The presence of red blood cells (RBCs) in cerebrospinal fluid (CSF) usually indicates bleeding, but it can also be caused by a traumatic spinal tap (lumbar puncture).
Potential Causes of RBCs in CSF
Here's a breakdown of the possible reasons for finding RBCs in CSF:
1. Subarachnoid Hemorrhage (SAH)
- This is the most serious cause and involves bleeding into the space surrounding the brain.
- Cause: Often caused by a ruptured aneurysm or arteriovenous malformation (AVM). AVMs are abnormal tangles of blood vessels in the brain.
- Other symptoms: Sudden, severe headache, stiff neck, vomiting, loss of consciousness.
2. Traumatic Lumbar Puncture ("Traumatic Tap")
- This occurs when the spinal tap needle damages a blood vessel during the procedure.
- Distinguishing Features:
- The amount of blood typically decreases from the first tube of CSF collected to the last.
- The CSF may clear as more fluid is collected.
- No xanthochromia (yellowish discoloration of the CSF), unless the tap was performed several hours after a bleed.
3. Intracerebral Hemorrhage
- Bleeding directly into the brain tissue can also result in RBCs entering the CSF.
- Cause: High blood pressure, trauma, aneurysms.
4. Arteriovenous Malformation (AVM)
- As referenced, a cerebral AVM can lead to bleeding, thus leading to RBCs in the CSF.
How to Differentiate Between Traumatic Tap and SAH
| Feature | Traumatic Tap | Subarachnoid Hemorrhage |
|---|---|---|
| Blood Amount | Decreases from first to last tube. | Remains consistent across tubes. |
| CSF Clarity | Clears as more fluid is collected. | Remains bloody or xanthochromic. |
| Xanthochromia | Absent (unless delayed tap after a real bleed) | Present (occurs hours after bleeding due to RBC breakdown). |
Importance of Diagnosis
Determining the source of RBCs in the CSF is crucial for appropriate treatment. If a traumatic tap is suspected, no further intervention is necessary. However, if SAH or another cause of bleeding is identified, immediate medical attention and treatment are required to prevent serious complications like brain damage or death.
