Cardiac Surgery is Associated with Biomarker Evidence of Neuronal Damage

Background: Anesthesia and surgery is commonly associated with central nervous system sequelae and cognitive symptoms, which may be caused by neuronal injury. Neuronal injury can be monitored by plasma concentrations of the neuronal biomarkers tau and neurofilament light protein (NFL). Currently, there are no studies examining whether neuronal injury varies between surgical procedures. Objective: Our aim was to investigate if neuronal damage is more frequent after cardiac than after otolaryngeal surgery, as estimated by tau and NFL concentrations in plasma. Methods: Blood samples were drawn before, during, and after surgery and concentrations of tau, NFL, A beta(40), and A beta(42) were measured in 25 patients undergoing cardiac surgery (9 off-pump and 16 on-pump) and 26 patients undergoing otolaryngeal surgery. Results: Tau increased during surgery (1752%, p =0 .0001) and NFL rose seven days post-surgery (1090%, p <0.0001) in patients undergoing cardiac surgery; even more in patients on-pump than off-pump. No changes were observed in patients undergoing otolaryngeal surgery and only minor fluctuations were observed for A beta(40) and A beta(42). Conclusion: Cardiac surgery is associated with neuronal injury, which is aggravated by extracorporeal circulation. Analyses of NFL and tau in blood may guide development of surgical procedures to minimize neuronal damage, and may also be used in longitudinal clinical studies to assess the relationship of surgery with future neurocognitive impairment or dementia.