Eosinophil Count in Cerebrospinal Fluid (CSF)

Why Is This Test Done?

Your doctor may order this test if you have symptoms like headaches, neck stiffness, seizures, or neurological problems that suggest an infection, inflammation, or other condition affecting the brain or spinal cord. It can help identify causes like meningitis, eosinophilic granulomatosis with polyangiitis (EGPA), or parasitic infections.

What Does a High or Low Count Mean?

Elevated eosinophil counts in CSF are often associated with certain infections (e.g., fungal meningitis), autoimmune diseases, or parasitic infections. Very low counts may suggest normal immune response or conditions like Guillain-Barré syndrome, though this is less common. Interpretation depends on clinical context and other test results.

How Is the Test Performed?

A small amount of CSF is collected through a procedure called lumbar puncture (spinal tap). The sample is then analyzed in a lab to count eosinophils. This test is typically done alongside other CSF tests (like protein or glucose levels).

Preparation for the Test

No special preparation is needed. You may be asked to empty your bladder before the procedure. Avoid heavy lifting or strenuous activity for 24 hours afterward to reduce risk of complications.