When a 50-year-old man presented to doctors with trouble talking and walking for the past three months, they eventually discovered the cause was a rare, decades-old STI.

In addition to gait ataxia and cerebellar dysarthria, examination revealed the man also had uncontrolled eye movements and tremors.

The patient denied any high-risk sexual exposure, and considering his age, doctors entertained the idea of vitamin B12 deficiency, hypothyroidism, immune-mediated cerebellar ataxias, as well as chronic infectious diseases, such as fungal or TB infections of the CNS.

However, brain MRI showed mild cerebellar atrophy, which along with CSF abnormalities and positive syphilis serology, pointed to a diagnosis of neurosyphilis.