Quantification of elbow muscle tone from an instrumented manual stretch-reflex test

Abstract

Objective: To evaluate a method for objectively quantifying elbow muscle tone in a clinical setting using an instrumented manual stretch-reflex test.Methods: Seventy-nine participants with upper motor neuron syndrome (stroke, spinal cord injury, cerebral palsy and multiple sclerosis) were evaluated for elbow flexor and extensor tone using a wearable sensor system. Modified Ashworth Scale (MAS) scores of elbow flexors and extensors, and spasticity metrics derived from a uniform-jerk model during manual stretch-reflex test, were used in a linear discriminant analysis (LDA) to generate a probability based 0-10 score (.1 increment) that maps onto the MAS continuum.Results: Sensor derived metrics correlated significantly with EMG (onset time: r 2 =.7, p<.001; duration: r 2 =.9, p<.001) and explained as much as 50% of the variance in therapist-rated MAS score. The LDA resulted in 73% classification accuracy, although the "gold standard" MAS rating was a considerable source of error. Conclusions:The study demonstrates that a simple wearable sensor system in combination with a routine manual stretch-reflex test can be used to objectively quantify elbow flexor and extensor tone. These findings offer new hope of achieving objective measurement of muscle tone in the clinic.

A Regression-Based Framework for Quantitative Assessment of Muscle Spasticity Using Combined EMG and Inertial Data From Wearable Sensors

“…These investigations focus on assessing the muscular mechanics of spasticity, and have achieved highly reliable assessment for spasticity. For example, McGibbon et al (2016) presented a kinematic model and addressed the issue of identifying categorical degrees of muscle spasticity by classification learning using a linear discriminant analysis algorithm. However, specific devices such as the isokinetic and torque sensors and well-controlled laboratory environments are generally required to ensure precise measurement and accurate quantification (Condliffe et al, 2005; Ardabili et al, 2011).…”

Evaluation of a toolkit for standardizing clinical measures of muscle tone

“…Spasticity data for this study and associated testing protocols have been published elsewhere for the elbow (McGibbon et al 2013, McGibbon et al 2016 and for the knee (Whelan et al 2018). For the elbow, an instrumented stretch-reflex test was conducted where the therapist moved the forearm slowly through elbow flexion, and then rapidly through extension to stretch the elbow flexors.…”

“…Full time records of FOG and EMG sensors were stored for off-line analysis, as described elsewhere (McGibbon et al 2016, Whelan et al 2018.…”

“…Detailed analyses of objective spasticity metrics from manual stretch-reflex data for elbows and pendulum test data for knees can be found elsewhere (McGibbon et al 2016, Whelan et al 2018. Correlation analysis was used to examine the relationship between spasticity measures (clinical and objective) and voluntary muscle strength, passive-active limit angle (paresis), and passive limit angle (contracture), for the elbow and the knee.…”