Periodic alternating gaze deviation is an involuntary, continuous (except during sleep), cyclic disorder of eye movements. A single cycle consists of a conjugate horizontal deviation of the eyes to one side for about two minutes, followed by a slow conjugate horizontal movement of the eyes to the opposite side, maintenance of the conjugate horizontal deviation to this latter side for about two minutes, and then slow conjugate horizontal movement of the eyes back to the original side.
This phenomenon is rare. The only other patient reported was briefly described by Kestenbaum.5 "Both eyes were turned to the right in a conjugate deviation. After a certain time, both eyes wandered slowly to the left and stayed there in conjugate deviation to the left. Then the eyes returned to the right, etc. The periods of each deviation lasted from 1 to 2 minutes. The patient had a complete palsy of voluntary
ROBERT T. GOLDBERG, CALEB GONZALEZ, GOODWIN M. BREININ, RICHARD N. REUBEN. Periodic Alternating Gaze Deviation With Dissociation of Head Movement. Arch Ophthalmol. 1965;73(3):324–330. doi:10.1001/archopht.1965.00970030326006