Most, but not all, patients with vertebral artery dissection have a headache.7 Headache is severe, unilateral, and often posterior-occipital. Whereas patients with carotid artery dissection may present with a wide variety of types of headaches, the quality of the headache in vertebral artery dissection is much more consistently unilateral and severe.7 Almost half of patients have neck pain of gradual onset. Less commonly, patients will present with isolated neck pain and no headache. On exam, patients may have neck tenderness with palpation. Do not be falsely reassured by reproducible neck pain when it comes to evaluation of vertebral artery dissection.
Explore This IssueACEP News: Vol 32 – No 02 – February 2013
When compared to carotid artery dissection, vertebral artery dissection is more likely to affect younger patients. It is more common in women and in patients with chronic migraines.
Once you suspect cervical artery dissection, choosing the appropriate imaging modality is key. The usual approach to a new headache in the emergency department is a non-contrast head CT and possible lumbar puncture. Unfortunately this may miss uncomplicated cervical artery dissection, leading to delays in the diagnosis and subsequent stroke or death. Historically, cerebral angiography has been the “gold standard” for diagnosis of dissection. Angiographic findings suggestive of dissection include intimal flaps, pseudo- aneurysm, and luminal stenosis or occlusion.3 However, cerebral angiography is less commonly used today due to the invasive nature and the risks of the procedure. Conventional angiography has been replaced in the ED by the faster and more readily available magnetic resonance angiography (MRA) and computed tomography angiography (CTA). In some populations, the introduction of MR and CT has increased the rate of diagnosis of cervical artery dissection up to 10-fold.8 Ultrasound has been studied in cervical artery dissection, but it is less sensitive than CTA or MRA.
The largest series comparing MRA to traditional angiography found a sensitivity of 83% and a specificity of 99% for carotid artery dissection and a sensitivity of 20% and a specificity of 100% for vertebral artery dissection.9 Accuracy of CTA has improved over the past decade with the use of multi-detector CT scanners, with a sensitivity of 90% and a specificity of 100%.10
The general consensus among experts is that CTA is the better screening test because it is faster, cheaper, and shows excellent visualization of large vessels, including the carotids and vertebrals. If CTA shows dissection, MRA is an appropriate follow-up test because it allows for better visualization of small vessels and will also show cerebral ischemia if present. A reasonable initial approach to a patient with a suspected cervical artery dissection would be to obtain a non-contrast head CT, and if negative, proceed with a CTA head and neck. If dissection is identified, obtain MR brain and MRA head and neck for further evaluation.