Electromyographic Response to Manual Passive Stretch of the Hemiplegic Wrist: Accuracy, Reliability, and Correlation With Clinical Spasticity Assessment and Function

Abstract

Background. The management of spasticity is important in neurorehabilitation and needs to be assessed accurately. The commonly used clinical tools have been criticized for lack of validity and sensitivity. Objective. To investigate the reliability of electromyographic (EMG) response to manual stretches of the hemiplegic wrist and its correlation with clinical assessments of spasticity and physical function. Methods. EMG activity was measured in 10 stroke patients and control participants (53.7 ± 10 and 32 ± 9.1 years respectively, mean ± SEM) during 3 cycles of 10 seconds passive manual movements of the wrist at 60 to 360° • s-1. Isometric maximal voluntary contractions (MVC) strength, range of movement (ROM) of the wrist flexors and extensors, spasticity (Modified Ashworth Scale [MAS]) and hand function (Block and Box Test [BBT]) were also assessed. Results. EMG activity of the stroke patients increased with velocity from 4% to 40% MVC (P < .001) but there was none in the controls. It was unaffected by repetition and good to moderate reliability occurred at all speeds (ICC, 0.71-0.81). EMG correlated negatively with MVC strength (r = -.9), active wrist flexion ROM ( r = -.8), and hand function scores (r = —.7), but not with clinical measures of spasticity except at the lowest velocity (r = .72). Conclusions. Consistent and accurate stretch velocities and EMG responses can be achieved with manual wrist stretches for the assessment of the neural component of spasticity. These objective tests did not correlate well with the standard clinical assessment of spasticity. They showed significant negative relationships with function, indicating that increased reflex excitability contributes to hand disability after stroke.