The dorsomedial thalamus communicates with the frontal eye field and supplemental eye field in the motor cortex having a role as a relay between the parietal cortex and brainstem ocular motor pathways. In this report, we present a case with unilateral dorsomedial thalamic stroke who presented with upward gaze paralysis, bilateral lid retraction (Collier’s sign) and contralesionally pseudo-abducens paresis.  

A 66-year-old right handed Caucasian male presented with two days of sudden onset of vertical diplopia. His examination revealed bilateral upward gaze palsy with relatively preserved downward gaze, skew deviation, convergence nystagmus on attempted vertical gaze, limited right eye abduction with esotropia, and Collier’s sign on attempted upward gaze. CT head did not show acute findings. CT angiogram of the head and neck showed chronic proximal right vertebral occlusion with distal reconstitution. A diffusion-weighted magnetic resonance image showed an acute infarct in the left dorsomedial thalamus. 

The area of ischemia in our patient have resulted in damage to the vertical gaze center and adjacent neurons; as well as disruption of descending mesencephalic inhibitory convergence (MIC) pathways. Saccadic innervation is bilateral to the elevator muscles but only ipsilateral for downgaze which explains why a unilateral lesion can cause up gaze palsy and bilateral lesions produce downward gaze palsy. MIC pathways lesions can lead to decreased inhibition and can produce a tonic discharge to the medial rectus muscles causing convergence and esodeviation, which may appear as a VI paresis. The Collier’s sign is caused by overstimulation in a group of cells near that lead to excess eyelid elevation. 

Isolated vertical gaze palsy is an unusual presentation in acute settings. Our case is unique due to presence of incomplete signs of dorsal midbrain syndrome with pseudo-six palsy due to a unilateral ischemic stroke of paramedian thalamus.