Spinal Tap (or Lumbar Puncture)

Your brain and spinal cord are bathed in spinal fluid. A spinal tap, also called a lumbar puncture, is a procedure that removes fluid from your spinal canal. Tests on this fluid may help your doctor diagnose disorders of the brain and spinal cord, including multiple sclerosis.

The fluid, called cerebrospinal fluid (CSF), contains glucose (sugar), proteins, and other substances that are also found in the blood. Analysis of the fluid includes looking at the number and types of white blood cells (infection fighting cells), the level of glucose, the types and levels of various proteins (especially immune system proteins called antibodies or immunoglobulins), and testing for bacteria, fungus, or other abnormal cells.

How Does a Spinal Tap Assist in the Diagnosis of MS?

A spinal tap that reveals a large number of immunoglobulins (antibodies) as well as oligoclonal bands (the pattern of immunoglobulins on a more specific test) or certain proteins that are the breakdown products of myelin is suggestive of MS. These findings indicate an abnormal autoimmune response within the brain and spinal cord, meaning that the body is attacking itself.

Over 90% of people with MS have oligoclonal bands in their CSF. While increased immunoglobulin in the CSF and oligoclonal bands are seen in many other brain and spinal cord conditions, their presence is often useful in helping to establish a diagnosis of MS.

However, a "negative" spinal tap does not rule out MS or other diseases. An abnormal autoimmune response in CSF is found in a number of other diseases, so the test is not specific for MS. Conversely, some 5%-10% of people with MS never show these CSF abnormalities. Therefore, analysis of the CSF by itself cannot confirm or rule out a diagnosis of MS. It must be part of the total clinical picture that takes into account other diagnostic procedures such as evoked potentials and magnetic resonance imaging.

How Do I Prepare for the Test?

No preparation is needed unless your doctor gives you special instructions.

Discuss with your doctor stopping the use of alcohol, aspirin products, and anticoagulants prior to the test.

If you are allergic to latex or any medications, tell your doctor.