Downbeat Nystagmus

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: This is a 40-year-old man with 2 years of progressive ataxia and oscillopsia. On examination, he had downbeat nystagmus (DBN), an ocular motor finding that is usually (but not always) associated with flocculus/paraflocculus dysfunction, which causes overaction of the anterior canal (upward or anti-gravity) pathways relative to posterior canal (downward or gravity) pathways. This results in a continuous slow upward phase and subsequent fast downward phase, causing the DBN. In his case, there was a history of a testicular seminoma (s/p resection) several years prior to presentation, and during the initial work-up he was found to have a CSF lymphocytic pleocytosis, but unrevealing paraneoplastic panel, brain MRI and body PET/CT. There was no clear response to steroids and IVIG, and for his DBN, trials of 4-aminopyridine and chlorzoxazone were ineffective. After 2 years, significant cerebellar atrophy was apparent on his MRI. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: This patient experienced progressive ataxia and oscillopsia over two years of unknown etiology. Unfortunately, trials of 4-aminopyridine, clonazepam, baclofen, and chlorzoxazone were ineffective. After 2 years, significant cerebellar atrophy was apparent on his MRI. https://collections.lib.utah.edu/ark:/87278/s6wq42f0