Neurosyphilis

Neurosyphilis is an infection of the central nervous system by Treponema pallidum that can occur at any stage of syphilis. It may present with or without symptoms and can involve the brain, spinal cord, or meninges. Diagnosis relies on serologic testing and cerebrospinal fluid analysis to detect CNS involvement.

Neurosyphilis can be asymptomatic or manifest with neurologic or neuropsychiatric symptoms. Risk increases in untreated syphilis and in people with HIV. Onset can be early, within months of infection, or late, years after initial exposure.

Clinical forms include asymptomatic neurosyphilis (CSF abnormalities without symptoms), meningovascular syphilis (headache, meningitis, stroke-like deficits), tabes dorsalis (dorsal column dysfunction with ataxia and lancinating pains), and general paresis (progressive cognitive decline and psychiatric symptoms). Ocular and otic syphilis may occur and require assessment of vision and hearing.

Diagnosis combines CSF and serum testing. A CSF VDRL test is highly specific for neurosyphilis, though it may lack sensitivity; CSF cell count and protein are often elevated, with normal glucose. CSF can be supplemented by treponemal tests such as FTA-ABS or TP-PA. Serum testing typically uses non-treponemal tests (RPR or VDRL) for screening and treponemal tests for confirmation. HIV status can influence presentation and interpretation of results.

Treatment is intravenous penicillin G: 18-24 million units per day, given as 3-4 million units IV every 4 hours or by continuous infusion for 10-14 days. Penicillin allergy requires desensitization; alternatives like ceftriaxone have limited evidence. After treatment, CSF examination is often repeated every 6 months until abnormalities resolve, and serologic titers are monitored to gauge response.

Prognosis varies; some deficits improve with treatment, while others may persist. Early diagnosis and appropriate therapy are essential for better outcomes.