Abstracts

Rationale: Pentobarbital is a widely used treatment of refractory status epilepticus. The EEG is continuously monitored during the withdrawal period. The reappearance of seizure patterns on the EEG may prompt the treating physician to resume pentobarbital coma. We previously observed a pattern of periodic sharp EEG discharges in a patient with traumatic brain injury where pentobarbital was used to control increased intracranial pressure. Thus, we explored the presence and significance of periodic sharp EEG discharges during pentobarbital withdrawal in patients treated for increased intracranial pressure. Methods: In addition to our previously observed patient, we identified patients treated with pentobarbital coma for increased intracranial pressure in the last 3 years by searching our EEG database. We reviewed the EEG tracings for periodic discharges during pentobarbital withdrawal. We also reviewed the clinical history, including occurrence of clinical seizures and eventual outcome in all patients. Results: Our previously observed patient was a 10 year old boy who was placed on pentobarbital for increased intracranial pressure after a gunshot wound to the head. Pentobarbital coma was used for 16 days. Withdrawal was delayed because EEG was interpreted as electrographic status epilepticus on three withdrawal attempts prior to successful discontinuation. A total of 20 patients were identified in the last 3 years. Out of 20 patients, eleven died during the monitoring and six others had EEG discontinued early during pentobarbital withdrawal. The EEG patterns at the time of discontinuation for these patients were burst-suppression (with suppression ranging from 8-15 seconds) or complete suppression. Among the remaining three patients, two patients, aged 17 and 20, had a pattern of sharply contoured periodic complexes, typically with a recurrence rate of one every 0.5-2 seconds, which developed during pentobarbital withdrawal. Both patients had closed head injury with duration of pentobarbital coma of 4 days and 3 days respectively. The pattern of periodic sharp complexes was either transient with continued withdrawal or was waxing and waning without evolution. None of the patients had clinical seizures during or after pentobarbital withdrawal. Clinical recovery occurred, though not necessary back to prior neurological baseline. Conclusions: A periodic EEG pattern may occur in association with pentobarbital withdrawal. Our experience is that this is a transient non-ictal pattern that should not be a reason to resume pentobarbital coma. We propose that pentobarbital coma should be resumed only if clinical seizure activity or classical ictal discharges are seen.