Postoperative cognitive function as an outcome of regional anesthesia and analgesia

Background and Objectives: It has been suggested that intraoperative neuraxial (spinal, epidural) anesthesia may decrease postoperative cognitive dysfunction when compared with general anesthesia, but the issue remains controversial. We systematically reviewed the data from published studies to determine the effect of intraoperative neuraxial anesthesia versus general anesthesia on postoperative cognitive dysfunction and delirium. Methods: Studies were identified by searching the PubMed database of the National Library of Medicine (1966 to 2003) for terms related to cognitive dysfunction after surgery. Inclusion criteria were a comparison of intraoperative neuraxial anesthesia versus general anesthesia, and the outcome of postoperative cognitive dysfunction. A total of 196 abstracts were identified, and 24 articles were analyzed. Each article was reviewed, and data were extracted from tables or text or extrapolated from figures as needed. Results: Of the 24 trials obtained, 19 were randomized and 4 were observational (nonrandomized) trials (1 trial was a combination of randomized and observational data). The age of patients studied was typically greater than 60 years, and a wide range of neuropsychometric tests were used to evaluate cognitive function. The majority of trials (23/24 of all trials and 18/19 of randomized trials) did not demonstrate a benefit from neuraxial anesthesia in decreasing the incidence of postoperative cognitive dysfunction. Conclusions: The use of intraoperative neuraxial anesthesia does not appear to decrease the incidence of postoperative cognitive dysfunction when compared with general anesthesia. There are methodologic and study-design issues present in many studies, and further elucidation of the pathophysiology of postoperative cognitive dysfunction may provide a direction for future studies.