Single-channel electroencephalography of epileptic seizures in the out-of-hospital setting: an observational study.

OBJECTIVES: To evaluate whether single-channel electroencephalography (EEG) recording can be conducted in the out-of-hospital setting and whether it can be used to record electrographic signs of convulsive epileptic seizures. METHODS: This prospective observational feasibility study included patients who presented with a recent or ongoing epileptic seizure during out-of-hospital emergency treatment. Bifrontal single-channel EEG recordings were conducted by ambulance physicians throughout the initial treatment. The data recorded were analysed for the quality of recording and the occurrence of ictal EEG patterns. RESULTS: There were 45 adult patients who had a recent or an ongoing epileptic seizure in the study group and 15 patients with no neurological disorders in the control group. The median percentage of time during which no artefacts were detected by the device was 88.0% in the study group and 96.0% in the control group. EEG recordings for 3 out of 45 (6.6%) patients were of poor quality and not evaluable. Spike/wave or polyspike patterns were found in 98% and 100% of patients in the study and control groups, respectively, whereas the occurrence of periodic epileptiform discharges and delta waves with spikes showed a sensitivity and specificity of 100% (10/10) for the presence of an ongoing epileptic seizure. CONCLUSIONS: Single-channel EEG can be performed outside the hospital and yields useful recordings in most patients with acceptable rates of artefact. The diagnosis of generalised convulsive epileptic seizures by offline analysis of out-of-hospital EEG showed a high sensitivity and specificity when compared with the clinical diagnosis.