How the Test is Performed

A sample of CSF is needed. A lumbar puncture (spinal tap) is the most common way to collect this sample. For information on this procedure, see the article on lumbar puncture.

Other methods for collecting CSF are rarely used, by may be recommended in some cases. They include:

• Cisternal puncture
• Ventricular puncture
• Removal of CSF from a tube that is already in the CSF, such as a shunt or ventricular drain.

After the sample is taken, it is sent to a laboratory for evaluation.

How to Prepare for the Test

See: Lumbar puncture

How the Test Will Feel

See: Lumbar puncture

Why the Test is Performed

The CSF cell count may help diagnose meningitis and infection of the brain or spinal cord, a tumor, abscess, or area of tissue death (infarct), and it helps identify inflammation. The cell count may also help identify bleeding in the spinal fluid.

Normal Results

The normal white blood cell count is between 0 and 5. The normal red blood cell count is 0.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What Abnormal Results Mean

An increase of white blood cells indicates infection, inflammation, or bleeding into the cerebrospinal fluid. Some causes include:

• Abscess
• Encephalitis
• Hemorrhage
• Meningitis
• Multiple sclerosis
• Other infections
• Stroke
• Tumor

Finding red blood cells in the CSF may be a sign of bleeding. However, red blood cells in the CSF may also be due to the spinal tap needle hitting a blood vessel while entering the skin or dura.

It is important to see if the red blood cell count returns to normal in samples taken later in the procedure as opposed to earlier. A ratio of the red blood cells to the white blood cells is also calculated to help with diagnosis.

Additional conditions which this test may help diagnose include:

• Arteriovenous malformation (cerebral)
• Cerebral aneurysm
• Delirium
• Dementia
• Guillain-Barre syndrome
• Hemorrhagic stroke
• Neurosyphilis
• Primary lymphoma of the brain
• Seizure disorders, including epilepsy
• Spinal tumor
• Stroke secondary to syphilis
• Syphilitic aseptic meningitis
• Syphilitic myelopathy

Risks

Risks of lumbar puncture include:

• Allergic reaction to the anesthetic
• Discomfort during the test
• Headache after the test
• Bleeding into the spinal canal
• Infection

Brain herniation may occur if performed on a person with a mass in the brain such as a tumor or abscess. This can result in brain damage or death. For this reason, a lumbar puncture is not done if other tests show signs of a tumor or abscess.

There may be temporary leg discomfort if a nerve root is irritated by the needle. This passes when the needle is withdrawn.

References

Griggs RC, Jozefowicz RF, Aminoff MJ. Approach to the patient with neurologic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier. 2007: chap 418.

Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 2008:chap 63.

Update Date: 4/30/2012

Reviewed by: Kevin Sheth, MD, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine;David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.