Evolution of Quantitative Approaches for Muscle Spasticity Measurement

About 20 years ago, I first joined the spasticity measurement research group at biosignal laboratory (leaded by Dr. Jia-Jin Jason Chen) of Institute of Biomedical Engineering, National Cheng Kung University. At that time, the limitation of clinical approach for spasticity evaluation was initially noted by the researchers [1]. We developed our first quantitative measurement system based on driven motor and torque sensor to precisely measure the reactive resistance of elbow flexors during constant-velocity stretches [2]. We also proposed a parameter (ASRT, averaged speed-dependent reflex torque) to overcome the gravity and inertia problems in vertical stretch circumstance and to quantify the elbow spasticity of stroke patients under the constant-velocity stretch. During the development of spasticity, the changes of ASRT and velocity sensitivity of ASRT (i.e. velocity-dependent properties) of the involved and the intact elbow joints are presented and discussed in the same article [2].