Forehead EEG electrode set versus full-head scalp EEG in 100 patients with altered mental state.

Abstract

Acute EEG is vastly underutilized in acute neurological settings. The most common reason for this is simply the fact that acute EEG is not available when needed or getting EEG is delayed as it requires trained technicians and equipment to be properly recorded. We have recently described a handy disposable forehead EEG electrode set that is suitable for acute emergency EEG recordings. The specific objective in this study was to assess the forehead electrode's utility when the clinical demand was to exclude SE. One hundred consecutive acute neurological patients (53 women, 47 men, age: 18-90 years) with unexplained altered mental state were studied with acute emergency EEG to rule out SE. Electroencephalographic recordings were obtained simultaneously with forehead EEG electrode and routine 10-20 system full-head scalp electrodes to clarify the clinical usefulness of forehead EEG electrode in this setting. Electroencephalographic recordings were interpreted blindly by three experienced clinical neurophysiologists first only based on forehead EEG and then by full-head EEG. Ninety-six out of the 100 patients did not show EEG evidence of SE. There was 100% agreement with forehead and routine EEG. Four out of the 100 patients showed EEG evidence of SE in routine EEG, with 50% agreement between different electrode types. The forehead EEG missed two cases because the EEG findings supporting SE were restricted to the posterior parts of the brain. With a forehead EEG set, the sensitivity of detecting NCSE was 50%. There were no false positive cases yielding a specificity of 100%. Patients with AMS can benefit from forehead EEG recording in prehospital, hospital, and ICU settings. Since EEG recording can be started within a few minutes with the forehead EEG set, it will significantly reduce the delay in treatment of SE. This article is part of a Special Issue entitled "Status Epilepticus".