A novel sensor-based assessment of lower limb spasticity in children with cerebral palsy

Seoyoung Choi,Yong Beom Shin,Soo-Yeon Kim,Jonghyun Kim

doi:10.1186/s12984-018-0388-5

Abstract

BackgroundTo provide effective interventions for spasticity, accurate and reliable spasticity assessment is essential. For the assessment, the Modified Tardieu Scale (MTS) has been widely used owing to its simplicity and convenience. However, it has poor or moderate accuracy and reliability.MethodsWe proposed a novel inertial measurement unit (IMU)-based MTS assessment system to improve the accuracy and reliability of the MTS itself. The proposed system consists of a joint angle calculation algorithm, a function to detect abnormal muscle reaction (a catch and clonus), and a visual biofeedback mechanism. Through spastic knee and ankle joint assessment, the proposed IMU-based MTS assessment system was compared with the conventional MTS assessment system in 28 children with cerebral palsy by two raters.ResultsThe results showed that the proposed system has good accuracy (root mean square error < 3.2°) and test-retest and inter-rater reliabilities (ICC > 0.8), while the conventional MTS system has poor or moderate reliability. Moreover, we found that the deteriorated reliability of the conventional MTS system comes from its goniometric measurement as well as from irregular passive stretch velocity.ConclusionsThe proposed system, which is clinically relevant, can significantly improve the accuracy and reliability of the MTS in lower limbs for children with cerebral palsy.

Highlights

To provide effective interventions for spasticity, accurate and reliable spasticity assessment is essential
We found that the deterioration in reliability of the Modified Tardieu Scale (MTS) assessment is due to the combined causes of goniometric measurement and unregulated passive stretch velocity (PSV)
For the inertial measurement unit (IMU)-based MTS assessment, with consideration to the clinical environment, we developed a magnetometer-free joint angle calculation method, a muscle reaction detection function, and a visual biofeedback method to help regulate PSV

Summary

Introduction

To provide effective interventions for spasticity, accurate and reliable spasticity assessment is essential. The Modified Tardieu Scale (MTS) has been widely used owing to its simplicity and convenience. It has poor or moderate accuracy and reliability. Cerebral palsy (CP) is defined as a non-progressive brain disorder of movement and posture. Most children with CP experience spasticity, a motor disorder caused by increased tonic stretch reflexes [1], due to upper motor neuron syndrome [2]. CP children have difficulties walking independently due to abnormal posture and gait, and they have joint deformity and pain in severe cases. Spasticity assessment has been used to predict the severity of CP in activities in daily life (ADL) [1, 4]

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Results

Discussion

Conclusion