TY - JOUR
T1 - Analysis of interactive effect of stretch reflex and shortening reaction on rigidity in Parkinson's disease
AU - Xia, Ruiping
AU - Sun, Junfeng
AU - Threlkeld, A. Joseph
N1 - Funding Information:
Authors acknowledge the support of the National Institute of Health (R15-HD061022), Creighton University School of Pharmacy and Health Professions Faculty Development Fund and Nebraska Tobacco Settlement Biomedical Research Development Fund, USA. We would like to thank all the subjects for their participation in the study.
PY - 2009/7
Y1 - 2009/7
N2 - Objective: To examine the correlation between rigidity and interaction of stretch reflex and shortening reaction during passive movements of the wrist and to compare this correlation with that between rigidity and stretch reflex alone. Methods: Twelve subjects with Parkinson's disease participated in the study in Off-medication and On-medication states. A servomotor imposed wrist flexion and extension within ±30° at velocities 50 and 280°/s, while joint torque and EMG of the wrist flexors and extensors were recorded. Rigidity was quantified by integrating torque with joint angle, i.e., objective rigidity (OR) score, for extension and flexion, respectively. The interaction between EMG responses was estimated by calculating a ratio of normalized EMG in stretched to shortened muscles for both movements. Results: The OR scores were more strongly correlated with the EMG ratios than with EMG of the stretched muscles alone. The strongest and significant correlation was found between the OR score and EMG ratio during the extension at high velocity in the Off-medication (r = 0.792, p = 0.002). Conclusions: Both stretch reflex and shortening reaction are important determinants of rigidity. Significance: Study findings provide new insight into mechanistic descriptions of rigidity and have implications for development and evaluation of interventions.
AB - Objective: To examine the correlation between rigidity and interaction of stretch reflex and shortening reaction during passive movements of the wrist and to compare this correlation with that between rigidity and stretch reflex alone. Methods: Twelve subjects with Parkinson's disease participated in the study in Off-medication and On-medication states. A servomotor imposed wrist flexion and extension within ±30° at velocities 50 and 280°/s, while joint torque and EMG of the wrist flexors and extensors were recorded. Rigidity was quantified by integrating torque with joint angle, i.e., objective rigidity (OR) score, for extension and flexion, respectively. The interaction between EMG responses was estimated by calculating a ratio of normalized EMG in stretched to shortened muscles for both movements. Results: The OR scores were more strongly correlated with the EMG ratios than with EMG of the stretched muscles alone. The strongest and significant correlation was found between the OR score and EMG ratio during the extension at high velocity in the Off-medication (r = 0.792, p = 0.002). Conclusions: Both stretch reflex and shortening reaction are important determinants of rigidity. Significance: Study findings provide new insight into mechanistic descriptions of rigidity and have implications for development and evaluation of interventions.
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U2 - 10.1016/j.clinph.2009.05.001
DO - 10.1016/j.clinph.2009.05.001
M3 - Article
C2 - 19487158
AN - SCOPUS:67649834524
VL - 120
SP - 1400
EP - 1407
JO - Clinical Neurophysiology
JF - Clinical Neurophysiology
SN - 1388-2457
IS - 7
ER -