A review of the properties and limitations of the Ashworth and modified Ashworth Scales as measures of spasticity

Background: The Ashworth Scale and the modified Ashworth Scale are the prim ary clinical measures of spasticity. A prerequisite for using any scale is a knowledge of its characteristics and limitations, as these will play a pa rt in analysing and interpreting the data. Despite the current emphasis on treating spasticity, clinicians rarely measure it. Objectives: To determine the validity and the reliability of the Ashworth a nd modified Ashworth Scales. Study design: A theoretical analysis following a structured literature revi ew (key words: Ashworth; Spasticity; Measurement) of 40 papers selected fro m the BIDS-EMBASE, First Search and Medline databases. Conclusions: The application of both scales would suggest that confusion ex ists on their characteristics and limitations as measures of spasticity. Re sistance to passive movement is a complex measure that will be influenced b y many factors, only one of which could be spasticity. The Ashworth Scale ( AS) can be used as an ordinal level measure of resistance to passive moveme nt, but not spasticity. The modified Ashworth Scale (MAS) will need to be t reated as a nominal level measure of resistance to passive movement until t he ambiguity between the '1' and '1+' grades is resolved. The reliability o f the scales is better in the upper limb. The AS may be more reliable than the MAS. There is a need to standardize methods to apply these scales in cl inical practice and research.