The overall risk is probably very small but the link between stroke and neck cracking is real, says neurologist Wade S. Smith, MD, PhD, director of the neurovascular service at the University of California, San Francisco. Although not specifically addressed in this article, it is important to mention that chiropractic manipulation is generally not recommended in people with spondylitis because of the potential for serious complications.

Researchers studied and questioned 51 people who had a stroke caused by arterial dissection to 100 people who had strokes due to other causes. All participants were under the age of 60. Arterial dissection occurs when one of the two arteries that wind through the back of the neck to the brain starts to tear and forms a blood clot, which can easily enter the brain and cause a fatal stroke. This is one of the leading causes of stroke before the age of 45.

Interestingly, the study showed that people under 60 who have strokes or mini-strokes caused by tears in the neck arteries were six-times more likely to have had their neck manipulated by a practitioner within the past 20 days, compared to those who had strokes from other causes.

Of the 51 patients with arterial dissection, seven (14%) remembered getting their necks cracked before the stroke. Three patients without dissection had this procedure performed on them. Those with dissection had a stroke less than two days after the procedure, and those without dissection had their strokes more than eight days after the procedure.

57% of the patients with dissections said their head or neck pain increased after the chiropractic adjustment. Doctors say that if pain increases after a manipulation, people should seek medical attention. "It's possible that they could have a dissection and be at risk for stroke," explains Dr Smith. He elaborates that although some neurologists think chiropractors are causing a lot of strokes, he thinks it is a very low risk. Since the consequences of a stroke can be enormous and far-reaching, Dr. Smith believes that "anybody who does a procedure of any kind that carries a risk should tell their patients about that risk."

"Neck cracking" or cervical spinal manipulation, is the chiropractic technique that most concerns neurologists because the practitioner often gives the patient a high velocity twist. Chiropractors are trained to know the anatomy of the neck, but other practitioners may not be as well aware of the risks.

Dr. Smith says the cause of dissection is unknown in most cases, yet some rare medical conditions increase the person's chance of developing dissection. In addition, trauma from motor vehicle accidents and sports injuries also contributes to a person's chances. Spontaneous dissections cause about 16% of all strokes in young people.

Scott Haldeman, DC, PhD, MD, is a chiropractor and a neurologist at the University of Irvine. He says that this study has a major weakness because it relies on patients' memories of events in the past. The study also took place in California (where people do more spinal manipulations than anywhere else), but Dr. Haldeman claims that only seven cases of stroke could be linked in any way to neck cracking. "I think the basic information in the Smith study is very important. It does confirm that there is a temporal relationship between stroke and spinal manipulation that we cannot rule out. But their evidence that spinal manipulation is a major cause of stroke is weak. The risk is not zero, and none of us is suggesting there isn't some risk. What we have basically got here is a situation we have to put into perspective."

What if a person has neck pain? Dr. Haldeman says that taking aspirin or ibuprofen puts someone at a small but real risk of developing an ulcer, although no other medication is proven to work. Surgery is unproven and has risks. Dr. Haldeman says that there is evidence that exercise and spinal manipulation can ease neck pain in the short term.