CSF myelin basic protein

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Definition
CSF myelin basic protein is a test that measures the level of myelin basic protein in the cerebral spinal fluid (CSF). Myelin is a substance which covers the nerves and acts as an insulator. Without this insulation, information from nerves would be transmitted inefficiently which might result in weakness, sensory loss or other neurologic dysfunction.

Myelin basic protein (MBP) refers to one of the components found in myelin and is a marker of its presence. MBP is measured in the spinal fluid as to determine if there has been inflammation and myelin breakdown in the central nervous system.

How the test is performed

A lumbar puncture (spinal tap) is the most common means of collecting a specimen of CSF. You are positioned on your side with your knees curled up to your abdomen and your chin tucked in to your chest. (Occasionally, this procedure is performed with the person sitting bent forward).

The skin is scrubbed, and a local anesthetic is injected over the lower spine. The spinal needle is inserted, usually between the 3rd and 4th lumbar vertebrae. Once the needle is properly positioned, the fluid pressures can be measured and fluid can be collected.

After the sample is collected, the needle is removed, the area is cleaned, and a bandage is applied. You will be asked to remain flat, or nearly flat, for 6 to 8 hours after the test. The sample of at least 3 cc is taken immediately to the laboratory for evaluation.

How to prepare for the test
Be prepared to sign a consent form and to remain in the hospital for at least the 6 to 8 hours after the test (you must remain flat).

Testing infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

• Infant test or procedure preparation (birth to 1 year)
  
• Toddler test or procedure preparation (1 to 3 years)
  
• Preschooler test or procedure preparation (3 to 6 years)
  
• School age test or procedure preparation (6 to 12 years)
  
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel

The curled position may be uncomfortable, but you must remain still to avoid moving the needle and possibly injuring the spinal cord.

The scrub will feel cold and wet. The anesthetic will sting or burn when first injected. There will be a hard pressure sensation when the needle is inserted, and there is usually some brief pain when the needle goes through the covering of the spinal cord. This pain should stop in a few seconds.

Overall, discomfort is minimal to moderate. The entire procedure usually takes about 30 minutes, but it may take longer. The actual pressure measurements and fluid collection only take a few minutes.

Why the test is performed
This test is performed to determine if your nervous system shows active myelin breakdown. Multiple sclerosis is the most common cause for myelin breakdown (demyelination), but other causes may include:

• Encephalopathies
  
• Stroke
  
• Central nervous system hemorrhage
  
• Central nervous system trauma

Normal Values
There should be less than 4 ng/ml of myelin basic protein in the cerebral spinal fluid.

Note: ng/ml = nanogram per milliliter

What abnormal results mean
Myelin basic protein levels between 4 and 8 ng/ml may indicate a chronic breakdown of myelin, or recovery from an acute episode. If the myelin basic protein levels are greater than 9 ng/ml, active demyelination is occurring.

What the risks are

• Risks of lumbar puncture include:
  o Hypersensitivity (allergic) reaction to the anesthetic
  o Discomfort during the test
  o Headache after the test
  o Bleeding into the spinal canal
  o Brain herniation (if performed on a person with increased intracranial pressure) resulting in brain damage or death
  o Damage to the spinal cord (particularly if the person moves during the test)

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.

Special considerations
This test should not be performed on people in which increased intracranial pressure is suspected.

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