A new biomechanical method for objective measurement of spasticity: A preliminary study

The assessment of the various impairments in brain damage including spasticity is important. The purpose of this study was to develop a new biomechanical method based on quantification of velocity reduction (VR) suitable for clinical use. A highly reliable system was developed to apply a constant torque perturbation at the elbow. This system was used to measure the VR in 30 healthy adults and 10 hemiplegic patients. In healthy subjects, the mean VR was 3.02% (SE standard error) = 0.29). In hemiplegic patients, the mean VR in the impaired arm (81.47%, SE= 2.87) was significantly higher than the VR (%) either in the non-impaired arm (9.86%, SE= 0.92) (WSRT (Wilcoxon Signed Ranks Test) : Z = -12.74; p<0.001), or the normal (3.02%) p<0.001). The interaction between the associated reaction (AR) and the asymmetrical tonic neck reflex (ATNR) with head away from the impaired arm made a significant higher VR (90.41%, SE=3.43) (p<0.001). The correlation between the VR (%) and the Modified Ashworth Scale scores was significant (Spearman's rho = 0.77, p<0.001). It is concluded that the quantification of velocity reduction may be used as an objective method of measuring spasticity in neurological conditions.