Stroke from chiropractic neck manipulation occurs when an artery to the brain ruptures or becomes blocked by a clot as a result of being stretched. The injury often results from extreme rotation in which the practitioner’s hands are placed on the patient’s head in order to rotate the cervical spine by rotating the head [1].  The vertebral artery, which is shown in the picture to the right, is vulnerable because it winds around the topmost cervical vertebra (atlas) to enter the skull, so that any abrupt rotation may stretch the artery and tear its delicate lining. The anatomical problem is illustrated on page 7 of The Chiropractic Report, July 1999. A blood clot formed over the injured area may subsequently be dislodged and block a smaller artery that supplies the brain. Less frequently, the vessel may be blocked by blood that collects in the vessel wall at the site of the dissection [2]

Chiropractors would like you to believe that the incidence of stroke following neck manipulation is extremely small. Speculations exist that the risk of a serious complication due to neck manipulation are somewhere between one in 40,000 and one in 10 million manipulations. No one really knows, however, because (a) there has been little systematic study of its frequency; (b) the largest malpractice insurers won’t reveal how many cases they know about; and (c) a large majority of cases that medical doctors see are not reported in scientific journals.