Saccadic ping-pong gaze.

Ping-pong gaze (PPG), or short-cycle periodic alternating gaze, consists of horizontal conjugate ocular deviations alternating every few seconds. This alternating gaze has been described as appearing to be smooth. However, our electrooculographic study of four consecutive unconscious patients with PPG showed smooth waveforms in one patient but saccadic cog-wheeling in three patients. In one of the three patients with saccadic PPG, a transition from smooth to saccadic waveforms was noted with clinical improvement. Whereas the patient with smooth PPG died immediately, the patients with saccadic PPG survived in a persistent vegetative state. These findings suggest that saccadic PPG is a clinical variant of PPG in patients in a lighter state of consciousness, possibly related to less extensive brain damage.