What is the purpose of assessing VOR function across frequencies during rotary chair testing?

• A. To quantify bilateral vestibular function and detect asymmetry across frequencies
• B. To measure cochlear hair cell function during motion
• C. To evaluate neck muscle reflexes during head movement
• D. To assess higher cognitive processing during spatial navigation

Answer: (A)

Assessing VOR across frequencies in rotary chair testing targets how both vestibular systems respond to angular motion over a range of speeds. This helps quantify bilateral vestibular function and detect asymmetry, because normal VOR gain should be similar on both sides across frequencies, and a deficit on one side reduces eye movement gain in a way that can be seen across the spectrum. Testing at multiple frequencies reveals subtle or frequency-dependent dysfunction that might be missed with a single speed, since low-frequency responses probe slower canal dynamics and high-frequency responses probe faster ones. Patterns of reduced gain and any phase shifts across frequencies guide understanding of the extent and nature of the vestibular loss. This approach isn’t about cochlear hair cell function, neck muscle reflexes, or higher cognitive processing, which lie outside the VOR assessment.