Studies in posterior circulation stroke

• Main Author: Khan, Sofia
• Published: St George's, University of London 2012
• Subjects: 616.81
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589798

Posterior circulation ischemic stroke accounts for a quarter of ischemic strokes. Recent studies have shown that these patients have a high early risk of further ischaemic events especially if they have 2:50% vertebrobasilar (VB) stenosis; there is paucity of data on the diagnosis and management of these patients. The gold standard technique to diagnose VB stenosis is intra-arterial angiography (IAA) which carries a risk of stroke; this can be avoided by using non-invasive imaging techniques. I systematically reviewed the literature on studies which compared the accuracy of three commonly used non-invasive imaging techniques (contrast-enhanced magnetic resonance angiography (CE-MRA), computed tomographic angiography (CTA) and duplex ultrasonography) to IAA, the gold standard, in order to diagnose VB stenosis. There were 13 studies for vertebral stenosis, these showed CE-MRA and possibly CTA to be better than duplex. I then performed the first prospective study (40 patients) comparing CE-MRA, CTA and duplex to IAA in the same patient group demonstrating that CE-MRA had the highest sensitivity followed by CTA and then duplex. The two main studies which have shown that 2:50% symptomatic VB stenosis carries a high risk of further ischaemic events followed-up patients for 90 days. I examined my patient group with longer term follow-up (mean 14 months). This study showed a higher risk of recurrent ischaemic events (odds ratio (OR) 2.56(95%CI 1.11-5.9),p=0.023) and VB stroke or TIA (OR 2.8(95%CI 1.24-6.32),p=0.01 ). I reviewed data from patients who had endovascular vertebral intervention at St George's and systematically reviewed the literature. This study showed that vertebral artery stenting is a technically successful procedure (99.4%) with a periprocedural stroke risk of 0.5%; one year TIA, stroke and mortality rate was 3.9%, 5.0%, and 3.6% respectively. However, the included studies were retrospective studies of varying quality; large-scale prospective trials are needed to determine the benefits of stenting.