TY - JOUR
T1 - Amplitude- and velocity-dependency of rigidity measured at the wrist in Parkinson's disease
AU - Powell, Douglas
AU - Joseph Threlkeld, A.
AU - Fang, Xiang
AU - Muthumani, Anburaj
AU - Xia, Ruiping
N1 - Funding Information:
This study was funded by the National Institutes of Health under Grants R15-HD061022 and R15-HD061022-S1 . The authors would like to acknowledge the contributions of Lauren Kremer and Lindsey Wagner for their diligent work in data processing.
Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/4
Y1 - 2012/4
N2 - Objective: Quantify the effects of increased amplitude and rate of muscle stretch on parkinsonian rigidity. Methods: Eighteen subjects with Parkinson's disease participated in this study. Subjects' tested hand was passively displaced through 60° and 90° ranges of wrist flexion and extension at velocities of 50°/s and 280°/s in both treated and untreated conditions. Joint angular position, resistance torque, and surface electromyography (EMG) of the wrist flexors and extensors were recorded. Rigidity was quantified by normalized work scores and normalized angular impulses for flexion and extension, separately. Reflex responses of stretched and shortened muscles were quantified by mean EMG and EMG ratio. A series of ANOVAs was performed to determine the effect of amplitude, velocity and medication on selected variables. Results: Both work scores and angular impulses revealed that the larger displacement amplitude and the higher velocity were associated with significantly greater rigidity, increased EMG ratio and mean EMG of stretched muscles. Dopaminergic medication was not associated with a reduction in rigidity. Conclusions: Parkinsonian rigidity is modulated by the amplitude and rate of muscle stretch. Significance: These findings shed light on the biomechanical underpinnings and physiological characteristics of rigidity and may inform clinical rigidity assessment in Parkinson's disease.
AB - Objective: Quantify the effects of increased amplitude and rate of muscle stretch on parkinsonian rigidity. Methods: Eighteen subjects with Parkinson's disease participated in this study. Subjects' tested hand was passively displaced through 60° and 90° ranges of wrist flexion and extension at velocities of 50°/s and 280°/s in both treated and untreated conditions. Joint angular position, resistance torque, and surface electromyography (EMG) of the wrist flexors and extensors were recorded. Rigidity was quantified by normalized work scores and normalized angular impulses for flexion and extension, separately. Reflex responses of stretched and shortened muscles were quantified by mean EMG and EMG ratio. A series of ANOVAs was performed to determine the effect of amplitude, velocity and medication on selected variables. Results: Both work scores and angular impulses revealed that the larger displacement amplitude and the higher velocity were associated with significantly greater rigidity, increased EMG ratio and mean EMG of stretched muscles. Dopaminergic medication was not associated with a reduction in rigidity. Conclusions: Parkinsonian rigidity is modulated by the amplitude and rate of muscle stretch. Significance: These findings shed light on the biomechanical underpinnings and physiological characteristics of rigidity and may inform clinical rigidity assessment in Parkinson's disease.
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U2 - 10.1016/j.clinph.2011.08.004
DO - 10.1016/j.clinph.2011.08.004
M3 - Article
C2 - 21890404
AN - SCOPUS:84857791558
SN - 1388-2457
VL - 123
SP - 764
EP - 773
JO - Electroencephalography and Clinical Neurophysiology - Electromyography and Motor Control
JF - Electroencephalography and Clinical Neurophysiology - Electromyography and Motor Control
IS - 4
ER -