Teaching Video NeuroImages: Thalamic infarct with pseudo-abducens and vertical gaze palsies and an unusual stroke mechanism

A 32-year-old man presented with confusion and diplopia. His examination showed complete vertical gaze palsy with relatively preserved vertical vestibulo-ocular reflexes, convergence nystagmus on attempted upgaze, alternating adducting hypertrophic skew deviation, limited right eye abduction with esotropia, and right limb ataxia (video on the Neurology® Web site at Neurology.org). MRI showed a left paramedian thalamic infarct (figure 1). Vertical gaze palsy results from damage to the rostral interstitial nucleus of the medial longitudinal fasciculus. The contralateral abduction limitation is consistent with pseudo-abducens palsy, attributed to disruption of descending mesencephalic inhibitory convergence pathways.¹ Stroke mechanism was believed to be paradoxical embolus from a rare cardiovascular malformation (figure 2).

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Figure 1 MRI

Axial diffusion-weighted imaging sequence images show left paramedian thalamic infarct (A) with extension into the rostral medial midbrain (B). This location is suggestive of cardioembolic source in young adults presenting with thalamic infarcts.²

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Figure 2 CT reconstruction of partial anomalous pulmonary venous connection (PAPVC)

An abnormal vessel (white arrow) connects the portal vein to the pulmonary vein resulting in a porto-systemic shunt with confirmed bidirectional flow. Given the lack of vascular risk factors and negative hypercoagulable workup, stroke mechanism was most likely embolization of transient thrombus in the PAPVC vessel.

• © 2016 American Academy of Neurology