This modified Ashworth scale calculator measures spasticity in patients with multiple sclerosis or with associated muscle spasticity conditions. Below the form, there is more information on the two versions of the scale and their reliability validations.
How does this modified Ashworth scale calculator work?
This health tool assesses spasticity in the muscles, often in the evaluation of multiple sclerosis severity and in the monitoring of associated therapies.
Currently the modified Ashworth scale is the one most in use but the original version of 1964 stays as its basis, although it originates as a monitoring scale of the antispastic effect of medication rather than a patient oriented scale.
The following table presents in parallel the two versions that you can find in the two tabs of the modified Ashworth scale calculator:
| Score | Ashworth Scale (1964) | Modified Ashworth Scale by Bohannon & Smith (1987) |
| 0 (0) | No increase in tone. | No increase in muscle tone. |
| 1 (1) | Slight increase in tone giving a catch when the limb was moved in flexion or extension. | Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion when the affected part(s) is moved in flexion or extension. |
| 1+ (2) | Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the reminder (less than half) of the ROM (range of movement). | |
| 2 (3) | More marked increase in tone but limb easily flexed. | More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved. |
| 3 (4) | Considerable increase in tone - passive movement difficult. | Considerable increase in muscle tone passive, movement difficult. |
| 4 (5) | Limb rigid in flexion or extension. | Affected part(s) rigid in flexion or extension. |
Both scales are quick to administer, their time duration depending on the number of muscles/ joints evaluated, but usually less than 5 minutes.
The populations reviewed are generally adults and children with Central Nervous System (CNS) lesions leading to conditions such as:
■ Cerebral Palsy;
■ Pediatric Hypertonia;
■ Spinal Cord Injury;
■ Stroke;
■ Traumatic Brain Injury.
The Ashworth scale models allow a global assessment of the resistance to passive movement of extremities, not just stretch-reflex hyperexcitability. This also means that the whole response is influenced by soft tissue properties, dystonia, stretch reflexes or intrinsic joint stiffness.
The modified AS is also considered more of an abnormality in tone or resistance to passive movements scale rather than a direct spasticity scale.
Ashworth scales scoring system
The original version is based on a five item scale ranging from 0 to 4. The modified version includes a sixth item, noted as +1, therefore comprises of six items but in the same scale range of 0 to 4.
Scores closer to 0,1 indicate no resistance while scores of 3 and 4 are suggestive of muscle/joint rigidity.
As a result of subsequent validation studies in different disability inducing neurological conditions, the test retest reliability was deemed excellent to adequate for elbow assessments for example. The interrater reliability was quantified at 42.5-50% while the intrarater reliability performed slightly better in the range of 57.7-85%.
Modified Ashworth scale administration
While adequate training is not compulsory, in order to ensure inter-rater reliability, the examiner should have knowledge of the musculoskeletal system and the connections with neurological mechanisms and spasticity. One of the criticisms received by the model is that reliability depends on the examined muscles and that the whole procedure should be standardized.
The AS and MAS methods, as muscle strength scales, represent a straight forward method to assess muscle tone during flexion and extension. Usually certain instructions precede the application: first of all the patients needs to be placed on a therapy mat in supine position.
The flexor muscles of a joint, either belonging to the upper or the lower body, are placed in a maximally flexed position and moved to a maximally extended position over a 1 second span.
The extensor muscles of a joint are evaluated through the position of maximal extension and then moved to a maximally flexed position over a 1 second period.
After each movement, the test is correlated with the scale in use. A certain clinical repetition is accepted in order to increase accuracy; however, muscles should not be tested for more than 3 times in a row.
References
1) Bohannon RW, Smith MB. (1987) Interrater reliability of a modified Ashworth scale of muscle spasticity. Phys Ther; 67(2):206-7.
2) Damiano DL, Quinlivan J et al. (2007) What does the Ashworth scale really measure and are instrumented measures more valid and precise? Developmental Medicine & Child Neurology; Volume 44, Issue 2;
3) Ansari NN, Naghdi S, Arab TK, Jalaie S. (2008) The interrater and intrarater reliability of the Modified Ashworth Scale in the assessment of muscle spasticity: limb and muscle group effect. NeuroRehabilitation; 23(3):231-7.
03 Feb, 2016