Concussion and vestibular processing deficits
Reviewed by Victor Osei-Lah

It is well known that patients with mild traumatic brain injury (mTBI), also referred to as concussion, display longstanding vestibular symptoms but often clinical signs and objective vestibular function test abnormalities are lacking. The aim of the study was to determine the most helpful sensitive objective measure(s) to identify post-concussion vestibular deficits. Fourteen subjects with persistent post-concussion symptoms and 58 healthy age-matched controls were recruited. All participants were subjected to a series of balance (using a virtual reality-based device), oculomotor (saccades, smooth pursuit, OKS and near point convergence) and vestibular tests (dynamic visual acuity, horizontal gaze stabilisation test, horizontal head thrust test). The participants rated their symptoms before and after these tests. The concussion cohort showed a greater sway of centre or pressure (COP) sway area and variability than the healthy controls especially in dynamic visual motion. Head thrust test was normal in all subjects. Although the oculomotor tests induced statistically significant symptoms (dizziness, headache and nausea) in the concussed group, there were no observable abnormalities of smooth pursuit, saccades and gaze leading the authors to suggest that “visual-vestibular processing deficits are present subacutely following mild traumatic brain injury”. The near point convergence test was abnormal in the concussed group suggesting abnormalities in the oculomotor control systems and not only the brainstem in mTBI. The authors admit the limitations of the study including the self-rating of symptoms and other variables such as cognitive, emotional and psychogenic issues that may overlap with mTBI symptomatology. However, they conclude that the findings and sensitive tools used can be valuable in assessing chronic symptoms in mTBI patients to guide therapy.

Visual-vestibular processing deficits in mild traumatic brain injury.
Wright WG, Tierney RT, McDevitt J.
JOURNAL OF VESTIBULAR RESEARCH
2017;27:27-37.