Spinocerebellar Ataxia Type 3 with Gaze-Evoked Nystagmus and Bilateral Vestibular Loss

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 50-year-old woman with an established diagnosis of spinocerebellar ataxia type 3 (SCA 3) with severe imbalance and head movement-induced oscillopsia. On examination, she had 1) bilateral vestibular loss (BVL) demonstrated by bilaterally abnormal head impulse test (HIT, with corrective saccades and low gains seen bilaterally with bedside and video HIT), as well as 2) cerebellopathy demonstrated by gaze-evoked nystagmus and saccadic smooth pursuit. Her vestibulo-ocular reflex suppression (VORS) was nearly normal appearing because there was no VOR to suppress (given her BVL). SCA 3 is in the differential diagnosis of chronic, progressive imbalance due to BVL and cerebellopathy in addition to other SCAs (mainly 1, 4, 6, 25), as well as multiple system atrophy, superficial siderosis (also with bilateral hearing loss), CANVAS (cerebellar ataxia, neuropathy, vestibular areflexia syndrome), and Friedreich's ataxia among others. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient, with a known diagnosis of spinocerebellar ataxia type 3 (SCA 3), presented with severe imbalance and head movement-induced oscillopsia. On examination, she had (1) bilateral vestibular loss (BVL) demonstrated by bilaterally abnormal head impulse test (HIT, with corrective saccades and low gains seen bilaterally with bedside and video HIT), as well as (2) cerebellopathy demonstrated by gaze-evoked nystagmus and saccadic smooth pursuit. Her vestibulo-ocular reflex suppression (VORS) was nearly normal appearing because there was no VOR to suppress (given her BVL). SCA 3 is in the differential diagnosis of chronic, progressive imbalance due to BVL and cerebellopathy in addition to other SCAs (mainly 1, 4, 6, 25), as well as multiple system atrophy, superficial siderosis (also with bilateral hearing loss), CANVAS (cerebellar ataxia, neuropathy, vestibular areflexia syndrome), and Friedreich's ataxia among others https://collections.lib.utah.edu/ark:/87278/s60k7jb4