Ashworth Scale /Modified Ashworth Scale (AS/MAS)

Background:

In the original Ashworth Scale, resistance to passive movement about a joint with varying degrees of velocity is measured on a scale of 0 (no resistance) to 4 (rigidity). In the modified Ashworth Scale, a 1+ scoring category is added to indicate resistance through less than half of the movement (Bohannon & Smith, 1987).

Psychometrics:

Psychometric evaluation of the MAS is discussed in Blackburn et al. (2002) and Gregson et al. (1999; 2000).

Author of Tool:

Richard Bohannon PT, PhD and Melissa Smith, PT

Key references:

Blackburn, M., van Vliet, P., et al. (2002). “Reliability of measurements obtained with the modified Ashworth scale in the lower extremities of people with stroke.” Physical Therapy 82(1): 25.

Bohannon, R. and Smith, M. (1987). “Interrater reliability of a modified Ashworth scale of muscle spasticity.” Physical Therapy 67(2): 206.

Brashear, A., Zafonte, R., et al. (2002). “Inter-and intrarater reliability of the Ashworth Scale and the Disability Assessment Scale in patients with upper-limb poststroke spasticity* 1.” Archives of physical medicine and rehabilitation 83(10): 1349-1354.

Gregson, J., Leathley, M., et al. (1999). “Reliability of the Tone Assessment Scale and the modified Ashworth scale as clinical tools for assessing poststroke spasticity.” Archives of physical medicine and rehabilitation 80(9): 1013-1016. Find it on PubMed

Gregson, J., Leathley, M., et al. (2000). “Reliability of measurement of muscle tone and muscle power in stroke patients.” Age and Ageing 29(3): 223.

Haas, B., Bergström, E., et al. (1996). “The inter rater reliability of the original and of the modified Ashworth scale for the assessment of spasticity in patients with spinal cord injury.” Spinal Cord 34(9): 560-564.

Primary use / Purpose:

The Ashworth Scale was initially designed to examine the effects of anti spasticity drugs on spasticity in Multiple Sclerosis (MS). The Modified Ashworth Scale (MAS) purports to measure spasticity in patients with lesions of the central nervous system.

Modified Ashworth Scale Instructions

General Information (derived Bohannon and Smith, 1987):

  • Place the patient in a supine position
  • If testing a muscle that primarily flexes a joint, place the joint in a maximally flexed position and move to a position of maximal extension over one second (count "one thousand one”)
  •    If testing a muscle that primarily extends a joint, place the joint in a maximally extended position and move to a position of maximal flexion over one second (count "one thousand one”)
  •    Score based on the classification below

Scoring (taken from Bohannon and Smith, 1987):

  • No increase in muscle tone
  • 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+        Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder (less than half) of the ROM

  • More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved
  • Considerable increase in muscle tone, passive movement difficult
  • Affected part(s) rigid in flexion or extension

Patient Instructions:

The patient should be instructed to relax.

Modified Ashworth Scale Testing Form

Name:                                                                                    Date:                        Muscle Tested                                     Score

Reference for test instructions:

Bohannon, R. and Smith, M. (1987). "Interrater reliability of a modified Ashworth scale of muscle spasticity." Physical Therapy 67(2): 206.