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research update

Risk of Vertebral Stroke and Chiropractic Care

Results of a Population-Based Case-Control and Case-Crossover Study
Welcome to the first in a series of key research-article summaries from the Palmer Center for Chiropractic Research.

The Palmer Center for Chiropractic Research, headquartered on the Palmer College of Chiropractic campus in Davenport, is the largest institutional chiropractic research effort in the world.
exterior shot of the William and Jo Harris building

Summary: Vertebral artery (VBA) dissection and stroke are very rare and generally occur with no obvious cause. Headache and neck pain are common symptoms of VBA dissection, preceding an estimated >80 percent of VBA strokes. These symptoms may precipitate the patient to seek medical physician/chiropractic treatment.

Cassidy et al., (2008) analyzed the records of 818 patients who were hospitalized with VBA strokes in Ontario hospitals (April 1, 1993 to March 31, 2002) to determine if an association existed between chiropractic visits and VBA stroke or primary care physician visits and VBA stroke. Of the 818 cases, 54.2 percent were categorized as vertebral occlusion and stenosis, 41.2 percent were coded as basilar occlusion and stenosis, and 4.7 percent had both codes.

In patients under age 45, there was an increased association between both chiropractic and medical physician visits (within the month prior to) and VBA stroke. In patients older than 45, no increased association between VBA strokes and chiropractic visits were found. In addition, the authors found no increase in risk associated with chiropractic treatment when compared to treatment by a medical doctor.

Take-home Message: There doesn’t appear to be an increased risk of VBA stroke associated with chiropractic care when compared to medical physician visits. The association between VBA stroke and both chiropractor and medical doctor visits is most likely explained by patients with neck pain and headache seeking relief from health-care providers before their VBA stroke.

Practical Applications for Chiropractors: It’s important to think about the possibility of VBA when a patient presents with headache and neck pain. Once should also be aware of confounding factors, which may increase the risk of VBA stroke, such as obesity, smoking and untreated hypertension, and screen for undiagnosed vertebral artery dissection when appropriate.

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