"Ping-pong" gaze. Periodic alternating gaze deviation.

A clinicopathologic study of patient with periodic alternating gaze deviation is presented. The patient's eye moved rhythmically and conjugately from one extreme lateral position to the other. A 0.45-cm hemorrhage, found in the midline deep vermis, is thought to have disrupted the neural integrator that holds positions of gaze, resulting in periodic alternating gaze deviation. Three previous cases of periodic alternating gaze deviation are reviewed and illustrate the role of the cerebellum in the control of eye movements.