Intra-labyrinthine schwannoma affecting the low but not high frequency function of the vestibulo-ocular reflex: implications for vestibular physiology

Peripheral vestibular hypofunction can be identified by asymmetric vestibular responses to caloric irrigation of the horizontal semicircular canal or by the head impulse test (Halmagyi-Curthoys test). Whereas the former test investigates the low frequency function of the vestibulo-ocular reflex (VOR) the latter assesses the high-frequency function. The biologically more relevant high-frequency VOR function is usually more persistently impaired in unilateral vestibular lesions (e.g. vestibular neuritis) than the low-frequency function and thus the more sensitive parameter to detect chronic peripheral vestibular d…