Bispectral Index Values Are Accurate Diagnostic Indices Correlated With Glasgow Coma Scale Scores.

OBJECTIVE: The Glasgow Coma Scale (GCS) is widely used in neurosurgery to evaluate the depth of coma in patients with brain injury. The bispectral index (BIS) was developed primarily to monitor the depth of unconsciousness. Recent evidence suggests that BIS may also help in the assessment of brain injury. This study explores the correlation between GCS scores and BIS values in patients with brain injury. METHODS: Fifty patients were divided into 2 groups-moderate (GCS 9-12) and severe (GCS 3-8)-in this prospective, double-blind, observational study. Bispectral index data were recorded when electromyography was less than 40 and signal quality index was greater than 75 for 5 minutes. Linear regression was used to examine the correlation between BIS and GCS, and receiver operating characteristic curves were plotted. Cutoff points were identified to show the feasibility and accuracy of BIS for assessing brain injury. RESULTS: The mean BIS value of the moderate group was 65.62 ± 12.84, and that of the severe group was 46.27 ± 17.35. Bispectral index values were significantly correlated with GCS (R = 0.729, P < .01). The regression line and 95% confidence interval were determined; the regression equation was BIS = 5.46*GCS + 12.72. The receiver operating characteristic curve showed high diagnostic accuracy when GCS is less than 9; the area under the curve was 0.8164, and the cutoff point (BIS value) corresponding to the maximum sensitivity (0.91) and specificity (0.63) was 60.2. CONCLUSION: BIS values and GCS scores were significantly correlated in patients with brain injury. As a continuous and objective measurement, BIS is a viable evaluation and monitoring tool for brain injury.