Dr. Sang and associates looked at how well people recovered after treatment for a stroke due to a blockage in the basilar artery. The basilar artery is critical to the brain because it brings blood to deep brain structures like the brainstem, which is important in controlling involuntary body functions such as breathing. The treatment they studied is called endovascular therapy (EVT). More specifically, they looked at time to treatment (which they measured as onset to puncture time [OPT]). In other words, once the stroke had occurred, they looked at the connection between when the treatment was given and how well the person recovered.