Research Review By Dr. Shawn Thistle©

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Date Posted:

November 2010

Study Title:

Late sequelae of whiplash injury with dissection of cervical arteries

Authors:

Hauser V et al.

Author's Affiliations:

Department of Neurorehabilitation, Clinic Valens, Valens; Department of Neurology, Philipps University Marburg, Marburg , Germany

Publication Information:

European Neurology 2010; 64: 214-218.

Background Information:

All manual medicine providers are familiar with the potential association of vertebral artery dissection and upper cervical spinal manipulation. We know it is extremely rare, and that it can be caused by everyday activities and movements. We discuss it prudently with our patients during the informed consent process and we are constantly looking for warning signs of this condition.

My intent in reviewing this particular paper is not to review the literature on vertebral artery dissection. That being said – a brief review of some simple concepts is in order. Arterial dissections are normally categorized as post-traumatic (~1/3 of cases) or spontaneous/non-traumatic (~2/3 of cases). They involve a tear forming in the tunica intima of an artery that results in blood accumulating in the space between the intima and media. In time this can lead to complete occlusion of the vessel which is often followed by recanalization after several months.

During this process thrombosis/embolism can occur. Depending on the artery involved, neurological deficits can arise in the form of a stroke.

This retrospective case analysis investigated the incidence of posttraumatic cervical artery dissections (including those involving the vertebral artery) in patients who had sustained a whiplash injury in a motor vehicle collision. The results certainly warrant further study and should raise our vigilance even further in patients who have sustained such injuries.

Study Summary:

This study, conducted in Switzerland, involved a retrospective analysis of medical records of 500 patients who had suffered neck injury (whiplash) subsequent to a motor vehicle collision (front end and rear end collisions were included).

The authors found 8 cases of cervical artery dissection that occurred within 12 months of the initial collision.

What does this mean? Well, in the general population in Switzerland, the incidence of cervical artery dissections is 41/1000000, or 0.0041%. The incidence revealed in this study group was 8/500, or 1.6% - this is a significant difference, suggesting that there is an association between whiplash injury and cervical artery dissection in this study sample.

It is also worth noting that the risk of CAD was still increased 4-12 months after the accident. The authors mentioned that there was no information in the files of the 8 identified CAD cases suggesting that other conditions or trauma contributed to the CAD.

Clinical Application & Conclusions:

This study revealed a higher incidence of CAD in subjects who had sustained a neck injury in a motor vehicle collision compared to existing population data. Indeed, the retrospective study design cannot establish cause and effect for this association, but it certainly should raise awareness of this potential association, as well as practitioner vigilance to screen and monitor our whiplash patients for the development of CAD (even months after the collision).

Subsequent research on larger patient samples, utilizing a prospective cohort approach would help clarify this issue. Until then, prudent clinicians should be aware that:
  • Those who have suffered a whiplash injury may be at higher risk of developing CAD
  • CAD is not always recognized immediately after an accident, and may remain asymptomatic for a number of months (presumably even during treatment)
To answer what may perhaps be your first question about this study: There was no mention or investigation into whether the 8 cases of CAD had seen a chiropractor.

Stay tuned for further research on this important topic.

Study Methods:

This was a retrospective analysis of medical records of 500 patients with whiplash injury. The authors searched for cases where cervical artery dissection occurred within 12 months of the accident.

Study Strengths / Weaknesses:

This study did not have a robust study design and included a review of only 500 cases. As such, a cause and effect relationship cannot be established. However, the results certainly warrant larger studies to investigate this possible relationship.