Measurement of ankle plantar flexor spasticity following stroke: Assessment of a new quantitative tool

OBJECTIVE: To assess the ability of a newly developed portable instrument (the Electric Spastic Ankle Measure (E-SAM)) to quantitatively measure ankle plantar flexor muscle tone and spasticity. DESIGN: Comparison of quantitative measurements of the E-SAM with those obtained manually with the Modified Ashworth Scale (MAS). PARTICIPANTS: Seven adult men with stroke of more than 8 months' duration with a MAS score of 3, and 7 healthy age-matched control subjects. MAIN OUTCOME MEASURES: Quantitative measurements of the reactive and viscoelastic components of muscle tonus and spasticity. RESULTS: Analysis of the pooled data of all subjects revealed 2 components: an initial negative peak (indicating visco-elasticity), and subsequent positive peaks (denoting reactive contractions of the plantar flexor muscles). Positive, reactive contraction, peaks of the subjects with stroke were significantly higher than those of age-matched controls (p<0.01, t-test). CONCLUSION: The E-SAM appears to provide meaningful information on muscle tone and spasticity that is more specific and quantitative than that obtained with the MAS. While further study is necessary, this instrument shows promise as an easy-to-use clinical and research tool for the measurement of spasticity and muscle viscosity.