Early and persistent impaired percent alpha variability on continuous electroencephalography monitoring as predictive of poor outcome after traumatic brain injury.
OBJECTIVE
Early prediction of outcomes in patients after they suffer traumatic brain injury (TBI) is often nonspecific and based on initial imaging and clinical findings alone, without direct physiological testing. Improved outcome prediction is desirable for ethical, social, and financial reasons. The goal of this study was to determine the usefulness of continuous electroencephalography (EEG) monitoring in determining prognosis early after TBI, while the patient is in the intensive care unit.


METHODS
The authors hypothesized that the reduced percentage of alpha variability (PAV) in continuous EEG tracings indicates a poor prognosis. Prospective continuous EEG monitoring was performed in 89 consecutive patients with moderate to severe TBI (Glasgow Coma Scale [GCS] Scores 3-12) from 0 to 10 days after injury. The PAV was calculated daily, and the time course and trends of the PAV were analyzed in comparison with the patient's Glasgow Outcome Scale (GOS) score at the time of discharge. In patients with GCS scores of 8 or lower, a PAV value of 0.1 or lower is highly predictive of a poor outcome or death (positive predictive value 86%). The determinant PAV value was obtained by Day 3 after injury. Persistent PAV values of 0.1 or lower over several days or worsening of the PAV to a value of 0.1 or lower indicated a high likelihood of poor outcome (GOS Scores 1 and 2). In comparison with the combination of traditional initial clinical indicators of outcome (GCS score, pupillary response to light, patient age, results of computerized tomography scanning, and early hypotension or hypoxemia), the early PAV value during the initial 3 days after injury independently improved prognostic ability (p < 0.01).


CONCLUSIONS
Continuous EEG monitoring performed with particular attention paid to the PAV is a sensitive and specific method of prognosis that can indicate outcomes in patients with moderate to severe TBI within 3 days postinjury.
Department of Neurology, School of Medicine, University of California at Los Angeles, 90095, USA. Pvespa@mednet.ucla.edu
Paul M
PM
Vespa
W John
WJ
Boscardin
David A
DA
Hovda
David L
DL
McArthur
Marc R
MR
Nuwer
Neil A
NA
Martin
Valeriy
V
Nenov
Thomas C
TC
Glenn
Marvin
M
Bergsneider
Daniel F
DF
Kelly
Donald P
DP
Becker
D000328:Adult; D000513:Alpha Rhythm; D001930:Brain Injuries / Q000175:diagnosis* / Q000601:surgery*; D003422:Critical Care / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011183:Postoperative Complications / Q000175:diagnosis; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D016896:Treatment Outcome