Tubercular Meningitis: Clinical Profile And Validation Of Thwaites Diagnostic Criteria

Back ground Tubercular meningitis (TBM) has protean manifestations and there is no gold standard test. Thwaites criteria help in differentiating pyogenic meningitis from tubercular meningitis. The main objective was to study the clinical profile and validate Thwaites diagnostic criteria. Methods The case records of all patients admitted for TBM irrespective of all age and gender for the past three years were obtained from the medical record department using International Classification of Diseases code A170 G01. From each medical case file, the patient's demographics, clinical features, medication and medical history, physical findings, radiographs and reports of biochemical laboratory investigations and other investigation were extracted. Thwaite's diagnostic criteria were used to calculate the diagnostic index score. Data were analyzed using SPSS 20.0 version Results A total of 95 patients were diagnosed with TBM and 61(64.2%) were males. The mean age was 35.3 ±17.3 years. Thwaite's diagnostic criteria were used to calculate the diagnostic index score for TBM, in which out of 95 patients 91(95.8%) scored <4 indicating TBM and 4 (4.2%) scored >4 indicating bacterial meningitis respectively. Among the study population 63 (66.3%) were diagnosed at earlier stage and in 32 (33.7%) the diagnosis was delayed. Forty (42.1%) patients were in BMRC stage I (early -lasts up to 2 weeks), 27 (28.4%) were in stage II (intermediate -lasts from days to weeks) and 28 (29.5%) were in stage III (advanced). Head ache is the most common symptom (68.4%). Characteristic features at presentation include fever 17(17.9%), meningismus 53(55.8%), cranial nerve palsy 7(7.4%) and Monteux positivity in 3 (3.2 %). Neuroimaging showed hydrocephalus in 24(25.3%) patients. In this analysis the true positivity rate for Thwaites is found to be 0.96 and for Ahujas 0.62."KAPPA" measure of agreement showed Kappa statistic =0.07, p=0.298. We observe Poor agreement between Thwaites and Ahuja criteria. Conclusion: Our results show poor correlation between Ahuja's and Thwaites Criteria in diagnosing Tubercular meningitis and more number of cases could be diagnosed when Thwaites diagnostic criteria are applied. TBM can present with many protean clinical manifestations and a high index of suspicion is warranted to diagnose TBM. Thwaites criteria have high specificity and are useful in Indian setting.