M. Stojak1, K.R. Campbell1,2, J. Ghammachi3, T. Shimabukuro3, & L.A. King PhD1,2

1Oregon Health and Science University, Portland OR, 2Veterans Affairs Portland Health Care System, Portland, OR, 3Lewis &Clark College, Portland, OR

Vestibular and ocular motor impairments after mild traumatic brain injury (mTBI) may lead to protracted recovery and potentially affect coordination. Ocular motor function is typically measured in a static seated position. Mobile eye-tracking can measure eye movements while performing dynamic tasks. Recently, we showed that people with mTBI had decreased saccade frequency, velocity, and duration while walking. It is currently unknown if vestibular rehabilitation after mTBI improves saccade function while walking. PURPOSE: To compare changes in saccadic function pre-post physical therapy to those recovering naturally without intervention. METHODS: All participants were symptomatic from an mTBI (2-12 weeks post-injury). Subjects completed baseline and 6-week follow-up testing either after rehabilitation (rehab, n = 43, age = 33.6 ± 12.1) or no intervention (non-rehab, n = 50, age = 34.5 ±1 2.4). The rehab group received 8 sessions of physical therapy that included cervical, aerobic, and vestibular therapy. At both testing timepoints, participants did a continuous 1-minute walking task over a straight 9m path while wearing a mobile eye-tracking system to record gaze coordinates. A validated algorithm calculated saccade duration, peak velocity, and frequency. Linear mixed effect models were used that included fixed factors for group, time, and their interactions. RESULTS: There were no significant effects on saccade duration or peak velocity during the 1-minute walk for either group at the baseline and follow-up tests (p’s>0.05). The rehabilitation group significantly increased saccade frequency after rehabilitation while the non-rehab group did not change (βgroupXtime = 0.29 [95%CI: 0.08, 0.51]). However, the rehab group had significantly reduced saccade frequency at baseline compared to the non-rehab group (βgroup = -0.37 [95%CI: ‑0.66, ‑0.08]). CONCLUSIONS: While we observed significant effects of rehabilitation on saccade frequency, other saccade measures did not show similar improvements. Furthermore, baseline group differences on saccade frequency suggest this finding should be interpreted with caution. The overall null findings on saccade function may be attributed to the lack of ocular motor exercises in the physical therapy program.

Funding was provided by the US Department of Defense Award Number:W81XWH-17-1-0424.

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