BACKGROUND: Endovascular or intra-arterial treatment (IAT) increases the 
likelihood of recanalization in patients with acute ischemic stroke caused by a 
proximal intracranial arterial occlusion. However, a beneficial effect of IAT on 
functional recovery in patients with acute ischemic stroke remains unproven. The 
aim of this study is to assess the effect of IAT on functional outcome in 
patients with acute ischemic stroke. Additionally, we aim to assess the safety 
of IAT, and the effect on recanalization of different mechanical treatment 
modalities.
METHODS/DESIGN: A multicenter randomized clinical trial with blinded outcome 
assessment. The active comparison is IAT versus no IAT. IAT may consist of 
intra-arterial thrombolysis with alteplase or urokinase, mechanical treatment or 
both. Mechanical treatment refers to retraction, aspiration, sonolysis, or use 
of a retrievable stent (stent-retriever). Patients with a relevant intracranial 
proximal arterial occlusion of the anterior circulation, who can be treated 
within 6 hours after stroke onset, are eligible. Treatment effect will be 
estimated with ordinal logistic regression (shift analysis); 500 patients will 
be included in the trial for a power of 80% to detect a shift leading to a 
decrease in dependency in 10% of treated patients. The primary outcome is the 
score on the modified Rankin scale at 90 days. Secondary outcomes are the 
National Institutes of Health stroke scale score at 24 hours, vessel patency at 
24 hours, infarct size on day 5, and the occurrence of major bleeding during the 
first 5 days.
DISCUSSION: If IAT leads to a 10% absolute reduction in poor outcome after 
stroke, careful implementation of the intervention could save approximately 1% 
of all new stroke cases from death or disability annually.
TRIAL REGISTRATION: NTR1804 (7 May 2009)/ISRCTN10888758 (24 July 2012).