The sinusoidal harmonic acceleration rotary chair test. Theoretical and clinical basis.

Sinusoidal harmonic acceleration has become a common method used in diagnostic vestibular testing. When properly used, it can produce normal and abnormal patterns that can be interpreted in the context of the nature of the stimulus and the physiologic processes that describe the responses to it. Thus, the aim of this review is to present specific information regarding the sinusoidal harmonic acceleration stimulus and vestibular physiology in a way that will hopefully aid in test interpretation.