A cerebrospinal fluid (CSF) differential cell count is a laboratory test that determines the percentage of each type of white blood cell (WBC) present in a sample of CSF. This analysis helps distinguish between different types of infections and other conditions affecting the central nervous system.
Understanding the CSF Differential
The CSF is a clear fluid that surrounds the brain and spinal cord. It provides cushioning, transports nutrients, and removes waste products. Analyzing the cells within the CSF can provide valuable information about the health of the central nervous system.
The differential cell count specifically focuses on the different types of WBCs, which are key players in the immune response. The main types of WBCs found in CSF are:
- Neutrophils: These are typically the first responders to bacterial infections.
- Lymphocytes: These are commonly elevated in viral infections and some autoimmune conditions.
- Monocytes: These can be elevated in various conditions, including chronic infections and inflammation.
Normal CSF Differential Cell Count in Adults
In a healthy adult, the CSF differential typically shows:
- Lymphocytes: Approximately 70%
- Monocytes: Approximately 30%
- Neutrophils: Very few (ideally, 0%)
Interpreting Abnormal Results
An abnormal CSF differential cell count can indicate various conditions. Here are some examples:
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Increased Neutrophils: This often suggests a bacterial infection like bacterial meningitis. Elevated neutrophils can also be seen in tuberculous and fungal meningitis, amoebic encephalitis, tumors, and abscesses.
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Increased Lymphocytes: This can indicate a viral infection (e.g., viral meningitis), fungal infection, tuberculosis, or autoimmune disorders such as multiple sclerosis.
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Increased Monocytes: This can be seen in chronic inflammatory conditions, fungal infections, or tuberculosis.
The CSF differential cell count is usually interpreted in conjunction with other CSF tests, such as the total WBC count, protein levels, glucose levels, and Gram stain/culture, to arrive at a definitive diagnosis.
