Atypical late neurosyphilis presenting as status epilepticus: diagnostic and screening implications

Neurosyphilis is a serious complication of poorly treated syphilis due to Treponema pallidum invasion of the central nervous system. Symptoms vary from silent infection to severe neurological deficits. Despite progress in diagnostics and treatment, the diagnosis is frequently missed because it is not considered, particularly in atypical presentations and in patients with no evident risk factor. .

A 45-year-old man presented with confusion, speech difficulties, and left-sided weakness following subtle behavioral changes. In the emergency department, he had a witnessed focal-to-bilateral tonic-clonic seizure starting with head deviation to the left and tonic posturing of the left arm. Brain CT was normal, while MRI revealed right thalamic and bilateral temporal FLAIR hyperintensities with diffusion restriction in the thalamus. CSF showed mild pleocytosis (17 WBC/µL) and raised protein (67.6 mg/dL). Serum treponemal screening was positive with an RPR titre > 1:32. Neurosyphilis was confirmed by a reactive CSF non-treponemal test (RPR 1:2) in a patient with compatible clinical and CSF findings; the CSF TPHA titre was >1:10,240, which is supportive but not in itself a diagnostic criterion.Levetiracetam was started on admission and intravenous penicillin G on day 2, after the diagnosis was confirmed. Because EEG and MRI suggested possible focal status epilepticus, valproate and phenytoin were added. The patient developed respiratory failure needing mechanical ventilation and deep vein thrombosis. After extended ICU stay and rehabilitation, he recovered with mild residual critical illness myopathy and cognitive deficits.

Neurosyphilis is not intrinsically difficult to diagnose, provided it is considered, including outside the classically recognised risk groups such as men who have sex with men.