Spasticity
Modified Ashworth Scale
The Modified Ashworth Scale grades resistance to passive movement on a six-point scale from 0 to 4, including a 1+ grade. It is the standard way spasticity is documented before and after treatment, and because grading depends on the examiner, the same assessor should repeat it wherever possible.
What it measures
How much a muscle resists being moved by someone else. Grade 0 is no increase in tone; grade 4 is a limb rigid in flexion or extension. The 1+ grade captures a catch followed by minimal resistance through the remaining range of movement.
Why we never report it alone
Reducing tone is not the goal. Some patients stand on spastic tone and lose the ability to stand when it is reduced. We therefore always report the MAS alongside a walking or activity measure, so that a fall in tone which costs function is visible rather than presented as progress.
Key facts
| Abbreviation | MAS |
|---|---|
| Number of items | 1 |
| Score range | 0, 1, 1+, 2, 3, 4 (per joint) |
| Time to administer | Under 5 minutes per joint |
| Training required | Clinical training in passive movement assessment |
| Cost | Free |
| Equipment | None |
| Domains | Muscle tone |
| ICF domain | Body function |
| Age range | Adult and paediatric |
| Populations | Stroke · Cerebral palsy · Spinal cord injury · Multiple sclerosis · Traumatic brain injury |
| Languages | Universal |
Psychometrics by population
The same instrument behaves differently in different conditions. A cut-off established in older adults does not transfer to Parkinson's disease, and a minimal detectable change from one study does not apply to another population.
| Population | Cut-off | MDC / MCID | Reliability | Validity |
|---|---|---|---|---|
| StrokeThis is the scale’s main limitation and the reason serial measurements should use the same assessor | — | — | Inter-rater reliability is moderate at best and varies by joint — better at the elbow than the ankle | — |
| Cerebral palsyCombining with the Tardieu Scale is common practice in paediatrics | — | — | Lower in children | — |
Things to be careful about
- Speed of passive movement changes the grade and must be kept consistent
- Does not distinguish spasticity from contracture or from voluntary resistance
- A reduction in tone is not automatically a functional gain — always pair with an activity measure
Frequently asked questions
What do the Modified Ashworth grades mean?
Grade 0 is no increase in muscle tone. Grade 1 is a slight catch at the end of the range, and 1+ a catch followed by minimal resistance through the rest of it. Grades 2 and 3 mark progressively more resistance, and grade 4 is a limb rigid in flexion or extension. Each joint is graded separately.
Is less spasticity always better?
No, and this is the most important thing to understand about the scale. Some patients stand on spastic tone and lose the ability to stand when it is reduced. Reducing tone is not the goal in itself — we always report the grade alongside a walking or activity measure, so a fall in tone that costs function is visible rather than presented as progress.
Why should the same person perform the assessment each time?
Because agreement between different examiners is moderate at best and varies by joint — better at the elbow than the ankle. That is the scale’s main limitation. The speed of the passive movement also changes the grade, so serial measurements should use the same assessor moving at the same speed.
Does the scale distinguish spasticity from stiffness?
No. It records resistance to passive movement without separating spasticity from contracture or from voluntary resistance by the patient. A joint that has shortened over months and a muscle that is neurologically overactive can produce the same grade, and they need entirely different treatment — which is why the grade is read alongside a clinical examination, not instead of one.
Sources
- Bohannon RW, Smith MB. Interrater reliability of a modified Ashworth scale of muscle spasticity — Physical Therapy (1987)
Topic
Related instruments
- Rehabilitation outcomeFunctional Independence Measure (FIM)The FIM is an 18-item scale scoring how much assistance a person needs across thirteen motor and five cognitive tasks.
- Daily livingBarthel IndexThe Barthel Index is a ten-item scale of independence in daily activities, scored from 0 to 100 in five-point increments.
- Balance and fallsBerg Balance ScaleThe Berg Balance Scale assesses static and dynamic balance through fourteen everyday tasks, each scored 0 to 4, giving a total out of 56.
