Opposed adducting saccades in convergence-retraction nystagmus: a patient with sylvian aqueduct syndrome.

We report high resolution oculographic recordings on a patient with convergent-retraction nystagmus (Parinaud's Sign). Recordings show opposed adducting saccades which are slightly asynchronous (8 ms), in contrast to the conjugate horizontal saccades which are exactly synchronous (0.3 ms). Normal saccadic velocity of these opposed adductions necessarily implies reciprocal innervation of horizontal and vertical agonist-antagonist pairs. Lateral view cine films show absence of retraction, apparently as a consequence of normal orbital mechanics. We suggest that normal mechanisms for dynamic overshoot saccades are involved in the production of these abnormal opposed adducting saccades.