Detecting functional deficits following sub-concussive head impacts: the relationship between head impact kinematics and visual-vestibular balance performance

Introduction: Mild traumatic brain injury (mTBI) continues to be a significant issue facing the US military. While TBI cases in deployed environments are of significant concern, an estimated 80% of diagnoses occur in garrison settings (e.g., military training). Objective: With the aim of improving the detection of potentially concussive exposures, the objective of this study was to evaluate the relationships between head impact kinematics and performance on a visual-vestibular balance task. Methods: Participants (n = 51) were enrolled in the Basic Airborne Training Course. Two sensors to measure head impacts sustained were worn. Performance was measured at four time points: baseline and at the end of each week of the course. Results: Visual-vestibular balance task performance tended to decrease over the course of airborne training for our participants, however, limited to the most challenging levels of the task. Also, head impact kinematic measures correlated with performance outcomes to suggest that worse performance was associated with greater number of impacts and greater linear and rotational acceleration and rotational velocity. Discussion: Our findings suggest that visual-vestibular balance task performance may be a useful measure for detection of sub-concussive impacts and that wearable sensors may provide useful data on head impact kinematics that relates directly to functionally relevant performance.