Abstract
We report a case of either brainstem encephalitis or cerebellitis, featuring ocular flutter and truncal ataxia. A 33-year-old man visited our hospital complaining of nausea and vomiting whenever he changed his head position. No positional or positioning nystagmus was observed. Over the next few weeks, ocular flutter which was sometimes accompanied by shivering movements in his head and symptoms of truncal ataxia rapidly progressed. The lymphocyte in the CSF increased, but no lesion was found on brain MRI. After steroid pulse, anti-virus and antibiotic therapies were administered, these symptoms all resolved without sequelae within 3 months. All the observed abnormalities in eye movements in this case were considered to be related to the saccadic eye movements. The neurophysiological basis of saccades suggested that either the pontine pause neuron itself or the cerebellar fastigial nuclei that affect the pause neuron function might have been responsible for the ocular flutter and other related abnormalities in this case.
