Expanded Disability Status Scale (EDSS) and MS

How Your Doctor May Score Your Disability
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The Expanded Disability Status Scale (EDSS) is a rating system that is frequently used for classifying and standardizing the severity and progression of multiple sclerosis (MS).

While the EDSS has many shortcomings and is complicated to use and understand, it's important that people with MS at least know what it is and how it's applied. Some neurologists will use it to determine how their patients' MS is progressing (like whether they are becoming more disabled). EDSS is also widely used in clinical trials, both to determine who can participate and in reporting results (like whether an MS therapy is effective).

How an EDSS Score Is Calculated

The EDSS score is based on neurological testing and an examination of functional systems (FS), which are areas of the central nervous system which control bodily functions. These functional systems are:

  • Pyramidal (ability to walk)
  • Cerebellar (coordination)
  • Brain stem (speech and swallowing)
  • Sensory (touch and pain)
  • Bowel and bladder functions
  • Visual
  • Mental
  • Other (includes any other neurological findings due to MS)

After examining these systems, a neurologist will then score the patient based on his or her findings. The EDSS score ranges from 0.0 to 10.0.

0.0: Normal neurological exam.

1.0: No disability, but minimal signs in one functional system (FS) are present.

1.5: No disability, but minimal signs in more than one FS are present.

2.0: Minimal disability in one FS is present.

2.5: There is mild disability in one FS or minimal disability in two FS.

3.0: There is moderate disability in one FS or mild disability in three or four FS. However, the person is still fully ambulatory.

3.5: The person is fully ambulatory, but has moderate disability in one FS and mild disability in one or two FS, or moderate disability in two FS; or mild disability in five FS.

4.0: The person is fully ambulatory without aid, and is up and about most of the day (12 hours) despite relatively severe disability. He or she is able to walk 500 meters without aid or rest.

4.5: The person is fully ambulatory without aid, and is up and about much of day. He or she is able to work a full day, but may otherwise have some limitations of full activity or require minimal assistance. This is considered relatively severe disability. Able to walk 300 meters without aid.

5.0: The person is able to walk 200 meters without aid or rest. Disability impairs full daily activities, such as working a full day without special provisions.

5.5: The person is able to walk 100 meters without aid or rest. Disability precludes full daily activities.

6.0: The person needs intermittent or unilateral constant assistance (cane, crutch or brace) to walk 100 meters with or without resting.

6.5: The person needs constant bilateral support (cane, crutch or braces) to walk 20 meters without resting.

7.0: The person is unable to walk beyond five meters even with aid, and is essentially restricted to a wheelchair. However, he or she wheels self and transfers alone and is active in wheelchair about 12 hours a day.

7.5: The person is unable to take more than a few steps and is restricted to wheelchair, and may need aid to transfer. He or she wheels self, but may require a motorized chair for a full day's activities.

8.0: The person is essentially restricted to bed, a chair or a wheelchair, but may be out of bed much of day. He or she retains self-care functions and has generally effective use of arms.

8.5: The person is essentially restricted to bed much of day, but has some effective use of arms and retains some self-care functions.

9.0: The person is confined to bed, but still able to communicate and eat.

9.5: The person is totally helpless and bedridden and is unable to communicate effectively or eat and swallow.

10.0: Death due to MS.

Disadvantages of Using the EDSS for MS

Researchers and experts have noted the following shortcomings of the EDSS to characterize MS patients and their disease progression:

  • The EDSS places too much emphasis on the ability to walk.
  • It is insensitive to cognitive dysfunction in MS (like most scales based on a standard neurological exam).
  • Calculating EDSS scores is complicated, as the rules for how to rate findings on the neurological exam and translating these into scores on the functional system status are ambiguous and complex.
  • Because of the way the scale is designed (see preceding points), the EDSS is not sensitive to many clinical changes that a person with MS experiences. In other words, people seem to “jump” from one part of the scale to another, rather than exhibiting a smooth decline.
  • In terms of interpretation, a one-point difference in the score is not equal, depending on where within the scale you are examining. For example, going from a score of 8.0 to 9.0 is a big deal, as it means a person is essentially going from being self-functional to bed-bound. On the other hand, going from a 1.0 to a 2.0 means a person is going from no disability to minimal disability. Overall, this caveat can make a change in score difficult to interpret in scientific studies.

    When Is the EDSS Useful?

    It's possible to move back and forth on the scale. For instance, a fully functional patient with sensory symptoms might have an EDSS score of 1.0 most of the time. A relapse involving optic neuritis could bump their score up to a 3.0 until they are treated or the symptoms remit on their own. They would then move back down to a 1.0 (or a 1.5 if there were some lingering symptoms).

    While most neurologists do not formally use EDDS scores to monitor patients, some use it to determine when to take action like if a Solu-Medrol treatment or physical therapy is warranted.

    A Word From Verywell

    While learning all the details and nuances of the EDSS is likely not worth your time, it's good that you can now recognize what the EDSS is when you read it in an MS study, or if you hear your neurologist say it. It may also provide comfort to some of you, knowing that there is a standard way of classifying disability in MS.

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