Abstract: Objective To analyze the results of laboratory examination in cerebrospinal fluids of the patients with syphilis and explore the significance of laboratory detection for the diagnosis of neurosyphilis. Methods The data of cerebrospinal fluids (CSF) examinations of 41 inpatients were retrospectively analyzed for TRUST, TPPA, CSF, biochemical markers and IgG from 2015 to 2016. Results Thirteen cases of neurosyphilis were definitely diagnosed, 4 cases were suspected of neurosyphilis, and 24 were excluded. Positive TRUST of CSF were found in 9 cases and positive TPPA were noted in 17 cases. The number of CSF leukocytes increased (>10×106/L) in 3 cases (3/13) and the level of abnormal proteins elevated (>0.6g/L ) in 7 cases (7/13). Eleven cases（11/13） had increased level of IgG (>34mg/L). No significant changes of glucose and chloride were found compared with the non-neurosyphilis group. Conclusion Early neurosyphilis is asymptomatic and easy to be misdiagnosed. Early CSF examination is recommended for timely treatments of neurosyphilis in suspected cases.

Key words: Cerebrospinal fluid , Neurosyphilis , TRUST, TPPA, IgG antibody