Alternating Hypertropias - Bilateral 4th Nerve Palsies and Alternating Skew Deviation

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: Seen here are two patients with alternating hypertropias. The first is a 70-year-old woman with a diagnosis of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS). In the video, both spontaneous downbeat nystagmus (DBN) and gaze-evoked nystagmus (GEN) are apparent, in addition to a right hypertropia in right gaze and a left hypertropia in left gaze, also referred to as an alternating skew deviation or an abducting hypertropia. The combination of these three findings (DBN, GEN, alternating skew) is highly suggestive of cerebellar flocculus/paraflocculus disease.1 The second patient is a 40-year-old woman who also has an alternating hypertropia, although in her case this is an adducting hypertropia due to bilateral 4th nerve palsies. In her case, there is a right hypertropia in left gaze and a left hypertropia in right gaze. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: Seen here are two patients with alternating hypertropias. The first is a 70-year-old woman with a diagnosis of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS). In the video, both spontaneous downbeat nystagmus (DBN) and gaze-evoked nystagmus (GEN) are apparent, in addition to a right hypertropia in right gaze and a left hypertropia in left gaze, also referred to as an alternating skew deviation or an abducting hypertropia. The combination of these three findings (DBN, GEN, alternating skew) is highly suggestive of cerebellar flocculus/paraflocculus disease. The second patient is a 40-year-old woman who also has an alternating hypertropia, although in her case this is an adducting hypertropia due to bilateral 4th nerve palsies. In her case, there is a right hypertropia in left gaze and a left hypertropia in right gaze. https://collections.lib. utah.edu/ark:/87278/s6d83n91