No increased risk of stroke associated chiropractic care

That’s the conclusion from a 9-year study by researchers in Ontario, Canada.

First, the details.

  • The researchers reviewed the records of patients with vertebrobasilar artery (VBA) strokes admitted to Ontario hospitals from 1993 to 2002.
    • Vertebral arteries travel along the spine and form a single basilar artery (hence the name vertebrobasilar arteries) at the base of the skull.
    • During a hemorrhagic stroke, an artery on the surface of the brain ruptures, causing bleeding and damage to the brain.
  • Each case was matched to a non-stroke case based on age and gender.
  • Then, the exposures to chiropractors and primary care physicians were determined from health billing records in the year before the stroke.

And, the results.

  • Among patients younger than 45 years, patients with VBA stroke were about 3 times more likely to have seen a chiropractor or a primary care doctor before their stroke.
  • There was no increased association between chiropractic visits and VBA stroke in those older than 45 years.
  • Positive associations were found between primary care doctor visits and VBA stroke in all age groups.
  • Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA stroke.

The bottom line
VBA artery stroke is rare. It occurs when a neck artery supplying blood to the brain is torn. A stroke can occur when a clot formed on the torn membrane is dislodged (presumably from twisting and puling the neck) and travels to the brain, blocking circulation.

Unlike a study in 2001 that investigated the relationship between chiropractic visits and vertebral artery stroke, these researchers also studied visits to family doctors that preceded this kind of stroke.

The authors concluded, “The increased risks of VBA stroke associated with chiropractic and primary car visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke.”

In a related article, author Dr. Frank Silver cautioned that looking for symptoms of a stroke caused by a tear inside a neck artery can be difficult. And just because a person has neck pain or headache doesn’t mean it will lead to a stroke. Dr. Silver cautioned, some of the symptoms to look for include double vision associated with pain, droopy eyelids, numbness down one side of the body and dizziness.

1/19/08 17:57 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.