Indications and Diagnostic Findings in Cerebrospinal Fluid (CSF) Analysis for Meningitis

Introduction

Meningitis is a serious medical condition characterized by inflammation of the meninges, often caused by infectious agents. Cerebrospinal fluid (CSF) analysis plays a crucial role in diagnosing meningitis by differentiating between bacterial, viral, fungal, and other causes.

Indications for CSF Analysis

• Suspected meningitis (fever, headache, neck stiffness, altered mental status)
• Evaluation of neurological symptoms of unknown origin
• Monitoring of known CNS infections or inflammatory conditions
• Detection of malignancies involving the central nervous system

Normal vs Abnormal CSF Parameters

Normal CSF Parameters

• Appearance: Clear and colorless
• Opening Pressure: 6-20 cm H₂O
• White Blood Cell Count (WBC): <5 cells/µL
• Protein: 15-45 mg/dL
• Glucose: 50-80 mg/dL (or ~2/3 of blood glucose level)
• Culture: No growth of microorganisms

Abnormal CSF Findings in Meningitis

Type	Appearance	WBC	Protein	Glucose	Culture
Bacterial Meningitis	Cloudy/Purulent	High (>1000 cells/µL)	Elevated (>100 mg/dL)	Low (<40 mg/dL)	Positive for bacteria
Viral Meningitis	Clear/Cloudy	Moderate (10-100 cells/µL)	Normal/Slightly elevated	Normal	Negative
Fungal/Tubercular Meningitis	Cloudy	Moderate (<500 cells/µL)	High (>100 mg/dL)	Low	Positive for fungal/TB organisms

Conclusion

CSF analysis remains the cornerstone of meningitis diagnosis, providing critical insights into its etiology and guiding treatment decisions. Prompt evaluation of CSF parameters enables accurate differentiation between infectious causes and appropriate therapeutic interventions.