You read that title right, there is no evidence chiropractic care causes stroke and this is not pro-chiropractic propaganda either but a statement I can make because of what has been published in peer-reviewed scientific journals. Chiropractors have been on the defensive on this topic for many years, primarily because of the lack of evidence to support what we believed was the reality. The other side didn’t have any real evidence to support their claim either but because it was medical doctors largely making these claims they were able to control the narrative based on their authority alone. All that is finally changing thanks to a few key studies, including the one I am going to highlight here.
First lets take time for a little background on this story. The type of stroke chiropractic care, primarily neck adjustments, have been assumed to cause is vertebral artery dissections (VAD). The VAD is best described as a tear in the inner layer of the vertebral artery in which blood, and it’s particular matter, get trapped and eventually build up to block the artery. This is the rarest type of stroke for anyone to get, they cause less than 2% of all strokes, it is not something seen often by any healthcare provider. Without any knowledge of the kind of forces created during a chiropractic adjustment of the cervical spine, anti-chiropractic folks, guessed that the neck adjustment could tear the vertebral artery. Today, though, despite knowing the kind of forces that will acutely tear an artery in the neck are not achievable during a neck adjustment this has not changed the assumptions by some in healthcare. We continue to get patients who are advised to avoid chiropractic care entirely or avoid a neck adjustment because some refuse to read the literature and instead believe the dogma.
It is difficult to find where the assumption that chiropractic care can cause a stroke started but wherever the beginning it has become medical dogma, believed by many despite no evidence to support it. It most likely started as one of many attempts to marginalize the chiropractic profession, perhaps by the AMA which lost an anti-trust lawsuit brought forth by a group of chiropractors in the 1970’s – 1980’s. In this suit the chiropractors where able to show that the AMA had long history of illegal behavior including an unlawful conspiracy in restraint of trade to contain and eliminate the chiropractic profession. The other factor to consider is the few cases of patients who had a stroke following a visit to a chiropractor. These anecdotal studies were the basis for the assumption for many years included in this were cases were patients who saw a chiropractor anywhere from hours to months prior to the stroke occurring. This includes cases where untrained or under-trained persons performed a neck adjustment, including but not limited to, hair dressers, barbers, karate instructors, physical therapists, and medical physicians. This basically means that this belief was based on a correlative data not causative data and really poor correlative data at that.
A correlation can be easily described as such; Since 1936, during a presidential election year, if the Washington Redskins win their last home game before the election the party that won the previous election wins the next election and if the Redskins loose the challenging party’s candidate wins. This is called the Redskins rule and has only proven false twice but ultimately it is completely ridiculous to think that the outcome of a football game could effect the outcome of an election. This is a correlation, and a correlation does not equal a causation or just because two events seem related doesn’t mean that one causes the other. Just because a neck adjustment happened within some time prior to a stroke doesn’t mean that the adjustment caused the stroke. In fact the evidence actually shows that the patient was likely in the process of having the stroke prior to the adjustment and the adjustment added nothing to the cause.
The Cassidy study published in 2008 was a great study to show that the correlation between stroke and a visit to a chiropractor was just as strong as the correlation between a visit to a medical doctor and stroke. They studied the records of 3982 cases of patients and found that a VAD was very rare, that the majority who had them went straight to the hospital, the few that didn’t equally saw a chiropractor or medical doctor, and that the medical doctor missed the stroke at the same rate as the chiropractor. The Cassidy study showed what we knew all along that the stroke was occurring prior to a visit to the chiropractor (or medical doctor) and the patient was presenting with neck pain and headaches, among other symptoms. This is why I was taught, ten years ago, to take a detailed patient history because you can almost always ferret this out if you ask the right questions. While I was in chiropractic college a student asked the right questions, prior to adjusting, and thought a patient might be having a stroke and got him to the hospital right away and it was found he was having a stroke and received the right care.
Finally we get to source of today’s post, this great paper published in February 2016 and authored by medical doctors. This paper has the title; Systemic Review and Meta-analysis of Chiropractic Care and Cervical Artery Dissection: No Evidence of Causation. This papers findings are great but let me talk a bit about it’s authors, none of whom I know by the way. The authors of this paper are neurosurgeons and residents in the neurosurgery program at Penn State Hershey Medical Center. Think about that for a minute, this paper with such a definitive title (NO EVIDENCE OF CAUSATION) was published not by chiropractors but medical doctors whose specialty is neurosurgery. If any source would hold a large amount of weight on this topic it would be neurosurgeons, if they can look at the evidence and find no evidence of causation anyone can. In this study the authors searched for any published evidence on chiropractic and stroke. They found 253 articles and out of those only included six which meet their quality standards for inclusion, read the paper if you are curious what standards they used. After reviewing these studies the authors found no evidence that chiropractic care causes stroke, they go into great detail to describe the correlation and how it is not evidence of a causation. They also mention 80% of patients with VAD have neck pain or a headache and this is likely the reason patients having a stroke would seek the care of a chiropractor. The authors go on to discuss the medical dogma that is the assumption that chiropractic care causes a stroke and that this unfounded belief may have dire consequences.
This paper has me excited for a future where I will no longer have patients question the safety of an adjustment because their physician planted the idea in their head. Chiropractic care, when performed properly by a trained chiropractor is safe and effective. It doesn’t cause strokes, it doesn’t herniate discs, it doesn’t cause arthritis, and it doesn’t injure joints. The only way to combat this dogma is with evidence, with studies like this the evidence is on our side and we can stand up to the fear mongers with confidence that we are right. If you are reading this and still have doubts read this paper, it’s free, and they reference the highlights of the Cassidy study which is not free to read. If you are a current chiropractic patient getting grief from your physicians print this study out and hand it to them on your next visit and know with confidence you are in good hands with chiropractic.