2. EEG predictors of outcome in patients with disorders of consciousness

Abstract

Although standard EEG is performed routinely in patients with severe disorders of consciousness, little is known about the prognostic value of its classical descriptors (i.e., amplitude, frequency, and reactivity). This study examined the prognostic value of EEG in patients with severe disorders of consciousness, and generated a novel clinical scoring system to utilize its descriptors prognostically. EEGs recorded at admission in 106 patients were analyzed retrospectively. EEG amplitude, frequency, and reactivity to stimuli were correlated to patient outcomes according to the Coma Recovery Scale Revised (CRS-R) at 3 months after admission. Data were integrated to generate a novel Amplitude–Frequency–Reactivity (AFR) scale. Patients with reduced amplitudes showed less improvement at 3 months compared to patients with normal amplitudes. Alpha, theta, and delta frequencies were associated with the greatest, intermediate, and the least improvement, respectively. Patients with EEG reactivity showed greater improvement. The AFR scores for these patients were also significantly correlated with outcomes. Reduced EEG amplitudes and delta frequencies correlated with poor clinical outcomes, while alpha frequencies and reactivity correlated with positive outcomes. AFR scores of 3 and 4 were predictive of poor outcomes, while scores of 6 and 7 were predictive of positive outcomes.