We describe a case of a 23-year-old male who developed viral upper respiratory illness symptoms, progressing to include diplopia, dizziness, imbalance, and dysarthria. Examination following transfer to our facility revealed nystagmus, ataxic speech, and ataxic gait. MRI of the brain and cervical and lumbar spine were unremarkable. Lumbar puncture showed lymphocytic pleocytosis and elevated protein. The patient was treated with high-dose intravenous steroids escalating to IVIG due to minimal response. Serum autoimmune and paraneoplastic encephalopathy panel resulted negative. ITPR1 and GRAF1 antibodies would later result positive in CSF. Malignancy work-up was negative. 

A PET Scan revealed a metabolic pattern consistent with autoimmune encephalitis and globally diminished metabolism in the cerebellum, which persisted on follow up PET approximately five months later. Currently, he is undergoing a trial of rituximab and scheduled IVIG. Trials of dalfampridine and clonazepam for his nystagmus have not provided lasting improvement of his oscillopsia and vertigo. Approximately six months after his initial imaging, repeat MRI brain demonstrated mild caudal, vermian, and medial cerebellar hemispheric volume loss.