Diagnostic and prognostic use of bispectral index in coma, vegetative state and related disorders.
OBJECTIVE
This study investigates (1) the utility of the bispectral index (BIS) to distinguish levels of consciousness in severely brain damaged patients and, particularly, disentangle vegetative state (VS) from minimally conscious state (MCS), as compared to other EEG parameters; (2) the prognostic value of BIS with regards to recovery after 1 year.


METHODS
Multi-centric prospective study.


METHODS
Unsedated patients recovering from coma were followed until death or transferal. Automated electrophysiological and standardized behavioural assessments were carried out twice a week. EEG recordings were categorized according to level of consciousness (coma, VS, MCS and Exit MCS). Outcome was assessed at 1 year post-insult.


RESULTS
One hundred and fifty-six EEG epochs obtained in 43 patients were included in the analyses. BIS showed a higher correlation with behavioural scales as compared to other EEG parameters. Moreover, BIS values differentiated levels of consciousness and distinguished VS from MCS while other EEG parameters did not. Finally, higher BIS values were found in patients who recovered at 1 year post-insult as compared to patients who did not recover.


CONCLUSIONS
EEG-BIS recording is an interesting additional method to help in the diagnosis as well as in the prognosis of severely brain injured patients recovering from coma.
Schnakers
C
C
Coma Science Group, Cyclotron Research Centre, University of Liège, Belgium. c.schnakers@student.ulg.ac.be
Ledoux
D
D
Majerus
S
S
Damas
P
P
Damas
F
F
Lambermont
B
B
Lamy
M
M
Boly
M
M
Vanhaudenhuyse
A
A
Moonen
G
G
Laureys
S
S
D001930:Brain Injuries / Q000175:diagnosis* / Q000534:rehabilitation; D020207:Coma, Post-Head Injury / Q000175:diagnosis* / Q000503:physiopathology; D003243:Consciousness / Q000502:physiology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000503:physiopathology; D011379:Prognosis; D011446:Prospective Studies; D012720:Severity of Illness Index