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How Is Multiple Sclerosis Diagnosed?

No single test can diagnose MS. The medical history, neurologic exam and lab tests help healthcare providers rule out other diseases and confirm the MS diagnosis.


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In this article

Overview of diagnosing MS

At this time, there are no symptoms, physical findings or laboratory tests that can, by themselves, determine if you have MS. Healthcare providers will use several strategies to determine if you meet the long-established criteria for an MS diagnosis and to rule out other possible causes of whatever symptoms you are experiencing. These strategies include a careful medical history, a neurologic exam and various tests including magnetic resonance imaging (MRI)cerebrospinal fluid analysis and blood tests to rule out other conditions.

Timely and accurate diagnosis

There are many possible causes of neurological symptoms. To diagnose MS, healthcare providers must first exclude these other causes through the tools and tests outlined below. While this process of exclusion may be quick for some, it can also take much longer and involve repeat testing, to look for changes.

Making the diagnosis of MS as quickly and accurately as possible is important for several reasons:

  • You are living with frightening and uncomfortable symptoms and need to know the reason for your discomfort. Getting the diagnosis allows you to begin the adjustment process and relieves worries about other diseases.
  • Since we now know that permanent neurologic damage can occur even in the earliest stages of MS, it is important to confirm the diagnosis so that you can start the appropriate treatment(s) as early in the disease process as possible.

Criteria for a diagnosis of multiple sclerosis

Currently MS is diagnosed by applying several types of tests and assessments because no single test or examination can confirm that you have MS. In order to make an MS diagnosis, the physician must:

  • Find evidence of damage in at least two separate areas of the central nervous system (CNS), which includes the brain, spinal cord and optic nerves AND
  • Find evidence that the damage occurred at different points in time AND
  • Rule out all other possible diagnoses.
The McDonald Criteria, published in 2017 by the International Panel on the Diagnosis of Multiple Sclerosis, include specific guidelines for using MRI and cerebrospinal fluid analysis to speed the diagnostic process. The MRI can be used to look for a second area of damage in a person who has experienced only one attack (also called a “relapse” or an “exacerbation”) of MS-like symptoms — referred to as clinically-isolated syndrome (CIS). The MRI can also be used to confirm that damage has occurred at two different points in time. In some circumstances, the presence of oligoclonal bands in a person’s cerebrospinal fluid analysis can be used instead of dissemination in time to confirm the MS diagnosis.

Tests and tools for diagnosing MS

Healthcare providers have a series of tests and tools for diagnosing MS, which include learning your medical history and conducting neurologic exams, screening and imaging tests, and blood tests to rule out other potential causes of your symptoms.

Medical history and neurologic exam

Your healthcare provider:
  • Takes a careful history to identify any past or present symptoms that might be caused by MS.
  • Gathers information about birthplace, family history, environmental exposures, history of other illnesses and places visited that might provide further clues.
  • Performs a comprehensive neurologic exam, which includes tests of cranial nerves (vision, hearing, facial sensation, strength, swallowing), nerve conduction (to test sensation in the extremities), reflexes, coordination, walking and balance.

In many instances, medical history and a neurologic exam provide enough evidence to meet the diagnostic criteria. Other tests are used to confirm the diagnosis or to identify other possible causes of the symptoms or neurological exam findings.

Magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI) is a diagnostic tool that offers the most sensitive, noninvasive way to examine the brain, spinal cord or other areas of the body. It is a valuable tool for diagnosing MS and tracking the progression of the disease.

Cerebrospinal fluid (CSF) analysis

Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds the brain and spinal cord. 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. Spinal fluid is collected through a lumbar puncture (also known as a spinal tap). The CSF is then sent for testing and analysis.

Blood tests

While there is no definitive blood test for MS, blood tests can rule out other conditions that cause symptoms similar to those of MS, including lupus erythematosus, Sjogren's syndrome, vitamin and mineral deficiencies, some infections and rare hereditary diseases.

Find an MS care provider

The National MS Society’s Partners in MS Care program connects you to local healthcare providers and medical facilities that have demonstrated exceptional care, knowledge and expertise in treating patients with MS. All partners, whether they are a neurologist or social worker, have a strong relationship with the Society and connect their patients to the information, resources and support they need to live their best lives with MS. Find a Partner in MS Care.


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