The Use Of Positional Head Impulse Test In Vertical Nystagmus: Evidence For Vestibular Imbalance

Upbeat (UBN) and downbeat nystagmus (DBN) have been ascribed to an imbalance between circuits generating upward and downward eye movements within either the vestibular (semicircular canals [SCC]- and/or otolithrelated pathways), pursuit, or the neural integrator system. Positional modulation of UBN and DBN seems to favour the vestibular imbalance theory. Video-head impulse test (VHIT) is a recent tool that enables us to quantify SCC in the upright position. We used VHIT in a patient evidencing both UBN and DBN to assess SCC function in prone, upright and supine position.