Steven Brown, DC, CICE, Dipl Ac 

For many years, it was considered dogma among clinicians and physicians that Chiropractic cervical spine manipulation could cause vertebral artery dissection and resultant vertebrobasilar artery stroke. However, research does not support a causal link between Chiropractic cervical spine manipulation and vertebral artery dissection. Thus, a medico-legal argument that includes Chiropractic cervical spine manipulation causing vertebral artery dissection and resultant vertebrobasilar stroke is no longer viable.

However, the research has long supported a mechanism by which Chiropractic cervical spine manipulation could directly cause a vertebrobasilar artery stroke. Surprisingly, this mechanism has not gained much traction in the medico-legal community.

No Causal Association between Spinal Manipulation & Arterial Dissection

Research has shown that the strain to the vertebral artery during Chiropractic cervical spine manipulation is too small to injure a vertebral artery. Vertebral artery strains obtained during cervical spine manipulation are significantly smaller than those obtained during diagnostic and cervical spine range-of-motion testing, and are much smaller than failure strains. Researchers have concluded that cervical spine manipulation performed by trained clinicians does not appear to place undue strain on the vertebral artery, and thus is not a factor in vertebrobasilar artery injuries.1

Although there is an association between vertebrobasilar stroke and Chiropractic visits, there is a similar association between vertebrobasilar stroke and primary care physician visits. The two most common symptoms of vertebral artery dissection are neck pain and headache. Patients with undiagnosed vertebral artery dissection tend to seek clinical care, Chiropractic and otherwise, for headache and neck pain before having a VBA stroke. Patients with neck pain and headache reporting vertebrobasilar stroke after Chiropractic and primary care physician visits likely had an undiagnosed vertebral artery dissection before their office visit. 2

Although research does not support a causal association between Chiropractic cervical spine manipulation and vertebral artery dissection, many clinicians and physicians still assume a causal association between Chiropractic cervical spine manipulation and vertebral artery dissection.

Neurosurgeons at PennState Hershey Medical Center have addressed this phenomenon, “In spite of the very weak data supporting an association between chiropractic neck manipulation and CAD (cervical artery dissection), and even more modest data supporting a causal association, such a relationship is assumed by many clinicians. In fact, this idea seems to enjoy the status of medical dogma. Excellent peer reviewed publications frequently contain statements asserting a causal relationship between cervical manipulation and CAD. We suggest that physicians should exercise caution in ascribing causation to associations in the absence of adequate and reliable data. Medical history offers many examples of relationships that were initially falsely assumed to be causal, and the relationship between CAD and chiropractic neck manipulation may need to be added to this list.” “There is no convincing evidence to support a causal link between chiropractic manipulation and CAD. Belief in a causal link may have significant negative consequences such as numerous episodes of litigation.”4

Duty to Diagnose

A Doctor of Chiropractic is under a duty to diagnose and refer a patient to another licensed health care professional when necessary. When a patient presents with symptoms consistent with a pre-existing cervical artery dissection, the Doctor of Chiropractic is under a duty to refer the patient for CT angiography and emergency medical care. This is the standard of care for the Chiropractic profession.

Although treatment of a cervical artery dissection is outside the scope of practice for a Doctor of Chiropractic, diagnosis of a cervical artery dissection is within the scope of practice for a Doctor of Chiropractic. However, Doctors of Chiropractic often fail to perform the thorough history taking and physical examination necessary to diagnose a cervical artery dissection.

When a Doctor of Chiropractic fails to diagnose a pre-existing vertebral artery dissection and proceeds with treatment, the research supports a mechanism by which Chiropractic cervical spine manipulation could directly cause a vertebrobasilar artery stroke.

A Mechanism of Direct Causation

Although Chiropractic cervical spine manipulation has not been shown to cause vertebral artery dissection, cervical spine manipulation is contraindicated in the presence of a pre-existing vertebral artery dissection.5 In the presence of a pre-existing vertebral artery dissection, Chiropractic cervical spine manipulation may exacerbate the pre-existing vertebral artery dissection and result in a vertebrobasilar artery stroke.9 This could happen under the following circumstances:

  1. There is a vertebral artery dissection present before Chiropractic cervical spine manipulation. This can be determined by reviewing the medical records. As the two most common symptoms of vertebral artery dissection are neck pain and headache, many patients visit a Doctor of Chiropractic with neck pain and headache that they assume is musculoskeletal. Doctors of Chiropractic often fail to perform the thorough history taking and physical examination necessary to diagnose vertebral artery dissection.
  2. There is a close temporal relationship between the Chiropractic cervical spine manipulation and the onset of ischemic vertebrobasilar artery stroke symptoms.
  3. There is a correlation between the level of the Chiropractic cervical spine manipulation and location of the vertebral artery dissection on CT angiography, and on autopsy examination if the patient is deceased as a result of the vertebrobasilar artery stroke.Under the above circumstances, Chiropractic cervical spine manipulation may exacerbate an undiagnosed, pre-existing vertebral artery dissection and result in a vertebrobasilar artery stroke. It is unlikely that a pre-existing vertebral artery dissection, which had been present and stable prior to the Chiropractic visit, coincidentally evolved into a vertebrobasilar artery stroke soon after Chiropractic cervical spine manipulation.

    Contrary to popular belief, a vertebral artery dissection is not destined to evolve into a vertebrobasilar artery stroke. In fact, research shows that most dissections of the vertebral arteries heal spontaneously and especially, extracranial vertebral artery dissections generally carry a good prognosis.6

    The Healthy Vertebral Artery
    While research does not support the opinion that Chiropractic cervical spine manipulation could result in vertebrobasilar artery stroke, the research applies to patients with a normal, healthy vertebral artery, not a patient with an undiagnosed, pre-existing vertebral artery dissection. Researchers are careful to make this point, here are examples with emphasis added:

    “Our data suggest that the mechanical strain produced by SM (spinal manipulation) seems to be innocuous to the joints and surrounding tissues in healthy subjects.”7

    “There were no significant changes in blood flow or velocity in the vertebral arteries of healthy young male adults after various head positions and cervical spine manipulations.”8

    “Therefore, we conclude that cervical spinal manipulations, as tested here, are safe from a mechanical point of view for normal, healthy VA (vertebral artery).”1

    The Unhealthy Vertebral Artery

    For many years, research has supported the opinion that Chiropractic cervical spine manipulation may exacerbate a pre-existing vertebral artery dissection and result in vertebrobasilar artery stroke. For example:

    “However, the current study does not exclude cervical manipulation as a possible cause or contributory factor in the occurrence of VBA (vertebrobasilar artery) stroke.”3

    “Awareness of the non-specific symptoms of VAD (vertebral artery dissection) is important because SMT (spinal manipulative therapy) could exacerbate the condition and lead to complications such as stroke.”9

    “Physical triggers, including SMT (spinal manipulative therapy), can serve as plausible final link between the underlying disease and stroke (for instance, in case of arterial dissection with existing connective tissue weakness)”.10

    “We have not ruled out neck manipulation as a potential cause of some VBA (vertebrobasilar artery) strokes”. “It might also be possible that chiropractic manipulation, or even simple range-of-motion examination by any practitioner, could result in a thromboembolic event in a patient with a pre-existing vertebral artery dissection.”2

    “No cause-and-effect relationship has been established between cervical spine manipulation and CAD (cervical artery dissection), but it seems that cervical manipulation may be capable of triggering dissection in a susceptible patient or contributing to the evolution of an already existing CAD.”11

    “In some cases, neck pain is the only sign of a vertebral artery dissection, motivating a person to seek chiropractic treatment. In this case, cervical manipulation could trigger a dramatic brain stem stroke.”12

    “Thus, cervical pain that precedes and motivates chiropractic cervical manipulation may be the first symptom of a hitherto unrecognized spontaneous (or traumatic) dissection. In such a case, cervical manipulation would precipitate stroke by either worsening arterial damage, leading to positional occlusion of an already narrowed artery, or dislodging an intraluminal thrombus.”13

    Range-of-Motion Examination

    Cervical spine range-of-motion examination is also contraindicated in the presence of vertebral artery dissection. Cervical spine range-of-motion examination, by any practitioner, could result in vertebrobasilar stroke in a patient with a pre-existing vertebral artery dissection.2

    In fact, researchers have found that cervical spine range-of-motion examination causes more vertebral artery strain than Chiropractic cervical spine manipulation. Therefore, cervical spine range-of-motion examination is even more likely to exacerbate a pre-existing vertebral artery dissection than a Chiropractic cervical spine manipulation.1

    History taking, especially regarding the time of symptom onset, is the single most important factor for detecting subtle symptoms of vertebral artery dissection.14 If the history taking indicates a possible vertebral artery dissection, then not only is cervical spine manipulation contraindicated, cervical spine range-of-motion examination is also contraindicated.

    Physical Medicine Modalities

    Medical and legal professionals tend to fixate on Chiropractic cervical spine manipulation in vertebrobasilar artery stroke cases. However, many Doctors of Chiropractic also perform physical medicine modalities that are contraindicated in the presence of a pre-existing vertebral artery dissection. For example:

    Electric stimulation to the cervical paraspinal and trapezius muscles is contraindicated in the presence of thrombosis (blood clotting), such as a pre-existing vertebral artery dissection.15

    Therapeutic ultrasound to the cervical paraspinal and trapezius muscles is contraindicated in the presence of arterial disease, such as a pre-existing vertebral artery dissection.15

    Cervical spine mechanical traction is contraindicated in the presence of vascular compromise, such as a pre-existing vertebral artery dissection.15

    Case Study

    A patient presented to a Doctor of Chiropractic with constant, severe, worsening, dull, left craniocervical pain, left headache, and nausea that was not relieved by anything, affected all her daily activities, did not dissipate for five days, and was the result of injury five days earlier. The patient had no history of this type of pain, and no history of migraines. The Doctor of Chiropractic failed to perform the thorough history taking and physical examination necessary to diagnose a vertebral artery dissection.

    The Doctor of Chiropractic misdiagnosed the patient with a migraine, and performed cervical spine range-of-motion examination, cervical spine manipulation to the C1 level, electric stimulation, therapeutic ultrasound, and cervical spine mechanical traction on the patient in the presence of an undiagnosed, pre-existing vertebral artery dissection.

    The patient suffered an ischemic vertebrobasilar stroke soon after and died. As evidenced by a review of the medical records, the extracranial vertebral artery dissection had been present and stable for a week. CT angiography and autopsy revealed the pre-existing vertebral artery dissection was at the C1-C2 level, the same level as the Chiropractic cervical spine manipulation.

    Before I acquired this case, it was stuck in limbo because the attorney was attempting to argue that the Chiropractic cervical spine manipulation caused the vertebral artery dissection. No Chiropractic expert witness would accept the case. However, no Chiropractic expert witness informed the attorney that he had a strong case for direct causation by way of exacerbation of the pre-existing vertebral artery dissection. Also, no Chiropractic expert witness informed the attorney that he had an even stronger case for failure to diagnose and refer.

    Conclusion

    Although Chiropractic cervical spine manipulation has not been shown to cause vertebral artery dissection, Chiropractic cervical spine manipulation can result in vertebrobasilar stroke by way of exacerbation of an undiagnosed, pre-existing vertebral artery dissection. If cervical spine range-of-motion examination and physical medicine modalities are performed, they may also contribute to the exacerbation of the pre-existing vertebral artery dissection.

    About the Author

    Steven Brown, DC, CICE, Dipl Ac, is an expert witness specializing in Chiropractic malpractice cases. He is Certified Independent Chiropractic Examiner with the American Board of Independent Medical Examiners, and holds Advanced Certification in Whiplash Biomechanics & Injury Traumatology from the Spine Research Institute of San Diego. He also has completed post-graduate training in medical malpractice with SEAK Expert Witness Training. Dr. Brown is located in Gilbert, Arizona and can be reached at 480-377-1226 or drbrown@brownchiro.com.

    References

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