Modified Ashworth Scale

Purpose

The Modified Ashworth Scale is considered the primary clinical measure of muscle spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
in patients with neurological conditions. However, some publications question its ability to measure spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
and advocate the Modified Ashworth Scale as a rating scale to measure abnormality in tone or the resistance to passive movements, since there is no clinically direct method for measuring spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
(Gregson, Leathley, Moore, Sharma, Smith & Watkins, 1999; Pandyan, Johnson, Price, Curless, Barnes & Rodgers, 1999).

In-Depth Review

Purpose of the measure

The Modified Ashworth Scale is considered the primary clinical measure of muscle spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
in patients with neurological conditions. However, some publications question its ability to measure spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
and advocate the Modified Ashworth Scale as a rating scale to measure abnormality in tone or the resistance to passive movements, since there is no clinically direct method for measuring spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
(Gregson, Leathley, Moore, Sharma, Smith & Watkins, 1999; Pandyan, Johnson, Price, Curless, Barnes & Rodgers, 1999).

Available versions

The Ashworth Scale was initially developed in the early 1960s by Bryan Ashworth, to estimate the efficacy of anti-spastic drugs in clients with Multiple Sclerosis. It is a 5-point scale, with a grade score of 0, 1, 2, 3, or 4 (Ashworth, 1964). In 1987, Bohannon and Smith added the grade “1+” and proposed slight changes on the definitions of each score in order to increase the sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also "Specificity."
of the measure and facilitate scoring. The new measure was then called the Modified Ashworth Scale and is considered by many as the gold standardA measurement that is widely accepted as being the best available to measure a construct.
for measuring spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
(Bohannon & Smith, 1987).

Features of the measure

Items:

Although there are no standardized guidelines for its use, the Modified Ashworth Scale can be applied to muscles of both the upper or lower body. The rater should extend the client’s limb from a position of maximal flexion to maximal extension until the first soft resistance is felt. Moving a client’s limb through its full range of motion should be done within one second by counting “one thousand and one” (Bohannon and Smith, 1987).

Mehlroz, Wagner, Meibner, Grundmann and Zange (2005) suggest testing of the upper limbs should take place while the client is lying supine, with the upper limbs parallel to the trunk, elbows extended, wrists in a neutral position, and the lower limbs positioned parallel to one another. Exceptions are made for the shoulder extensors, where the arm should be moved from extension to 90 degrees of flexion, and for the shoulder internal rotators, where the arm should be moved from neutral to a maximum external rotation.

For the lower limbs, Blackburn, van Vliet, and Mockett (2002) recommend that the client should be side lying. Specifically for testing the soleus muscle, the hips and knees should be positioned in 45 degrees of flexion and the ankle is moved from maximum plantar flexion to maximum dorsiflexionTurning an appendage in an upward direction, for example turning the foot so that the angle between the foot and the leg decreases.
. For the gastrocnemius muscle, hips should be in 45 degrees of flexion with the knees in maximum extension and the ankle is moved from maximum plantar flexion to maximum dorsiflexionTurning an appendage in an upward direction, for example turning the foot so that the angle between the foot and the leg decreases.
. For the quadriceps femoris muscle, knees and hips should be in maximal extension and the knee is moved from maximum extension to maximum flexion.

Throughout testing the client should be instructed to remain calm and relaxed, and when repeated testing is undertaken, testing should be initiated at the same time of the day to minimize possible changes in spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
levels due to medication interaction (Bohannon and Smith, 1987).

Scoring:

The Modified Ashworth Scale is a 6-point scale. Scores range from 0 to 4, where lower scores represent normal muscle tone and higher scores represent spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
or increased resistance to passive movement.

Specific score definitions for the Ashworth Scale and for the Modified Ashworth Scale are as follows:

Time:

Not reported, but it will vary with the numbers of muscles being tested.

Subscales:

None

Equipment:

• Therapy mat
• Paper

Training:

None typically reported.

Alternative form of the Modified Ashworth Scale

• Ashworth Scale:
  Published in 1964, the Ashworth Scale was the original measure for resistance to passive movement. It is a 5-point scale, with a grade score of 0, 1, 2, 3, or 4. The Ashworth Scale is less sensitive than the Modified Ashworth Scale (Brashear, Zafonte, Corcoran, Galvez-Jimenez, Gracies, Gordon et al., 2002).
• Modified Modified Ashworth Scale:
  Published in 2006, the Modified Modified Ashworth Scale aims to improve the reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
  of the Modified Ashworth Scale. It is a 5-point scale, where the authors omitted the grade “1+” from the Modified Ashworth Scale and slightly redefined the grade “2” (Ansari, Naghdi, Younesian, & Shayeghan, 2008). The definition for each grade is as follows:

Client suitability

Can be used with:

• Clients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More.
• Clients with other neurological impairment such as multiple sclerosis, traumatic
  brain injury, spinal cord injury.

Should not be used in:

• To date, there is no information on restrictions for using the Modified Ashworth Scale.

In what languages is the measure available?

English

Summary

Psychometric Properties

Overview

We conducted a literature search to identify all relevant publications on the psychometric properties of the Modified Ashworth Scale in individuals with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. We identified twenty studies. The Modified Ashworth Scale shows conflicting results regarding its reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of "true" variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to "noise" in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
and validityThe degree to which an assessment measures what it is supposed to measure.
.

Reliability

Note: The Modified Ashworth Scale’s reliabilityReliability can be defined in a variety of ways. It is generally understood to be the extent to which a measure is stable or consistent and produces similar results when administered repeatedly. A more technical definition of reliability is that it is the proportion of “true” variation in scores derived from a particular measure. The total variation in any given score may be thought of as consisting of true variation (the variation of interest) and error variation (which includes random error as well as systematic error). True variation is that variation which actually reflects differences in the construct under study, e.g., the actual severity of neurological impairment. Random error refers to “noise” in the scores due to chance factors, e.g., a loud noise distracts a patient thus affecting his performance, which, in turn, affects the score. Systematic error refers to bias that influences scores in a specific direction in a fairly consistent way, e.g., one neurologist in a group tends to rate all patients as being more disabled than do other neurologists in the group. There are many variations on the measurement of reliability including alternate-forms, internal consistency , inter-rater agreement , intra-rater agreement , and test-retest .
appears to be muscle-dependent. In general, assessments of the elbow and wrist showed better results when compared to assessments of the knee and ankle plantar muscle.

Intra-rater:
Gregson, Leathley, Moore, Sharma, Smith, and Watkins (1999) estimated the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of the Modified Ashworth Scale in 32 clients with acute strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More and a median age of 74 years by measuring muscle tone at the elbow. Participants were assessed by the same rater within a 1-day interval at the same time of the day. Intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
, as calculated using weighted kappa was excellent (weighted kappa = 0.83).

Gregson, Leathley, Moore, Smith, Sharma, and Watkins (2000) evaluated the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of Modified Ashworth Scale in 35 clients with acute strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More and a median age of 75 years by measuring muscle tone of flexors and extensors of the elbow, wrist, knee and ankle. Participants were assessed by the same rater within a 1-day interval at the same time of the day. Intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
, as calculated using weighted kappa was excellent for the elbow (weighted kappa = 0.83), wrist (weighted kappa = 0.88), and knee weighted kappa = 0.94) and adequate for the ankle (weighted kappa = 0.64).

Blackburn, van Vliet, and Mockett (2002) measured the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of the Modified Ashworth Scale in 20 clients with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More and 16 clients with chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More measuring muscle tone of the gastrocnemius, soleus and quadriceps femoris. Participants were evaluated by the same rater within a 1-week interval. Intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
as calculated using Kendall’s tau-b was adequate for the Modified Ashworth Scale, (Kendall’s tau-b = 0.56) as well as for each muscle tested: gastrocnemius (Kendall’s tau-b = 0.44), soleus (Kendall’s tau-b = 0.58), and quadriceps femoris (Kendall’s tau-b = 0.66). Lower scores on the Modified Ashworth Scale showed higher levels of agreement. A score of 0 indicated that an intra-rater agreement of 60% was achieved while at score of 2 indicated only 12% of intra-rater agreement.

Mehrholz, Wagner, Meibner, Grundmann, and Zange (2005) estimated the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of Modified Ashworth Scale and the Modified Tardieu Scale (MTS) in 30 clients with, either from strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More, traumatic brain injury or cerebral hypoxia by measuring muscle tone of the shoulder, elbow, wrist, hip, knee and ankle. Participants were re-assessed within a 1-day interval, at the same time of the day and position, by the same rater. Intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
, as calculated using kappa statistics were adequate for all muscles as follows: Shoulder flexor (kappa = 0.55), shoulder external rotator (kappa = 0.47), elbow flexor (kappa = 0.47), elbow extensor (kappa = 0.53), wrist flexor (kappa = 0.58), wrist extensor (kappa = 0.51), hip flexor (kappa = 0.53), hip extensor (kappa = 0.49), knee flexor (kappa = 0.52), knee extensor (kappa = 0.55), ankle extensor with knee joint flexed (kappa = 0.62), ankle extension with knee joint fully extended (kappa = 0.47). When compared with the MTS, the intra-rater reliabilityThis is a type of reliability assessment in which the same assessment is completed by the same rater on two or more occasions. These different ratings are then compared, generally by means of correlation. Since the same individual is completing both assessments, the rater’s subsequent ratings are contaminated by knowledge of earlier ratings.
of the MTS was significantly higher for all muscles (P<0.05), except for the extensor and internal rotator muscles of the shoulder (P>>0.05).

Inter-rater:
Bohannon and Smith (1987) analyzed the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 30 clients with intracranial lesions either from multiple sclerosis (n = 1), closed head injuries (n = 5) or strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More (n = 24) by measuring muscle tone of the elbow flexors. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using Kendall’s tau-b, was excellent (Kendall’s tau-b = 0.84).

Bodin and Morris (1991) estimated the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 18 clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More by measuring muscle tone at the wrist. Participants were assessed by two different raters, independently, under three different conditions: immediately after positioning, after a 90 second stretch of the flexors and after a 90 second stretch of the extensors. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using Kendall’s tau-b, was excellent (Kendall’s tau-b = 0.85) and adequate when agreement was calculated using kappa values (kappa = 0.74).

Sloan, Sinclair, Thompson, Taylor, and Pentland (1992) verified the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 34 clients with hemiplegiaComplete paralysis of the arm, leg, and trunk on one side of the body that results from damage to the parts of the brain that control muscle movements. Hemiplegia is not a progressive condition, nor is it a disease. secondary to strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More by assessing muscle tone of the knee flexors, elbow flexors and extensors. Participants were assessed by four raters independently. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using Spearman’s rho, ranged from adequate to excellent at the elbow (rho = 0.56 to 0.90) and from poor to excellent at the knee (rho = 0.26 to 0.62).

Gregson et al. (1999) estimated the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 32 clients with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More and a median age of 74 years by measuring muscle tone at the elbow. Participants were assessed by two different raters at approximately the same time of the day. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
as calculated using weighted kappa was excellent (weighted kappa = 0.84).

Gregson et al. (2000) evaluated the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 35 clients with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More and a median age of 75 years by measuring the muscle tone of flexors and extensors of the elbow, wrist, knee and ankle. Participants were assessed by two different raters at approximately the same time of the day. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using weighted kappa was excellent for the elbow (weighted kappa = 0.96), wrist (weighted kappa = 0.89) and knee (weighted kappa = 0.79) and adequate for the ankle (weighted kappa = 0.51).

Blackburn et al. (2002) measured the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 20 clients with acute strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More and 16 clients with chronic strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. Muscle tone of the gastrocnemius, soleus and quadriceps femoris was measured. Participants were evaluated by two different raters. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale, as calculated using Kendall’s tau-b, was poor (Kendall’s tau-b = 0.06). Kendall’s tau-b ratings were also poor for the gastrocnemius (Kendall’s tau-b = 0.15), soleus (Kendall’s tau-b = 0.19), and quadriceps femoris (Kendall’s tau-b = 0.28). Agreement between raters occurred mostly at a score of 0, in which an agreement of 40.8% was achieved. Higher scores, such as a score of 2, showed 0% of agreement between raters.

Ansari, Naghdi, Moammeri, and Jalaie (2006) assessed the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale in 15 clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More by measuring muscle tone of the elbow flexors. Participants were assessed by two different raters. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using kappa statistics, was poor (kappa = 0.21).

Mehrholz et al. (2005) estimated the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the Modified Ashworth Scale and the Modified Tardieu Scale (MTS) in 30 clients with severe cerebral damage, either from strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More, traumatic brain injury or cerebral hypoxia by measuring muscle tone of the shoulder, elbow, wrist, hip, knee and ankle. Participants were re-assessed by four different raters. Inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
, as calculated using kappa statistics was adequate for elbow extension (kappa = 0.42) and poor for all other muscles, as follows: shoulder flexors (kappa = 0.29), shoulder external rotators (kappa = 0.16), elbow flexors (kappa = 0.33), wrist flexors (kappa = 0.34), wrist extensors (kappa = 0.30), hip flexors (kappa = 0.31), hip extensors (kappa = 0.24), knee flexors (kappa = 0.28), knee extensors (kappa = 0.35), ankle extensors with knee flexed (kappa = 0.20), and ankle extensor with knee fully extended (kappa = 0.14). When compared with the MTS, the inter-rater reliabilityA method of measuring reliability . Inter-rater reliability determines the extent to which two or more raters obtain the same result when using the same instrument to measure a concept.
of the MTS was significantly higher for all muscles (P<0.05) except for wrist extensor muscles (P>0.05).

Validity

Content:

Pandyan, Johnson, Price, Curless, Barnes, and Rodgers (1999) performed a literature review to gather evidence for a theoretical basis of the Modified Ashworth Scale. The implicit assumptions for the Modified Ashworth Scale appear to be that: 1) Changes in the resistance to passive movement are due to changes in spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
; 2) Stretch mechanoreceptors in the muscle would elongate with similar velocity during repeated measures and 3) The range of movement on each joint during repeated measures is unaltered. Also, caution is required when stating that the Modified Ashworth Scale is a measure of spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
since evidence suggests that the resistance to passive movement is not an exclusive measure of spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
, and will vary according to the level of activity in the alpha motor neuron of agonist and antagonist muscles, the viscoelastic properties of soft tissues and joints.

Criterion:

Concurrent:
Cooper, Musa, van Deursen, and Wiles (2005) assessed the concurrent validityTo validate a new measure, the results of the measure are compared to the results of the gold standard obtained at approximately the same point in time (concurrently), so they both reflect the same construct. This approach is useful in situations when a new or untested tool is potentially more efficient, easier to administer, more practical, or safer than another more established method and is being proposed as an alternative instrument. See also “gold standard.”
of the Modified Ashworth Scale by comparing it to surface electromyography as the gold standardA measurement that is widely accepted as being the best available to measure a construct.
for spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
in 31 clients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More and 20 healthy individuals. A poor correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
was reported between the Modified Ashworth Scale and surface electromyography, as calculated using Spearman’s rho (rho = 0.21).

Predictive:
No studies have examined the predictive validityA form of criterion validity that examines a measure's ability to predict some subsequent event. Example: can the Berg Balance Scale predict falls over the following 6 weeks? The criterion standard in this example would be whether the patient fell over the next 6 weeks.
of the Modified Ashworth Scale.

Construct:

Convergent/Discriminant:
Katz, Rovai, Brait, and Rymer (1992) tested the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the Modified Ashworth Scale by comparing it to the Fugl-Meyer Assessment (Fugl-Meyer, Jääskö, Leyman, Olsson, & Steglind, 1975) and objective measurements of spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
including electromyography, torque, pendulum testThis is a test for spasticity. The patient sits on a table and the examiner holds the patient’s foot with the knee as fully extended as possible. The examiner drops the leg, and a computer records the motion and vibration.
, and H/M ratio in 10 clients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. Correlations as calculated using Pearson correlations were excellent between the Modified Ashworth Scale and the Fugl-Meyer Assessment (r = -0.94), the electromyography (r = -0.79), and the pendulum testThis is a test for spasticity. The patient sits on a table and the examiner holds the patient’s foot with the knee as fully extended as possible. The examiner drops the leg, and a computer records the motion and vibration.
(r = -0.67). No significant correlations were found between the Modified Ashworth Scale, torque, and H/M ratio, and therefore their respective values were not described by the authors.

Lin and Sabbahi (1999) measured the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the Modified Ashworth Scale by comparing it to hyperactive stretch reflex measures such as electromyography, torque response and velocity sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.”
of the stretch reflexes as well as to motor performance measures such as the Fugl-Meyer Assessment (Fugl-Meyer, Jääskö, Leyman, Olsson, & Steglind, 1975), the Box and Block test (Cromwell, 1965; Mathiowetz, Volland, Kashman, & Weber, 1985a), active range of motion and grip strength in 10 clients with chronic strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. Correlations were calculated at two points in time using Spearman’s rho. Correlations between the Modified Ashworth Scale and motor performance measures for both day 1 and 2 were all excellent: Fugl-Meyer Assessment (rho1 = -0.83; rho2 = -0.76), Box and Block Test (rho1 = -0.83; rho2 = -0.76), active range of motion (rho1 = -0.74; rho2 = -0.62) and grip strength (rho1 = -0.86; rho2 = -0.85). With respect to the hyperactive stretch reflexes,excellent correlations were found between the Modified Ashworth Scale and electromyography of muscles at rest on day 1 (rho = 0.77) and day 2 (rho = 0.67), electromyography of active muscles at day 1 (rho = 0.77), on day 2 (rho = 0.74) and the torque of muscles at rest on day 1 (rho = 0.80). Adequate correlations were found between the Modified Ashworth Scale and velocity sensitivitySensitivity refers to the probability that a diagnostic technique will detect a particular disease or condition when it does indeed exist in a patient (National Multiple Sclerosis Society). See also “Specificity.”
on day 1 (rho = 0.52) and day 2 (rho = 0.57). Poor correlations were found between the Modified Ashworth Scale and torque of muscles at rest on day 2 (rho = -0.25) and the torque of active muscles on day 1 (rho = 0.26) and on day 2 (rho = 0.21).

Pandyan, Price, Rodgers, Barnes and Johnson (2001) estimated the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the Modified Ashworth Scale by comparing it to biomechanical measures of resistance to passive movement of the elbow in 16 clients with acute strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. In this study, the correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
using Kappa statistics was poor (kappa = 0.36).

Pandyan, Price, Barnes, and Johnson (2003) evaluated the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the Modified Ashworth Scale by comparing it to a biomechanical measure of resistance to passive movement of the elbow in 63 clients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. An adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
was found using Spearman’s rho (rho = 0.51).

Pizzi, Carlucci, Falsini, Verdesca and Grippo (2005) estimated the convergent validityA type of validity that is determined by hypothesizing and examining the overlap between two or more tests that presumably measure the same construct. In other words, convergent validity is used to evaluate the degree to which two or more measures that theoretically should be related to each other are, in fact, observed to be related to each other.
of the Modified Ashworth Scale by comparing it to neurophysiologic assessments of spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
(H-reflex and M-response), passive range of motion of the elbow and wrist, and pain in 65 clients with strokeAlso called a “brain attack” and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a “schemic stroke”, or the formation of a blood clot in a vessel supplying blood to the brain. More. Correlations were calculated using Spearman’s rho and Fisher exact test. An adequate correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
between the Modified Ashworth Scale and the neurophysiologic assessment of the wrist was found (rho = 0.40). Also, higher scores (>3) on the Modified Ashworth Scale were associated with a decrease in passive range of motion (F = 6.8). No correlationThe extent to which two or more variables are associated with one another. A correlation can be positive (as one variable increases, the other also increases – for example height and weight typically represent a positive correlation) or negative (as one variable increases, the other decreases – for example as the cost of gasoline goes higher, the number of miles driven decreases. There are a wide variety of methods for measuring correlation including: intraclass correlation coefficients (ICC), the Pearson product-moment correlation coefficient, and the Spearman rank-order correlation.
was found between pain and Modified Ashworth Scale values for either the elbow or the wrist.

Known groups:
Bakheit, Maynard, Curnow, Hudson, and Kodapola (2003) analyzed whether Modified Ashworth Scale scores were able to distinguish between individuals with higher values in the H- reflex latency and H/M ratio from those with lower values of H-reflex latency and H/M ratio in 24 clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. Known groups validityKnown groups validity is a form of construct validation in which the validity is determined by the degree to which an instrument can demonstate different scores for groups know to vary on the variables being measured.
, as calculated using the student t-test, showed that the Modified Ashworth Scale is not able to distinguish between clients with lower and higher values of H-reflex latency and H/M ratio, two neurophysiologic tests for spasticityInvoluntary muscle tightness and stiffness that can occur after a stroke. It is characterized by exaggerated deep tendon reflexes that interfere with muscular activity, gait, movement, or speech. Spasticity can increase initially but wane down later on, after stroke.
.

Kumar, Pandyan, and Sharma (2006) verified whether the Modified Ashworth Scale was able to differentiate clients with four different levels of stiffness (no stiffness, mild, moderate, and severe stiffness) in 111 clients with strokeAlso called a "brain attack" and happens when brain cells die because of inadequate blood flow. 20% of cases are a hemorrhage in the brain caused by a rupture or leakage from a blood vessel. 80% of cases are also know as a "schemic stroke", or the formation of a blood clot in a vessel supplying blood to the brain. More. Known groups validityKnown groups validity is a form of construct validation in which the validity is determined by the degree to which an instrument can demonstate different scores for groups know to vary on the variables being measured.
, as calculated using Analysis of Variance (ANOVA), showed that the Modified Ashworth Scale was not able to distinguish between individuals with different levels of stiffness.

Responsiveness

No studies have examined the responsivenessThe ability of an instrument to detect clinically important change over time.
of the Modified Ashworth Scale.

References

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See the measure

How to obtain the Modified Ashworth Scale?

The Modified Ashworth Scale can be obtained from its original publication: Bohannon & Smith (1987).

The following publications also present the full tool described: Bakheit et al., (2003); Pandyan et al., (1999); Salter, Jutai, Teasell, Foley and Bitensky (2005).

By clicking here, you can access a video showing how to administer the assessment.

It is also available on the Shirley Ryan Ability Lab website.