Opsoclonus provoked by convergence

This is a 40-yo-man with post-infectious opsoclonus-myoclonus syndrome. Opsoclonus was intermittently evident in primary position, but was consistently provoked (and intensified) by convergence. Occasionally, opsoclonus (back-to-back saccades in horizontal, vertical, torsional planes without an intersaccadic interval) or ocular flutter (in the horizontal plane only) can be subtle or even difficult to distinguish from high frequency jerk nystagmus. However, these saccadic oscillations can be provoked with certain maneuvers such as eyelid closure (i.e., observing the corneal bulge under eyelids), following voluntary saccades, or with convergence. The underlying pathophysiology of opsoclonus/flutter is thought to involve damage to the pontine omnipause cells (dysfunction of the normal saccade-inhibiting circuitry) and/or disinhibition of the fastigial nucleus in the cerebellum (where the fastigial nucleus is part of the circuitry responsible for initiation of saccades).