Endovascular therapy for acute basilar artery occlusion: a review of the literature.

Basilar artery occlusion is an infrequent form of acute stroke; clinical outcomes are heterogeneous, but the condition can be fatal. There is a lack of randomized controlled trial data in this field. Case series suggest that patients who are recanalized have much better outcomes than those who are not, and it is generally accepted that intra-arterial techniques achieve high rates of recanalization. Controversially, several studies, including a meta-analysis and registry-based investigation, that have compared intravenous thrombolysis (IVT) and intra-arterial treatment suggest similar outcomes. However, there are many potential sources of bias in each of these studies, precluding a firm conclusion. Indeed, there are many confounding factors that can influence the outcome including severity of presentation, site of occlusion, clot load, degree of collateral flow, timing of therapy, agent used for recanalization and dose of thrombolytic agent. Additionally, pretreatment infarct core imaging using diffusion-weighted imaging and the posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) scoring systems have been shown to predict outcome and therefore may be useful in selecting patients for aggressive therapy. Protocols combining intravenous agents such as glycoprotein IIb/IIIa receptor antagonists or thombolytics agents with intra-arterial techniques ('bridging' therapy) have shown encouraging improvements in neurological outcome and survival. Furthermore, initial case series describing the use of mechanical clot extraction devices or aspiration catheters suggest high rates of recanalization. What would be useful is a randomized trial comparing IVT, endovascular approaches and a combined IVT/endovascular approach. However, the small numbers of patients and multiple confounding factors are barriers to the development of such a trial.