What is cerebrospinal fluid (CSF)?
Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds the brain and spinal cord. Its primary function is to cushion the brain within the skull and serve as a shock absorber for the central nervous system. But CSF also circulates nutrients and chemicals filtered from the blood and removes waste products from the brain. Changes to cells and atypical cells in the CSF can be evidence of damage or other issues in the central nervous system. CSF analysis is one of several tools for diagnosing MS, in addition to a medical examination, evaluation and MRI.
Cerebrospinal fluid in people with multiple sclerosis
In MS, damage to myelin causes certain types of proteins to be released into the spinal fluid. When these proteins are identified in the spinal fluid but not in the blood, MS is thought to be one of the possible diagnoses.
How is a lumbar puncture done?
Spinal fluid is obtained through a lumbar puncture (also known as a spinal tap). Your doctor would perform it in their clinic. For this procedure, you lay on your side or bend forward while seated. The doctor cleans an area of your lower back and injects a numbing medicine. They then insert a needle and use a syringe to remove a small amount of spinal fluid, which they send for testing.
High protein levels in spinal fluid: A potential indicator of multiple sclerosis
The CSF of people with MS usually contains:
- A specific group of proteins called oligoclonal bands
- Elevated CSF protein levels
These findings indicate an abnormal immune response within the central nervous system and may be suggestive of MS. Oligoclonal bands indicate inflammation of the central nervous system. In MS, inflammation does much of the damage that causes MS symptoms.
It is important to know that an abnormal immune response in the CSF is found in other diseases so the test is not specific for MS. In people with a confirmed diagnosis of MS, 5-10% do not show abnormalities in the CSF. Therefore, CSF analysis by itself cannot confirm or exclude an MS diagnosis. Your MS care provider will consider the results along with your medical history, a neurological examination, MRI and tests to rule out other conditions to make an accurate diagnosis.
Learn more about how MS is diagnosed.