Assessing the spastic condition of individuals with upper motoneuron involvement: Validity of the Myotonometer

Objectives: To examine the validity of a newly developed tissue compliance device to measure muscle tone and to quantify the level of severity of the spastic condition. Design: Validity study. Setting: Research laboratory. Participants: Twenty subjects, 10 with upper motoneuron (UMN) disorders (spastic-type cerebral palsy or adult-onset cerebrovascular accident) who comprised the experimental group; and 10 nondisabled, age-equivalent subjects, who served as controls. Interventions: Not applicable. Main Outcome Measures: Muscle tone of the biceps brachii muscle was assessed with the MyotonometerTM and Modified Ashworth Scale (MAS). The Myotonometer was used to quantify the muscle's resistance to stretch in a relaxed state and during maximal voluntary isometric contractions. Analyses of variance determined differences among subjects. Correlations between Myotonometer measurements and MAS scores were calculated. Results: Significant differences (p