<prompt> A 30 yr old person has fever headache from 20 days.CSF values is following: glucose 38 mgdl, protein 60 mgdl, lymphocytes pleocytosis with 20cells mm3. Initial lx should include:Indian ink smear of CSFAFBToxoplasmosisHSV detection  <response>: Ans: D HSV...-Most probable answer In Q pt is presented with feature of meningitis with normal glucose N value40-70 mgdl, normal slightly?ed protein N value 20-50mgdl lymphocytic pleocytosis So, most probably it is a case of viral meningitisIn Viral meninigitis, glucose remains normal, protein- slightly increased 20-80 mgdl lymphocytic pleocytosis 25-500 pi cellsHarrison 17th2621-27Patients with viral meningitis usually present with headache, fever, and signs of meningeal irritation coupled with an inflammatory CSF profileViral meningitis: The typical profile is a lymphocytic pleocytosis 25-500 cellsuL, a normal or slightly elevated pro tein concentration , a normal glucose concentration, and a normal or mildly elevated opening pressure 100-350 mmH2O. Organismsare not seen on Grams or acid-fast stained smears or India ink preparations of CSFThe typical CSF profile with viral CNS infections is a lymphocytic pleocytosis with a normal glucose concentration, in contrast to PMN pleocytosis and hypoglycorrhachia characteristic of bacterial meningitisUsing a variety of diagnostic techniques, inciuding CSF PCR, culture, and serology, a specific viral cause can be found in 75-90 of cases of viral meningitis. The most important agents are enteroviruses, HSVtype 2 HSV-2, and arbovirusesA CSFserum glucose ratio 0.4 is highly suggestive of bacterial meningitis but may also be seen in other conditions, inciuding fungal, tuberculous, and carcinomatous meningitis In cryptococeal meningitis, CSF examination usually reveals evidence of chronic meningitis with mononuclear ceil pleocytosis and increased protein levels. A particularly useful test is cryptococeal antigen CRAg detection in CSF and bloodDifferential Diagnosis of Viral MeningitisThe most important issue in the differential diagnosis of viral meningitis is to consider diseases that can mimic viral meningitis, including 1 untreated or partially treated bacterial meningitis; 2 early stages of meningitis caused by fungi, mycobacteria, or Treponema pallidum neurosyphilis, in which a lymphocytic pleocytosis is common, cultures may be slow growing or negative, and hypoglycorrhachia may not be present early; 3 meningitis caused by agents such as Mycoplasma, Listeria spp.. Brucella spp., Coxiella spp., Leptospira spp., and Rickettsia spp.; 4 parameningeal infections; 5 neoplastic meningitis; and 6 meningitis secondary to noninfectious inflammatory diseases, including hypersensitivity meningitis, SLE and other rheumatologic diseases, sarcoidosis, Behcets syndrome, and the uveomeningitic syndromesTable Harskmohan 6th876: CSF changes in Infection of CSSParameter Normal valuesBacterial MeningitisTubercu lous MeningitisViral MeningitisPressureRaisedRaisedRaisedGross appearanceTurbidClear may clotClearProtein Normal: 20-50 mgdLHighVery HighSlightly highGlucose 40-70 mg dLVery lowLowNormalChloride 116-122 pgdLLowVery LowNormalCells 5microlitNeutrophilsPlecoytosisLympho cytosisTUBERCULAR MENINGITISLu mho r pa flebu re is the cornerstone of diagno sis.In general, examination of the cerebrospinal fluid CSF reveals a high leukocyte count up to 1000pL, usually with a predominance of lymphocytes but sometimes with a predominance of neutrophils in the early stage; a protein content of 1-8 gL 100-800 mgdL; and a low glucose concentration. However, any of these three parameters can be within the normal range.AFB are seen on direct smear of CSF sediment in up to one- third of cases, but repeated lumbar punctures increase the yield. Culture of CSF is diagnostic in up to 80 of cases and remains the gold standard. Polymerase chain reaction PCR has a sensitivity of up to 80, but rates of false-positivity reach 10.The ADA concentration may be a sensitive test but has low specificity. Imaging studies CT and MRI may show hydrocephalus and abnormal enhancement of basal cisterns or ependyma. 