[Nystagmus in subjects exposed to asymmetric changes in otolith afferents]

Patients with unilateral cochleo-vestibular disorders (23 patients) were rotated in the dark about the horizontal plane with their head positioned differently in relation to the rotation axis; central position (the rotation axis lies between the centrifugal force of 0.5 G acted either in the occipital-frontal direction or in the frontal-occipital direction. In each position a pair of oppositely directed nystagmus was recorded. These nystagmus pairs recorded at different levels of otolith activities were compared. In 19 patients, otolith asymmetry symptoms were observed: in them at least one of the changes of otolith activities was accompanied by an increase of the nystagmus duration of one direction and a decrease of the nystagmus duration of the opposite direction. In 10 patients, changes observed were similar to those detected in pigeons with peripheral otolith asymmetry: alteration of the centrifugal force direction in these patients changed the sign of nystagmus shifts (duration of nystagmus that increased during rotation in one of the off-axis positions diminished during rotation in the other position and vice versa); changes of the nystagmus that occurred when the centrifugal force increased differed in sign from those that occurred when the centrifugal force decreased.