By Richard H. Adler, Attorney at Law
A recent research study published in Spine (2008)1 investigated the association between chiropractic visits and vertebrobasilar artery (VBA) stroke, then compared it to the association between family physician care and VBA stroke.
Earlier published studies had cast a cloud on the chiropractic profession suggesting chiropractic adjustments resulted in some patients suffering from a stroke after treatment. One such study, published in 2000 in the Canadian Medical Association Journal, concluded there was a 1 in 5.85 million risk a chiropractic neck adjustment could cause a stroke.2 The current study first published in Spine (2008) is more instructive as it investigated not only the relationship between chiropractic visits and VBA stroke, but also between pre-stroke family doctor visits and VBA stroke.
Reports on vertebrobasilar artery dissection following chiropractic care have attracted media attention and calls by some medical specialists to avoid neck manipulation for acute neck pain. The prevailing theory is that extension and/or rotation of the neck can damage the vertebrobasilar artery, particularly within the foramen transversarium at C1-C2 level. It has also been theorized that since patients with vertebrobasilar artery dissection commonly present with headaches and neck pain, before a chiropractic adjustment, it is possible that subsequent VBA stroke occurs spontaneously, implying that the association between chiropractic care and VBA stroke is not causal. Since patients also seek medical care with their family physician for headache and neck pain, the researchers looked at the association between VBA stroke following chiropractic and following primary care physician visits.
The results of this 2008 study challenge previously held beliefs on the connection between chiropractic care and VBA. The authors concluded:
There was no increased association between chiropractic visits and VBA stroke in those older then 45 years. Positive associations were found between PCP [primary care physician] visit and VBA stroke in all age groups. Practitioner visits billed for headache and neck complaints were highly associated with subsequent VBA strokes.
Conclusion. VBA stroke is a rare event in the population. The increased risks of VBA stroke associated with chiropractic care and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic compared to primary care. (Emphasis Added)
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1. Cassdy, DJ, et al., Risk of Vertebrobasilar Stroke and Chiropractic Care: Result of a Population-Based Case-Control and Case-Crossover Study. Spine. 33:45: S176-S183 (2008)
2. Cassdy, DJ, et al., Risk of Vertebrobasilar Stroke and Chiropractic Care: Result of a Population-Based Case-Control and Case-Crossover Study. Spine. 33:45: S176-S183 (2008)