One of the side effects from some general anesthesia used to sedate you for surgery can be amnesia that is experienced post-operatively. Referred to as post-operative cognitive dysfunction (POCD) by anesthesiologists and surgeons, it can last for more than a year or it can ameliorate much sooner. In some cases, physicians have found memory impairment to continue into old age. To date, there is no known way to reverse the memory loss, other than allowing it to resolve on its own.
General anesthesia differs from a local anesthesia in that rather than being injected into a specific spot to numb it, with general anesthesia you are chemically induced into an unconscious state. This is achieved by you either breathing vapors in through a mask or having the anesthesia injected into your arm or an IV (a tube that runs directly into a vein so medicines can be injected more easily). In reality, your anesthesiologist is actually creating controlled amnesia, so you don't remember the surgery. When the surgery is over, your anesthesiologist stops the medication, and you gradually wake up.
Post Operative Cognitive Dysfunction (POCD)
More prevalent among the elderly (individuals over 60) who have anesthesia-assisted surgeries, POCD can manifest as confusion post-operatively and has been documented as occurring to 44 percent of all elderly patients undergoing hip replacement surgery under anesthesia. According to the Society for Ambulatory Anesthesia (SAMBA), it is estimated that for all surgeries involving anesthesia, a 26 percent impairment in memory and cognitive abilities is not unusual one week post-op. When patients were evaluated three months post-op, 10 percent reduction in cognition and memory was documented.
Depth of Anesthesia
One of the responsibilities of your anesthesiologist is to monitor the depth of the anesthesia that you are being given to prevent your being overloaded with the medicine. As the anesthesiologist begins the process of inducing unconsciousness, your mind goes through several stages of ability as you go deeper. "Count backwards from 100," is a common phrase in operating rooms because as you go under, your ability to process information and retain it disappears. Incidentally, most people get to about 97 and then they're out. There are some theories that maintaining surgical levels of anesthesia and not allowing a patient to go as deep into unconsciousness may help stem POCD.
More appropriately known as regional anesthesia or conscious sedation, twilight sleep is used when a procedure is less invasive, such as plastic surgery or setting a broken bone. Many of the same medications that are used in general anesthesia are used for twilight sleep, just in smaller doses. With twilight sleep, selective amnesia occurs. In other words, you probably won't remember the procedure, even though you are able to talk and respond to questions while under the medication. Used primarily to relax a patient and eliminate anxiety, twilight sleep still can cause POCD in some people because the same medications are used.
Anecdotal evidence indicates that proper nutrition and exercise post-op can lessen the symptoms of anesthesia-related memory loss. Supplements like ginko-biloba have been mentioned as memory boosters, although there is no U.S. Food and Drug Administration evidence to support that claim. If you feel that you are experiencing significant memory loss after your surgery, talk to your doctor to see if there is something that he can recommend to help you.