Abstract: Objective To explore the method to diagnose tuberculous meningitis(TBM) at earlier period. Methods The level of ADA and anti-TB antibodies in cerebrospinal fluid(CSF) of patients with TBM was determined by the biochemical Methods and ELISA. Results The level of ADA in CSF of all patients suffering from TBM increased markedly compared with those from the patients with viral meningitis(P<0.05) and the normal(P<0.01).The positive ratio of anti-TB antibody was 80.4% in the early stage of diseases,and 100% at the following clinical observation,but negative in all patients with viral meningitis and all normal controls. Conclusion The elevation of ADA level and the positive PPD-IgG in CSF of patients might be helpful to diagnose TBM.

Key words: Tuberculous Meningitis, Cerebrospinal Fluid, Adenosine Deaminase, Viral Menigitis, PPD-IgG