Nystagmus episodes related to sea sickness.

In order to test the possible presence of nystagmus during episodes of sea sickness, we performed electronystagmography (ENG) on nine subjects before and during sailing on a 35-ton vessel in a somewhat heavy sea. In addition, the accelerations of the x, y and z axes of the ship were also monitored and simultaneously recorded. Nystagmus was not detected in pre-sailing recordings, while all of the subjects demonstrated clear positional nystagmus during sailing. The nystagmus was episodic, direction-fixed and its intensity was greater in sea-sick than in non-sick subjects. Our findings suggest that the nystagmus recorded is labyrinthine in origin and stems from temporary peripheral vestibular dysfunction elicited by sea sickness.