The Role of CSF LDH Estimation to Differentiate Different Types of Meningitis: A Cross Sectional Study

Introduction: Meningitis is a medical condition in which the meninges become inflamed.

Meningitis is a medical, neurologic, and sometimes neurosurgical emergency that necessitates a multidisciplinary treatment plan. Anatomically, meningitis is classified into two types: pachymeningitis (inflammation of the dura), which is less common, and leptomeningitis (inflammation of the arachnoid and subarchanoid space), which is more common.The key to a good outcome is early and accurate diagnosis. The cerebrospinal fluid examination is the cornerstone of diagnosis. Total count, differential count, protein, sugar, gramme staining culture and sensitivity, AFB staining, and in some cases, CSF ADA and Tuberculous RNA PCR are all part of the cerebrospinal fluid study. Other tests, such as CSF lactate, C-Reactive Protein, SGOT, glutamate level, and Lactate Dehydrogenase, may be performed (LDH). Though CSF abnormalities in meningitis is well documented, only few studies have been conducted in our part of the world. This study is conducted to know the role of CSF LDH to differentiate different types of meningitis.

Materials and Methods: This was a cross-sectional analysis conducted in a hospital.During the months of April 2012 and March 2013, all patients admitted to a tertiary care centre in South Kerala with recorded clinical and biochemical evidence of meningitis (viral, bacterial, or tuberculous) were included. After getting informed consent from Patients after applying inclusion and exclusion criteria, those fulfilling all the inclusion criteria were subjected to detailed evaluation, Lumbar puncture (for CSF collection and analysis of CSF) was done.

Patients were classified into four classes based on the criteria: viral, bacterial, tuberculous, and partially treated meningitis. The amount of LDH in the CSF was tested to see whether there was a connection to the diagnosis. The mean LDH level in different forms of meningitis was compared using the unpaired T test. The Chi square test was used to verify the association.

Observations: This study involved 180 patients, 111 of whom were males and 69 of whom were females. In bacterial and viral meningitis, the majority of patients were younger, ranging in age from 31 to 40 years, while in tuberculous meningitis, the majority of patients were older, ranging in age from 61 to 70 years. Among the total 180 patients,33% were categorized as bacterial, 33% as viral, 4.44% as tuberculous and 28.88% as partially treated meningitis according to the study definitions. The average white blood cell count of the CSF among patients with bacterial meningitis was 613,tuberculous meningitis was 656,and in viral meningitis was 101cells /mm3 .In the bacterial community, the differential count was mostly polymorphs, while in the other groups, it was mostly lymphocytic. The average CSF protein in the bacterial meningitis group was 102.4 mg/dl, 33.6 mg/dl in the viral meningitis group, 89.4 mg/dl in the tuberculous meningitis group, and 75.47 mg/dl in the partially treated group. The average CSF sugar value in bacterial meningitis was 29.5 mg/dl, 68.4 mg/dl in viral meningitis, 23.3 mg/dl in Tuberculous meningitis, and 43.03 mg/dl in the partially treated community. The average ADA value in the bacterial meningitis group was 6.4, 4.8 in the viral meningitis group, and 20 in the tuberculous meningitis group. We noticed that the tuberculous category had the highest average ADA value. Among the 18 tuberculous patients, 17 had an ADA of more than 15. The average CSF LDH value was 94.1 IU/L in bacterial meningitis group, 30.2 IU/L in viral meningitis group &119.9 IU/L in tuberculous meningitis group. Out of the 72 patients who had viral meningitis in our study,18 (25%) had JE/WEST NILE virus positivity. This high frequency of encephalitis was not observed in other studies, which indicates a high frequency of JE in our part of the world. In those tested positive for JE, the CSF LDH was significantly high. We had 52 (28.88%) patients in the partially treated meningitis group. Among this 34 had features of bacterial &6 had features of tuberculous meningitis. The CSF LDH value was significantly elevated in these two catogories. Rest of the12 patients with features suggestive of viral meningitis only had a mild elevation of LDH. The mean CSF LDH in viral meningitis & tuberculous meningitis group were 77.2 & 22.5 % respectively.

Conclusion: CSF LDH was significantly elevated in Tuberculous meningitis and bacterial meningitis. In viral meningitis, CSF LDH showed only a mild elevation. Viral meningitis with increased CSF LDH were positive for JE. Hence in Viral meningitis with high LDH should raise suspicion of encephalitis.