Patient memories of anesthesia--historical perspective

Since the introduction of anesthetic agents for surgical pain relief in 1846, a number of clinical, experimental and anecdotal reports have been published concerning those patients having memories of their anesthesia. These reports can be divided into three broad categories: awareness of the surgical procedure or other intraoperative events; hallucinations, dreams or illusions; and transcendental experience. The history of each of these groups of experiences is reviewed.