Normally, cerebrospinal fluid (CSF) should contain very few, if any, blood cells.
In healthy individuals, CSF ideally contains no red blood cells (RBCs). A small number of white blood cells (WBCs), typically less than 5 per cubic millimeter, is considered normal. The presence of RBCs or an elevated number of WBCs in CSF can indicate an underlying medical condition requiring further investigation.
Here's a breakdown:
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Red Blood Cells (RBCs): The presence of RBCs in CSF is abnormal and often suggests bleeding into the subarachnoid space. This could be due to:
- Traumatic tap: Accidental puncture of a blood vessel during the lumbar puncture procedure.
- Subarachnoid hemorrhage: Bleeding from an aneurysm or arteriovenous malformation.
- Intracerebral hemorrhage: Bleeding within the brain tissue that has extended into the ventricles.
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White Blood Cells (WBCs): A slightly elevated number of WBCs (pleocytosis) can indicate:
- Infection: Meningitis (bacterial, viral, or fungal) or encephalitis.
- Inflammation: Autoimmune disorders or inflammatory conditions affecting the central nervous system.
- Neoplastic disease: Cancer involving the meninges.
In summary, while a very small number of WBCs can be considered normal, the presence of RBCs in CSF is generally considered abnormal and warrants further medical evaluation.
