[Nystagmus].

Physiological nystagmus stabilizes gaze during head movements and pathological nystagmus reflects a disorder of the vestibulo-ocular reflex (VOR). Pathological nystagmus appears or strengthens usually during change in head position. Therefore, dizziness or nystagmus associated with head movements is not specific to benign paroxysmal positional vertigo unless it is verified in specific positional test. Peripheral nystagmus decelerates during visual fixation, accelerates when gaze is turned towards the fast phase, does not change direction, and is usually composed of several directional components unlike central nystagmus. The velocity and frequency of the slow phase of nystagmus can be measured with electronystagmography or video-oculography.