Opsoclonus Provoked by Convergence

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: 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). 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient experienced a parainfectious opsoclonusmyoclonus syndrome. Opsoclonus was intermittently evident in primary position, but was consistently provoked 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 relate to one or more of the following: heightened membrane excitability of the glutaminergic excitatory burst neurons (EBN); increasing firing when EBNs are released from inhibitory release from omnipause cells (which inhibit burst neurons during fixation), referred to as post-inhibitory rebound; decreased glycinergic (omnipause cell) inhibition. https://collections.lib.utah.edu/ark:/87278/s6b02t5j