THE INVESTIGATION OF CRITERION VALIDITY OF THE MODIFIED ASHWORTH SCALE USING THE ALPHA MOTONEURON EXCITABILITY INDICATORS

Despite the large body literature focused on the modified Ashworth Scale (MAS), validity of the scale for measuring spasticity is still questionable. The purpose of this study was to investigate the validity of the MAS by using both the conventional (Hmax/Mmax ratio) and the new indicators (Hslp/Mslp) of motoneuron excitability. Main outcome measures were the MAS and electrophysiologic assessments. The latter was performed using both conventional and new indicators of alpha motoneuron excitability. Data on 20 hemiplegic patients (17 men and three women) were analyzed. Correlation between the MAS and either soleus Hmax/Mmax or soleus Hslope/Mslope was not significant. In 10 patients whose H-reflex could be evoked bilaterally, only new spinal excitability indicator showed significant difference between the affected and non-affected sides. Based on the results of this study, there is no relationship between the MAS and the indicators of alpha motoneuron excitability. This research suggests that the MAS is not a valid measure for the assessment of spasticity in ankle plantar flexors.