Does a Chiropractic Adjustment Cause a Stroke?
There is no human, experimental evidence that Chiropractic adjustments are causally related to strokes. End of discussion, right? I wish it were that easy. If there is no direct link, where does this idea come from that an adjustment causes a stroke?
Misconceptions about Chiropractic will always arise from those who don’t have all the facts, but to quote Fydor Dostoevsky, “Everything passes, only the truth remains.” The false belief that an adjustment causes a stroke comes not from any scientific facts but stems from a well-documented smear campaign from the not-so-distant medical establishment.
Historical Contexts
Chiropractic has garnered medical animosity ever since its humble beginnings in 1895. This was due to one prevailing fact: Chiropractic was competition. The medical community had a monopoly on healthcare in the 19th and early 20th centuries and was not willing to accept Chiropractic’s new approach to health intervention. Instead, they sought to dismantle the competition.
Medicine began to rally behind the American Medical Association (AMA). They started to create scathing reports about Chiropractic in their medical journals. As early as 1947, the Journal of The American Medical Association (JAMA) made allegations that the Chiropractic adjustment was a “severe trauma” to the spine. These claims were not based on any scientific research though. And since Chiropractors were barred from publishing their research in the journal, these kinds of statements continued unchecked.
Then in 1963, the AMA created an official “Committee on Quackery.” Joseph Sabatier, the chairman of the committee said that “rabid dogs and chiropractors fit into about the same category…. Chiropractors were nice but they killed people.” Finally in 1987, after many lawsuits, the U.S. District Courts confirmed that the AMA had violated the Sherman Antitrust Act. The U.S. Court asserted that “the AMA decided to contain and eliminate chiropractic as a profession” and that it was the AMA’s intent “to destroy a competitor.”
Even though justice was served in the courts, years of medical misinformation created a false identity in the public's eye of Chiropractic. Chiropractors now are tasked with reeducating the public (and medical doctors) on what Chiropractic is and is not and what an adjustment does and does not do. Every so often, I will see patients who are concerned that an adjustment will cause a stroke because their medical doctor said so. Facts might be on the side of Chiropractic, but belief systems don’t always line up with facts.
What is a Stroke?
A stroke is also known as a cerebrovascular accident or brain attack. It is when poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. A blockage in the arteries leading to the brain is the main cause of strokes. Symptoms of a stroke include:
Numbness or weakness in your face, arm, or leg, especially on one side.
Confusion or trouble understanding other people.
Difficulty speaking.
Trouble seeing with one or both eyes.
Problems walking or staying balanced or coordinated.
Dizziness.
Severe headache and neck pain that comes on for no reason.
Cervical Artery Dissection
Cervical artery dissection (CAD) is where one of the blood vessel walls in the neck tears. This tear can cause blood clots in your arteries, affecting the blood supply to your brain. Symptoms of CAD include:
Numbness and weakness on one side of your body.
Difficulties with your speech.
Loss of sight in one eye.
Confusion.
Numbness on one side of your face so it droops.
Problems with coordination.
Severe headache and neck pain that comes on for no reason.
While the exact cause is unknown, some theorize that extension and/or rotation of the neck can damage the vertebral artery, particularly within the transverse foramen at the C1–C2 level, tearing the vessel wall and resulting in blood clots. It has also been implicated that sudden or sustained rotation and extension of the neck, motor vehicle collisions, sports, lifting, working overhead, falls, sneezing, and coughing are mechanisms of injury.
Putting theories aside, most CAD cases occur spontaneously and involve other risk factors such as connective tissue disorders, migraine, hypertension, infection, vessel abnormalities, atherosclerosis, central venous catheterization, cervical spine surgery, cervical percutaneous nerve blocks, radiation therapy and diagnostic cerebral angiography.
Stroke: Correlation vs. Causation
Again, as early as 1947, the AMA began making false claims that an adjustment is a “severe trauma” to the neck. And because of the theory that damage to the neck causes CAD, this has extrapolated into the claim that an adjustment was a cause of strokes. Believers of this narrative have been trying to fill in the gaps of this argument ever since.
The main issue regarding adjustments and strokes focuses on the statistical formula known as correlation vs. causation. The statement “correlation does not imply causation” is the abbreviated explanation. Two unconnected events can have an observed association with each other without actually having a cause-and-effect relationship. For example, the sun can cause your ice cream to melt and cause your skin to tan. But this does not mean your tanning skin causes your ice cream to melt or vice versa. The melting ice cream and tanning skin are correlated events unconnected to a similar cause.
This concept comes to light in a study from 2008 titled “Risk of Vertebrobasilar Stroke and Chiropractic Care.” This was a population-based, case-control and case-crossover study that gathered information from 1993 to 2002. Quoting this article: “Our study shows an association between chiropractic visits and VBA (Vertebrobasilar Artery) strokes. However, we found a similar association between primary care physician visits and VBA stroke.”
What does this mean? Why is there an association between Chiropractic visits and not the adjustment?
A Chiropractic visit usually involves an adjustment. A medical doctor visit does not involve an adjustment. This study found that the incident of a stroke is similar for both Chiropractic visits and medical doctor visits. Since medical doctors do not perform adjustments, you can’t statistically claim that the adjustment is a direct cause of a stroke. A Chiropractic visit and a physician visit are both correlated events to a stroke, they don’t necessarily show causality.
Quoting again from the 2008 study: “The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke.”
The majority of people seek Chiropractic or medical care when problems arise. A sign or symptom presents itself and a patient looks for help. Symptoms such as headaches, neck pain, dizziness, numbness/tingling and muscle weakness are common reasons why a person seeks out a Chiropractor. These symptoms are also common to CAD and stroke. These symptoms are also common to many other conditions, such as but not limited to dehydration, cardiovascular disease and vertebral subluxation.
It is unfortunate when a patient seeks help and is undiagnosed for a life-threatening problem such as a CAD or stroke. That event, although extremely rare, creates a lot of buzz in the news world and on social media. Viral headlines will often read: “Patient has a stroke after seeing Chiropractor!” These types of associations between Chiropractic and a stroke are based on temporality. This means the patient was already in the midst of a dissection or stroke or was going to have one anyway and just so happened to have seen a chiropractor during that time frame.
Let me discuss one more important study. In 2016, The Cureus Journal of Medical Science published the article “Systematic Review and Meta-analysis of Chiropractic Care and Cervical Artery Dissection: No Evidence for Causation.” This article applied The Hill criteria to reach their conclusion. Sir Austin Bradford Hill was the famed epidemiologist and statistician who pioneered the randomized clinical trial. It was through his work that he made the connection between cigarette smoking and lung cancer. Hill’s criteria became the gold standard in public health research to establish epidemiologic evidence of a causal relationship between a presumed cause and an observed effect.
In this 2016 systematic review and meta-analysis, the researchers found “no convincing evidence to support a causal link between chiropractic manipulation [adjustment] and Cervical Artery Dissection [CAD].” Furthermore, they state that even though “the very weak data supporting an association between chiropractic neck manipulation and CAD” exists, an assumed relationship by many clinicians “seems to enjoy the status of medical dogma” in the “absence of adequate and reliable data.” This paper shows that not only does an adjustment not cause a stroke but the idea that it does is based more on a belief system than the facts.
It is up to the Chiropractor, medical physician, or any primary care doctor to complete the proper differential diagnosis to best fit the symptoms to the right diagnosis. Sometimes conditions are misdiagnosed or undiagnosed, especially ones that are rare. While not a contraindication to adjust, extra precaution should be used if a patient has a history of cancer, infection, fracture and/or vascular problems. It is better to err on the side of caution and rule out worst-case scenarios in these types of cases. Ultimately a thorough neurological, cardiopulmonary and physical examination will determine the best course of action if a stroke is suspected.
- Jarek Esarco, DC, CACCP
Related Blogs:
Are Chiropractic Adjustments Safe?
Who Can and Can Not Get Adjusted?
"I'm Pregnant, Might an Adjustment Harm My Child?"
My Medical Doctor Says That Chiropractors Break Spines!
Jarek Esarco, DC, CACCP is a pediatric, family wellness and upper cervical specific Chiropractor. He is an active member of the International Chiropractic Pediatric Association (ICPA). Dr. Jarek has postgraduate certification in Pediatric Chiropractic through the ICPA. Dr. Jarek also has postgraduate certification in the HIO Specific Brain Stem technique through The TIC Institute. Dr. Jarek is happily married to his wife Regina. They live in Youngstown, Ohio with their daughter Ruby.
Resources:
Cassidy, J. D., Boyle, E., Côté, P., He, Y., Hogg-Johnson, S., Silver, F. L., & Bondy, S. J. (2008). Risk of Vertebrobasilar Stroke and Chiropractic Care: Results of a Population-Based Case-Control and Case-Crossover Study. European Spine Journal, 17(Suppl 1), 176–183. https://doi.org/10.1007/s00586-008-0634-9
Church, E. W., Sieg, E. P., Zalatimo, O., Hussain, N. S., Glantz, M., & Harbaugh, R. E. (2016). Systematic Review and Meta-analysis of Chiropractic Care and Cervical Artery Dissection: No Evidence for Causation. Cureus, 8(2), e498. https://doi.org/10.7759/cureus.498