There is no satisfaction in hanging a man who does not object to it.
~ George Bernard Shaw

I work in a 5-hospital system and many of us practice at several hospitals. The residents rotate through at least three of the hospitals and the peripatetic nature of health care allows word of curious cases to percolate through the system.  My current resident mentioned that there was a case of a vertebral artery dissection in a young female shortly after chiropractic neck manipulation.

Man, that’s awful. Is she doing OK?

Evidently there were no permanent neurologic sequelae. She dodged that bullet. Or perhaps that noose, as I once calculated that the force of a neck crack is about 40% that of hanging by the neck and it has the same pathologic changes if it goes wrong. Every time I see a death in the movie where the neck is twisted to break it, I think chiropractic, although some tolerate it better than others.

I have not written on CNS events related to chiropractic since 2008, although the topic has been covered by Dr. Hall.  I still suspect that occasionally there is a perfect storm of bad luck, the forces are perfectly aligned in a susceptible patient and they get an embolic stroke or a vertebral artery tear.

It is rare and hard to do. It is very hard to injure people with what the chiropractors refer to as high velocity, low amplitude thrusts. That sounds so much better than whack em hard/whack em once. So the adverse events from a quick partial hanging are rare and proving causality with rare events is not easy.

Many people get the flu vaccine. Many people have heart attacks. A few people will get Guillain–Barré syndrome (GBS). By chance some people will have a heart attack after their vaccine and others will get Guillain–Barré. So did the vaccine cause the heart attack? Or the GBS? Not always a straight forward answer, as the relationship between declining pirate populations and increasing global temperatures demonstrates.

An aphorism we all live by is that association is not causation, although it is, like all aphorisms, lacking in qualifiers. Part of the willingness to assign causality depends in my mind, like much of SBM, upon consideration of prior plausibility.

Some issues are like parachutes. I don’t need extensive trials to realize cause and effect from parachute use and not splatting on the tarmac. Other relationships are more subtle; realizing that azithromycin, in the right situations, increases cardiac deaths. It took an examination of 3 million prescriptions to find that azithromycin leads to 47 to 245 excess cardiac deaths per million prescriptions, depending on the patient risk. There is biologic plausibility, given that some antibiotics can adversely affect the cardiac conduction system. But the average HCW will never give enough prescriptions to kill someone with azithromycin or even recognize it if they did.

In choosing an antibiotic, or any intervention, you have to weigh the risk and benefit from the treatment as well as the risks and benefits of alternative therapies. I am certainly less inclined to give azithromycin to patients with cardiac disease if I have equivalent alternative antibiotics. Since I am aware that I may do harm, even rarely, I need to be circumspect in my use of azithromycin.

As has been the topic of many posts, the efficacy for chiropractic, such as it is, mostly revolves around low back pain. No reason to approach the neck and whack it hard/whack it once. I can find no quality studies that demonstrate efficacy for neck pain. Good studies being those where the treatment is unknown to the patient and provider. Difficult to do in chiropractic, I know. But perhaps possible.

I will take it as written that the benefit from being whacked hard and whacked once to the neck is zero. Those who wish to discuss the issue can refer to other posts.  What then is the risk with a neck whacking?

It depends.

Some practitioners consider it a myth and others find no risk

“The 83 chiropractors administered >5 million career upper cervical adjustments without a reported incidence of serious adverse event.”

although rather than complications they had ‘symptomatic reactions (SRs)’:

“Three hundred thirty-eight (31.0%) patients had SRs meeting the accepted definition. Intense SR (NRS ≥8) occurred in 56 patients (5.1%).”

Symptomatic reactions included

“1) neck pain and/or stiffness/soreness, 2) radiating (arm or leg) pain/discomfort, 3) arm or leg weakness, 4) tiredness/fatigue, 5) headache, 6) dizziness/imbalance, 7) nausea/vomiting, 8) ringing in the ears, 9) blurred or impaired vision, 10) confusion or disorientation, 11) depression or anxiety, 12) fainting, 13) low back discomfort/soreness.”

And what are the symptoms of a vertebral artery transient ischemic attack, the most likely effect of whack em hard/whack em once?

“Dizziness, vertigo, headache, vomiting, double vision, loss of vision, ataxia, numbness, and weakness involving structures on both sides of the body are frequent symptoms in patients with vertebrobasilar-artery occlusive disease. The most common signs are limb weakness, gait and limb ataxia, oculomotor palsies, and oropharyngeal dysfunction.”

Anyone besides me worried when comparing and contrasting the two lists? Remember that these are not recognized as worrisome:

“The 83 chiropractors administered >5 million career upper cervical adjustments without a reported incidence of serious adverse event.”

And this is not the only study that reported symptoms that could be due to a transient ischemic attack in the vertebral artery distribution

“Adverse events after any of the first 3 treatments were reported by 56%, and 13% of the study population reported these events to be severe in intensity. The most common adverse events affected the musculoskeletal system or were pain related, whereas symptoms such as tiredness, dizziness, nausea, or ringing in the ears were uncommon (<8%).”

In both series the symptoms were brief and mild in most patients.  Like I say, its hard to hurt people. Suggestive and worrisome, especially as the practitioners seem clueless about the potential significance of the symptoms they are apparently inducing. But not a surprise given their lack of real medical training.

I had to snicker when I read “Self-reported recognition of undiagnosed life threatening conditions in chiropractic practice: a random survey.” It was estimated that a chiropractor would see an undiagnosed serious illness every 2.5 years, noting a variety of illnesses covering everything but the disease they may be inducing.

There are case reports of strokes following whack em hard/whack em once. Seems a very reasonable complication to me given what they are doing to the fragile structure in the neck. But just because it seems reasonable does not necessarily follow that it is true.

There was an interesting report where they evaluated all the case reports of stroke that follow whack em hard/whack em once and they note that the quality of the case reports is poor.

They compared the information provided by case reports and used the Bradford-Hill causality criteria as the standard. Most of the case reports did not provide sufficient causality data from a Bradford-Hill perspective. They point out the need for standardized reporting to provide better information, which is a valid point across the medical literature.

They did find 901 cases of CAD (cervical artery dissection) and 707 incidents of stroke reported to be associated with whack em hard/whack em once. They conclude, as chiropractors might,

As a result, the value of these reports toward informing our understanding of the relation between [cervical spinal manipulation therapy] and CAD is minimal.

I am not so sure. While the case reports may not be perfect, when you read the individual reports they appear compelling given the potential mechanism of injury. Much closer to a parachute evaluation.

There is also a recent systematic review of stroke from whack em hard/whack em once. Being chiropractors, they are understandably reticent to conclude harm.

“Conclusive evidence is lacking for a strong association between neck manipulation and stroke, but is also absent for no association.”

When I read the Cassidy study, the one most often touted as demonstrating a lack of association between strokes and whack em hard/whack em once, I thought it demonstrated an increase in stroke in the young, the group who should not get a stroke.

I think they found the same result:

“Positive associations, especially with cervical and headache related visits, were only observed for chiropractic patients aged < 45 years, with 25 cases (24.5%) and 27 controls (6.6%) within 7 days for general visits. For headache or cervical visits within 7 days, results in the case–control study were OR crude = 3.11 (95% CI = 1.16–8.35) and accelerated bias corrected bootstrap 95% CI = 1.07–9.60, and for visits within 3 days the case-crossover study gave OR crude = 17.7 (95% CI = 2.04–153.3), bootstrap unavailable. However, for the PCP visits similar associations were observed for patients aged < 45 years and ≥ 45 years. For headache or cervical visits within 7 days for patients aged < 45 years, the case–control study resulted in OR crude = 37.60 (95% CI = 4.80–294), and for within 3 days the case-crossover study yielded OR crude = 28.00 (95% CI = 3.44–227.58), and in both cases the bootstrap was unavailable. Sensitivity analysis resulted in attenuation of the estimates towards the null with lower positive predictive values, but the associations remained positive and significant (data not presented)”

Right? Increased strokes in the young?  That is what they are saying?  There are those who have questioned my statistical sophistication and I will say that my continued re-reading of the above paragraph proves them right.

But why do the young have more strokes? In a wild flight of fancy they hypothesize it is due to drinking and infection:

“Cassidy et al. used a case-crossover design to correct for the lower health status of PCP patients, but this design is limited in controlling factors that can change rapidly.  Binge drinking and acute infection may precipitate occlusive strokes, which are capable of causing severe headache before stroke presentation. If PCP patients are more prone to sporadic binge drinking, and acute infection than chiropractic patients, this could lead to baseline elevation of the PCP visit association for the case-crossover analysis.”

More strokes yeah, the young drink, yeah, and they have more venereal diseases, oh yeah, so, it must be the fact they are drunken and infected.  That’s why they had more strokes. Yeah, that’s the ticket.

Weird. Me? I’d have to drink very heavily and have syphilitic dementia before I allowed someone to whack my neck real hard one time.

There may be an opportunity in the future to determine the risk of stroke from whack em hard/whack em once. Many hospitals now have stroke programs where they collect voluminous data about their patients. It would be interesting to graft a questionnaire onto the stroke program evaluation looking for the risk from whack em hard/whack em once and the development of a stroke. There is a research project for someone with the time and expertise.

If you are a preponderance of data kind of gal, as I am (preponderance of data, not a gal) there is more data to support the risk of stroke after whack em hard/whack em once to the neck to give one pause. We get black box warnings for less frequent drug complications. I doubt I will see a journal article entitled “The Myth of Azithromycin Death.” But then, I pay attention to the data and am not invested in an intervention with no basis in reality that offers only harm without benefit. It must be tough if your raison d’etre only causes harm. I kind of feel pity.

Hanging is too good for a man who makes puns; he should be drawn and quoted.
~ Fred Allen

Posted by Mark Crislip

Mark Crislip, MD has been a practicing Infectious Disease specialist in Portland, Oregon, since 1990. He is a founder and  the President of the Society for Science-Based Medicine where he blogs under the name sbmsdictator. He has been voted a US News and World Report best US doctor, best ID doctor in Portland Magazine multiple times, has multiple teaching awards and, most importantly,  the ‘Attending Most Likely To Tell It Like It Is’ by the medical residents at his hospital. His growing multi-media empire can be found at