Current Understanding of the relationship Between Cervical Manipulation and Stroke
Written by Editor   
Wednesday, April 30, 2014 11:25 AM

The understanding of the relationship between cervical manipulative therapy (CMT) and vertebral artery dissection and stroke (VADS) has evolved considerably over the years. In the beginning the relationship was seen as simple cause-effect, in which CMT was seen to cause VADS in certain susceptible individuals. This was perceived as extremely rare by chiropractic physicians, but as far more common by neurologists and others. Recent evidence has clarified the relationship considerably, and suggests that the relationship is not causal, but that patients with VADS often have initial symptoms which cause them to seek care from a chiropractic physician and have a stroke some time after, independent of the chiropractic visit.

This new understanding has shifted the focus for the chiropractic physician from one of attempting to "screen" for "risk of complication to manipulation" to one of recognizing the patient who may be having VADS so that early diagnosis and intervention can be pursued. In addition, this new understanding presents the chiropractic profession with an opportunity to change the conversation about CMT and VADS by taking a proactive, public health approach to this uncommon but potentially devastating disorder.

Cervical manipulative therapy (CMT) and vertebral artery dissection and stroke (VADS) have been linked in controversy for at least 75 years.  At the center of the controversy have been neurologists and other medical practitioners who have often perceived VADS to be a relatively frequent complication to CMT and chiropractors, who have generally perceived VADS after manipulation to be exceedingly rare.  Starting with isolated case reports and culminating in four case-control studies, our understanding of the relationship between CMT and VADS has evolved considerably.

There are several pathophysiologic processes that can lead to stroke, such as atherosclerosis, hemorrhage secondary to aneurism or arteriovenous malformation, and arterial dissection. Arterial dissection is a specific process in which a tear occurs in the wall of the involved artery. Cervical artery dissection is a general term for dissection that involves either the carotid artery (carotid artery dissection) or vertebral artery (vertebral artery dissection).

It is commonly assumed that if VADS occurs immediately or soon after CMT a clear causal relation is established. Cassidy, et al examined this assumption in a study that involved 109,020,875 person-years of observation over a period of nine years.  They found that the odds of stroke occurring within 24 hours of a visit to a primary care physician was virtually the same as stroke occurring within 24 hours of a visit to a chiropractor.

Therefore, based upon the best current evidence, it appears that there is no strong foundation for a causal relationship between CMT and VADS. The most plausible explanation for the association between CMT and VADS is that individuals who are experiencing a vertebral artery dissection seek care from a chiropractic physician or other manual practitioner for relief of the neck pain and headache that results from the dissection. Sometime after the visit the dissection proceeds along its natural course to produce arterial blockage, leading to stroke. This natural progression from dissection to stroke appears to occur independent of the application of CMT.

The weight of the evidence currently suggests that the most likely explanation for the occurrence of VADS following CMT is that a patient with neck pain and/or headache arising from the arterial dissection seeks the care of a chiropractic physician or other practitioner of manual therapy for relief from this pain, and sometime after this visit the condition independently progresses to a full stroke. It appears that this progression to stroke occurs as a result of the natural history of VADS.  

The concern for the chiropractic physician and other manual practitioner has shifted. Previously the focus had been on trying to "screen" for a patient who is "at risk" of a rare "complication to CMT". The issue for practitioners now is one of differential diagnosis. The responsibility of the practitioner is not to attempt to identify the patient who is at risk of "post-manipulative stroke", but to attempt to identify the patient who is having a dissection in progress so appropriate referral can be made.

The most common initial symptoms of VADS are neck pain and/or headache. Neurologic symptoms and/or signs can begin to manifest shortly after the onset of pain, particularly after the development of headache. In addition, the progression from neck pain and headache to full stroke is not always sudden - there is often a period in which subtle signs and symptoms may develop prior to the development of fully manifested stroke. In addition, it is important for the practitioner, in cases in which there are no detectable signs or symptoms of VADS but in which the patient develops these in the office after manipulation, to take appropriate steps to respond to this medical emergency.

 The classic recommendation regarding the detection of signs and symptoms suggestive of VADS is the "5 Ds And 3 Ns". That is, diplopia, dizziness, drop attacks, dysarthria, dysphagia, ataxia, nausea, numbness and nystagmus. This is a good general rule, however it must be remembered that many patients will not have these signs and symptoms early in the process and when they do manifest they may be subtle and may not be volunteered by the patient. So careful questioning may be necessary to detect their presence.  In a patient with sudden onset of severe unilateral neck pain and headache, particularly in the presence of neurologic symptoms, careful examination is advised and watchful waiting or further investigation should be considered.

In any patient who presents with new onset of neck pain and/or headache, neurologic examination is warranted. The entire central and peripheral nervous system can be screened on examination in two minutes or less with the following:  Heel, toe and tandem walking;  Sensory of the extremities; Romberg's position;  Motor of the extremities;  Visual fields;  Reflexes of the extremities;  Pursuit external ocular movement;  Plantar response;  Sensory of the face;  Rapid alternating movements;  Motor of the face;  Heel to shin movement;  Palate elevation;  Finger to nose movement;  Fundoscopy;  Pronator drift;  Tongue movements.

While current evidence suggests that CMT is associated with but not causally related to VADS, it can be expected that patients with undetected VADS will continue to see chiropractic physicians and it is essential that focused attention be made in an attempt at detection of this uncommon but potentially devastating disorder. In addition, the profession would do well to engage in a public health campaign designed to educate the public about VADS to increase recognition of the early signs of this disorder.