A 38-year-old gentleman was admitted to an inpatient psychiatric unit with a first episode of fluctuating affective psychosis. He initially presented as manic although subsequently evolved a severe depressive episode, with prominent bizarre, affect-incongruent delusions throughout this period. Upon admission, anisocoria was evident, although this was attributed to a past head injury. Over the course of his admission he developed emergent Parkinsonism, initially ascribed to prescription of aripiprazole. Given his anisocoria and worsening Parkinsonism, further investigation was undertaken. While his MRI brain scan was unremarkable, his serum and CSF specimens tested positive for Treponema pallidum serology, and he was diagnosed with neurosyphilis. He was treated with a single dose of intramuscular penicillin, but experienced marked deterioration of neurological symptoms (paraparesis and truncal ataxia) and was transferred to the general hospital for an extended 14 day course of intravenous penicillin. Following this extended course of antibiotic therapy, resolution of neurological symptoms was seen, but no sustained improvement in residual psychotic symptoms has been seen.

This case demonstrates the potential neuropsychiatric consequences of neurosyphilis, and serves as a reminder of its potential to imitate other psychiatric presentations. This gentleman, and many like him, continue to experience severe and enduring psychopathology despite penicillin treatment when cases are detected late. Given the potential consequences of this, we would advocate assertive screening for syphilis in patients admitted to psychiatric units.

The authors have not supplied their declaration of competing interest.