Association Between Changes in Cerebral Gray Matter Volume and Postoperative Cognitive Dysfunction in Elderly Patients Following Sevoflurane Anesthesia (POCD-MRI)

Background:

Anesthesia care for elective surgery of patients that are in their seventies or eighties is an ever-growing entity in clinical practice, given the demographic development in many countries of the Western world. Cognitive decline of variable degree is frequently observed after major surgery in elderly patients. A potential association between anesthesia and the development of dementia and brain atrophy in elderly patients is controversial. However, it is not uncommon that during preoperative visits by the anesthesiologist, patients express fear to suffer some sort of cognitive decline after the operation, and raise concerns about psychological or neurological long-term adverse effects (e.g. memory loss) related to anesthesia. Clinicians have identified this problem decades ago, and are adding postoperative cognitive dysfunction (POCD) to the list of frequent complications of anesthesia in elderly patients; yet, there is a lack of prospective clinical data and poor understanding of the pathophysiology of POCD, and no preventive strategy or treatment has been described so far.

One study reported an incidence of postoperative cognitive dysfunction (POCD) of 41% in surgical patients 60 years of age, or older. In a previous study conducted by our group, as many as 47% of patients over 65 years presented with POCD one week after surgery. In many patients, this is a transient problem, but some patients retain permanent deficits, with increased mortality and important consequences on the socioeconomic situation. An association between surgery and long-term cognitive decline has not been established yet; however, patients who develop postoperative delirium (a transient, but particularly severe form of POCD) have an increased risk of developing dementia in the years following surgery. However, in a cohort follow-up study, the diagnosis of POCD itself did not represent a significant risk factor for dementia. The pathophysiology of postoperative cognitive decline remains unclear. However, studies in animals have shown that the systemic inflammatory response elicited by the surgical procedure is associated with microglial activation and postoperative cognitive impairment. Furthermore, volatile anesthetics have been shown to be neurotoxic in cell cultures, and in some animal experiments exposure to clinical concentrations of volatile anesthetics was associated with postoperative cognitive decline. A recent retrospective analysis of cohort data suggests that surgery may be associated with a decrease in brain volume in patients. However, due to methodological limitations in this study, no analysis of a potential link between atrophy and cognitive functions was made.

Study Design:

Prospective cohort study