Understanding Neurological Rating Scales
What is the EDSS? - a detailed look
The EDSS is partly based on measurements of eight areas of the central nervous system known as functional systems. The earlier steps in the scale measure the degree of impairment in these systems, such as transient numbness in the face or fingers or visual disturbances. Later steps measure disability in terms of mobility mainly using walking distance.
The functional systems measured for the EDSS are:(1)
• pyramidal - voluntary movement
• brainstem - functions like eye movement, sensation and movement of the face, swallowing
• visual
• cerebral - memory, concentration, mood
• cerebellar - coordination of movement or balance
• sensory
• bowel and bladder
• Others - including fatigue:
These systems are graded according to the extent of impairment in each. These grades range from normal, which is zero, to maximum impairment, which can be five or six. These functional system grades, plus indications of mobility and restrictions in daily life, are used to define the 20 steps of the EDSS.
In the early steps of the scale, small increases in the number of symptoms cause an advance of one or more EDSS steps. This indicates the involvement of additional functional systems or more severe impairment/disability in a single functional system. From step four onwards, the ability to walk becomes the key factor in determining EDSS score. Changes in other functional systems at this part of the scale, such as movement in the arms or cognitive function, although having a definite effect on a person’s well being, do not result in an additional change of EDSS score.
The EDSS Scale
The main steps of the EDSS scale are:
0. Normal neurological findings
1. No disability and minimally abnormal examination findings
2. Minimal disability in only one functional system
3. Able to walk unaided, but has moderate disability in one of the functional systems
4. Able to walk unaided for at least 500 metres, but has severe disability in one of the functional systems
5. Able to walk unaided for at least 200 metres, but disability is too severe to be fit for full time work
6. Requires stick, crutch or other aid to walk 100 metres, with or without rests
7. Can cover no more than 5 metres, even aided, can propel wheelchair and transfer unaided
8. Restricted to chair, bed or wheelchair, arms functional but requires assistance with transfer
9. Helpless and bedridden, arms not functional, but can eat and talk
10 Death due to MS (uncommon)
The full EDSS scale
0
Normal neurological examination (all grade 0 in functional systems)
1.0
No disability and minimal signs in functional systems
1.5
No disability; minimal signs in more than one functional system
2.0
Minimal disability in one functional system
2.5
Minimal disability in two functional systems
3.0
Moderate disability in one functional system or mild disability in three or four functional systems though fully ambulatory
3.5
Fully ambulatory but with moderate disability in one functional system, and one or two functional systems grade 2; or two functional systems grade 3; or five functional systems grade 2 (others are 0 or 1)
4.0
Fully ambulatory without aid; self-sufficient and able to be up and about 12 hours a day, despite relatively severe disability consisting of one functional system grade 4 (others are 0 and 1) or combinations of lesser grades exceeding limits of previous steps; able to walk 500 metres without aid or rest
4.5
Fully ambulatory without aid; up and about much of the day; able to work a full day; may otherwise have some limitation of full activity or require minimal assistance; characterized by relatively severe disability usually consisting of one functional system grade 4 (others are 0 and 1) or combinations of lesser grades exceeding limits of previous steps; able to walk 300 metres without rest or aid
5.0
Disability is severe enough to preclude full daily activities, including working a full day; ambulatory without aid or rest for about 200 metres; usual functional system equivalents - one grade 5 alone (others are 0 or 1) or a combination of lesser grades, usually exceeding those for step 4.0
5.5
Ambulatory for about 100 metres without aid or rest; disability severe enough to preclude full daily activities; usual functional system equivalents - one grade 5 alone (others are 0 or 1) or a combination of lesser grades, usually exceeding those for step 4.0
6.0
Intermittent or unilateral constant assistance for walking about 100 metres, with or without resting; usual functional system equivalents - combinations with more than two functional systems grade 3+
6.5
Constant bilateral assistance required to walk about 20 metres without resting; usual functional systems equivalent - combinations with more than two functional systems grade 3+
7.0
Unable to walk beyond approximately 5 metres, even with aid; essentially restricted to a wheelchair; wheels self in standard wheelchair and transfers alone; up and about in wheelchair 12 hours a day; usual functional system equivalents are combinations with more than one functional system grade 4+; very rarely, pyramidal grade 5 alone
7.5
Unable to take more than a few steps; restricted to wheelchair; may need aid in transfer, wheels self but cannot stay in standard wheelchair a full day; may require motorized wheelchair; usually functional system equivalents are combinations with more than one functional system grade 4+
8.0
Essentially restricted to bed or a chair or perambulated in wheelchair but may be out of bed much of the day; retains many self-care functions and has effective use of the arms; usual functional system equivalents are combinations, generally grade 4+ in several systems
8.5
Essentially restricted to bed much of the day; retains some self-care functions; has some effective use of arms; usual functional system equivalents are combinations, generally grade 4+ in several systems
9.0
Helpless and bedridden; can communicate and eat; usual functional system equivalents are combinations, most grade 4+
9.5
Totally helpless and bedridden, unable to communicate effectively or eat/swallow; usual functional system equivalents are combinations, almost all grade 4+
10.0
Death due to MS results from respiratory paralysis, coma of uncertain origin, or following repeated epileptic seizures.
Reference
1. Gaspari M, Roveda G et al. An expert system for the evaluation of EDSS in multiple sclerosis. Artificial Intelligence in Medicine 2002:25;187-210.
