Abnormal Turning and Its Association with Self-Reported Symptoms in Chronic Mild Traumatic Brain Injury.

Turning is common in daily activity and requires rapid, coordinated reorientation of the head, trunk, and pelvis toward the new direction of travel. Yet, turning gait has not been well explored in populations with mild traumatic brain injury (mTBI) who may alter their turning behavior according to self-perceived symptoms or motor dysfunction. The purpose of this study was to examine turning velocities and coordination in adults with chronic mTBI (>3 months post-injury and still reporting balance complaints) during a task simulating everyday ambulation. We hypothesized that individuals with chronic mTBI would reduce their angular velocity when turning and increase the variability of head-pelvis coordination compared with controls, and that the reduction in velocity and increased variability would be associated with their self-reported symptom score. Forty-two adults (14 chronic mTBI, 28 controls) completed the Neurobehavioral Symptom Inventory before walking 12 laps around a marked course containing two 45-degree turns, four 90-degree turns, and two 135-degree turns. Inertial sensors collected angular velocities of the head and pelvis. After adjusting for covariates, participants with chronic mTBI had significantly slower lap times and peak angular velocities of the pelvis (p < 0.01) compared with the control group. The peak velocity timing (PVT) between peak velocities of the head and pelvis, and the variability of that timing was significantly greater in participants with chronic mTBI (p < 0.01). Within the chronic mTBI group, somatosensory symptoms were associated with slower angular velocities of the head and pelvis (p = 0.03) and increased PVT variability (p < 0.01). The results suggest individuals with chronic mTBI with worse somatic symptoms have impaired head stabilization during turning in situations similar to everyday life. These results encourage future research on turning gait to examine the causal relationship between symptoms and daily locomotor function in adults with chronic mTBI.