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How MS Disability Is Measured

Medically Reviewed by Arefa Cassoobhoy, MD, MPH on November 20, 2020

Multiple sclerosis progression varies from person to person. The various types of MS progress in different ways, too. Scans and other multiple sclerosis tests don't always tell the whole story about MS disability. Symptoms and how well you’re 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, gives you tests that help create scales like the ones below. These can provide a 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 mobility, particularly how well you can walk. So it’s a less sensitive measure of other types of multiple sclerosis disability.

For your EDSS score, your neurologist will examine you and rate your disabilities on a scale of 0-9.5, in increments of 0.5. It takes about 30 minutes to create a score. Then a few minutes are needed to establish your ratings in the EDSS scale.

What Is the Functional System Score?

Ratings 1-4.5 of the EDSS describe people with MS who can walk without help. This part of the scale measures impairment in seven “functional systems” of your body as well as an “other” category.

You might hear these measurements called the Functional System Score or FSS. They evaluate the function of these bodily systems based on symptoms like:

  • Muscle weakness and problems moving your arms and legs (these are pyramidal system functions)
  • Tremors, clumsiness, and loss of balance and coordination (cerebellar system)
  • Problems with speech, swallowing, and uncontrolled eye movements (brainstem system)
  • Numbness or loss of feeling (sensory system)
  • Bladder and bowel control (bladder and bowel system)
  • Thinking and memory issues (cerebral system)
  • Vision problems (visual system)

Each of the systems that are responsible for these functions are rated on a score of 0 (no disability) to 5 or 6 (more serious disability).

Steps 5-9.5 of the EDSS basically measure impairments to your ability to walk. (Step 10 is death from multiple sclerosis.)

What Do the Ratings Mean?

Here’s a breakdown of the FSS/EDSS ratings:

  • 0: No disability or symptoms in any of your functional systems.
  • 1: No disability, but minimal symptoms in one of your functional systems.
  • 1.5: No disability, but minimal symptoms involving more than one system.
  • 2: Minimal disability in one system.
  • 2.5: Mild disability in one system or minimal disability in two.
  • 3: Some disability in one system or mild disability in 3-4 systems.
  • 3.5: Moderate disability in one system and some disability in several others.
  • 4. Significant disability, but you’re self-sufficient and able to function 12 hours a day.
  • 4.5: Significant disability but you can be active much of the day, including working for a full day. Can walk 300 meters (about 328 yards) without help or resting.
  • 5: Disability gets in the way of daily activities. Can’t work a full day without accommodations. Can walk 200 meters (219 yards) without help or rest.
  • 5.5: Disability that prevents full daily activities. Can walk 100 meters (109 yards) without help or rest.
  • 6: You need a cane or crutch to walk 100 meters without resting.
  • 6.5: You need two crutches or canes to walk 20 meters (22 yards) without rest.
  • 7: You can’t walk more than about 5 meters (5 ½ yards) even with help. You can get in and out of a wheelchair and propel yourself without assistance.
  • 7.5: You can’t take more than a few steps. You might need help getting in and out of a wheelchair. You can’t move yourself around  in a non-motorized wheelchair for a full day. 
  • 8: You’re in a wheelchair, sitting, or lying down at all times.  You can still use your arms effectively and do most things to take care of yourself.
  • 8.5: You’re in bed most of the time. You have some use of your arms, and you can do some things to care for yourself.
  • 9: You’re in bed at all times, but you can still talk and eat on your own.
  • 9.5: You must stay in bed, and you depend on others for care. You can’t effectively talk or swallow.
  • 10: Death from multiple sclerosis

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.

Drawbacks of the FSS/EDSS System

While it’s easy to give and widely used, the EDSS has some drawbacks. They include:

  • The scoring rules are complicated.
  • A neurologist’s exam is somewhat subjective.
  • The upper end of the scale focuses mostly on walking. This doesn’t take into account how important your upper body is for independence in daily life.
  • It doesn’t measure things like mood, energy, and quality of life.

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 or nurse 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.

Here’s a breakdown of the DS ratings:

  • 0: No disability
  • 1: Mild disability or symptoms
  • 2: Moderate disability and/or your gait is visibly affected
  • 3: Early or occasional cane use
  • 4: Late cane use, or you’re dependent on a cane
  • 5: You need support on two sides to walk
  • 6: You must use a wheelchair
  • 7: Unclassifiable, for those who don’t fit into the above categories. This might include people with eyesight or thinking problems.

While it’s not as detailed as the EDSS, the DS rating is quick, uncomplicated, and can be given by a nurse practitioner.  People with MS can even rate themselves using a modified version of the DS. The intervals between its ratings are considered more consistent than those of the EDSS.

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.

Show 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," “Guidebook: Kurtzke Expanded Disability Status Scale (EDSS),” “Guidebook: Kurtzke Functional Systems Scores (FSS).” “Guidebook: Disease Steps Form,” “Disease Steps (DS).” 

Multiple Sclerosis Trust: “Expanded Disability Status Scale (EDSS)”

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