Modified Ashworth Scale (MAS): 6 Grades, Testing Protocol and Tardieu Comparison
In short
The Modified Ashworth Scale (MAS) is the primary clinical tool for grading velocity-dependent hypertonia and spasticity. Learn testing mechanics, grading and comparisons.
In this guide (4 sections)
What Is the Modified Ashworth Scale (MAS)?
The Modified Ashworth Scale (MAS) is an ordinal clinical grading scale used to evaluate muscle spasticity, defined by Lance as a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks.
Originally published by Bryan Ashworth in 1964 and modified by Bohannon and Smith in 1987 (adding the 1+ grade to improve sensitivity in the lower resistance range), the MAS measures passive resistance felt by the examiner during rapid joint displacement.
Standard Testing Procedure and Grading Definitions
The patient is positioned comfortably in supine. The limb is moved through its full available passive range of motion at slow speed to establish baseline joint excursion.
Spasticity is then tested by moving the joint passively across its full excursion over a duration of approximately one second (a rapid stretch velocity).
| MAS Grade | Score Value | Operational Clinical Definition | Kinematic Characteristic | |
|---|---|---|---|---|
| Grade 0 | 0 | No increase in muscle tone | Normal resting tone throughout full passive excursion. | |
| Grade 1 | 1 | Slight increase in muscle tone, manifested by a catch and release | Catch and release or minimal resistance at end of range of motion. | |
| Grade 1+ | 2 (or 1.5) | Slight increase in tone, catch followed by minimal resistance | Catch followed by minimal resistance through remainder (less than half) of ROM. | |
| Grade 2 | 3 | Marked increase in tone through most of ROM | Affected part easily flexed or extended despite noticeable resistance. | |
| Grade 3 | 4 | Considerable increase in tone, passive movement difficult | Significant resistance felt throughout; passive movement requires physical effort. | |
| Grade 4 | 5 | Affected part rigid in flexion or extension | Joint cannot be moved passively; locked in resting spastic posture. |
MAS vs Tardieu Scale: Why Velocity Matters
A key limitation of the MAS is that it evaluates passive resistance at a single uncontrolled speed without differentiating between neural spasticity and non-neural structural contracture.
The Tardieu Scale improves upon this by testing muscle stretch at three distinct velocities (V1 slow passive stretch, V2 gravity fall, and V3 fast velocity) and measuring the angle of the catch (R1) versus passive maximum range of motion (R2).
A large gap between R1 and R2 indicates a dynamic, neurogenic spasticity component responsive to botulinum toxin injection or oral antispasmodics. A small gap indicates established structural muscle contracture requiring prolonged serial casting or surgical lengthening.
Frequently Asked Questions
How many times should passive stretch be repeated during testing?
Perform the stretch no more than 2 or 3 times. Repeated stretches produce habituation, temporarily reducing stretch reflex excitability and underestimating spasticity.
Why was the 1+ grade added to the original Ashworth scale?
Bohannon and Smith added 1+ because clinicians observed that many patients had a catch followed by resistance through less than half the range, which fell between Ashworth grades 1 and 2.
Which muscle groups are most frequently assessed with the MAS?
In the upper limb: shoulder adductors, elbow flexors, forearm pronators and finger flexors. In the lower limb: hip adductors, quadriceps, hamstrings and gastrocnemius-soleus.
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