Neck adjustments performed by chiropractors or osteopathic physicians are routine for many, but the safety of such procedures is called into question by a new report suggesting an association with increased risk of stroke.

The American Heart Association (AHA) on Thursday released a statement detailing the findings of a writing group appointed by the AHA Stroke Council’s Scientific and Manuscript Oversight Committees that were charged with assessing the current state of evidence for any links between stroke and cervical manipulative therapy (CMT), or neck adjustments. Members reviewed a variety of literature and reports in their individual specialities, summarized existing evidence, and identified gaps in current knowledge.

The group found that the earnest thrusts and rotations used in CMT may cause tears in the arteries that run through the neck to supply blood to the head. If a tear forms, clots will then form to stop blood loss and promote healing. It is thought that these clots can sometimes dislodge and travel into the blood vessels of the brain where they may clog smaller vessels, leading to a stroke.

Four large-scale studies to date have found an association between CMT and stroke in patients 45 years of age and younger. The AHA writing group members stressed, however, that these studies were not able to demonstrate that CMT causes stroke. Regardless, the statement calls for chiropractors and osteopathic physicians to advise their patients of the risks involved with CMT.

“We strongly believe that patients should be informed of this association before undergoing neck manipulation,” said Jose Biller, chair of neurology at Loyola University Chicago Stritch School of Medicine.

The chiropractic community acknowledges the association but contends that there is likely no causal link between CMT and stroke.

“Two studies that have come out recently said that there is no evidence that the force or direction utilized in cervical manipulation reaches the threshold of stretching the arteries to the point that they can be damaged,” said Keith Overland, immediate past president of the American Chiropractic Association and a chiropractic doctor in Norwalk, Connecticut. Overland added that professionals who perform neck adjustments apply force that is “no greater than what people can do in activities of daily life.”