Multiple sclerosis (MS) disability scales are tools that can help doctors monitor the severity and progression of MS disability. The most popular scale is the Kurtzke Expanded Disability Status Scale (EDSS).

The EDSS focuses heavily on walking as a determinant of disability. However, doctors may use additional scales to help assess and monitor the progression of other effects of MS, such as loss of bladder control, visual impairment, and fatigue.

This article describes the Kurtzke EDSS, including its purpose and how it works. It also outlines some additional MS scales, explaining when doctors use MS disability scales and whether a person can measure themselves with a disability scale.

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According to the National Multiple Sclerosis Society (NMSS), the EDSS measures the extent of neurological impairment in people with MS.

The United Kingdom’s Multiple Sclerosis Trust (MST) explains that medical professionals use the EDSS to quantify levels of disability in people with MS and monitor changes in their disability levels over time.

According to the MST, researchers often use the EDSS as an assessment tool in clinical trials for MS.

How the scale works

The EDSS ranges from 0 through 10 in half-point increments, with 0 representing typical neurological functioning and 10 representing death due to MS.

A neurologist or appropriately trained nurse practitioner will perform the neurological examination necessary for completing the EDSS.

This may take between 15 and 30 minutes. As the table below demonstrates, scoring largely focuses on an individual’s ability to walk.

Score rangeMain determinant for EDSS
0.0 to 4.0 whether the person can walk without assistance
4.0 to 7.5how far a person can walk and the type of assistance they require for walking
6walking with a cane
7.5 to 10the person’s ability to move from a wheelchair to a bed and to perform self-care

Individuals who score between 1.0 and 4.5 on the EDSS can walk unaided. Scores within this range consider measures of impairment across eight functional systems (FS). This term refers to a network of neurons in the brain and spinal cord that performs a particular set of tasks.

Functional system

The table below shows the eight FS that the EDSS considers, alongside some of their associated tasks and some of the symptoms that could develop following damage to that FS.

Functional systemExample tasksExample MS symptoms
pyramidalmotor functions, such as walkingmuscle weakness
• difficulty moving limbs
cerebellarcoordinationataxia
loss of balance
• loss of coordination
tremors
brainstemspeech and swallowing• problems with speech
problems with swallowing
nystagmus (rapid, side-to-side eye movement)
sensorytouch, vibration, and painnumbness
• reduced sensation
bowel and bladderurination and defecationurinary urgency, hesitance, or retention
loss of bladder or bowel function
visualeyesightvisual impairments
cerebralcognition and memorymood changes
memory problems
fatigue
otherother functions not outlined aboveany other MS-related neurological issues

The person carrying out the EDSS will score each FS on a scale of 0 to 5 or 6, with 0 indicating no disability and 5 or 6 indicating the most severe disability.

Individuals who score between 5.0 and 9.5 on the EDSS cannot walk unaided. Scores within this range focus on impairments in walking.

Purpose

As the MST explains, doctors may use the EDSS to quantify levels of disability in people with MS and to monitor these levels over time.

The NMSS adds that researchers may also use the scale during clinical trials for MS to categorize participants or to help assess the effectiveness of certain MS treatments.

Learn more about the EDSS.

The EDSS has several limitations, including the following:

  • Subtle differences in the neurological examination affect scores at the lower end of the scale more than those at the middle and upper ends.
  • The EDSS overemphasizes the ability to walk and does not consider mobility in the upper body, such as the arms, hands, and fingers.
  • The EDSS does not take into consideration symptoms that a person cannot see, such as:
    • pain
    • fatigue
    • depression
  • The scale focuses on worsening disability and does not consider fluctuations in MS symptoms.

Neurologists may use additional scales to diagnose and monitor other potentially disabling symptoms of MS. Some examples include:

  • Bladder control scale (BLCS): A four-item self-report questionnaire to briefly assess bladder control and the extent to which bladder problems affect daily activities.
  • Bowel control scale (BWCS): A five-item self-report tool to briefly assess bowel control and how much bowel problems affect daily activities.
  • Impact of visual impairment scale (IVIS): A five-item self-report questionnaire to assess difficulties with simple visual tasks, such as reading and watching television.
  • Modified fatigue impact scale (MFIS): Assesses the effects of fatigue on physical, cognitive, and psychosocial functioning. The full-length version of this scale consists of 21 items, while the shorter version consists of five items.
  • Medical outcomes study (MOS) pain effects scale (MOS PES): A six-item scale to assess how pain and unpleasant sensations interfere with the following:
    • mood
    • walking or movement
    • sleep
    • work
    • recreation
    • enjoyment of life

Doctors may use the EDSS scale to monitor changes in disability in a person with MS. A neurologist will incorporate functional systems scores to determine disability in areas other than walking.

People who participate in clinical trials for MS may also undergo an assessment with the EDSS scale to help determine the effectiveness of any MS treatments.

Learn how doctors test for MS.

Can someone measure themselves with a disability scale?

To obtain an EDSS score, a person must undergo a neurological assessment from a neurologist or appropriately trained nurse. As such, it is not possible for a person to measure themselves with this disability scale.

However, some MS scales that focus on other types of physical or mental disability rely on self-report questionnaires that a person can usually complete with little to no help from an interviewer. These include:

  • the BLCS
  • the BWCS
  • the IVIS
  • the MFIS
  • the MOS PES

MS disability scales can help doctors monitor the severity and progression of the condition. The most popular of these scales is the Kurtzke Expanded Disability Status Scale (EDSS), which focuses heavily on a person’s ability to walk.

While doctors may use the EDSS to monitor the progression of disability in people with MS, researchers may use the scale to determine the efficacy of MS treatments in clinical trials.

Healthcare professionals may also use other scales or diagnostic tools to diagnose or monitor MS.