Quantification and localization of gait variability as biomarkers for mild traumatic brain injury

Motion capture technology and Magnetic Resonance Imaging with Diffusion Tensor Imaging (MRI-DTI) were used in this work to detect subtle abnormalities in patients with mild traumatic brain injury (MTBI). A new concept, termed dynamic variability, is introduced in this work to quantify and localize gait variability. Three chronic MTBI patients were recruited from the Veterans Affair Medical Center in Iowa City, IA, and three healthy controls with height, weight, and gender matched to the patients were recruited from the Reserve Officers' Training Corps in Iowa City, IA. Kinematic and kinetic data of the subjects were collected during the performance of three gait testing scenarios. The first test involved single-task walking and was used as a baseline. The second and third tests were dual tasks that involved walking while performing a cognitive or motor task and were designed to magnify gait abnormalities. The results showed that MTBI patients had reduced gait velocity, shortened stride length, and larger step width; findings that are consistent with those published in the literature. The new dynamic variability factor found that, as compared to controls, MTBI patients had more variability in their hip and ankle joint moments. MRI-DTI has been used to detect dysfunction of the major white matter tracts in chronic MTBI patients; although, the sample size of this study was too small to detect a difference between the MTBI and control subjects. The imaging and gait abnormalities are suggestive of frontal lobe-white matter tracts dysfunction.