Chiropractic neck adjustments may increase your risk of suffering a stroke, medical researchers said in a new report. The findings are unlikely to end the controversy about whether chiropractic manipulations cause tears in neck arteries, a leading cause of stroke in patients under 45.
"It's a real enough problem that it needs further study," said Dr. Wade S. Smith, a neurologist at UC San Francisco and lead author of the study published in the May 13 issue of the journal Neurology. "If there are [chiropractic] techniques that can be done that don't put vertebral arteries in peril, that would be good, because a lot of people swear by the benefit."
Although his study found a strong statistical connection between strokes caused by tears to arteries in the back of the neck and recent chiropractic care, the overall risk remains quite small, he said.
Chiropractors say their treatment is a safe and effective method of relieving neck pain and headaches. The American Chiropractic Assn., an industry group, says serious complications occur about once in every 2 million treatments. The group said in a statement that the latest study was flawed and "provides little new and useful information and needlessly alarms the public."
"Although the study found cases where vertebral artery stroke appeared to be correlated with a chiropractic visit, the stroke may not have been caused by the actual treatment," the association said. "Scientific evidence implicating a neck treatment as a true cause of this type of stroke is still preliminary and controversial."
Arterial tears, also called arterial dissections, allow blood to pool in an artery wall, causing a clot or weakness in the wall that can produce a stroke or mini-stroke. In 2001, actress Sharon Stone, then 44, suffered life-threatening bleeding into the brain as a result of an arterial tear. Stone, who was a patient of Smith's after the incident, said in interviews afterward that it may have stemmed from a riding injury "made worse by chiropractic adjustments."
Smith's study took place between 1995 and 2000 and involved patients under age 60. He compared 51 patients at UCSF and Stanford University who suffered arterial tears and strokes or mini-strokes with 100 control patients who suffered strokes from other causes. All were asked about such risk factors as high blood pressure, diabetes and high cholesterol, and whether they'd received chiropractic treatment in the month before their strokes.
Those with arterial tears were six times more likely to have undergone recent chiropractic treatment. Of seven subjects with arterial tears who recalled previous spinal manipulation, four reported substantially increased pain or severe new pain after treatment, while two suffered strokes within seconds of treatment. Smith said it's possible the spinal manipulations exacerbated existing artery tears. He recommended that anyone who experiences increased pain after chiropractic care seek immediate medical attention.
Canadian neurologists reported in the May 2001 journal Stroke that patients under 45 treated for strokes in back-of-the-neck vessels were five times more likely to have seen a chiropractor in the previous week than other stroke patients. In February 2002, University of Toronto neurologists presented data linking chiropractic manipulation to artery tears in nearly a quarter of 158 stroke patients younger than 45.