197: The Utility of a Novel Quantitative EEG Device as a Screening Tool In Patients With Mild Traumatic Brain Injury

Abstract

Currently there are no high-quality screening criteria for the need for CT scan in mild traumatic brain injury (mTBI). Recent evidence suggests that the changes from mTBI are too subtle to picked up by conventional imaging techniques and that electrophysiological abnormalities emerge earlier than structural changes. The present study was designed to investigate whether the Brainscope quantitative EEG (qEEG) can be readily adapted to the ED environment and can play a role in the initial triage of mTBI patients. Patients between the ages of 18 and 80, in the ED with mTBI and had a CT scan of the head as part of their planned evaluation, were eligible for enrollment at 8 academic medical centers. Patients were excluded if clinical conditions would not allow placement of the electrodes or if intoxicated, obtunded, known psychiatric disorder or chronic drug or alcohol abuse, chronic seizure history, mental retardation, or who were currently taking CNS active medication, were not eligible for the study. Written informed consent was obtained and all patient records were reviewed with CT scan findings obtained from final reports from neuroradiologists at each institution. The EEG data were collected over 10 minutes using self-adhesive electrodes from frontal electrode sites of the International 10/20 system which included FP1, FP2, AFz1(located just anterior to Fz on the forehead, below the hairline), F7, and F8, referenced to linked ears. A discriminant score (range 0-100) was used as an index of the probability of TBI CT+, where the larger the number, the greater the probability, a cut-off score of > 65, (95% confidence level from pilot study) was utilized to classify the CT+ and CT- patients within the current study. The CT scans of the CT+ group were scored using the Marshall criteria by a blinded investigator blinded to the EEG and all other clinical results. For comparison the New Orleans mTBI score was prospectively recorded. Descriptive statistics were used to evaluate the diagnostic accuracy. 252 patients were enrolled, 86 were CT+. Patient's average age was 48 and GCS was 14.9, with 59% male. CT+ patients tended to be older and have more seizures. Using the discriminate of > 65% the qEEG had a sensitivity of 92.9% a specificity of 54%, PPV of 50.3% and a NPV of 93.8% for predicting CT+. qEEG had a likelihood ratio for + of 2.02. Utilizing the New Orleans scoring as having any of the 7 criteria, the sensitivity was 92.5%, specificity of 38.2%, PPV or 38.2% and NPV of 90.6%. The likelihood ratio for + with New Orleans score was 1.24. In this study, the quantitative EEG had a high negative predictive value and fair positive predictive value in screening for CT+ patients with mTBI in the ED. The Brainscope qEEG had less false positives than the New Orleans criteria.