There is few randomized controlled clinical to investigated the impact of anesthetic type on outcome in patients with acute ischemic stroke in posterior cerebral circulation. It is unknown whether the choice of anesthesia is impacted on the outcomes for these patients or not. The investigators will perform a randomized controlled pilot clinical trial of general anesthesia versus sedation to explore and find out a potential fact whether anesthetic type alters perioperative neurological function in patients with acute ischemic stroke in posterior cerebral circulation.