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

Abstract

Objective: 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.

Design: Prospective cohort study.

Setting: Unit for severe acquired brain injuries.

Participants: Consecutive patients with UWS (N=28).

Interventions: Not applicable.

Main outcome measures: 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.

Results: 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).

Conclusions: 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.

Keywords: Consciousness disorders; Electroencephalography; Prognosis; Rehabilitation.