The health care provider will place a needle into the lower spinal area and take a sample of cerebrospinal fluid. The entire procedure takes about 20 minutes. For detailed information, see the article on lumbar puncture.

The fluid is sent to a lab, where it is examined under a microscope.

Under experienced hands there should not be any pain. There may be a feeling of pressure when the needle is inserted but with appropriate anesthetic, this should not hurt. Occasionally, some people may feel numbness shooting down the leg. This may be due to irritation of a nerve root.

Your doctor may order this test to help diagnose tumors, infection, inflammation of several groups of nerve cells, vasculitis, blood in the spinal fluid, or injury.

The normal protein range varies from lab to lab, but is typically about 15 to 45 mg/dL.

Note: mg/dl = milligrams per deciliter

When the protein level increases considerably, it may be a sign of a tumor, bleeding, nerve inflammation, or injury.

When the protein level decreases, it can mean your body is rapidly producing spinal fluid.

Additional conditions under which the test may be performed:

• Neuropathy, includingchronic inflammatory polyneuropathy
• Hemorrhage - subarachnoid

Risks of lumbar puncture include:

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

Brain herniation may occur if a lumbar puncture is done on a person with a mass in the brain (such as a tumor or abscess). This can result in brain damage or death. A lumbar puncture is not done if an exam or other tests show signs of a tumor or abscess.

Some persons have temporary leg numbness or tingling due to irritation of a nerve root by the needle.