Inventi Impact: Biomedical Engineering

Inventi:ebe/26137/18

Spasticity Assessment Based on the Hilbertâ??Huang Transform Marginal Spectrum Entropy and the\nRoot Mean Square of Surface Electromyography Signals: A Preliminary Study

Background: Most of the objective and quantitative methods proposed for spasticity\nmeasurement are not suitable for clinical application, and methods for surface electromyography\n(sEMG) signal processing are mainly limited to the time-domain. This study\naims to quantify muscle activity in the timeââ?¬â??frequency domain, and develop a practical\nclinical method for the objective and reliable evaluation of the spasticity based on\nthe Hilbertââ?¬â??Huang transform marginal spectrum entropy (HMSEN) and the root mean\nsquare (RMS) of sEMG signals.\nMethods: Twenty-six stroke patients with elbow flexor spasticity participated in\nthe study. The subjects were tested at sitting position with the upper limb stretched\ntowards the ground. The HMSEN of the sEMG signals obtained from the biceps brachii\nwas employed to facilitate the stretch reflex onset (SRO) detection. Then, the difference\nbetween the RMS of a fixed-length sEMG signal obtained after the SRO and the RMS of\na baseline sEMG signal, denoted as the RMS difference (RMSD), was employed to evaluate\nthe spasticity level. The relations between Modified Ashworth Scale (MAS) scores\nand RMSD were investigated by Ordinal Logistic Regression (OLR). Goodness-of-fit of\nthe OLR was obtained with Hosmerââ?¬â??Lemeshow test.\nResults: The HMSEN based method can precisely detect the SRO, and the RMSD\nscores and the MAS scores were fairly well related (test: Ïâ?¡2 = 8.8060, p = 0.2669; retest:\nÏâ?¡2 = 1.9094, p = 0.9647). The prediction accuracies were 85% (test) and 77% (retest)\nwhen using RMSD for predicting MAS scores. In addition, the testââ?¬â??retest reliability was\nhigh, with an interclass correlation coefficient of 0.914 and a standard error of measurement\nof 1.137. Blandââ?¬â??Altman plots also indicated a small bias.\nConclusions: The proposed method is manually operated and easy to use, and\nthe HMSEN based method is robust in detecting SRO in clinical settings. Hence, the\nmethod is applicable to clinical practice. The RMSD can assess spasticity in a quantitative\nway and provide greater resolution of spasticity levels compared to the MAS\nin clinical settings. These results demonstrate that the proposed method could be clinically more useful for the accurate and reliable assessment of spasticity and may be\nan alternative clinical measure to the MAS.