Natural Active Head Movement Testing

ABSTRACT

A modern conceptual framework for vestibular function is that of a biological control system. The use of control theory and techniques can have a major impact in vestibular testing through monitoring of natural movements. The vestibulo-ocular reflex (VOR) functions mainly to allow clear vision during walking by stabilizing the eye during faster head movements. The Vestibular Autorotation Test (VAT™) tests the VOR at higher frequencies (i.e, 2-6 Hz) encountered during natural, active movements. Horizontal and vertical head movements are recorded for 18 sec. Spectral coherence Fourier analysis in the VAT sorts head and eye movements into respective frequency components, and computes VOR gain, phase, and asymmetry. A clinical example is used to illustrate VAT gain and phase characteristics, and its effectiveness in monitoring vestibular rehabilitation. Comparisons with traditional vestibular tests illustrate the advantages of testing the vestibular system at higher frequencies with natural active head movements.

KEYWORDS

Vestibulo-ocular reflex - biological control - active head movements - Vestibular Autorotation Test - dizziness

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