Carotid Arterial Dissection: Time for a Randomized Clinical Trial

Abstract & Commentary

By John J. Caronna, MD, Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Caronna reports no financial relationships relevant to this field of study.

Synopsis: There are no randomized controlled treatment trials of cervical artery dissection, and the most effective therapy is uncertain.

Source: Menon R, et al. Treatment of cervical artery dissection: A systematic review and meta-analysis. J Neurol Neurosurg Psychiatry 2008;79:1122-1127.

Cerebral arterial dissection is an important cause of stroke, especially in the young. Potential stroke mechanisms include both hemodynamic compromise and embolism. Evidence from cerebral angiography and transcranial Doppler studies suggests that embolism is the more important cause of stroke.1 Natural history data indicate a high risk of early recurrent stroke, largely within the first month after onset.2

Menon et al performed a systematic review and a meta-analysis to determine the effectiveness of the different treatment approaches to carotid arterial dissection. They performed separate searches and reviews of: 1) antiplatelet and anticoagulant drugs, 2) thrombolysis, and 3) angioplasty with stenting. For each they searched Medline and PubMed from 1966 to April 2007.

There were sufficient data for meta-analysis, only to compare antiplatelet treatment with anticoagulation. No randomized controlled trial (RCT) was found. In 34 non-randomized studies comprising 762 patients there was no significant difference in the risk of stroke or death. There were four non-randomized studies of thrombolysis that provided insufficient data to assess efficacy. Complication rates were not greater than in thrombolysis for other causes of ischemic stroke.

Six studies comprised 96 patients who underwent stenting for both acute dissection and its chronic complications (stenosis and dissecting aneurysm). Data were insufficient for assessment of efficacy. Complication rates were similar to those published for stenting in atherosclerotic carotid stenosis.

The authors concluded that no data support the therapeutic superiority of anticoagulants over antiplatelet agents. Thrombolysis and stenting appear safe but conclusions about efficacy require more data.

Commentary

Like many other medical and surgical interventions intended to cure disease or prevent disability, the commonly used treatments for cervical artery dissection have not been subjected to rigorous testing by RCT. Observational studies from the Mayo Clinic3 among others have suggested that antiplatelet therapy is sufficient in carotid dissection without neurological deficits apart from Horner syndrome, but that anticoagulation should be employed in carotid dissection presenting with stroke. Clinicians have used their best judgment in choosing among the available treatments for carotid dissection and remain free to do so.

The systematic review of more than 700 patients treated with antiplatelet or anticoagulant therapy provides useful information for clinicians and justifies the need for an RCT. The authors lamented that "there were no data from randomized trials and much of the data were of poor quality." The authors' failure to find even one RCT reminds me of another systematic search for RCTs of "parachute use to prevent death and major trauma related to gravitational challenge."4 Alas, in that study, the tongue-in-cheek authors, too, could not find a single RCT of parachute use. They wisely concluded that the basis for parachute use is purely observational and its apparent efficacy potentially could be explained by bias in selection and reporting, "the healthy cohort effect." They invited those who advocate evidence-based medicine to demonstrate their commitment by volunteering for a double-blind RCT of the parachute. Any takers?

References

1. Srinivasan J, et al. Transcranial Doppler in the evaluation of internal carotid artery dissection. Stroke 1996;27:1226-1230.

2. Biousse V, et al. Time course of symptoms in extracranial carotid artery dissections. A series of 80 patients. Stroke 1995;26:235-239.

3. Mokri B, et al. Spontaneous dissection of the cervical internal carotid artery. Ann Neurol 1986;19:126-138.

4. Smith GC, Pell JJ. Parachute use to prevent death and major trauma related to gravitational challenge: Systematic review of randomised controlled trials. BMJ 2003; 327:1459-1461.