Challenging the Vestibular System Results in Slower Gait Speed in People With Persistent Symptoms After Mild Traumatic Brain Injury

Abstract

<h3>Research Objectives</h3> People with persistent symptoms after mild traumatic brain injury (mTBI) often complain of imbalance when walking with head turns, an activity that challenges the vestibular system. The purpose of this study was 1) to compare gait speed during usual walk and during walking with head turns (HT) between people with mTBI and controls, 2) and to compare the cognitive workload during usual walk and during HT walk between people with mTBI and controls. <h3>Participants</h3> Twenty-three individuals (mean age 55.7 ± 9.3 years) with persistent symptoms after mTBI, who were between 3 months to 2 years post-injury and 23 age and sex-matched controls. <h3>Interventions</h3> Gait speed was recorded while walking a 12-inch wide, 60-foot walkway, during walking when looking ahead and when walking with HT to identify letters and their colors that were placed every 5 feet on the wall. <h3>Main Outcome Measures</h3> Gait speed during usual walk, HT walk, and the dual-task cost for gait speed were calculated. The number of steps outside the path during both walks and number of missed letters were collected. Pupillary responses during both walks were collected by the TOBII® eye tracker and the Index of Cognitive Activity (ICA) was calculated using EyeWorks™ software. The Post-Concussion Symptom Scale (PCSS) was used to collect symptom severity. <h3>Results</h3> Participants in the mTBI group had slower usual gait speed (p<0.001), and slower HT gait speed (p<0.001) compared to controls, however, the dual task cost for gait speed was not different between groups (p=0.88). More people with mTBI took steps off the path during usual walk and during HT walking compared to control subjects. No differences were noted between groups in ICA in the right or left eye for usual walk or HT walk, or the DTC for ICA. Within group analysis showed that gait speed was lower during HT walk compared to usual walk in the people with mTBI (p<0.001) as well as in controls (p<0.001). Average ICA was higher with HT compared to usual walk in the mTBI group in the right eye (p=0.01) and left eye (p=0.001), and in controls in the right eye (p=0.01) and left eye (p=0.01). <h3>Conclusions</h3> People with persistent symptoms after mTBI have slower usual gait speed which is further reduced when they must move their head to scan for objects. The cognitive workload increased with a dual task compared to a single task, however, the dual-task cost for gait speed and cognitive workload were similar between groups, showing that both groups responded in a similar manner to dual tasking. <h3>Clinical Relevance</h3> Walking with head turns to identify objects in our surroundings, at home, in the grocery store are part of daily life. Increased time required, poorer stability, and higher mental effort required to walk with head turns may reduce community participation in people with mTBI and persistent symptoms.