Lumbar puncture is the most important specific diagnostic procedure for detecting viral meningitis and to exclude other causes of meningitis. It is indicated for all suspected patients of viral meningitis. The CSF findings in case of viral meningitis include high glucose concentration, normal or slightly high protein, increased number of lymphocytes and lactates level of <2.1 mmol/l. CT scan should be done before lumbar puncture procedure in the immune deficient patient or patients with increased intracranial pressure.^[1][2]

Lumbar puncture is indicated in all pateints with strong suspicion of meningitis for the following reasons:^[3]

• To confirm the diagnosis
• To differentiate the different causes of meningitis
• To diagnose the specific causative agent for bacterial meningitis
• To start the appropriate treatment as early as possible to prevent complications

• High count of white blood cells (10-100 cells/µL)
• High glucose ratio (CSF/plasma) >0.6
• Normal protein level but may be slightly elevated
• Increased number of the lymphocytes > granulocytes
• Lactate levels <2.1

Contraindications of lumbar puncture include the following:^[3]

• Increased intracranial pressure
• Mass lesion such as tumour
• Thrombocytopenia
• Bleeding diathesis