Downbeat Nystagmus ; Video 5.11 Downbeat nystagmus causing severe oscillopsia from Neuro-Ophthalmology and Neuro-Otology Textbook

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. - - : 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