A case report of several intraoperative convulsions while using the Narcotrend monitor: Significance and predictive use

INTRODUCTION: Intraoperative seizures under general anesthesia are rare and our observation is the first to demonstrate a distinct electroencephalogram (EEG) pattern on the Narcotrend monitor. PATIENT CONCERNS: We present the case of a 30-year-old man undergoing craniotomy for glioblastoma resection under general anesthesia who suffered tonic-clonic seizures captured in a specific pattern by the intraoperative EEG. DIAGNOSES: Our depth of anesthesia monitor recorded, before the seizure, a widening of the beta-wave performance in a distinct “triangular-shaped” pattern. This pattern was repeated before the second seizure. The patient had no previous history of seizures and following surgery no further seizures were recorded. INTERVENTIONS: A spectrogram analysis showed a distinct increase in mean absolute beta power immediately prior to the first seizure. The EEG immediately prior to the second seizure was characterized by broadband noise. Both seizures were characterized by increased mean absolute delta, theta, and beta power. OUTCOMES: The increase in EEG beta activity seen before the tonic-clonic movements may represent cortical irritability secondary to surgical manipulation, induced by electrical stimulation, reflecting progressive brain over-arousal. The attentive analysis of the relative beta power may have helped forecast the occurrence of the second seizure. LESSONS: We report the use of a simple, inexpensive, and portable EEG-based monitoring device to assist seizure detection and decision making.