Multiple sclerosis (MS) is a complex disease. 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
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.