Neck Manipulation: Safety, Contraindications, and Risks of Cervical Spine Manipulation

Vertebral Artery Dissection (VAD)
In the last ten years, a number of studies have appeared in medical journals that have found that a small percentage of patients who suffered a vertebral artery dissection (VAD) had cervical spinal manipulation at some time prior to the VAD incident. VAD is a weakening or tear of the artery in the upper cervical region which forms a blood clot that can block the flow of blood in the vessel. This blockage can lead to a stroke, a sudden deficit in the nervous system usually caused by lack of oxygen to the brain.

Roles Played by Plaques and Emboli
Most strokes are caused by narrowing of arteries from plaques. Plaques are fatty deposits that form on the lining of the artery (atherosclerosis) or by emboli. Emboli are pieces of plaque that have broken loose and block an artery. Factors association with various heart diseases can also cause stroke. VAD is considered a less common cause of stroke that primarily affects patients under 45-years of age.

Underlying Disorders
Most authors consider that an underlying disorder of the arteries must be present in order for a VAD to develop. Some disorders being considered that may make vessels vulnerable include conditions such as fibromuscular dysplasia, Marfan's syndrome, cystic medial necrosis, connective tissue abnormalities, and infection in the weeks prior to a VAD incident. While significant efforts have been made to identify and list warning signs, there are none yet that identify those patients at risk for VAD.

Retrospective Studies
The studies that associate VAD with spinal manipulation are "retrospective" studies, meaning they are based on the records of neurologists who treat stroke and identify patients who have had prior cervical spinal manipulation. In these studies, approximately 117 cases of post-manipulation stroke were reported in English language journals as of 2002.

According to the standards of scientific literature, these retrospective studies offer indications for future research, but they are not considered adequate to prove a "cause and effect" relationship. Unfortunately, stories appearing in the popular media ignored the tentative nature of this research and jumped to a more dramatic conclusion with warnings regarding the safety of cervical spinal manipulation.