Responses to rotational stimulation of the horizontal canals from patients with acoustic neuromas

Studies of eye movement responses to harmonic acceleration in patients with acoustic neuromas and Meniere's disease have demonstrated left-right asymmetries and phase decrements. This study examined the responses from 41 patients with acoustic neuromas. The phase measures and the frequency components of the response (spectral purity) were examined in detail. Results of the study suggests that phase decrements, although they are nonspecific responses of the vestibular system to injury, have different characteristics depending on the location of the lesion. In addition, when the injury is in the eighth nerve root entry zone, the linearity of the system reflects a severe decrement.