Nystagmus measured with video-oculography: methodological aspects and normative data

Detailed analysis of eye movements is essential in order to understand the pathophysiology underlying vestibular disturbances. We applied a commercial video-oculography (VOG) to measure spontaneous and provoked nystagmus in 20 healthy subjects. The slow-phase velocity (SPV) of the nystagmus was calculated. We also simultaneously recorded the eye movements on a standard VHS videotape to be able to confirm the results derived from the VOG paper charts. The nystagmus results derived from the VOG charts and the simultaneous videotaping agreed well. Nystagmus was found in 17 subjects. Spontaneous nystagmus was seen in 20%, positional nystagmus in 55%, and head-shaking nystagmus in 35% of the participants. Although nystagmus was frequent (85%), the mean SPV for nystagmus was low (1.7 degrees /s). The VOG is a modern and sensitive method to record eye movements, but visual inspection of the videotape may be needed in selected cases to confirm occurrence of nystagmus.