Impaired ipsilateral smooth pursuit and gaze-evoked nystagmus in paramedian pontine lesion

A 27-year-old man developed sudden dysarthria and left-sided weakness and paresthesia. Gaze-evoked nystagmus (GEN) was evident in bilateral horizontal gazes (see the video on the Neurology Web site at www.neurology.org). Rightward pursuit was interrupted by catch-up saccades while leftward pursuit was normal (figure, A, and video). Saccadic eye movements and vestibulo-ocular reflex were normal. Brain MRI …