The American Heart Association and the American Stroke Association recently addressed in Stroke that cervical or neck manipulation could increase the risk of getting cervical artery dissections (CAD), which can cause a stroke. In general, CAD accounts for about two out of every 100 strokes, and the risk increases among young and middle-age adults to between eight and 25 out of every 100 strokes. The research, which was led by neurologist José Billers from the Loyola University Chicago Strich School of Medicine, states that there is no sufficient evidence that neck manipulation causes CAD, clinical reports suggest that the forces from neck manipulation play a significant role in contributing to the number of CADs. Population controlled studies show a tie between neck manipulation and stroke among young patients.
In an arterial dissection, there is a tear in a layer in the arterial wall, which can result into a stroke if a blood clot forms, says Billers in a media interview. Such tears can also happen in a whiplash, contact sports or any sudden hyperextension or rotation of the neck, including manual neck manipulation. Among the literature and studies, the researchers found that patients who suffered from CAD were more likely to have their neck adjusted. However they could not conclude that such treatment was the primary cause of stroke because it is possible that they may have gotten their neck adjusted from early stages of stroke symptoms. Patients had neck pain and may have went to a healthcare professional, usually a chiropractor, to get neck manipulation.
Current scientific evidence does not support nor refute that neck manipulation could increase the risk of stroke. A 2012 systematic review published in International Journal of Clinical Practice examined five case-control studies, which included one case-crossover design, were examined. They concluded that there is lack of strong evidence that links neck manipulation and stroke, yet there is no evidence that suggests there is no such link. Some of the studies contain bias and confounders that influence the outcomes, such as under-reporting and exaggeration by patients and researchers of these studies.
It is quite possible that patients and health professionals do not always report their incident. While there are rare large studies of neck manipulation associating with CAD, a team of researchers from Texas Chiropractic College in Pasadena, Texas, stated in PLOS One that systematic reviews often exclude non-randomized-controlled trials, which can reduce the quality of data about the neck manipulation. These exclusions include case reports, which makes up a majority of the cases between neck manipulation and CAD. Researcher found among 43 studies that met their criteria for review, 32 out of 706 ischemic infarcts – which makes up about 85 percent of the cases of stroke – were reported.
One of the major limitations of this study was that there is a lack of reporting and data of events that preceded the onset of CAD or neck manipulation. Without knowing what originates the cause, it is difficult for clinicians to determine if there is a direct cause-and-effect relationship between CAD and neck manipulation. “If a CAD then occurs following [neck manipulation], it becomes difficult, if not impossible, to identify which event, if any, were associated with the injury,” the authors wrote. “This paper clearly demonstrates that there is a critical need to report all events surrounding CAD, not just the event immediately preceding the injury.”
Even though the chances of getting a stroke from neck manipulation is quite small, chiropractors and manual therapists who are qualified to do any neck adjustments should be informed about current findings and inform their patients who may request a “crack in the neck.” Science-Based Medicine suggests that neck manipulation should be performed under “uncomplicated musculoskeletal problem that results in loss of mobility” and the consultation with an orthopedist or neurologist should be considered before any neck adjustments are made. However, those with certain vascular or structural abnormalities or who are taking blood thinners or similar medications should not get their neck “adjusted.”
By Nick Ng