[Neurosyphilis with cerebellar ataxia, personality change and cognitive decline one year after onset of cerebral infarction].

A 51-year-old man with a cerebral lacunar infarction of the midbrain that had occurred two years before, was transferred from a regional psychiatric hospital with chronic progressive psychiatric symptoms including cognitive decline, irritability and hallucinations. Neurological examinations upon admission revealed cerebellar ataxia including dysarthria, ataxic gait and bilateral intention tremor. Brain FLAIR MRI on day 2 revealed abnormal hyperintense lesions in the bilateral insular cortex and temporal pole. Treponemal and non-treponemal specific antibodies were positive in both serum and cerebrospinal fluid (CSF), indicating a diagnosis of neurosyphilis. Treatment with intravenous penicillin (24 × 106 units/day × 28 days) improved his psychiatric symptoms, ataxia, imaging abnormalities and inflammatory CSF findings. Cerebellar ataxia is a rare symptom of neurosyphilis. Nonetheless, the possibility of neurosyphilis should be considered if a young adult ataxia accompanied by psychiatric symptoms.