Scientists and clinicians from ten countries attended the International Workshop on Perioperative Neurotoxicity in the Elderly this past May in Stockholm, Sweden. In this month’s issue of Anesthesia & Analgesia, Dr. Roderic G. Eckenhoff, Department of Anesthesiology & Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, and colleagues review the workshop proceedings in their article titled “Perioperative Neurotoxicity in the Elderly: Summary of the 4th International Workshop.”
A lack of consensus about diagnostic criteria for postoperative cognitive dysfunction makes it difficult to compare studies and draw conclusions. Attendees proposed the creation of a consensus panel to draft comprehensive nomenclature to allow comparisons among studies. While epidemiologic databases being used point to a link between anesthesia, surgery and postoperative cognitive dysfunction, prospective data needs to be collected that has specific points that are quantitated.
It is possible that undiagnosed preoperative cognitive dysfunction may be noticed postoperatively, skewing results. To address this a cognitive assay tool has been developed to detect a difference in cognition before and after surgery.
Using cytokines, calcium dysregulation, tauopathy, and amyloidopathy as markers, researchers are finding an association between surgery, anesthesia, and cognitive dysfunction. Human biomarkers are being sought to provide quantitative measures of injury and pathology. Amyloid beta and tau proteins, markers in cerebrospinal fluid for Alzheimer’s disease, are the primary biomarkers being studied. Investigators are also using brain imaging with functional MRI and PET to quantitate disease. Carriers of genes that predispose patients to Alzheimer’s disease genes show increased association between surgery and early dementia. However, this requires further study.
Current preclinical research involves studying inflammation as a possible cause of postoperative cognitive decline. Clinical studies have pointed to an association between postoperative cognitive dysfunction, and increased levels of CSF IL-6 as well as several cytokines. Although inflammation has been associated with POCDS, use of steroids has not proven useful for prevention. Some investigators have hypothesized that there would be a difference in incidence of POCDS in patients who received TIVA with propofol vs. inhalational anesthetics. However, this has not been found in prospective studies.
Because of the preliminary nature of data and no cohesive findings, no recommendations were made by attendees as to the type of anesthesia to use, or drugs to avoid. Attendees discussed the need to talk about postoperative cognitive decline with at-risk patients as part of informed consent. The workshop closed with a call for more research as more questions than answers remain.
This is an engaging summary of what must have been a spectacular meeting.