Ashworth Scale: what is it and what is it for?

A medical meter to measure Muscle tone and spasticity.

The Ashworth scale is an instrument that measures the degree of spasticity or increased muscle tone, a problem that causes stiffness and a loss of balance between contraction and contraction.It is a problem that causes stiffness in the patient and a loss of balance between contraction and relaxation of the muscles. It is a scale to be applied and completed by the professional, with the patient's help.

In this article we explain what the Ashworth scale and its modified version consist of, the items that compose it, how it is applied and its psychometric properties.

What is the Ashworth scale?

The Ashworth scale, also called the Ashworth spasticity scale, is a diagnostic tool used to measure muscle tone and spasticity, i.e. the ability of muscles to remain slightly contracted.

This scale was originally created by Ashworth in 1964 and was later modified by Bahannon and Smith in 1989 into what is now known as the Ashworth Spasticity Scale. into what is now known as the modified Ashworth scale. This new version better measures muscle hypertonia.

This instrument consists of a subjective clinical rating scale that allows direct assessment of muscle spasticity ranging from no increase in muscle tone to extreme stiffness when flexing or extending muscles.

The Ashworth scale was validated with neurological patients with different degrees of spasticity and has shown high interobserver reliability, both in the assessment of elbow flexor spasticity and in the measurement of plantar flexor spasticity.

The modified scale adds items including the angle at which resistance appears, monitoring passive movement velocity with a 1-second count. This improved version is easy to use and is suitable for all joints (although it performs better with the upper extremities). However, it still has room for improvement in the degree of discrimination (between +1 and -1) or sensitivity.

Scale items and application

The modified Ashworth scale contains five main items, graded from 0 to 4, including an additional item on scale 1.

Being a subjective assessment scale, the score depends on the personal appreciation of the health professional who applies it. It is important to know that this scale is heteroadministered, since neither the patient nor unqualified personnel are suitable for its application.

After observing the patient, the professional should assign values from 0 to 4, with the following meaning:

• 0: Normal muscle toneNormal muscle tone, total absence of increased muscle tone.

• 1: Mild hypertoniaconsists of an increase in muscle tone, either by flexion or extension. It can be observed by palpation or relaxation and implies some resistance at the end of the arc of muscle movement.

• 1+: Slight increase in the resistance of the muscle response to movement in flexion or extension, followed by in flexion or extension, followed by minimal resistance throughout the remainder of the arc of travel (less than half). This item complements the previous item,

• 2: Moderate hypertoniaThis item implies a marked increase in muscle resistance during most of the arc of joint movement, even though the joint moves easily and does not excessively limit its movement.

• 3: Intense hypertoniaconsists of a marked increase in muscle resistance and implies that passive movement is executed with difficulty.

• 4: Extreme hypertoniaThis last item implies that the affected parts are completely rigid, in flexion or extension, even when moving passively.

Psychometric properties

The psychometric properties of an instrument or rating scale include properties such as validity or reliability, aspects that take into account how effective and reliable an instrument is in assessing what it claims to measure, or the degree to which each of its component elements contributes to give stability to the measurement of each characteristic.

The modified Ashworth scale has several psychometric studies that have assessed its psychometric properties in order to test its efficacy and reliability for measuring and evaluating spasticity and muscle hypertonia.

The main conclusions reached are the following:

• Lhe Ashworth scale is reliable, useful and validIt responds correctly to the passive movement performed by the health professional in a specific joint.

• The modified scale has a greater variety of items than its predecessor, due to the fact that the assessment is made by joints and in each hemibody of the subject. There are also certain differences in the evaluation process.

• The diagnostic instrument is an evaluative tool that provides a suitable assessment by requiring quantitative clinical measures of the spasticity compromise of each subject.

• It is a suitable tool for assessing spasticity over time and, thus, for monitoring the patient's improvement.

• The reliability coefficient of the test tends to be at its maximum expressionThe reliability coefficient of the test tends to its maximum expression, so that the scale seems to be an instrument free of random errors, as the scores of successive diagnoses have been stable in the different evaluations.

• The modified Ashworth scale has proved to be a reliable instrument, both for the assessment of upper and lower limb spasticity.

• One of the negative aspects of the scale is that it seems to have low levels of sensitivity when there is little variability in the degree of spasticity of the subjects.

• As it is a subjective instrument, there are limitations related to the profile of each professional evaluator.

Other tests that evaluate spasticity

Beyond the Ashworth scale, there are a number of other tests capable of measuring spasticity. Some of the best known include:

1. counting clonic beats 2. counting clonic pulses.

In this test, the professional examiner looks for the presence and number of muscle contractions and relaxations (pulses) that make movements (pulses) that make movements, above and below the ankle, wrist and other joints.

The scale is graded from 0 to 3: 0 being no pulses; 1, no or few sustained pulses; 2, sustained or continuous pulses; and 3, spontaneous or elicited by a light or sustained touch.

2. Tardieu Scale

The Tardieu scale is an instrument in which the assessing professional moves the patient's muscles at different speedsThe Tardieu scale is an instrument in which the tester moves the patient's muscles at different speeds, fast and slow, to see if the resistance changes with the speed of the movement.

The scale is graded from 0 to 4 with 0, no resistance through the course of stretching; 1, little resistance at a specific angle through the course of stretching, with no clear muscle engagement; 2, clear engagement at a specific angle, interrupting the stretch, followed by relaxation; 3, clonia appearing at a specific angle lasting less than 10 seconds while the evaluator maintains pressure; and 4, same as the item, except for duration, which must be greater than 10 seconds.

3. Penn Spasm Frequency Scale

This scale is intended to report how often muscle spasms occur.. It is graduated from 0 to 4 as follows: 0, no spasms; 1, spasms induced only by stimuli; 2, spasms occurring less than once every hour; 3, spasms occurring more than once every hour; and 4, spasms occurring more than 10 times every hour.

Bibliographical references:

• Agredo, C. A., & Bedoya, J. M. (2005). Validation of the modified ashworth scale. Arq Neuropsiquiatr, 3, 847-51.

• Calderón-Sepúlveda, R. F. (2002). Scales for measuring motor function and spasticity in cerebral palsy. Rev Mex Neuroci, 3(5), 285-89.

• Vattanasilp W, Ada L. Comparison of the Ashworth scale and clinical laboratory measures for assessing spasticity. Aust J. Physiother 1999; 45: 135-139.