Intraoperative neuromonitoring is associated with a lower incidence of delirium, possibly by reducing extreme low BIS values. Therefore, in high-risk surgical patients, this may give the anaesthesiologist a possibility to influence one precipitating factor in the complex genesis of delirium. Clinical trial registration ISRCTN Register: 36437985. http://www.controlled-trials.com/ISRCTN36437985/.

Timing-dependent LTP (t-LTP) is a physiologically relevant type of synaptic plasticity that results from repeated sequential firing of action potentials (APs) in pre- and postsynaptic neurons. t-LTP can be observed in vivo and is proposed to be a cellular correlate of memory formation. While brain-derived neurotrophic factor (BDNF) is essential to high-frequency stimulation-induced LTP in many brain areas, the role of BDNF in t-LTP is largely unknown. Here, we demonstrate a striking change in the expression mechanism of t-LTP in CA1 of the hippocampus following two distinct modes of synaptic activation. Single postsynaptic APs paired with presynaptic stimulation activated a BDNF-independent canonical t-LTP. In contrast, a theta burst of postsynaptic APs preceded by presynaptic stimulation elicited BDNF-dependent postsynaptic t-LTP that relied on postsynaptic BDNF secretion. This suggests that BDNF release during burst-like patterns of activity typically observed in vivo may play a crucial role during memory formation.

All scores used were very specific, but the CAM and the DDS were less sensitive compared with the gold standard. Overall, the Nu-DESC was the most sensitive test in the recovery room to detect delirium.

Duration of preoperative fluid fasting and the choice of intraoperative analgesic are risk factors for postoperative delirium, and their modification provides a promising approach to reduce the incidence of postoperative delirium.

All scores showed high specificity but differed in their sensitivity. The Nu-DESC proved to be the most sensitive test for screening for a postoperative delirium on the surgical ward followed by the CAM and DDS when compared to the gold standard.