Intraoperative EEG power spectrum alterations in patients with malignant brain tumors.

BACKGROUND: Intraoperative electroencephalography (EEG) is increasingly used to guide anesthetic management. However, potential differences in EEG features remain poorly understood in patients with central nervous system pathologies, including brain tumors, leaving a critical knowledge gap regarding how structural brain lesions alter the anesthetic-induced EEG changes. METHODS: In this prospective observational pilot study, EEG data from patients undergoing craniotomies for the removal of malignant brain tumors (n = 21), benign brain tumors (n = 20), and from a control group of non-neurological surgeries (n = 32) were evaluated. The incidence of visually identified burst suppression during induction and maintenance as well as the power spectra from two artifact-free, burst suppression-free EEG episodes at the beginning and end of the maintenance were compared. RESULTS: Both benign and malignant tumor patients did not exhibit a significantly higher incidence of burst suppression during induction or maintenance compared to non-neurological controls. Malignant tumor patients had significantly lower absolute and relative beta band-power than benign tumor and control patients. CONCLUSIONS: The EEG patterns of patients with malignant brain tumors differed significantly from those of patients with benign tumors and non-neurological controls. Further studies are needed to better characterize the EEG alterations and their clinical implications in this vulnerable patient population.