Saccade abnormalities in patients with ocular flutter.

In a group of 8 patients with opsoclonus or ocular flutter, the eye movements were recorded by electro-oculography (EOG). The spontaneous eye movement pattern and the amplitude and peak velocity of the refixation saccade were analysed. The EOG recording demonstrated frequent bursts of horizontally and vertically directed saccades elicited without any intersaccadic interval. Three patients also demonstrated an increased frequency of square waves. In 6 of the 8 patients the peak velocity of the voluntary saccades was increased; in 5 patients this condition was found for saccades in both directions. Over-shooting oscillations or slightly hypermetric voluntary saccades occurred in 5 patients. It is proposed that the ocular flutter and the increased saccadic velocities found in the present series of patients is caused by a disorder of the burst cells in the brain stem saccadic control system.