Gaze palsies are common in patients with acute stroke of the frontal cortex or brainstem. The objective of this case report is to demonstrate that subcortical stroke can cause horizontal gaze palsy, indicating incomplete understanding of supranuclear gaze pathways.

Horizontal gaze is mediated by the paramedian pontine reticular formation, which receives input from the frontal eye field of the contralateral frontal lobe for saccades and ipsilateral input from the parietal, occipital, and temporal lobes for pursuit. Horizontal gaze is also influenced by the vestibular system via the oculocephalic reflex.

We report two cases of subcortical stroke producing contralateral horizontal gaze palsy.

 Case 1: 52-year-old male with history of intracranial atherosclerosis, and recent left corona radiata infarct presented with dysarthria and new left sided weakness. NIHSS 3. Initial exam notable for dysarthria and mild left arm drift. Preliminary CT head and CTA showed no change from prior. On day two, patient’s symptoms worsened showing notable pseudobulbar palsy, with inability to phonate and mildly labile affect. He was also noted to have absent voluntary horizontal gaze to the left, with preserved oculocephalic reflex. MRI showed acute right corona radiata infarction with basal ganglia involvement.

Case 2: 64-year-old female with history of hypertension and tobacco use presented with rightward-deviated gaze and left sided weakness. NIHSS 11. MRI was consistent with infarct of right posterior limb of internal capsule and parietal lobe. Exam showed dysarthria, left homonymous hemianopsia, horizontal gaze palsy, left facial droop, and diminished left-sided strength and sensation. Oculocephalic reflex was intact.

Our current understanding of the supranuclear gaze pathway does not fully explain the observed horizontal gaze palsies seen in these patients given the locations of the infarctions. Therefore, we conclude that there is need for further research into these neurologic pathways.