Convergence-Retraction Nystagmus in Dorsal-Midbrain Syndrome

A man in his early twenties was referred by optometrist for abnormal eye motility findings. He had a remote history of an excised pinealoma. On exam he had almost complete upgaze palsy, convergence-retraction nystagmus on attempted upgaze, and light-near dissociation of pupillary reaction, the classic triad seen in dorsal-midbrain (Parinaud) syndrome. Upgaze palsy occurs presumably because of the lesion affecting vertical gaze centers located in dorsal midbrain (riMLF). Globe retraction is best visible from the side and is likely secondary to co-contraction of lateral and medial recti on attempted upgaze. Pupillary light-near dissociation is presumably secondary to compression of Edinger-Westfall nuclei with sparing of the more ventral near-response nuclei