The application of air bag technology: An objective clinical measure of involuntary muscle spasm

Abstract

Objectives: To develop a technique which could objectively monitor and quantify spasms in spinal cord injured persons. Methods: This technique used accelerometers to detect movements in the limb caused by spasms. Accelerometer signals from movements caused by spasms and a variety of movements caused by other subject activities (movement in a wheelchair, transfers etc) were recorded and linear discriminant analysis was used to distinguish between spasms and other activities. Individual spasms were quantified by their duration, magnitude and energy and were recorded over a 24-h period. Results: Limb movements caused by spasms were shown to be well correlated with the EMG activity of the muscles causing the movement. Movements caused by spasms and movements caused by other subject activities could be reliably distinguished. Subjects showed a characteristic spasm pattern and it was possible to quantify the severity of the spasms and to determine precisely when they occurred. Conclusion: This technique for monitoring and quantifying spasms has the potential to be used as a clinical tool to aid in the evaluation and prescription of treatment.