The Modified Ashworth Scale is a six-level clinical scale used to record how much resistance an examiner feels while moving a relaxed limb. It is the most widely used clinical instrument for increased muscle tone, but the number is only the beginning of the conversation: resistance can reflect spasticity, tissue stiffness, or both. If you live with the effects of stroke, brain injury, spinal cord injury, multiple sclerosis, or cerebral palsy, knowing what the score captures and what it does not helps you ask better questions about rehabilitation.
What the Modified Ashworth Scale Actually Measures
The Modified Ashworth Scale, usually called the MAS, measures resistance to passive movement. “Passive” matters: the clinician moves your arm or leg rather than asking you to move it. The score reflects the resistance felt as the joint travels through its available range of motion.
The MAS is related to spasticity, but it is not a direct, pure measurement of it. In the classic definition from Jim Lance, spasticity is a velocity-dependent increase in the stretch reflex and is part of upper motor neuron syndrome. In practical terms, the speed of a stretch changes the reflex response. The MAS uses one controlled test speed, so it records the overall resistance at that moment rather than separating every source of that resistance.
Two broad contributors can be present at the same time. A neural contribution involves reflex-mediated activity. A biomechanical contribution can involve non-neural stiffness, including fibrotic change. An elbow that feels difficult to extend may therefore receive a higher MAS score without the scale showing how much came from each contributor. This distinction matters when your rehabilitation team interprets a change over time.
Take the elbow as an example. During passive elbow movement, an examiner may feel a brief catch and then very little additional resistance. That is different from resistance that persists through most of the motion, and different again from a limb that is rigid. The MAS supplies common language for recording those differences. It does not replace the wider clinical assessment.
Why the Scale Has a Distinctive 1+ Score
The story of the Ashworth Scale begins with multiple sclerosis. In 1964, Bryan Ashworth published the original Ashworth Scale while studying the effects of carisoprodol in people with MS. That original scale had five levels, from 0 to 4: 0 meant no resistance, while 4 described a limb rigid in flexion or extension.
In 1987, Bohannon and Smith added a level between 1 and 2. The addition was labeled 1+, producing the six levels used in the Modified Ashworth Scale: 0, 1, 1+, 2, 3, and 4. That small-looking change is the major practical difference between the original Ashworth Scale and the MAS. It gives clinicians an option for mild findings that are more than a minimal catch at the end of motion but do not rise to the level of score 2.
Bohannon and Smith tested the modified scale at the elbow flexors in 30 people with intracranial lesions. Their reported agreement was 86.7%, with a Kendall tau of 0.847. The finding helps explain why the scale became so widely used: it is quick to describe and can make repeated observations easier to communicate. Still, results from one muscle group and one testing situation do not remove the need for careful technique in every setting.
How Clinicians Perform the Modified Ashworth Scale
MAS testing is a clinical examination, not a home test or a diagnosis. Consistency is central because the score depends on what is felt during movement. The examination is typically done while you lie on your back, a position in which muscle tone is lowest. It is also done before range-of-motion measurement, rather than afterward.
- Choose the muscle group and starting position. The joint begins in maximum flexion or extension, depending on the muscle group being tested.
- Move through the full available range. The examiner passively moves the limb through its full range of motion.
- Keep the pace controlled. Ideally, the movement takes about one second, or approximately 130 degrees per second.
- Use a smooth motion. Jerking the limb, moving it too fast, or using excessive force can distort what the examiner feels.
- Repeat carefully when needed. Up to three repetitions may be used, with at least three seconds between them. The lowest score is documented.
These details make scores reproducible. If one assessment is much faster than the next, the examiner may feel a different response even if the underlying condition has not changed. A meaningful series of scores depends on comparable positioning, movement, timing, and muscle group.
Reliability also differs by body region. Interrater reliability is better in the upper extremity, such as the elbow flexors, than in the lower extremity, such as the ankle plantar flexors. In a 2020 study, novice raters using a metronome-guided speed of 130 degrees per second achieved moderate reliability for wrist flexors (kw = 0.54) but low reliability for ankle flexors (kw = 0.08). Read your score in context, especially when different people perform the assessment.
How Modified Ashworth Scale Scoring Describes Resistance
The MAS is an ordinal scale: its levels describe increasing categories of resistance. It should not be treated as a precise measurement of the force needed to move a limb. A score of 2 means more resistance than 1+, but the labels do not promise that the difference between every neighboring level is identical.
| MAS score | What the examiner records |
|---|---|
| 0 | No increase in muscle tone. |
| 1 | A slight increase in muscle tone, seen as a catch and release or as minimal resistance at the end of the range of motion. |
| 1+ | A slight increase in tone shown by a catch, followed by minimal resistance through the remainder of the movement, affecting less than half of the range of motion. |
| 2 | A more marked increase in tone through most of the range of motion, while the affected limb is still easily moved. |
| 3 | A considerable increase in tone; passive movement is difficult. |
| 4 | The affected limb is rigid in flexion or extension. |
What a score of 1+ means
A 1+ score does not simply mean “half a point better” or “half a point worse.” It has a specific description. The clinician feels a catch, then minimal resistance during the rest of the movement, and that resistance occurs through less than half of the range of motion. The added category improves sensitivity at the lower end of the scale, where a score of 1 may not fully describe the finding.
For you or your family, the clearest interpretation may be that the limb felt mildly tighter during the examination but was not difficult to move through most of its range. Your clinician can then connect that observation to your movement, comfort, and rehabilitation goals rather than treating the number as a stand-alone verdict.
Why a Score Helps but Cannot Tell the Whole Story
Over time, a MAS score can document change, support communication across a care team, and provide one reference point before and after an intervention. It cannot distinguish neural, reflex-mediated spasticity from biomechanical, non-neural stiffness. For that reason, a high score does not by itself identify the cause of resistance, and a low score does not answer every question about function.
The Modified Tardieu Scale works differently: it tests at two or three different speeds, so it better represents the velocity-dependent feature in Lance’s definition of spasticity. In studies of people with severe brain injury, test-retest reliability was significantly higher for the Modified Tardieu Scale, with kappa values of 0.52 to 0.87, than for the MAS, with kappa values of 0.47 to 0.62.
In cerebral palsy, this limitation is especially relevant. Spastic cerebral palsy is the most common form of cerebral palsy and affects more than 90% of people with CP. The MAS is used in children with spastic CP, yet a study of 37 children found low-to-average intraobserver reliability for the MAS and average-to-excellent reliability for the Modified Tardieu Scale. The result does not make the MAS useless. It means that choosing and interpreting a scale should match the clinical question.
A related tool, the Modified Modified Ashworth Scale, removes the 1+ category and redefines level 2. In a study of 64 patients, it was neither superior nor inferior to the MAS, with kw values of 0.892 and 0.868 respectively. Similar names do not make scores interchangeable, so ask which scale was used when you compare findings over time.
Where Spasticity Appears After Neurologic Injury
Spasticity can develop after conditions that affect the brain or spinal cord, and its frequency differs across groups. It affects about 35% of people after stroke, more than 90% of people with cerebral palsy, and about 50% of people after traumatic brain injury. After spinal cord injury, spasticity occurs in about 40% of people. In multiple sclerosis, reported prevalence ranges from 37% to 78%, depending on disease stage and the measurement method.
Post-stroke estimates also vary with who is studied and when. Among people with initial central paresis, 42.6% developed spasticity by six months; severe spasticity, defined as MAS 3 or higher, affected 15.6%. A 2020 meta-analysis of 12 cohort studies found a pooled post-stroke prevalence of 25.3%, rising to 39.5% among people with a first stroke and paresis. These figures describe groups, not a prediction for you.
In MS, disrupted signaling between the brain, spinal cord, and muscles can interfere with the coordination of contraction and relaxation. A sudden increase deserves attention. Urinary tract infections, skin wounds, and kidney or bladder stones are common triggers of a spasticity flare in MS. Before any medication change, your clinician should check for these triggers.
How a Score Can Inform a Treatment Conversation
A MAS number does not prescribe one treatment. It can help frame a discussion about where tone is increased, whether the issue is local or widespread, and whether the goal is to reduce resistance, make movement easier, or address a change from a previous assessment. Make treatment choices with a qualified clinician, especially when spasticity is new, worsening, or affecting daily care.
Stretching and daily management
Stretching is a foundation of spasticity management and is recommended daily. For mild spasticity, stretching alone may be enough. Effective stretches are held for at least 20 to 30 seconds per repetition. Ice, vibration, or electrical stimulation may temporarily reduce spasticity before stretching, and they are often combined with it.
The evidence needs a careful reading. A 2022 systematic review found no conclusive evidence that stretching alone is effective for post-stroke spasticity. At the same time, a randomized study of 21 people with chronic stroke found that a hand stretching device used twice daily, six days per week, improved the average MAS score from 2.83 to 1.20 after three weeks. One study and one protocol do not guarantee the same result for every person.
Botulinum toxin for local spasticity
For local spasticity, botulinum toxin type A can be injected directly into overactive muscles. The effect typically lasts about three to four months, and reinjection is recommended no sooner than 12 weeks. The treated muscle is intentionally weakened, which can impair function if that muscle is needed for everyday movement. This tradeoff is a central part of the treatment discussion.
Three commercial botulinum toxin type A products are available: onabotulinumtoxinA, abobotulinumtoxinA, and incobotulinumtoxinA. Their units are not interchangeable. Dose and product selection are medical decisions, so do not compare unit numbers across products as though they represented the same amount.
When a Baclofen Pump May Enter the Discussion
An intrathecal baclofen pump delivers baclofen directly into the spinal canal. It may be considered when spasticity is widespread, particularly in the legs, and other treatments have not provided enough relief. Because the medication arrives at the site of action, the pump can use up to 100 times less baclofen than oral treatment and can cause substantially less fatigue.
Before implantation, a screening test is required. A trial dose is injected into the spinal fluid to see whether you respond; people who do not respond to the screening doses are not considered suitable for an implanted pump. The ongoing dose varies widely from person to person and with the origin of the spasticity, so your treating team sets and adjusts it.
Over the long term, a pump also requires attention. The medication reservoir lasts one to six months, and the battery lasts about seven years before the pump must be surgically replaced. Unusual sleepiness, breathing problems, or loss of consciousness can signal baclofen overdose. A sudden return of spasticity, itching, or low blood pressure can signal withdrawal. Both overdose and withdrawal are emergencies and need urgent medical care.
Common Misunderstandings That Can Lead to Wrong Conclusions
- “The MAS measures only spasticity.” It measures resistance to passive movement, which can include neural and biomechanical components.
- “A score of 1+ is halfway between 1 and 2 in every respect.” It is a specific category: a catch followed by minimal resistance through less than half of the range of motion.
- “The same score always means the same experience.” Testing position, movement speed, body region, and examiner technique affect interpretation.
- “A score is a diagnosis.” The MAS is a clinical measurement, not a diagnosis or a complete explanation for increased tone.
- “A worsening score can be managed alone.” Discuss new or worsening spasticity with your doctor, particularly when MS triggers such as infection, a wound, or kidney or bladder stones may be involved.
Frequently Asked Questions
What does the Modified Ashworth Scale measure?
It measures the resistance an examiner feels while passively moving your limb. The result reflects overall resistance, not only velocity-dependent spasticity.
How do clinicians perform the Modified Ashworth Scale?
They position the joint at maximum flexion or extension as appropriate, move the limb passively through its full range at a smooth controlled pace of about one second, and may repeat the test up to three times with at least three seconds between trials. The lowest score is recorded.
What is a score of 1+ on the Modified Ashworth Scale?
It means there is a catch followed by minimal resistance during the remainder of movement, with that resistance occurring through less than half of the range of motion.
Is the Modified Ashworth Scale the same as a spasticity diagnosis?
No. It is a way to record resistance to passive movement. It cannot separate reflex-mediated spasticity from non-neural stiffness or fibrosis.
When should you see a doctor about spasticity?
See a doctor for new or worsening spasticity. In MS, possible triggers such as a urinary tract infection, skin wound, or kidney or bladder stone should be checked. If you use intrathecal baclofen, breathing problems, loss of consciousness, a sudden return of spasticity, itching, or low blood pressure require urgent medical care.
