CSF myelin basic protein is a test to measure the level of myelin basic protein (MBF) in the cerebrospinal fluid, the clear liquid that surrounds the brain and spinal cord.

MBP is found in the material that covers your nerves.

The health care provider will place a needle into the lower spinal area and take a sample of cerebrospinal fluid. This is called a spinal tap or lumbar puncture. 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.

For detailed information, see the article on lumbar puncture.

This test is done to see if myelin, the substance covering your nerves, is breaking down. Myelin breakdown is called demyelination. Multiple sclerosis is the most common cause for this, but other causes may include:

• Bleeding of the central nervous system
• Brain diseases (encephalopathies)
• Central nervous system trauma
• Infection of the central nervous system
• Stroke

Normal values vary depending on the lab, but in general there should be less than 4 ng/mL of myelin basic protein in the cerebral spinal fluid.

Note: ng/mL = nanogram per milliliter

Myelin basic protein levels between 4 and 8 ng/mL may be a sign of a chronic breakdown of myelin, or recovery from an acute episode of myelin breakdown.

If the myelin basic protein levels are greater than 9 ng/mL, myelin is actively breaking down.

Risks of lumbar puncture include:

• Allegic reaction to the anesthetic
• Discomfort during the test
• Headache after the test
• Bleeding into the spinal canal
• Damage to the nerves in the low back (particularly if the person moves during the test )
• 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.

Cisternal puncture or ventricular puncture are tests done in other areas of the spine or brain. Both procedures carry additional risk of damage to the brainstem or brain tissue and risk of bleeding within the brain.