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The Issue of Postoperative Cognitive Dysfunction

December 01, 2021

By Amanda Martin-Sanchez, MEd, BSN, RN, CNOR


The Issue of Postoperative Cognitive Dysfunction
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“After spinal surgery, the severe pain in my lower back was gone! The urinary incontinence I had for a while before surgery was almost completely resolved. But there were complications that I had not expected and were not mentioned preoperatively or on the consent. I couldn’t form sentences at first and had absolutely no attention span. I was in rehab for speech and cognitive therapy. It took almost three months to be able to concentrate long enough to read something and process it. My memory is still poor.”

Based on these comments, what do you think happened? A cardiac or coagulation issue? The patient’s medical record did not reflect these as probable causes. If you said a perioperative neurocognitive disorder (PND), a postoperative neurocognitive disorder, or postoperative cognitive dysfunction (POCD), you are correct. 

Cognitive Declines After Surgery

Cognitive declines in patients undergoing surgery and anesthesia were recognized more than 100 years ago. This known complication is underappreciated, and the possibility of its occurrence is often not conveyed to non-cardiac surgery patients in the preoperative process. The patient describing this postoperative experience is a highly educated, retired professional in his 80s. The population most vulnerable to postoperative cognitive changes are elderly patients undergoing prolonged anesthesia and surgery. Projections from the U.S. Census Bureau estimate that by 2030 more than 21% of the U.S. population will be over the age of 65.1 As this segment of the population continues to expand, a significant percentage of this group will undergo surgical procedures making this topic increasingly relevant.

There is research in the surgery and anesthesia realm focusing on POCD, but variability in testing methods and timing for testing has resulted in a lack of clinical application. The POCD research has been done in isolation from similar studies focused on cognitive dysfunction in the general population. There has been little recognition of POCD by the wider medical community, but this is changing.2 

The Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5)—used by psychiatry, neurology, and gerontology—lists distinct clinical features of cognitive decline. Based on the similarities between POCD and the symptoms of cognitive decline described in the DSM-5, an international, multidisciplinary group has recommended a new term—perioperative neurocognitive disorder—“to describe alterations in behavior, affect, and cognition that occasionally occur after anesthesia and surgery.”3 Use of this additional terminology will allow improved communication and integration of research and reviews across different medical specialties.3,4

Perioperative Neurocognitive Disorders (PND)

Cognitive decline identified in the postoperative period is usually self-limiting and generally improves in the first few months after surgery. This was true for the elderly patient reporting his experience at the beginning of this article. However, loss of function, decreased quality of life, higher healthcare costs, and increased mortality are associated with cognitive impairments.5,6

The incidence of cognitive decline after major non-cardiac surgery varies significantly among published studies. Recent studies have reported the incidence of POCD in all age groups to be between 19% and 41% at one week and between 10% and 17% at three months postop.4 In a study looking at adults age 70 and older undergoing major elective surgery, the prevalence of postoperative cognitive dysfunction was 47% at 1 month, 23% at 2 months, 15% at 6 months.7 

Cognitive impairments may be identified throughout the perioperative continuum. Considering the timing of the cognitive decline, experts recommend the following terminology for perioperative neurocognitive disorders:3,8:

  • Existing preoperative cognitive impairment: mild or major neurocognitive disorder (NCD), depending on the severity of symptoms
  • Within 7 days of procedure: postoperative delirium 
  • Up to 30 days after surgery: delayed neurocognitive recovery
  • Up to 12 months postop: mild or major NCD (postoperative)

The specific cause of PND is still unclear, but it is likely a combination of patient and surgery/anesthesia factors. Frequently cited risk factors include advanced age, pre-existing cognitive impairment, type of surgical procedure, frailty, psychotropic medications and comorbidities. The body’s inflammatory response to the surgical procedure is thought to play an important role in its development.4 

Currently, there are no prevention measures or specific treatments for PND. But looking to the most prevalent risk factor—advanced patient age—numerous medical professional societies are recommending strategies to address the healthcare needs of the elderly population. In the perioperative arena, the American College of Surgeons and the American Society of Anesthesiologists have been busy advancing changes to improve outcomes in elderly surgical patients.

  • 2012: American College of Surgeons with the American Geriatrics Society published Optimal Perioperative Assessment of the Geriatric Surgical Patient: A Best Practices Guideline.9
  • 2015: American Society of Anesthesiologists proposed the Perioperative Brain Health Initiative “to create a low-barrier access program to minimize the impact of pre-existing cognitive deficits and optimize the cognitive recovery and perioperative experience for adults 65 years and older undergoing surgery.”10 
  • 2019: the American College of Surgeons published standards for their Geriatric Surgery Verification Program, Optimal Resources for Geriatric Surgery, to improve surgical care and outcomes for elderly patients.11 The standards include preoperative screenings to identify modifiable vulnerabilities that influence surgical outcomes and decision-making. Impaired cognition, delirium risk, and impaired functional status are included in the eight high-risk characteristics for screening in this population. 

Risk Mitigation Strategies

Postoperative cognitive decline, especially in elderly patients, is an under-recognized complication. The potential for postoperative cognitive decline needs to be addressed in the wider medical community and with surgical patients. Here are a few strategies to bring more awareness to this issue:

  1. Provide counseling preoperatively so that cognitively demanding tasks can be accomplished before surgery and postoperative assistance arranged.6
  2. Include the possibility of neurocognitive dysfunction on surgical/anesthesia consents.8
  3. Consider performing a preoperative assessment of cognitive function as recommended by the American College of Surgeons National Surgical Quality Improvement Program and American Geriatrics Society best practice guideline for the geriatric surgical patient.9 

References

  1. U.S. Census Bureau.  2017 National Population Projections Tables: Main Series. 2017. https://www.census.gov/data/tables/2017/demo/popproj/2017-summary-tables.html.
  2. Evered LA, Silbert BS. Postoperative cognitive dysfunction and noncardiac surgery. Anesthesia and Analgesia. 2018;127(2):496-505.
  3. Evered L, Silbert B, Knopman DS, Scott DA, et al. Recommendations for the nomenclature of cognitive change associated with anaesthesia and surgery—2018. British Journal of Anaesthesia. 2018;121(5):1005-1012.
  4. Mahanna-Gabrielli E, Eckenhoff RG. Perioperative neurocognitive disorders. UpToDate. Updated April 15, 2021.
  5. Vacas S, Cole DJ, Cannesson, M. Cognitive decline associated with anesthesia and surgery in older patients. JAMA. Published online August 2, 2021.
  6. Green CM, Schaffer SD. Postoperative cognitive dysfunction in noncardiac surgery: a review. Trends in Anaesthesia and Critical Care 24. 2019;40-48.
  7. Daiello LA, Racine AM, Gou RY, Marcantonio ER, et al. Postoperative delirium and postoperative cognitive dysfunction: overlap and divergence. Anesthesiology. 2019;131:477-491.
  8. Evered L, Culley DJ, Eckenhoff RG. Cognitive dysfunction and other long-term complications of surgery and anesthesia. In Miller’s Anesthesia, 9th Edition. 2020. Elsevier: Philadelphia. [Chaper 82]
  9. Chow WB, Rosenthal RA, Merkow RP, Ko CY, Esnola NF, American College of Surgeons National Surgical Quality Improvement Program; American Geriatrics Society. Optimal preoperative assessment of the geriatric surgical patient: a best practices guideline from the American College of Surgeons National Surgical Quality Improvement Program and the American Geriatrics Society. J Am Coll Surg. 2012;215(4):453-466.
  10. What is the Perioperative Brain Health Initiative? American Society of Anesthesiologists website. https://www.asahq.org/brainhealthinitiative/about.
  11. American College of Surgeons. Optimal resources for geriatric surgery: 2019 standards. htts://www.facs.org/quality-programs/geriatric-surgery.


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