Intraoperative neurophysiological monitoring improves postoperative neuropsychological performance in adult cardiac surgery patients

Introduction: Adverse cognitive outcomes after cardiac surgery are the results of multifactorial intraoperative factors (i.e., cerebral hypoperfusion or embolization) mostly related to cardiopulmonary bypass. Neurophysiological Monitoring (NM) can intraoperatively detect the potential ischemic injury and contribute to reduce cognitive decline after cardiac surgery. Objective: To investigate the effectiveness of intraoperative NM in reducing postoperative cognitive decline as a consequence of brain ischemia in patients undergoing cardiac surgery. Methods: We retrospectively selected 32 patients underwent intraoperative NM and 32 without NM matched for preoperative level of education and risk-stratification score. Both groups were administered a neuropsychological assessment before and after cardiac surgery to evaluate attention, memory and language. It included the Trail Making Test A and B (TMT A/B), Memory with Interference 10 and 30 seconds, Phonemic Fluency and Digit Span Test. Statistical analyses were performed using the exact Mann-Whitney U Test. Results: Both groups did not differ in age (p = 0.46), years of education (p = 0.34) and risk-stratification score (p = 0.84). Moreover, no significant differences were observed in preoperative scores of TMT A (p = 0.07), TMT B (p = 0.07), Memory with Interference 10 (p = 0.75) and 30 sec (p = 0.83), Phonemic Fluency (p = 0.32) and Digit Span Test (p = 0.19). NM group postoperatively exhibited a significant better performance in TMT B (p< 0.03) and Digit Span Test (p < 0.05) compared to group without NM. No significant differences were obtained in postoperative scores of TMT A (p = 0.08), Memory with Interference 10 (p = 0.68) and 30 sec (p = 0.34) and Phonemic Fluency (p = 0.15). Conclusion: Intraoperative neurophysiological monitoring enables early detection of events associated with brain ischemic damage; it might also represents an useful procedure in order to reduce postoperative cognitive decline and to improve functional outcome of patients.