By: Dan Sperling, MD

It has long been observed that the use of general anesthesia for surgical procedures can result in short-term and even long-term memory loss and disorientation after the patient regains consciousness. Adverse effects such as delirium and sustained memory loss were recognized as early as 1955.[i] The term for this condition is postoperative cognitive dysfunction (POCD), and it is assessed by administering pre- and post-operative psychometric tests. The question, “What long-term harm may result from anaesthesia, particularly following repeated anaesthetics?” is one of the top 10 research priorities recently listed by the National Institute of Academic Anaesthesia in partnership with the James Lind Alliance.[ii] The elderly are particularly susceptible to POCD. In fact, a significant percentage of elderly patients sustain anesthesia-related dysfunction, and it is more difficult for an aged person to recover from POCD and regain pre-operative mental function levels. According to Zurek et al. (2014), POCD affects “…41% of elderly patients at hospital discharge and 13% of elderly patients at 3 months after surgery. These deficits are associated with poor patient outcomes, including reduced quality of life, loss of independence, and increased mortality.”[iii]

The causes of POCD have not been fully understood. One theory of the mechanism underlying POCD has to do with an inflammatory reaction of the immune system to the invasive trauma of surgery. When this reaction occurs, it may trigger a cascade of biochemical events that compromise the blood-brain barrier, ultimately allowing certain immune system cells to damage the memory center of the brain, the hippocampus. A research team led by Agnieszka Zurek from the University of Toronto adds a new element of information. They believe that the drugs used to induce the coma-like lack of awareness actually activate memory-loss receptors in the brain, and sustain their activity afterward. How long this lasts varies with the amount of time under anesthesia (the longer the time, the more lasting the impairment), the pharmacologic drugs used, and the age and existing cognitive abilities of the patient. They warn that these are potent drugs: “Patients – and even many doctors – think anesthetics don’t have long-term consequences. Our research shows that our fundamental assumption about how these drugs work is wrong.”[iv]

As the Baby Boomers age, the proportion of elderly patients increases in the general population. Growing older brings its own medical issues at the same time that normal activity and functional levels are declining. Some diseases, such as cancer, are directly related to the genetic breakdown of aging cells. As life expectancy has been extended, thanks to better science and lifestyle habits, the incidence of prostate cancer is on the rise. The chances of developing prostate cancer increase from 2.2% in men between 40 and 59 years to 13.7% in men between 60 and 79 years.[v]

At the same time that demographics are shifting, advances in robotic surgeries such as radical prostatectomy (surgical removal of the prostate gland, abbreviated RP) have reduced risk factors (bleeding, long time under anesthesia, long hospital recovery with exposure to bacteria, etc.) that historically contraindicated RP for men over age 70 or with preexisting medical conditions. Older patients were instead offered radiation therapy, which requires no anesthesia, or a minimally invasive treatment such as cryotherapy (freezing) which can be done in less than an hour with a choice of general anesthesia or low spinal numbing. Today, however, robotic surgery is pushing the “age barrier” higher for RP because it is feasible to reduce the surgical risks of performing RP on older prostate cancer patients. However, the fact of technical feasibility does not take the risk of POCD into account.

Although drugs are in development to curtail the action of the brain’s memory-loss receptors, and hopefully regain any anesthesia-related memory deficits, if an operation requires general anesthesia it is wise to explore alternative procedures that take less time than major surgery. Even better, many procedures are now done under what is called monitored anesthesia care (MAC). This means light sedation (oral medication or intravenous infusion) combined with a local nerve block, similar to a dentist administering Novocain. For example, image-guided targeted treatment for prostate cancer such as Focal Laser Ablation (FLA) can be done by giving the patient Valium as a relaxant, and injecting a numbing agent into the periprostatic nerve to block sensation in the prostate area.

As new information about general anesthesia becomes available, and its impact is better understood, it will interface with the trend toward minimal-to-noninvasive procedures. This means patients will spend less procedure time, recover more quickly, and preserve good mental function. It will also reduce medical expenses and healthcare costs. Minimizing the use of anesthesia means everybody wins.

[i] Bedford PD. Adverse cerebral effects of anaesthesia on old people. Lancet. 1955:259–263.

[ii] Boney O, Bell M, Bell N, Conquest A et al. Identifying research priorities in anaesthesia and perioperative care: final report of the joint National Institute of Academic Anaesthesia/James Lind Alliance Research Priority Setting Partnership. BMJ Open. 2015 Dec 16;5(12):e010006. doi: 10.1136/bmjopen-2015-010006.

[iii] Zurek A, Yu J, Wang D-S, Haffey S et al. Sustained increase in ?5GABA_A receptor function impairs memory after anesthesia. J Clin Invest. 2014 Dec;124(12):5437-41.

[iv] Heather Callaghan. “Researchers finally acknowledge link between anesthesia and memory loss.” Activist Post, Nov. 6, 2014. http://www.sott.net/article/288614-Researchers-finally-acknowledge-link-between-anesthesia-and-memory-loss

[v] Stangelberger A, Waldert M, Djavan B. Prostate cancer in elderly men. Rev Urol. 2008 Spring; 10(2): 111–119.