In this issue of JNN, the article by Michelson and colleagues1 is an excellent example of researchers exploring solutions for triaging challenges of patients with traumatic brain injury (TBI) who present to the emergency department (ED) under the influence of drug and/or alcohol (DA). The study shows the potential use of integrating electroencephalogram (EEG)-based biomarkers into the triage process.

Both DA-related ED visits and TBI-related ED visits are on the rise, with 35% and 80% of alcohol-intoxicated patients reported with TBI in the adult population. Studies show that patients with alcohol-related head injuries are twice likely to have abnormal computed tomography (CT) than sober head-injured patients. Presence of DA adds difficulty to both patient assessment and management.

Although a CT scan is the accepted "standard" for TBI workup in the ED, around 91% of these patients are found to be negative. The EEG-based Structural Injury Classifier (SIC) and EEG-only Brain Function Index (BFI) are outputs that indicate the likelihood of a structural or functional injury. In a multisite, prospective, US Food and Drug Administration validation trial, BrainScope One showed to have high accuracy in predicting the likelihood of TBI visible on CT (CT+), with a high negative predictive value, and the BFI showed to scale significantly with functional impairment.

Purpose

The purpose of this study was to retrospectively investigate the influence of intoxication on the accuracy of an EEG-based SIC and BFI.

Methods

Seven hundred one (N = 701) subjects of this retrospective study were a subset selected from a prospective US Food and Drug Administration clinical validation trial. The retrospective study was used to validate a novel EEG-based algorithm for likelihood of TBI. All subjects included had a Glasgow Coma Scale score of 15 at the time of evaluation. The inclusion criteria for the parent study were individuals between the ages of 18 and 85 years presenting within 72 hours of closed-head injury. Exclusion criteria were history of neurological disease or stroke and skull defects that prevented appropriate placement of electrodes.

The DA group had 131 subjects (n = 131). Alcohol presence was defined as a blood alcohol level of 10 mg/dL or greater; drugs that triggered drug subgroup included cocaine, amphetamines, opiates, fentanyl, cannabinoids, tetrahydrocannabinol, and benzodiazepines. On the basis of current standard clinical practice, head CT referrals were given to 127 patients (97%) from the DA group. Using BrainScope One, a handheld device, 5 to 10 minutes of resting EEG was acquired from frontal and frontotemporal electrodes. The artifact-free data, free from any biological and nonbiological contamination, were subjected to quantitative analyses.

Data Analysis

Structural Injury Classifier sensitivity is defined as the ratio of true positives over the total number of CT+ subjects, and specificity is the ratio of true negatives over the total number of CT- subjects. Comparisons between subjects with DA and without DA were performed. Group comparisons were performed using a t test.

Results

The mean (SD) age of the subjects was 43.7 (18.7) years, and 60.6% were male. Documented DA group was 19% (n = 131): 51 subjects with alcohol alone, 56 with drugs alone, and 24 with both drugs and alcohol. Most of the DA group (74%) was men. One hundred forty-six subjects were adjudicated as CT+, with 37% of the DA group and 17% of the no-DA group. The difference between the incidence of CT+ in the 2 groups (DA group and no-DA group) was significant (P < .0001). CT+ findings in those with alcohol only present were approximately 3 times that of those with no DA present. From the DA group, n = 49 were adjudicated to be CT+, and later, n = 82 were adjudicated to be CT- (number of unnecessary scans). The integration of BrainScope One as an aid in triage referral would have resulted in 58 subjects referred for CT scans who were later found to be CT-, which would represent a potential 29.3% fewer unnecessary CT scans compared with clinical site practice.

The sensitivity of the SIC for the full group (N = 701) was 91.8%; and specificity, 52.3%. Although no significant difference in sensitivity of the SIC was found (P = .256), comparing the subgroups with DA and without DA, a significant difference in the specificity was found (P < .001). The subjects with DA had significantly higher prevalence of loss of consciousness and altered mental status than those without. Comparing the asymptomatic controls with DA to those without DA, no significant differences in BFI were found (P = .313)

Implications

The findings suggest that head-injured subjects who test positive for DA are at a high risk of being CT+. The higher prevalence of altered mental status and loss of consciousness among the DA group suggests that such symptoms could be "TBI mimics in the presence of DA and potentially the reason for lower SIC specificity found in that group."

One of the challenges for ED triage nurses in triaging patients with TBI is that many of these patients present with DA influence, which can confound the clinical presentation. This study supports the clinical use of the BrainScope One EEG-based biomarkers in the evaluation of head-injured patients with or without DA, to help in determining the likelihood of patient having sustained a structural brain injury (CT+) and a functional injury when likely CT-. The study also supports the use of such a device in determining which head-injured patients under the influence of DA should have a CT scan.

Reference