Abstract
Background
Neurosyphilis, a severe manifestation of syphilis caused by Treponema pallidum invasion into the central nervous system, exhibits diverse clinical subtypes. Detailed, subtype-specific analyses of neurosyphilis within regional populations are needed to complement broad epidemiological data.Methods
This retrospective cohort study analyzed 90 Human Immunodeficiency Virus (HIV)-negative neurosyphilis patients from a tertiary dermatosis hospital in Dalian, China (2023-2024). Demographic information and laboratory indicators were collected, and differences across subtypes (asymptomatic, meningeal, meningovascular, general paresis) of neurosyphilis were analyzed.Results
Asymptomatic neurosyphilis was the most prevalent subtype (46.67%, n = 42). The cohort was primarily composed of middle-aged patients (40-59 years, 63.33%, n = 57). Notably, 3.33% (n = 3) of patients were as young as 20-29 years (the youngest being 21 years old). most of whom had a low educational level (76.67%, n = 69) and were unemployed or inactive (66.67%, n = 60). Of the 90 patients, 5 (5.56%) presented with neurological symptoms, while the remaining 85 were identified through other means (incidental discovery, routine screening, or partner notification). Serum rapid plasma reagin (RPR) titers showed no significant differences among subtypes, and more than half of the patients (52.22%, n = 47) presented with titers ≤ 1:16. Additionally, cerebrospinal fluid (CSF) RPR titers and protein levels increased significantly with clinical severity, from the lowest in asymptomatic neurosyphilis to the highest in general paresis. A moderate positive correlation was observed between serum and CSF RPR titers.Conclusions
This study reveals a trend toward asymptomatic and younger-onset neurosyphilis, primarily observed in middle-aged, low-educated, and unemployed individuals. Most cases were detected incidentally or through screening rather than neurological symptoms, indicating a high risk of underdiagnosis. Furthermore, over half of the patients had serum RPR titers ≤ 1:16, suggesting that using a threshold of > 1:16 for lumbar puncture would miss more than half of the cases. CSF RPR and protein levels increased with clinical severity, highlighting their critical role in differential diagnosis.