Positional and positioning nystagmus in healthy subjects under videonystagmoscopy

OBJECTIVE: The eye-focused video camera as sensitive to infrared light is very useful for detecting nystagmus with open eyes in the dark. The existence of physiological nystagmus has been reported. We investigated how frequently physiological positional and positioning nystagmus is seen in healthy individuals under infrared video goggles. MATERIALS AND METHODS: Eighty-nine healthy individuals were examined in this study. Positional and positioning nystagmus was examined with infrared video goggles. RESULTS: Positional nystagmus could be detected in 65 of the 89 subjects under infrared video goggles. The majority of nystagmus was horizontal nystagmus, and vertical nystagmus was also seen in four subjects. Nystagmus was most frequently recognized in right or left shoulder down position. Positioning nystagmus was detected in 40 subjects. CONCLUSIONS: Positional and positioning nystagmus frequently exist in healthy subjects. This finding means that the existence of physiological nystagmus must be considered when diagnosing dizzy patients using this equipment.