Visual Fixation in the ICU: A Strong Predictor of Long-Term Recovery After Moderate-to-Severe Traumatic Brain Injury*

Behavioral signs of recovery from unresponsive wakefulness syndrome to emergence of minimally conscious state after severe brain injury

BACKGROUND

A precise description of behavioral signs denoting transition from an unresponsive wakefulness syndrome/vegetative state (UWS/VS) to minimally conscious state (MCS) or emergence from MCS after severe brain injury is crucial for prognostic purposes. A few studies have attempted this goal but involved non-standardized instruments, limited temporal accuracy or samples or focused on patients with (sub)acute condition.

OBJECTIVES

We aimed to describe the behavioral signs that led to a change in diagnosis as well as the factors affecting this transition in a large sample of patients with chronic disorders of consciousness after severe brain injury.

METHODS

In this retrospective cohort study, patients in UWS/VS or MCS were assessed with the Coma Recovery Scale Revised (CRS-R) at 5 times within the 2 weeks after their admission to a neurorehabilitation center and then weekly until emergence from MCS, discharge or death.

RESULTS

Of the 185 patients included, 33 in UWS/VS and 45 in MCS transitioned to another state. Transition to MCS was mostly denoted by one behavioral sign (71%), predominantly visual fixation, followed by localization to noxious stimulation, and visual pursuit, and could be predicted by etiology, time post-injury and age. Emergence from MCS was characterized by one sign in 64% of patients and by 2 signs (functional communication and objects use) in the remaining patients and could be predicted by time post-injury and number of behavioral signs at admission.

CONCLUSIONS

Transition from UWS to MCS was predominantly signalled by visual fixation and could be predicted by etiology, time post-injury and age. Emergence from MCS was mostly signalled by one sign and could be predicted by time post-injury and number of behavioral signs at admission. Clinicians should pay particular attention to visual and motor subscales of the CRS-R to detect behavioral recovery after severe brain injury. Database registration. ClinicalTrials.gov: NCT04687397.

Fixation stability as a biomarker for differentiating mild traumatic brain injury from age matched controls in pediatrics

OBJECTIVES

Traumatic brain injury (TBI) is an increasingly significant health concern worldwide, compounded by the difficultly in detection and diagnosis. Fortunately, a growing body of research has identified oculomotor behavior, specifically fixations, saccades and smooth pursuit eye movements as a promising endophenotype for neurotrauma. To date, limited research exists using fixation stability in a comparative study to indicate the presence of a mild TBI (mTBI), especially in the pediatric population.

METHODS

The present study examined data from 91 individuals clinically diagnosed with mTBI and a further 140 age- and gender-matched controls. They all completed the RightEye fixation stability test using a remote eye tracker. Participants were compared on five fixation metrics: Bivariate Contour Ellipse Area (BCEA), Convergence Point, Depth, Disassociated Phoria, and Targeting Displacement.

RESULTS

Results were analyzed using one-way univariate ANOVAs, ROC analysis, and stepwise logistic regression. BCEA results revealed significant differences between groups with the mTBI group showing a larger gaze spread, indicative of less ability to keep the eyes close to the target without deviating.

CONCLUSIONS

Fixation stability is detrimentally impacted by mTBI in pediatric patients, and the oculomotor test can be used to differentiate between those with and without an mTBI.

Oculomotor Behavior as a Biomarker for Differentiating Pediatric Patients With Mild Traumatic Brain Injury and Age Matched Controls

IMPORTANCE

Children have the highest incidence of mild traumatic brain injury (mTBI) in the United States. However, mTBI, specifically pediatric patients with mTBI, are notoriously difficult to detect, and with a reliance on traditional, subjective measurements of eye movements, the subtle but key oculomotor deficits are often missed.

OBJECTIVE

The purpose of this project is to determine if the combined measurement of saccades, smooth pursuit, fixations and reaction time represent a biomarker for differentiating pediatric patients with mild traumatic brain injury compared to age matched controls.

DESIGN

This study used cross-sectional design. Each participant took part in a suite of tests collectively labeled the "Brain Health EyeQ" to measure saccades, smooth pursuit, fixations and reaction time.

PARTICIPANTS

The present study recruited 231 participants - 91 clinically diagnosed with a single incident mTBI in the last 2 days as assessed by both the Glasgow Coma Scale (GCS) and Graded Symptoms Checklist (GSC), and 140 age and gender-matched controls (n = 165 male, n = 66 female, M age = 14.20, SD = 2.78).

RESULTS

One-way univariate analyses of variance examined the differences in performance on the tests between participants with mTBI and controls. ROC curve analysis examined the sensitivity and specificity of the tests. Results indicated that together, the "Brain Health EyeQ" tests were successfully able to identify participants with mTBI 75.3% of the time, providing further validation to a growing body of literature supporting the use of eye tracking technology for mTBI identification and diagnosis.

Vertical smooth pursuit as a diagnostic marker of traumatic brain injury

AIM

Neural deficits were measured via the eye tracking of vertical smooth pursuit (VSP) as markers of traumatic brain injury (TBI). The present study evaluated the ability of the eye tracking tests to differentiate between different levels of TBI severity and healthy controls.

METHODOLOGY

Ninety-two individuals divided into four groups (those with mild, moderate or severe TBI and healthy controls) participated in a computerized test of VSP eye movement using a remote eye tracker.

RESULTS

The VSP eye tracking test was able to distinguish between severe and moderate levels of TBI but unable to detect differences in the performance of participants with mild TBI and healthy controls.

CONCLUSION

The eye-tracking technology used to measure VSP eye movements is able to provide a timely and objective method of differentiating between individuals with moderate and severe levels of TBI.

Horizontal and vertical self-paced saccades as a diagnostic marker of traumatic brain injury

Aim:

Eye tracking tests to measure horizontal and vertical saccades as a proxy for neural deficits associated with traumatic brain injury (TBI) were evaluated in the present study.

Methodology:

A total of 287 participants reporting either no TBI, mild, moderate or severe TBI participated in a suite of eye tracking tests to measure horizontal and vertical saccadic performance.

Results:

The horizontal saccades test offered a sensitivity of 0.77 and a specificity of 0.78, similarly the vertical saccades tests offered a sensitivity of 0.64 and a specificity of 0.65.

Conclusion:

The results indicated that using eye-tracking technology to measure these metrics offers an objective, reliable and quantifiable way of differentiating between individuals with different severities of TBI, and those without a TBI.