Electroencephalography and Bispectral Index Reactivity to Predict Outcome in Unconscious Patients with Acute Severe Traumatic Brain Injury: A Prospective Observational Study

Background and aims: This observational study aimed to assess electroencephalographic reactivity (EEG-R) and bispectral index reactivity (BIS-R) as early prognostic indicators and to evaluate their association with functional outcomes in patients with acute severe traumatic brain injury (sTBI). Patients and methods: Patients aged over 18 years with a Glasgow Coma Scale Score ≤8 were enrolled between days 3 and 5 postinjury. Baseline pan cranial electroencephalography (EEG) and BIS (from the hemisphere contralateral to injury) were recorded, followed by two painful and two auditory stimuli on each side at two-minute intervals. Electroencephalographic reactivity was independently rated as present or absent by three assessors. Bispectral index reactivity was defined as a change of ten or more points from baseline within 20 seconds of stimulation. Functional outcome was assessed at 3 and 6 months using the Glasgow Outcome Scale Extended (GOSE). Results: = 0.016). Absence of EEG-R demonstrated specificity and positive predictive value of 100% for non-recovery of consciousness at 3 months. Bispectral index reactivity was observed in 21 patients (52.5%) and absent in 19 (47.5%). Bispectral index reactivity did not show a significant association with functional outcomes and demonstrated poor concordance with EEG-R. Conclusion: The absence of EEG-R in the acute phase of sTBI was a strong predictor of poor clinical outcome. Bispectral index reactivity showed limited prognostic value in this study. How to cite this article: Sakrikar G, Surve RM, Venkatapura R, Chakrabarti D, Mundlamuri R, Shukla D. Electroencephalography and Bispectral Index Reactivity to Predict Outcome in Unconscious Patients with Acute Severe Traumatic Brain Injury: A Prospective Observational Study. Indian J Crit Care Med 2026;30(4):275-281.