Purpose: Postoperative cognitive dysfunction (POCD) is a formidable public health issue, which would not only affect the quality of life among elderly patients but also lead to pulmonary infection and increased mortality. While, there is a lack of an effective indicator in predicting POCD. As one pivotal part of the limbic system in brain, hippocampus is associated with cognitive function. Hippocampal atrophy could indicate the degree of changes in cognitive function.
Methods: Forty-one ASA II or III patients (23 male, 18 female) aged ≥65 years undergoing open gastrointestinal tract surgery were enrolled in this study. MRI was performed to measure the volume of hippocampal formation before surgery and the results were standardized according to individual intracranial volume. All patients underwent a battery of neuropsychological tests including sensitive tests on the Wechsler adult memory scale and Wechsler adult intelligence scale, trail making test and the grooved pegboard test. We used the Z score to identify POCD as recommended by ISPOCD. All patients were then divided into POCD group and non-POCD group according to the results of the neuropsychological tests. The results of the tests were correlated with the volume of hippocampal formation measured by MRI. The value of MRI measurement of hippocampal volume in predicting POCD was analyzed. Multivariate linear correlation analyses of compositive Z score using potential contributing factors such as age, duration of anesthesia, education and hippocampal volume was carried out.
Results: Thirty-six patients completed the whole battery of neuropsychological tests after surgery. Thirteen of the 36 patients were found to have POCD (36 %) on the postoperative 4th day. The hippocampal volume was significantly smaller in POCD group (4.75 ± 0.23) than in non-POCD group (5.06 ± 0.31). Hippocampal volume had great influence on Z score, and had negative correlation with Z score.
Conclusion: The MRI measurement of hippocampal volume is suggested to be valuable as a predictor of POCD in the elderly.