May 12, 2003 -- If you've got a pain in the neck, think twice about getting your neck cracked. Spinal manipulative therapy, as chiropractors call it, increases your 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.
"Some neurologists think chiropractors are causing a lot of strokes, but we think it is a very low risk," Smith tells WebMD. "I don't think it is so low that a patient doesn't need to be informed about it. The consequences of a stroke can be enormous. People should be aware that spinal manipulation increases risk of stroke. Anybody who does a procedure of any kind that carries a risk should tell their patients about that risk."
One of the leading causes of stroke before age 45 is something called cervical arterial dissection. That's when one of the two arteries that wind through the back of the neck to the brain starts to tear. The lining of the artery bleeds and forms a blood clot. This clot can easily enter the brain and cause a fatal stroke.
Earlier studies in Canada compared stroke registries with medical records. Strokes in younger adults were strongly associated with seeing a chiropractor. Was there a real cause-and-effect connection? Smith looked for more evidence.
His team looked at all patients under the age of 60 who from 1995-2000 visited two large medical centers for cervical dissections resulting in strokes or the passing stroke-like episodes called transient ischemic attacks. They found 151 such patients; 51 were available for study. The patients were compared with 100 age-matched patients whose strokes were not due to arterial dissection. All were asked a battery of questions -- including whether they had head or neck pain in the 30 days before their stroke, and whether they got a spinal manipulation during that time.
Of the 51 patients, seven (14%) remembered getting their necks cracked before their stroke. Only 3% of the control patients remembered seeing a chiropractor in the month before their stroke. After controlling for all other factors, getting a spinal adjustment upped the risk of stroke 6.62-fold.
"If a person has any of the symptoms of stroke, he or she should bypass the chiropractor and go directly to the hospital," Smith says.
These red flags are:
- One side of the body becomes weak, numb, or paralyzed.
- Double vision, blurry vision, or loss of sight.
- Trouble speaking or difficulty understanding speech.
- Loss of balance or coordination; dizziness.
- Sudden severe headache.
"Neck cracking," or cervical spinal manipulation, is the chiropractic technique that most concerns neurologists. To make this adjustment, the practitioner often gives the neck a high velocity twist. Chiropractors are trained to know the anatomy of the neck. Other kinds of practitioners, Smith says, may not be so well aware of the risks. He notes that many chiropractors already are adopting a less forceful technique for cracking necks.
Scott Haldeman, DC, PhD, MD, is a chiropractor as well as a neurologist. As clinical professor of neurology at the University of California, Irvine, he's studied many cases of arterial dissection in chiropractic patients.
Haldeman says the Smith study has a major weakness: It relies on patients' memories of events years in the past. Also, he notes that even though the study took place in California -- where people do more spinal manipulations than anywhere else -- 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," Haldeman tells WebMD. "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."
If you have neck pain, Haldeman asks, what are you supposed to do? Taking aspirin or ibuprofen puts you at small but real risk of getting an ulcer. No other medication is proven to work. Surgery is unproven and has its own risks. However, Haldeman says, there is evidence that exercise and spinal manipulation can ease neck pain in the short term.
"At the end of last week I was having neck pain," Haldeman says. "I know very well there is a risk of complication, but I didn't want to go through the weekend with my neck hurting. So on Saturday, I had an adjustment on my neck."