Changes in Standard Electroencephalograms Parallel Consciousness Improvements in Patients With Unresponsive Wakefulness Syndrome.

Abstract

To identify changes in the standard electroencephalograms (EEGs) of patients with unresponsive wakefulness syndrome (UWS) who did or did not recover consciousness 6 months after admission to a rehabilitation department. Prospective cohort study. Unit for severe acquired brain injuries. Consecutive patients with UWS (N=28). Not applicable. EEG amplitude (reduced or normal), dominant frequency (alpha, theta, or delta), and reactivity (absent or present) were scored at admission and 6 months later. The cumulative Amplitude-Frequency-Reactivity score was evaluated. Clinical assessments were made using the Coma Recovery Scale-Revised. Sixteen (57.1%) of the 28 patients with UWS recovered consciousness after 6 months, while 12 patients (42.9%) did not recover consciousness. EEG improvements occurred in 14 patients with consciousness recovery (87.5%) and 2 patients without consciousness recovery (16.7%) only. Improvements in EEG dominant frequency (from the theta to the alpha band or from the delta to the theta band), reappearance of EEG reactivity, and Amplitude-Frequency-Reactivity score increase (P<.01) differentiated patients with consciousness improvement from those without consciousness improvement. Six months after admission for rehabilitation, patients with EEG improvements showed higher Coma Recovery Scale-Revised scores than did those without EEG changes (P<.01). Most patients who emerge from UWS demonstrate improvement in basic EEG characteristics over time. EEG changes in patients with UWS may aid in the timely recognition of patients transitioning into a minimally conscious state.