Ever cracked your own neck, or helped to crack somebody else's? Perhaps you've been to a chiropractor or osteopath, and they've manipulated your head suddenly to one side or another to leave you with the swift "crack" noise and that sweet feeling of relief. Cracking your neck, or cervical manipulation, may be a standard part of the chiropractic arsenal, but it's a somewhat controversial practice that could, in rare cases, seriously mess up your arteries, and might even lead to stroke.
The sound caused by neck manipulation is thought to be part of the therapeutic benefit of the process, like cracking one's knuckles. The process itself, however may be placing people at risk. The problem? There are a number of arteries in your head and neck that are at risk of dissection with sudden manipulation.
But not everyone is sure of the link between neck-cracking and this rare injury. Chiropractors, scientists and doctors disagree amongst themselves about how bad the practice might be and whether neck-cracking is really a big risk factor, or if it's all hype. Throw in some contradictory studies, a lack of regulation and some under-reporting, and you have a pretty big mess. An impressive hooplah for something that looks, on the surface, like a simple way to cure a back-ache.
How Bad Is Neck Cracking, Really?
Suddenly moving the head can, in a minority of cases, cause what's called a vertebral artery dissection: an injury to one of the major arteries in the neck that can lead to internal bleeding, and potentially stroke. Symptoms of vertebral artery dissection include pain and numbness of the face, unequal hearing loss, vertigo, and even hiccups. Vertebral artery dissection leading to stroke is what appears to have caused the death of Snapchat model Katy May in 2016. While rare, it is deeply unpleasant, and throwing in the risk of stroke, it's also dangerous.
Experts disagree, however, about how common this risk is, and how many patients should be warned about it before going to a neck-cracking session (or manipulating their own necks). In 2012, there was a debate about the safety of the procedure in the British Medical Journal, where it was pointed out that the rate of vertebral artery bleeds in the United States is miniature (1 to 1.7 per 100,000 people), and the number of strokes smaller still (0.75 to 1.12). But a big part of the difficulty with assessing the true danger is that it might be underreported.
Numerous studies were undertaken throughout the 2000s trying to understand exactly how many people may have experienced bleeds and strokes from neck manipulation, but the numbers kept differing. One 2013 study found that in a small group of patients, neck cracking raised the risk of stroke by 6.62-fold, while a review of 10 years of research published in the same year found 707 cases of stroke that might have been caused by cervical manipulation. Another study in 2015, however, found that in a cohort of over a million people who'd been to a chiropractor or GP for neck pain, the likelihood of stroke caused by neck manipulation was "extremely low" (in fact, too small to measure) and increases in stroke risks in general were minimal.
Why Don't We Know More?
Unfortunately, tracing strokes definitively back to neck cracking is extremely difficult, because vertebral artery bleeds can be caused by other things: neck injuries and accidents, genetic predispositions to artery weakness or hypermobility, or random incidents. "Some precipitating events associated with hyperextension or rotation of the neck," a 2008 study noted, "include practicing yoga, painting a ceiling, coughing, vomiting, sneezing, the receipt of anesthesia, and the act of resuscitation." Which means that pinning the blame on cracking one's neck at a chiropractor's or in an idle moment at a desk can be very tricky.
The fact that the professionals performing neck manipulations tend to be chiropractors or osteopaths is another factor that complicates matters. Chiropractors are sometimes regulated — the Professional Standards Authority in the UK regularly audits the General Chiropractic Council, for instance, while many American states require licenses — but in different areas of the world, it's less formal. That can create issues with collecting information about patients and their treatments, and with what training these practicitioners receive. When people aren't aware of the signs of vertebral dissection or the risks involved in neck cracking, it's also entirely possible that underreporting is also playing havoc with the numbers.
If you do want to crack your neck, experts do agree that the risks of stroke are incredibly low. But it might be worth being careful next time you feel the urge to do it yourself.