Reliability of the tone assessment scale and the modified ashworth scale as clinical tools for assessing poststroke spasticity

Abstract

Objectives: To establish reliability of the Tone Assessment Scale and modified Ashworth scale in acute stroke patients. Setting: A North Liverpool university hospital. Patients: Eighteen men and 14 women admitted with acute stroke and still in hospital at the study start date (median age, 74 yrs; median Barthel score, 8). Main Outcome Measures: The modified Ashworth scale and the Tone Assessment Scale. Study Design: The 32 patients were examined with both scales on the same occasion by two raters (interrater comparison) and on two occasions by one rater (intrarater comparison). Results: The reliability of the modified Ashworth scale was very good ( κ w = .84 for interrater and .83 for intrarater comparisons). The reliability of the Tone Assessment Scale was not as strong as the modified Ashworth scale, with marked variability in the assessment of posture ( κ = .22 to .50 for interrater and .29 to .55 for intrarater comparisons) and associated reaction ( κ ϰ w = −.05 to .79 for interrater and .19 to .83 for intrarater comparisons). However, those aspects of the Tone Assessment Scale that addressed response to passive movement and that are scored similarly to the modified Ashworth scale showed good to very good interrater reliability ( κ w = .79 to .92) and good to very good intrarater reliability ( κ w = .72 to .86), except for the question related to movement at the ankle where agreement was only moderate ( κ w = .59). Conclusions: The modified Ashworth scale is reliable. The section of the Tone Assessment Scale relating to response to passive movement is reliable at various joints, except the ankle. It may assist in studies on the prevalence of spasticity after stroke and the relationship between tone and function. Further development of a measure of spasticity at the ankle is required. The Tone Assessment Scale is not reliable for measuring posture and associated reactions.