The utility of EEG in the emergency department

Seizure-related visits are common in the emergency department (ED) but the clinical situations for ordering emergency electroencephalography (EEG) are unclear. The aim of this study is to identify which clinical conditions meet with the pathological EEG and whether patient management is changed by abnormal results.

A retrospective chart review study of all patients visiting the ED with a seizure or symptoms mimicking a seizure was performed. Patients who recorded an EEG within 16 h after the initial event were enrolled. Demographic data and EEG results of patients with provoked and unprovoked seizures were recorded and related factors were analysed.

A total of 449 patients (219 men) of mean ± SD age of 45.48 ± 21.83 years were evaluated. The seizure was thought to be provoked in 98 patients (21.8%) and unprovoked in 352 (78.2%) patients (31.2% remote symptomatic and 47.4% idiopathic). The EEG results of 281 patients (62.6%) revealed an abnormality, and the abnormal EEG ratio was high in patients with presumed seizure (p<0.001). One hundred and thirty-eight patients (30.7%) were hospitalised and the remainder (n=311, 69.3%) were discharged from the ED. An abnormal EEG was found in 98 (71%) of the hospitalised patients and in 183 (59.5%) of those discharged (p=0.019).

EEG provides useful diagnostic information and should be considered in all patients presenting to the ED with a seizure. Since the timing of the study affects the diagnostic efficacy of the test, EEG recordings might be done within 24 h either in the ED or epilepsy clinic.