Efficacy and safety of the treatment modalities from 2006 to 2009 and 2012 to 2014.

Fisher-exact tests and Chi-Square tests examine the 0-Hypothesis H0 that there is no difference regarding the rates of symptomatic ischemic stroke, occlusion rate, rebleeding, direct mortality and reinterventions between the two treatment modalities (endovascular group versus microsurgical group).