Introduction of a procedure to objectively quantify spastic movement impairment during freely performed voluntary movements.

Spastic impaired limb function is a frequent result of brain lesions. Although its assessment is important for clinical and therapeutical management, it still lacks an objective measure to quantify the functionality of the affected limb. The present paper reports a procedure based on the muscular activation recorded by Surface Electromyography (sEMG), which enables the assessment of the degree of spastic impairment. 15 healthy subjects and 7 patients with impaired upper limb function due to spasticity were included in the study. SEMG was recorded from the biceps and brachioradialis during active elbow extension at different movement velocities. The spastic impairment was clinically assessed by the Tardieu-Test and the Wolf Motor Function Test. Results of the clinical assessment and parameter values quantifying the muscular activation at different joint positions and movement velocities have been set in relation to one another. The results show that spastic impairment leads to a changed correlation between the muscular activation and movement velocity as well as to a changed inter-muscular co-ordination of biceps and brachioradialis. These changes, reflected in the sEMG, can be quantified by 5 newly introduced parameters. This way could allow the assessment of spastic impairment in the context of functional everyday tasks, for the first-time.