Early Diagnosis Of Tuberculous Meningitis

Background: Tuberculous meningitis(TBM) is an infectious disease of the central nervous system caused by mycobacterium tuberculosis. It accounts for about 50 percent of tuberculosis. The most common involvements are meningeal and parenchymal. More over, spinal cord and meninges can be also involved. The disease often occur secondary to miliary tuberculosis and tuberculosis outside the central nervous system and the susceptible populations are children and HIV-infected persons. Tuberculosis which had been called “white plague” in 1950 s was a killer of harm to people’s health and was considered to have been conquered in 1980 s. Reemergence of tuberculosis according to “disease death map” has become to the new challenge. The key question is early diagnosis. But the early clinical presentation of tuberculous meningitis is non-spectific which may lead to misdiagnosis, delayed treatment and drug resistance. TBM that can bring huge burden to both family and country is often associated with severe neurological sequelae and even high mortality rates. In addition, even treated promptly to patients with drug resistance, we still can’t evaluate the effects and guide the clinicals with better treatments to patients. In all, early, accurate and rapid diagnosis is the most important factor to reduce mortality and morbidity and it is the urgent need of prevention and treatment of tuberculosis. Over the years, domestic and overseas scholars always devote themselves to TB diagnosis. Although great strides have been made in our understanding of tuberculous meningitis, there are still many questions. The best way to improve survival is early diagnosis and treatment. An international tuberculous meningitis workshop established a consensus case definition for tuberculous meningitis for use in future clinical research in South Africa, in May, 2009. A diagnosis of definite tuberculous meningitis should be made when one or more of the following criteria are met according to the uniform case definition: Acid fast bacilli seen in the cerebrospinal fluid, M tuberculosis cultured from cerebrospinal fluid, or cerebrospinal fluid M tuberculosis positive by commercial nucleic acid amplification test.Part Ⅰ Applying the new consensus case definition to tuberculousmeningitisObjective: To evaluate the new consensus case definition to tuberculous meningitisMethods: A total of 175 outpatients and inpatients were enrolled in this study between January 2012 and October 2013 from department of Neurology, the Second Hospital of Hebei Medical University. The case group were 117 cases and the control group were 38 cases. We retrospectively analysed 117 cases of patients in case group and the patients were defined as definite, probable, possibel and not tuberculous meningitis according to the case definition. Then we compared the result with the modified acid fast stainning. A case-control study was adopted between case group and control group to compare the relationship of parameters in the diagnostic score and the diagnosis of tuberculosis. We used multivariate logistic regression to look for dependent of influential factors.Results:(1) Group situationThere were 29 definite cases, 28 probable cases, 50 possible cases and none not tuberculous meningitis.(2) Comparison of each group by acid fast stainThere were 29 cases tested positive in definite group, 22 cases in probable group and 56 cases in possible group. The positive rate was 91.5% in the case group. A large difference was observed among the three groups(P<0.05).(3) Single factor analysisThe following variables showed a large difference between case group and control group: symptom duraion of more than 5 days, cranial nerve palsy, cells of cerebrospinal fluid: 10-500 per ul, lymphocytic predominance(50%), protein concentration greater than 1 g/L, cerebrospinal fluid to plasma glucose ratio of less than 50% or an absolute CSF glucose concentration less than 2.2 mmol/L, tuberculoma, infarct and CT/MRI/ultrasound evidence for tuberculosis outside the central nervous system.(4) Multivariable analysisNine variables were analyzed by logistic regression and the following fouor variables were enrolled in the prediction model: symptom duraion of more than 5 days, cells of cerebrospinal fluid: 10-500 per ul, protein concentration greater than 1 g/L and cerebrospinal fluid to plasma glucose ratio of less than 50% or an absolute CSF glucose concentration less than 2.2 mmol/L. The model: Y=-42.166+39.768(cells of cerebrospinal fluid: 10-500 per ul)+20.251(protein concentration greater than 1g/L)+19.858(cerebrospinal fluid to plasma glucose ratio of less than 50% or an absolute CSF glucose concentration less than 2.2 mmol/L)+4.007(symptom duraion of more than 5 days). The model accurately predicted 96.6% of the cases with tuberculous meningitis and 97.4% of the cases with viral meningitis.Conclusion: The new consensus case definition to tuberculous meningitis has good predictability, the system could provide reliable basis for early diagnosis of TBM. Part Ⅱ Prediction of cerebrospinal fluid parameters for tuberculousmeningitisObjective: The measurement of cerebrospinal fluid parameters can provide early information for diagnosis. The present study focus on the validity of the cut-off value of cerebrospinal fluid parameters according to the Lancet consensus of scoring system for diagnosis of tuberculous meningitis.Methods: A total of 100 confirmed patients were enrolled in this study. We evaluated significance of protein level(>1g/l), chloride level(<120 mmol/l), glucose level(<2.2mmol/l), cell counts(10-500cells/μl, lymphocytic pleocytosis(>50%) and neutrophil predominance(>50%) in early diagnosis of tuberculous meningitis.Results: The cerebrospinal fluid parameters were significantly different between the tuberculous meningitis group and the control group. The independent factors for diagnosis of tuberculous meningitis were protein level(>1g/l), glucose level(<2.2mmol/l), cell counts(10-500cells/μl and neutrophil predominance(>50%). Neutrophil predominance(>50%) performed the best with the area under the curve of 89.7%. The sensitivity of protein level(>1 g/l), glucose level(<2.2 mmol/l), cell counts(10-500 cells/μl) and neutrophil predominance(>50%) for diagnosis of tuberculous meningitis were 66%, 58%, 86% and 54%, and the specificity were 84%, 98%, 32% and 98%. There are 84% patients in tuberculous meningitis group at least having 2 positive parameters among the four independent parameters, while only 10% in control group.Conclusion: The cerebrospinal fluid parameters can help the clinicians to make a prompt diagnosis in the early stage of the disease. Part Ⅲ Application of fluorescence microscopy for Ziehl-Neelsen stainingin the diagnosis of tuberculous meningitisObjective: To improve the detection rate of traditional Ziehl-Neelsen stainning and establish an effective and convenient method for early diagnosis of tuberculous meningitis.Methods: Outpatients and inpatients that were diagnosed as tuberculous meningitis were enrolled in this study between January 2012 and January 2014 from department of Neurology, the Second Hospital of Hebei Medical University. All the patients were scored according to diagnostic criteria. The control group contained patients with non tuberculous meningitis. Each cerebrospinal fluid specimen was observed successively under transmission light and under the green excitation wavelength and then recorded the results.Results:(1) General conditionA total of 99 cases with 219 specimens were enrolled in this study. There were 27 definite TBM cases with 104 smears, 22 probable TBM cases with 39 smears, 50 possible TBM cases with 76 smears. 68 TBM patients were classified as stage 1(less than one month), the other 31 patients as stage 2(one month and more). In control group there were 56 cases with 56 specimens.(2) Micrographs of AFB obtained with the two methodsThe fuchsin-stained AFB showed red, lightly curved rods or bulbiform against a blue backgroud under transmission light or bright orange-red fluorescing rods agnist a black backgroud under fluorescence. We also identified intracellular M. tuberculosis in the neutrophils, monocytes and lymphocytes.(3) Comparision of light microscopy and fluorescence microscopyA total of 52 CSF samples which were identified as TBM with 44 CSF samples were tested positive under transmission light while 50 were tested positive under fluorescence. Hence, the sensitivity of fluorescence microscope(FM) was 96.2% while that of light microscopy(LM) was 84.6%(P<0.05). The positive predict value was 89.3%.There were 56 specimens in control group, 6 samples tested positive, so the specificity of FM was 89.3%. The negative predict value was 96.2%.When analyzed by all the samples, the positive rate was 67.6% with LM observation, while 78.5% with FM observation(P<0.05). When analyzed by patients, the LM observation showed a positivity of 82.8%, whereas the FM observation showed a positivity of 90.9%(P<0.05).(4) Comparison of the disease duration prior to hospitalization and the positive rate of fluorescence microscopyThe positive rate of samples in stage 1 was 86.8% by LM observation, while it was 95.6% by FM observation. In stage 2, the positive rate of FM and LM observation was 77.4% and 77.4% respectively. The positive rate between FM and LM was significantly different in stage 1.(P<0.05) But there was no statistically significant difference in stage 2.The positive rate of FM observation between stage 1 and stage 2 was also significantly different(P<0.05).Conclusion: Fluorescence microscopy for Ziehl-Neelsen staining should be an effective, rapid and convenient method for early diagnosis of tuberculous meningitis, specimens should be inspected as early as possible and more than once to improve the detection rate. Part Ⅳ Application of Gene Xpert MTB/RIF in the diagnosis oftuberculous meningitisObjective: To investigate Gene Xpert MTB/RIF in the diagnosis of tuberculous meningitis.Methods: A total of 92 outpatients and inpatients in the case group that were diagnosed as tuberculous meningitis were enrolled in this study between January 2012 and January 2014 from department of Neurology, the Second Hospital of Hebei Medical University. There were 30 cases in the control group. All the cerebrospinal fluid samples were tested by Xpert MTB/RIF. The results were compared with clinical diagnosis, traditional PCR and modified acid fast staining.Results:(1) Of all 92 patients, 82 cases tests positive by modified acid fast staining, 11 cases tests postive by Xpert MTB/RIF. 57 cases were examined using traditional PCR and 18 of them tested positive. 30 cases were all tested negative by Xpert MTB/RIF in the control group.(2) The sensitivity of Gene Xpert MTB/RIF was 12.0%(n=11/92) against clinical diagnosis. 7 cases were tested positive in the definite group, 4 cases in probable group and none in the possible group.(3) The sensitivity of Gene Xpert MTB/RIF was 13.4%(n=11/82) against modified acid fast staining.(4) The sensitivity of Gene Xpert MTB/RIF was 61.1%(n=11/18) against traditional PCR.(5) Compared the results of Xpert MTB/RIF with modified acid fast staining, there was no significantly different(P>0.05). The sensitivity of Xpert MTB/RIF was significantly lower than the sensitivity of traditional PCR(P<0.05). Conclusion: Xpert MTB/RIF can be served as “gold standard” in diagnosis of tuberculous meningitis, but the sensitivity is low. We should optimize the treating processes of the specimens and improve the applicationin early diagnosis.Conclusion: Xpert MTB/RIF can be served as “gold standard” in diagnosis of tuberculous meningitis, but the sensitivity is low. We should optimize the treating processes of the specimens and improve the applicationin early diagnosis.