Continuous EEG monitoring in patients with traumatic brain injury reveals a high incidence of epileptiform activity

Background - EEG is the only available method for real time monitoring of the brain and is therefore of great interest in the neurointensive care. The present study describes our experiences from implying continuous EEG monitoring as a routine method. We also present EEG patterns observed on patients with traumatic brain injury (TBI). Methods - Seventy TBI patients requiring neurointensive care were included. Digital EEG was recorded continuously. Five minutes every hour were analysed off-line. Results - Twenty-three patients (33%) developed seizures, 74 +/- 47 h after trauma. The seizures were brief, responding to phenytoin, or persistent, requiring propofol or barbiturate sedation. Six out of eight patients with persistent seizures had intracerebral contusions. Eighteen patients (26%) displayed focal high frequency activity that proceeded to seizures in eight cases. Twelve patients (17%) developed recurrent paroxysmal delta activity. The patients in the seizure group were significantly older (62 +/- 12 vs. 28 +/- 17 years) and more often exposed to low energy trauma (87% vs 22%) compared to the paroxysmal delta pattern group. Conclusion - TBI implies high risk for development of epileptiform activity, with a time lag between trauma and seizure onset. TBI patients also displayed other EEG pattern that should be investigated further in order to obtain a better understanding of posttraumatic mechanisms.