Teaching Video NeuroImages: Alternating skew deviation with abducting hypertropia following superior colliculus infarction.

A 63-year-old patient was admitted with acute ataxia and binocular oblique diplopia. Neuroophthalmologic examination revealed abducting hypertropia on lateral gaze, better seen during upgaze, mimicking bilateral inferior oblique palsy (video, figure). There was no ocular cyclotorsion. Brain MRI revealed focal ischemic lesions in the right cerebellar hemisphere and left superior colliculus (figure). The diagnosis of alternating abducting hypertropic skew deviation was made. This rare type of skew deviation is related to central otolithic dysfunction. Similar cases have been described with Figure Ocular motor examination and MR images