Multiple Sclerosis Diagnosis: How to Test for MS

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Multiple sclerosis (MS) is a chronic autoimmune condition in which the immune system damages the protective myelin sheath around neurons within the central nervous system (CNS), affecting the brain, spinal cord, and eyes.

Diagnosing MS can be a difficult, frustrating, and lengthy process because there is no single test or symptom that can 100% confirm MS. Instead, healthcare providers must use a combination of tests to diagnose MS and rule out any other possible conditions. The results of these tests must match the 2017 McDonald criteria, a diagnostic tool for MS.

In this article, learn more about the different tests for MS.

Imaging technician talks to person about to have MRI

Cavan Images / Getty Images

Testing for MS

Diagnosing MS can involve a combination of blood tests, magnetic resonance imaging (MRI), a spinal tap, and more.

Blood Tests

Blood tests cannot diagnose MS, but they can rule out other conditions that have similar symptoms. They are an important part of the MS diagnostic process.

Some blood tests that your healthcare provider may order when you have symptoms of MS include:

What to Expect With Blood Tests

You can get all of these blood tests at your healthcare provider's office or wherever you typically get your blood drawn. Some test results, like the complete blood count, may come back on the same day. Other tests have to be sent out to specialty centers, and results take a week or more to return. Your healthcare provider should schedule a follow-up appointment with you to discuss the results of your blood tests.

Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is one of the most important tests for MS. It has been referred to as a breakthrough for MS diagnosis. An MRI can identify both type and location of abnormal areas of tissue called lesions in the brain and spinal cord. When a contrast agent with gadolinium is used, an MRI can also identify active lesions in someone having an MS attack.

Additionally, an MRI can reveal both "dissemination in time" and "dissemination in space" of lesions, meaning lesions that occurred at more than one time and affect more than one area of the central nervous system. Evidence of both of these is a requirement for a diagnosis of MS.

Beyond the diagnostic process, a yearly MRI is often recommended for people with MS. This can help monitor the progression of MS and any new lesions.

What to Expect With MRIs

Depending on what type of MRI you are having, you may or may not require an intravenous (IV) contrast (a dye that improves the clarity of images being scanned) before the MRI. For the MRI, you will have to take off all metal products and wear a hospital gown.

You will lie on a table that then slides into the MRI scanner, which is usually a long white tube. An MRI can take an hour or more and can be loud. Your MRI technician may let you listen to music or wear soundproof headphones to make the experience more comfortable.

Lumbar Puncture (Spinal Tap)

In some cases, a lumbar puncture (also called a spinal tap) may be performed when MS is suspected. For this procedure, a needle is inserted into the protective area around the spinal cord to withdraw cerebrospinal fluid (CSF) for analysis.

When analyzing CSF, healthcare providers are looking for abnormal proteins that may be present in CSF when demyelination happens. In particular, they are looking for oligoclonal bands, which are bands of immunoglobulins that can indicate inflammation in the CNS.

Oligoclonal bands are found in almost all MS patients, but they can also be found in other conditions. A finding of oligoclonal bands alone cannot diagnose MS.

What to Expect With a Spinal Tap

For a spinal tap, you will wear a hospital gown and be instructed on what position to sit or lie in. You will likely get a local anesthetic in your back to reduce any pain or discomfort. When the needle is inserted, you will probably feel strong pressure but no pain. The procedure shouldn't take more than an hour, and most people can go home the same day.

Evoked Potential Test

In people with MS, the myelin sheath covering nerves is damaged, which can slow down nerve impulses. When the person has a sensory experience, such as seeing flashing lights or hearing a loud bang, the electrical signals that send this information to the brain may get delayed or distorted.

An evoked potentials (EP) test examines how fast nerve signals travel and how big the response is. Slowness to respond or smaller responses can indicate damage to the CNS, which is why it is sometimes used as a test for MS.

Evoked potential tests are painless. Sensors will be applied to your scalp to measure the electrical signals, but after that, your exact experience will differ based on what type of EP test you are having. The most common ones used in the MS diagnostic process include:

  • Visual evoked potentials (VEP): This test measures how the signals from your eyes to your brain are working. You will look at a flashing checkerboard.
  • Somatosensory evoked potentials (SSEP): This test measures how tactile (feeling) sensation signals to your brain are working. You will receive small electrical pulses to a leg or arm.
  • Brain stem auditory evoked potentials (BAEP): This test measures how auditory signals to your brain are working. You will listen to clicking noises for approximately an hour.

Newer Testing Options

Scientists are constantly looking for new ways to speed up and simplify the MS diagnostic process. As of yet, no single test for MS has been identified.

One of the newest tests is an antibody test of the CSF. The test is more affordable than the typical test for oligoclonal bands, only takes 20 minutes to process as opposed to over four hours, and is more objective.

This is not widely in practice yet as the research to support it was only published in April 2022. However, it is promising for the future of MS testing.

Diagnostic criteria were updated to include the presence of oligoclonal bands in the CSF, which can help lead to faster diagnosis and treatment.

Early Symptoms of MS

Knowing the early symptoms of MS can lead to a faster diagnosis, earlier treatment, and ultimately better outcomes.

Some early signs and symptoms of MS to be aware of include:

Common Misdiagnoses

Misdiagnosis of MS does happen. Some research estimates that about 30% of people originally referred for a MS diagnosis ultimately end up diagnosed with another condition.

Conditions that may be misdiagnosed as MS include:

When to See a Healthcare Provider

If you have any of the signs or symptoms of MS, it's important to see a healthcare provider. This includes if you have new or unexplained eye pain, incontinence, blurry vision, fatigue, constipation, eye pain, muscle spasms, and more.

Your healthcare provider can order some simple blood tests or refer you to a specialist. Even if you are not ultimately diagnosed with MS, it's important to look into these symptoms when they occur,

Summary

Diagnosing MS is complex. There is no single test or biomarker that can diagnose MS. A combination of MRI, spinal tap, blood tests, and evoked potential tests may be used to test for MS. The results of these tests in the context of each other may indicate MS, or they may lead your healthcare provider to consider another diagnosis to explain your symptoms.

A Word From Verywell 

Unfortunately, diagnosing MS isn’t simple. It often requires a number of tests to reach a diagnosis. On the bright side, scientists are constantly looking into new and simpler tests for MS, and your healthcare provider will work with you to get treatment if you're experiencing symptoms.

Frequently Asked Questions

  • At what age does MS usually start?

    Most people with MS are diagnosed between the ages of 20 and 50 years old. However, MS can happen at any age.

  • What are the first signs of MS?

    The first signs of MS can vary from person to person, but commonly include vision problems, fatigue, numbness, spasms, bladder or bowel problems, and more. These symptoms may come on slowly and last for multiple days or weeks.

  • Can MS be detected in a blood test?

    MS cannot be detected in a blood test. Blood tests are used in the MS diagnostic process for the purpose of ruling out other possible conditions, like vitamin deficiencies, lupus, and Lyme disease.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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