Teaching Video NeuroImages: Upbeat and horizontal gaze-evoked nystagmus in bilateral medial medullary infarction

A 41-year-old man with progressive quadriparesis and generalized tingling sensation showed spontaneous upbeating nystagmus and horizontal gaze-evoked nystagmus (video at [Neurology.org][1]). The initial diffusion-weighted images showed an equivocal hyperintensity at midline of rostral medulla (upper row). Follow-up MRIs (lower row) showed characteristic heart appearance sign (figure). [1]: http://neurology.org/lookup/doi/10.1212/WNL.0000000000004634