Predicting Postoperative Delirium Using Intraoperative Neuromonitoring in Patients Undergoing Craniotomy for Aneurysm Clipping Surgery.

Introduction: Postoperative delirium (POD) that is associated with intracranial surgeries can have several adverse outcomes, including a high rate of morbidity and mortality. The use of intraoperative neurophysiological monitoring (IONM) via somatosensory evoked potentials (SSEP) and electroencephalography (EEG) provides continuous information regarding cerebral blood flow (CBF) during aneurysm clipping. In this study, we hypothesize that CBF changes during aneurysm clipping increase the risk of POD. We aimed to demonstrate that significant changes in IONM data during surgery increase the risk of POD after adjusting for clinical and intraoperative factors.

Methods: 470 patients undergoing craniotomy for aneurysm clipping surgery with IONM were retrospectively reviewed for the development of POD. Significant IONM changes were evaluated based on a visual review of EEG and SSEP data and documentation of significant changes during surgery. Data changes during IONM were classified as SSEP changes, EEG changes, or IONM changes (SSEP and/or EEG changes).

Results: Of the 470 patients who underwent aneurysm clipping, 115 (24.5%) had POD and 35 (30.4%) had IONM changes. IONM and SSEP changes were significantly associated with POD (p < 0.001). After adjusting for confounding variables, IONM and SSEP changes were significantly associated with POD (adjusted odds ratio (aOR) 2.4 [CI: 1.40-4.17]; p = 0.002) and (aOR 2.49 [CI: 1.39-4.45]; p = 0.002), respectively. We also found that the odds of POD were higher in patients with ruptured aneurysms and in patients who developed focal neurological deficits postoperatively (aOR 2.76, 1.72-4.42; p < 0.001) and (aOR 2.11, 1.02-4.36, p = 0.04), respectively.

Conclusion: Patients who develop POD after craniotomy for aneurysm clipping surgery are twice as likely to have experienced significant IONM or SSEP changes during the surgery. Patients with ruptured aneurysms and who develop postoperative focal neurological deficits are also more than twice as likely to develop POD. These findings provide a strong platform for future research in testing therapeutic interventions based on IONM changes, which aim to decrease the risk of POD after aneurysm clipping surgeries.