Absence of recall after general anesthesia: implications for theory and practice.

To investigate the possibility that recall of auditory information occurs following general anesthesia, letter-work pairs were presented to 36 patients receiving light planes of general anesthesia for short operations. Postoperative testing which tapped auditory and visual memory demonstrated no evidence of recall. In a subsequent study, a single work was repeated during brief obstetric procedures in 12 patients. Postoperative testing was designed to maximize apparent recall. The only patient able to remember the experimental word had awakened during anesthesia. Even without the use of more sophistaicated physiologic and psychologic measures of recall, the data presented indicate that, for all practical purposes, an adequately anesthetized patient does not remember information presented during surgery. Apparent recall probably indicates inadequate or uneven anesthesia. Anesthetic agents may interfere with memory formation by altering brain RNA or protein synthesis or electrochemical activity, or they may produce retrograde amnesia.