Modified Ashworth Scale

Key takeaways

The Modified Ashworth Scale grades muscle spasticity across six steps: 0, 1, 1+, 2, 3 and 4.

You grade the resistance you feel while moving the limb passively through its full range at a slow, steady speed.

Agreement between clinicians is moderate to good, so serial scores are most trustworthy when the same person tests the same joint.

The American Physical Therapy Association does not currently recommend the scale for multiple sclerosis, citing thin evidence and validity concerns.

Record the joint, the side, the speed and the patient’s position, or your next score will not be comparable.

The Modified Ashworth Scale grades how much resistance you feel when you move a patient’s limb passively. Scores run from 0, meaning no increase in tone, to 4, meaning the affected part is rigid. Bohannon and Smith added the 1+ step in 1987 to catch changes the original scale kept missing.

Physical and occupational therapists use it after stroke, spinal cord injury and traumatic brain injury. It takes around two minutes and needs nothing beyond a goniometer. What it does need is discipline, because a grade only means something next to another grade taken the same way. This guide covers the six steps, the technique behind them, and how to write the result into a patient record.

What is the Modified Ashworth Scale?

The Modified Ashworth Scale, or MAS, is a clinical tool that grades muscle spasticity on a six-point scale. It runs from 0, no increase in muscle tone, to 4, affected part rigid. Bohannon and Smith built it in 1987 by refining the original Ashworth Scale of 1964. Their addition was an intermediate grade of 1+, which catches tone changes the five-point version could not separate.

Spasticity itself is a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes. It usually follows an upper motor neuron lesion. The scale gives you a quick, repeatable way to record resistance to passive movement. Because it needs no equipment beyond a goniometer, it has become the most widely used spasticity measure in rehabilitation.

Why measuring spasticity matters

Spasticity limits motor control, adds fatigue and closes down range of motion. Without a measure you are left with impressions, and impressions do not survive a handover. Tone is better than last week means one thing to the therapist who felt it and nothing to the colleague reading the note.

A grade gives the team one shared language. When someone writes Grade 2 for the right ankle plantarflexors, anyone reading the record knows what that hand felt. Occupational therapy and physical therapy teams often share the same patient, so a common grading language matters as much as the grade itself.

The grading scale, from 0 to 4

The scale grades tone from 0 to 4, with 1+ sitting between 1 and 2. Each grade has a standardized descriptor that guides your judgment while you move the joint.

The 1+ grade is the reason the modified version exists. It covers patients whose tone catches early and then eases off before halfway through the range. That extra step makes the scale sensitive to small gains that would otherwise stay invisible.

How to administer the test

Technique drives the score more than the patient’s tone does. Move too fast and you trigger velocity-dependent reflexes, which inflates the grade. Test only the end of the range and you miss a catch that happened earlier.

1. Position and settle the patient. Supine is the reference position in the original protocol. Explain that you will move the limb and that they should stay relaxed. A tense patient produces artificially high tone.
2. Pick the joint and write it down. Wrist flexors, ankle plantarflexors and knee extensors are the usual test sites. Record which one you used, or later comparisons mean nothing.
3. Move the limb slowly and steadily. Take about one second for the full range, counting one thousand one. Use the same speed at every visit.
4. Feel the whole range, not only the end. Note any catch, meaning a sudden resistance that then releases, and note where in the range it happened.
5. Score it straight away. Use the descriptors in the table above. If you sit between two grades, take the one that matches what your hand felt.
6. Log the joint, the side, the speed and the date. A range of motion record alongside the grade shows whether the limb is losing length as well as gaining tone.

Common pitfalls. Testing too fast, skipping the relaxation step and grading from end-range alone all produce numbers you cannot trust.

Which patient groups the scale suits

The scale has been used across most upper motor neuron conditions. The evidence behind it is not equally strong in each one, and one professional body has said so plainly.

• Stroke: The most heavily studied population. Post-stroke spasticity usually appears two to 12 weeks after the event and shapes the recovery trajectory. Many teams pair it with a motor assessment scale to track function as well as tone.
• Multiple sclerosis: The American Physical Therapy Association does not currently recommend the scale here. Its task force found the supporting evidence too thin and flagged validity problems at grades 1, 1+ and 2. Use it with caution in MS, and record what else you measured.
• Cerebral palsy: Widely used in pediatric practice, though agreement between raters drops in younger children. Age and developmental level both change what your hand feels.
• Spinal cord injury: Spasticity is common after SCI, and the scale tracks upper and lower limb tone through rehabilitation. Clinicians usually read it next to the ASIA impairment scale.
• Traumatic brain injury: Tone can be widespread after TBI. The grade records a baseline and monitors the response to anti-spasticity treatment, often alongside the Rancho Los Amigos scale.

How reliable the scores are

Knowing where the scale is strong and where it wobbles stops you over-reading a single grade.

Inter-rater reliability describes how closely two clinicians agree on the same patient. Reported intraclass correlation values, or ICCs, sit between 0.60 and 0.90. Agreement is best at the wrist and ankle in adult stroke samples. It falls at the hip and knee, and in children, which means two therapists can honestly disagree by a full grade.

Validity is the more contested side. Grades do track other spasticity measures and correlate with functional limitation. They also pick up soft tissue stiffness rather than reflex activity alone, which is part of why the scale draws criticism.

Minimal detectable change is the smallest shift larger than measurement error. In most populations that is roughly one grade. A move from Grade 2 to Grade 1 is therefore worth acting on. A feeling that tone seems lighter is not.

Where the scale falls short

The MAS is practical and quick, and both of those come at a price. Knowing the price keeps it from carrying more weight than it can bear.

• It is ordinal, not interval. The step from 0 to 1 is not the same size as the step from 3 to 4. You cannot average grades or drop them into parametric statistics without transforming them first.
• The velocity question is unsettled. The scale is meant to be velocity-independent, but researchers argue it still captures velocity-dependent reflexes. Move too quickly and the result reflects your hand rather than the patient.
• Raters disagree. Serial assessments by one clinician are far more reliable than comparisons made across a team.
• It ceilings at Grade 4. Once a limb is rigid, further worsening is invisible. Very high-tone patients need a second measure running alongside it.
• Training changes the numbers. The technique is simple to describe and easy to do badly. Untrained assessors produce the widest spread of grades.

MAS vs Tardieu scale: which to use when

Both scales are defensible. The choice comes down to how much time you have and what you need the number to prove.

For a busy caseload the MAS is the faster instrument. The Tardieu tells you more about how tone changes with speed, at the cost of five to 10 extra minutes per joint. Whichever you pick, run it on a fixed schedule. Automated reminders keep reassessments landing at the same interval for every patient.

How to document MAS scores

A grade with no context is close to useless. Grade 2 on its own tells the next clinician almost nothing about the patient in front of them.

1. Date, time and assessor. Same-rater comparisons are the reliable ones, so the name matters as much as the number.
2. Joint and side. Write right ankle plantarflexors, Grade 2. Never just Grade 2.
3. Speed and patient state. If the patient was tense, or the movement was slower than usual, say so. The next reader needs that context.
4. Functional consequence. Right ankle Grade 2 restricts dorsiflexion in swing phase and slows gait. That line is what a patient and a payer both understand.
5. Comparison to baseline. Grade 2 today against Grade 3 at intake, after two weeks on a home exercise program. The trend carries more weight than the grade.

Physical therapy records make this repeatable once the fields already exist. A date, an assessor, a joint picker and a fixed grade dropdown stop the team inventing its own shorthand. A progress notes cheat sheet helps while the habit is still forming.

Scores also travel outside the therapy team. When tone changes enough to alter medication or trigger a referral, the grade is the evidence a multidisciplinary review works from.

When to reach for a different measure

For most spasticity assessments the MAS is enough. Five situations call for something else, or for something extra alongside it.

• You need velocity detail. The Tardieu, or modified Tardieu, separates the response at slow speed from the response at fast speed.
• The patient is a young child. Rater agreement falls below age five. The modified Tardieu or the Gross Motor Function Classification System may fit better.
• The limb is already rigid. At Grade 4 the scale stops moving. Add goniometry or a functional measure such as the functional reach test.
• You want the patient’s view. The MAS is a clinician-rated impairment measure. A patient-reported tool such as the outcome rating scale captures what the person notices day to day.
• You are running a study. Ordinal data limits your statistics. Interval measures or quantitative electromyography may be required instead.

What is inside the free PDF form

The form linked at the top of this page is one printable sheet. It carries the Bohannon and Smith administration instructions, all six score definitions, and the reminder to have the patient relax before you start.

The recording area is deliberately small. There is a name and date header, a single muscle tested line, a score column from 0 to 4, and an additional comments box. Print one sheet per muscle you assess, then file each one against the visit it belongs to.

How Pabau keeps spasticity scores comparable

Most practices record MAS grades in free-text notes. The number goes in, the joint sometimes does, and the speed and position almost never do. Six visits later nobody can say whether the tone changed or the technique did.

Practice management software like Pabau lets you build the assessment as a structured form instead. The joint, the side and the grade become fields rather than sentences, so every therapist records the same things in the same order. The completed form sits in the client record next to the appointment and the treatment note.

Once the fields are fixed, the trend does the work for you. You can pull one patient’s grades for a single joint across every visit and see the direction of travel. That is what a referrer, a payer or a case conference actually asks for.

Record outcome measures the same way every visit

Pabau’s structured clinical forms keep every assessment inside the client record. Serial scores stay comparable, so progress is easy to evidence for referrers and payers.

Book a demo

Conclusion

The MAS earns its place on three counts. It is fast, it needs almost no equipment, and it gives a whole team one word for what a limb feels like. Treated as a rough instrument used carefully, it will show you change worth acting on.

What decides whether it works is repeatability. Each assessment has to repeat the same joint, the same side, the same speed and the same patient position. Get that wrong and you are comparing two techniques, not two visits.

Print the form, agree the protocol with your team, and store the results somewhere they can be lined up. Book a demo to see how Pabau keeps outcome measures structured and trackable across a rehabilitation caseload.

Continue your research

Tracking upper limb recovery after stroke? Action Research Arm Test scores grasp, grip, pinch and gross movement on a scale you can repeat every few weeks.

Need to show what tone costs a patient day to day? ADL assessment tool turns limitations in washing, dressing and feeding into a record a payer will read.

Want the patient to set the goal? Canadian Occupational Performance Measure captures the activities the patient cares about, then rates performance and satisfaction.

Assessing a child with cerebral palsy? Pediatric Balance Scale gives you a 14-item functional balance measure built for school-age children.

Following an upper limb through discharge? QuickDASH outcome measure is an 11-item patient-reported score for arm, shoulder and hand function.

Frequently asked questions