Vestibular function assessment using the NIH Toolbox

Objective: Development of an easy to administer, low-cost test of vestibular function. Methods: Members of the NIH Toolbox Sensory Domain Vestibular, Vision, and Motor subdomain teams collaborated to identify 2 tests: 1) Dynamic Visual Acuity (DVA), and 2) the Balance Accelerometry Measure (BAM). Extensive work was completed to identify and develop appropriate software and hardware. More than 300 subjects between the ages of 3 and 85 years, with and without vestibular dysfunction, were recruited and tested. Currently accepted gold standard measures of static visual acuity, vestibular function, dynamic visual acuity, and balance were performed to determine validity. Repeat testing was performed to examine reliability. Results: The DVA and BAM tests are affordable and appropriate for use for individuals 3 through 85 years of age. The DVA had fair to good reliability (0.41–0.94) and sensitivity and specificity (50%–73%), depending on age and optotype chosen. The BAM test was moderately correlated with center of pressure ( r = 0.42–0.48) and dynamic posturography ( r = −0.48), depending on age and test condition. Both tests differentiated those with and without vestibular impairment and the young from the old. Each test was reliable. Conclusion: The newly created DVA test provides a valid measure of visual acuity with the head still and moving quickly. The novel BAM is a valid measure of balance. Both tests are sensitive to age-related changes and are able to screen for impairment of the vestibular system. BAM= : Balance Accelerometry Measure; COP= : center of pressure; DS= : double-limb feet together stance; DVA= : dynamic visual acuity; ETDRS= : Early Treatment Diabetic Retinopathy Study; ICC= : intraclass correlation coefficient; logMAR= : logarithm of the minimum angle of resolution; NPL= : normalized path length; SOT= : sensory organization testing; SVA= : static visual acuity; TS= : tandem stance; VH= : vestibular hypofunction; VOR= : vestibulo-ocular reflex; VSP= : vestibulospinal outputs