Yonsei Med J.  2005 Aug;46(4):546-554. 10.3349/ymj.2005.46.4.546.

Biomechanical Assessment with Electromyography of Post-Stroke Ankle Plantar Flexor Spasticity

• Kim DY
• Park CI
• Chon JS
• Ohn SH
• Park TH
• Bang IK

• KMID: 1716526
• DOI: http://doi.org/10.3349/ymj.2005.46.4.546

Abstract

Spasticity has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflex (muscle tone). Muscle tone consists of mechanical-elastic characteristics, reflex muscle contraction and other elements. The aims of this study were to determine whether to assess spasticity quantitatively, and to characterize biomechanical and electromyographic spasticity assessment parameters. These assessment parameters were described by investigating the correlation between clinical measures and the response to passive sinusoidal movement with consecutive velocity increments. Twenty post-stroke hemiplegic patients and twenty normal healthy volunteers were included in the study. Five consecutive sinusoidal passive movements of the ankle were performed at specific velocities (60, 120, 180, and 240 degrees/ sec). We recorded the peak torque, work, and threshold angle using a computerized isokinetic dynamometer, and simultaneously measured the rectified integrated electromyographic activity. We compared these parameters both between groups and between different velocities. The peak torque, threshold angle, work, and rectified integrated electromyographic activity were significantly higher in the post-stroke spastic group at all angular velocities than in the normal control group. The threshold angle and integrated electromyographic activity increased significantly and linearly as angular velocity increased, but the peak torque and work were not increased in the post-stroke spastic group. Peak torque, work, and threshold angle were significantly correlated to the Modified Ashworth scale, but the integrated electromyographic activity was not. The biomechanical and electromyographic approach may be useful to quantitatively assess spasticity. However, it may also be very important to consider the different characteristics of each biomechanical parameter.

Keyword

Spasticity; electromyographic activity; peak torque; threshold angle; stretch reflex

MeSH Terms

Adult
Aged
Ankle/*physiopathology
Biomechanics
Cerebrovascular Accident/*physiopathology
Electromyography
Female
Humans
Male
Middle Aged
Muscle Spasticity/*physiopathology
Regression Analysis
Research Support, Non-U.S. Gov't
Torque

Figure

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  Fig. 1 Experiment setting for biomechanical assessment with electromyography of ankle plantar flexor spasticity.

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  Fig. 2 Changes in peak torque with respect to angular velocity increments.

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  Fig. 3 Changes in work with respect to angular velocity increments.

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  Fig. 4 Changes in threshold angle with respect to angular velocity increments.

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  Fig. 5 Changes in integrated electromyographic activity with respect to angular velocity Increments.

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