A Multimodal Assessment of the Heterogeneous Nature of Post-mTBI Dizziness

Dizziness after mild traumatic brain injury (mTBI) is commonly attributed to impairment within the vestibular system. However, oculomotor, mobility, and autonomic dysfunction can also contribute to patient-reported dizziness. The purpose of this preliminary study was to examine whether a multimodal battery of assessments could help explain patient-reported dizziness after mTBI. Twenty-three participants with concussion-related symptoms completed the Dizziness Handicap Inventory (DHI) to evaluate burden imposed by dizziness on daily activities and a battery of tests designed to incorporate domains that have been shown to contribute to dizziness (e.g., vestibular, oculomotor, balance and mobility, and autonomic dysfunction). Specific outcomes included quantitative variables obtained from: Vestibular Ocular Motor Screening (VOMS); standing for 30 seconds with feet together, eyes closed, with hands on their hips on both firm and foam surfaces; walking for one minute at a comfortable pace; and a Head-up Tilt (HUT) Test. Univariate associations between DHI and individual measures were assessed, and a backwards-stepwise regression model determined the multi-variable association. There were no strong associations and only a few moderate associations between individual functional measure and DHI total score. A total of eight variables had univariate correlation coefficients larger than 0.20 in magnitude. The final model from the backwards-stepwise procedure explained 69% of the variance in DHI and retained only three variables: peak turning speed from the one-minute walk; mean blood pressure (MBP) during the HUT; and the total VOMS score. Isolated assessments of individual domains of function have weak-to-moderate associations with post-mTBI dizziness. Conversely, a multivariable model that contained measures of mobility, autonomic function, and symptomatic complaints to vestibular and ocular provocation explained 69% of the variance in dizziness. These results suggest that dizziness is physiologically heterogeneous in nature and support the use of multi-domain assessments in patients with dizziness after mTBI.