Posture dependent direction reversal of spontaneous vertical nystagmus

Abstract

A patient demonstrated a spontaneous primary position downbeat nystagmus in the sitting position and an upbeat nystagmus in the supine position. This posture dependent reversal of direction is exceptional and implies an otolith-related component. For clinical practice, this implies that position tests are necessary in the examination of nystagmus. Variation in pathophysiology of vertical nystagmus is suggested.

Key Words:

• direction reversal
• vertical nystagmus
• posture