Cerebrospinal Fluid Analysis

Cerebrospinal fluid (CSF) is a clear, colorless fluid produced in the brain. It surrounds the brain and spinal cord to provide cushioning and protection. It also contains glucose (sugar), proteins, and other substances found in the blood. This allows CSF to deliver nutrients to the brain and spinal cord. It also helps eliminate waste products from the brain.1

What is cerebrospinal fluid analysis?

Studying a small sample of CSF can be helpful in diagnosing a variety of neurological conditions. Doctors will look at the amount of protein and glucose in a person’s CSF. Red and white blood cells may also be present in CSF. The presence of these cells may help point toward specific conditions.

CSF is collected through a process called a lumbar puncture, sometimes called a spinal tap. A needle is inserted through the back and into the spinal column. A small sample of CSF can be pulled out into a container. This sample will then be taken to a lab for further analysis. As you can imagine, this process can be painful. In most cases, the person receiving a spinal tap will be awake. However, numbing medicine is used to reduce the pain.1-3

Is cerebrospinal fluid required to diagnose MS?

CSF is not required to diagnose MS. If a person’s symptoms are typical of MS, they have had multiple attacks of these symptoms and have lesions on brain imaging that show multiple areas of brain involvement over different periods of time. In this case, MS can be diagnosed without further testing. However, in some cases, all of these characteristics are not present.

Some people may have less common symptoms or belong to groups of people who would be less likely to have MS (like children). Others may have findings that seem like MS but could also point to other conditions. Since CSF can be helpful in pointing toward or away from certain issues, it may become an important test.1-4

What are the signs of MS in cerebrospinal fluid?

The immune system makes antibodies when there is inflammation. Antibodies are a type of protein that helps fight foreign invaders. In many autoimmune conditions, these antibodies mistakenly target healthy tissue. Examples of antibodies are proteins called IgG, IgA, and IgM, but there are others. When a person has MS, the levels of antibodies in their CSF may be increased.

If these antibodies are made in the central nervous system (CNS), they will not be found in the blood. The presence of these antibodies in the CSF but not the blood points toward a CNS issue like MS.1-3

What are oligoclonal bands?

CSF antibodies can be further studied through a process called electrophoresis. When a specific type of IgG antibody goes through this process, it will create oligoclonal bands (O-bands). O-bands may be present in 90 percent or more of those with MS. However, it is possible to have MS without O-bands.1-3

O-bands may also be present in other conditions, including but not limited to:1-3

  • Lupus
  • HIV
  • Certain types of meningitis
  • Tuberculosis that has spread to the CNS

Because of this, CSF analysis is not a perfect diagnostic test. However, it can be used alongside other diagnostic tests and symptoms to lead to an MS diagnosis.

Revised McDonald criteria

The McDonald criteria are a set of guidelines that help doctors diagnose MS. They take into account the number of attacks a person has as well as their symptoms. They also take into account the number, location, and age of lesions seen on brain imaging. However, in some cases, diagnosing MS may be more complex. In 2017, the McDonald criteria were revised to allow CSF fluid to play a bigger role in MS diagnosis.

CSF – specifically O-bands found on CSF – can be used in the diagnosis of MS if a person has had 1 attack of MS-like symptoms that point to more than 1 area of the brain being affected. O-bands can also be helpful when a person has 1 attack of MS-like symptoms that seem to only impact 1 area of the brain. In these cases, O-bands can be used alongside various MS-like imaging findings to point toward an MS diagnosis.

O-bands can also be used in cases of MS that are progressive since onset. In these cases, the presence of O-bands alongside at least 1 year of progressively worsening symptoms is considered MS.2-4

Your doctor can help collect all required pieces of information to determine whether or not your condition would be classified as MS.

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Written by: Casey Hribar | Last reviewed: June 2021.