Selective Unidirectional Horizontal Saccadic Paralysis From Acute Ipsilateral Pontine Stroke.

BACKGROUND: Impairment of unidirectional horizontal saccades with sparing of smooth pursuit has been described in human lesions in the dorsomedial pons. They have been too large to allow localization to the pontine paramedian reticular formation (PPRF).

METHODS: Single case report.

RESULTS: A patient with impaired rightward saccades but spared rightward pursuit eye movements had a brain MRI showing a discrete area of restricted diffusion in the region corresponding to the PPRF.

CONCLUSIONS: This case provides support for the concept that PPRF lesions in humans may selectively impair unidirectional horizontal saccades.