How MS Disability Is Measured

Multiple sclerosis progression varies from person to person. And, the various MS types of disease progress in different ways, too. Scans and other multiple sclerosis tests don't always tell the whole story about MS disability; signs and symptoms and how well you are functioning each day -- from seeing to moving to thinking -- are also important measures of how well your central nervous system is working.

That's why a variety of tools are useful in assessing multiple sclerosis disability. These help you and your doctor gauge whether your MS is improving, progressing, or staying about the same. Doctors also use these measures in clinical studies. This helps to see how well multiple sclerosis treatment is working.

A trained examiner, often a neurologist, administers tests that help create scales like the ones below. These can provide a kind of snapshot of your MS progression.

MS Progression: Expanded Disability Status Scale (EDSS)

This commonly used scale is sometimes called the Kurtzke scale, named for the neurologist who developed it. The EDSS focuses mainly on your ability to walk. It is a less sensitive measure of other types of multiple sclerosis disability. It takes about 30 minutes to create a score. Then a few minutes are needed to establish the ratings in the EDSS scale.

Functional System Score (FSS)

On a scale of 0 to 6, FSS measures how well your major central nervous systems are working and assigns a score to your disability. This incorporates information about your gait and use of assistive devices. It also involves observation of functions like these:

  • Weakness or trouble moving limbs
  • Tremor or loss of coordination
  • Problems with speech, swallowing, or involuntary eye movements
  • Numbness or loss of sensation
  • Bowel and bladder function
  • Visual function
  • Mental functions

The EDSS Scale

With the help of the FSS, the examiner rates your disability on the EDSS scale. It ranges from 0 to 10, with half points for greater specificity. Lower numbers indicate less severe disability. Higher numbers reflect a greater degree of disability, mostly in relation to mobility:

  • 0 = Normal
  • 1-1.5 = No disability, but some abnormal neurological signs
  • 2-2.5 = Minimal disability
  • 3-4.5 = Moderate disability, affecting daily activities, but you can still walk
  • 5-8 = More severe disability, impairing your daily activities and requiring assistance with walking
  • 8.5-9.5 = Very severe disability, restricting you to bed
  • 10 = Death

It's important to recognize that a one-point change at the lower end of the scale reflects more subtle changes than at the upper end of the scale. For example, a one-point change between 2 and 3 is not as great a progression of disability as between 8 and 9.

Continued

MS Progression: Disease Steps (DS)

This is a simple way to measure MS disability, mainly based on your ability to walk. Doctors use it as a way to know when to begin therapy and to tell how you are responding to therapy. Scores range from 0, which is normal, to 6, which means you are unable to walk at all.

To establish the rating, you walk 25 feet. In addition, the doctor takes a medical history and performs both physical and neurological exams. Altogether, the time needed to create the rating is no more than about 30 minutes.

MS Progression: Multiple Sclerosis Functional Composite (MSFC)

The MSFC is a newer measurement system. It is sensitive to changes other than mobility. Although office staff can administer it, the MSFC takes more time to do, so it is currently used less in clinical practice and more for clinical trials. Computer-based tests are being developed, however, which may make it easier to use in the future.

Here's what the MSFC measures:

  • Walking speed, using a timed 25-foot walk
  • Arm and hand dexterity, using a nine-hole peg test
  • Cognitive function, such as how well you can do math calculations, using the Paced Auditory Serial Additions Test (PASAT)

Other Measures of MS Disability

A wide range of other measures is used to assess multiple sclerosis disability. In many cases, these are simple questionnaires. For example, the Multiple Sclerosis Quality of Life questionnaire asks you questions about your:

  • Physical, cognitive, social, and sexual function
  • Limitations due to physical or emotional problems
  • Perceptions about your health
  • Pain
  • Energy
  • Overall quality of life
  • Emotional health

Other scales measure specific aspects of disability such as:

Additional tests may help with measuring MS progression in the future. Work closely with your neurologist to determine which tests are recommended.

WebMD Medical Reference Reviewed by Neil Lava, MD on June 12, 2016

Sources

SOURCES:

MSAA: "How MS is diagnosed and the tools used to measure disease activity."

Polman, C. Neurology 2010; vol 74: pp S8-S15.

National Multiple Sclerosis Society: "FSS and EDSS."

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