The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke

<p>Abstract</p> <p>Background</p> <p>Spasticity is a common impairment that follows stroke, and it results typically in functional loss. For this reason, accurate quantification of spasticity has both diagnostic and therapeutic significance. The most widely used clinical assessment of spasticity is the modified Ashworth scale (MAS), an ordinal scale, but its validity, reliability and sensitivity have often been challenged. The present study addresses this deficit by examining whether quantitative measures of neural and muscular components of spasticity are valid, and whether they are strongly correlated with the MAS.</p> <p>Methods</p> <p>We applied abrupt small amplitude joint stretches and Pseudorandom Binary Sequence (PRBS) perturbations to both paretic and non-paretic elbow and ankle joints of stroke survivors. Using advanced system identification techniques, we quantified the dynamic stiffness of these joints, and separated its muscular (intrinsic) and reflex components. The correlations between these quantitative measures and the MAS were investigated.</p> <p>Results</p> <p>We showed that our system identification technique is valid in characterizing the intrinsic and reflex stiffness and predicting the overall net torque. Conversely, our results reveal that there is no significant correlation between muscular and reflex torque/stiffness and the MAS magnitude. We also demonstrate that the slope and intercept of reflex and intrinsic stiffnesses plotted against the joint angle are not correlated with the MAS.</p> <p>Conclusion</p> <p>Lack of significant correlation between our quantitative measures of stroke effects on spastic joints and the clinical assessment of muscle tone, as reflected in the MAS suggests that the MAS does not provide reliable information about the origins of the torque change associated with spasticity, or about its contributing components.</p

Muscle and reflex changes with varying joint angle in hemiparetic stroke

<p>Abstract</p> <p>Background</p> <p>Despite intensive investigation, the origins of the neuromuscular abnormalities associated with spasticity are not well understood. In particular, the mechanical properties induced by stretch reflex activity have been especially difficult to study because of a lack of accurate tools separating reflex torque from torque generated by musculo-tendinous structures. The present study addresses this deficit by characterizing the contribution of neural and muscular components to the abnormally high stiffness of the spastic joint.</p> <p>Methods</p> <p>Using system identification techniques, we characterized the neuromuscular abnormalities associated with spasticity of ankle muscles in chronic hemiparetic stroke survivors. In particular, we systematically tracked changes in muscle mechanical properties and in stretch reflex activity during changes in ankle joint angle. Modulation of mechanical properties was assessed by applying perturbations at different initial angles, over the entire range of motion (ROM). Experiments were performed on both paretic and non-paretic sides of stroke survivors, and in healthy controls.</p> <p>Results</p> <p>Both reflex and intrinsic muscle stiffnesses were significantly greater in the spastic/paretic ankle than on the non-paretic side, and these changes were strongly position dependent. The major reflex contributions were observed over the central portion of the angular range, while the intrinsic contributions were most pronounced with the ankle in the dorsiflexed position.</p> <p>Conclusion</p> <p>In spastic ankle muscles, the abnormalities in intrinsic and reflex components of joint torque varied systematically with changing position over the full angular range of motion, indicating that clinical perceptions of increased tone may have quite different origins depending upon the angle where the tests are initiated.</p> <p>Furthermore, reflex stiffness was considerably larger in the non-paretic limb of stroke patients than in healthy control subjects, suggesting that the non-paretic limb may not be a suitable control for studying neuromuscular properties of the ankle joint.</p> <p>Our findings will help elucidate the origins of the neuromuscular abnormalities associated with stroke-induced spasticity.</p

DPT 835 Neurophysiological Therapeutics l

This course addresses the physical therapy examination, evaluation, diagnosis, prognosis and plan of care (including interventions) for adults with movement problems stemming from dysfunction of the supra-spinal central nervous system. Emphasis will be on Stroke, Parkinson's disease, and Other Basal Ganglia Disorders or Movement Disorders. Laboratory sessions are taught in parallel with the materials of the course, and will be used to provide students with an opportunity to practice and refine skills related to the evaluation and treatment of neurologic patients

Position dependence of Reflex stiffness gain () for paretic, non-paretic and normal groups as functions of position (Group averages)

Error bars indicate ± 1 standard error. NP: Neutral Position (90°).<p><b>Copyright information:</b></p><p>Taken from "Muscle and reflex changes with varying joint angle in hemiparetic stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/6</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():6-6.</p><p>Published online 27 Feb 2008</p><p>PMCID:PMC2292203.</p><p></p

A segment from a typical sequence trial for a spastic under relaxed conditions

Position, Half-wave rectified gastrocnemius electromyogram (GS), Predicted intrinsic torque, Predicted reflex torque and Predicted overall torque (thick curve) superimposed on the actual torque (thin curve). Displacements in the PF direction were taken as negative and those in the DF direction as positive. Torque was assigned a polarity consistent with the direction of the movement that it would generate (e.g. PF torque was taken as negative).<p><b>Copyright information:</b></p><p>Taken from "Muscle and reflex changes with varying joint angle in hemiparetic stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/6</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():6-6.</p><p>Published online 27 Feb 2008</p><p>PMCID:PMC2292203.</p><p></p

Percentage change of stroke effects as functions of position (Group averages)

Reflex stiffness gain (), Intrinsic stiffness gain (), Intrinsic viscous parameter (). Error bars indicate ± 1 standard error. NP: Neutral Position (90°). The dotted lines reflect the mean percentage change over the range of motion.<p><b>Copyright information:</b></p><p>Taken from "Muscle and reflex changes with varying joint angle in hemiparetic stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/6</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():6-6.</p><p>Published online 27 Feb 2008</p><p>PMCID:PMC2292203.</p><p></p

Paretic stiffness parameters plotted against non-paretic values for all stroke subjects

Reflex stiffness gain (), Intrinsic stiffness elasticity or gain (), and Intrinsic stiffness viscosity ().<p><b>Copyright information:</b></p><p>Taken from "Muscle and reflex changes with varying joint angle in hemiparetic stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/6</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():6-6.</p><p>Published online 27 Feb 2008</p><p>PMCID:PMC2292203.</p><p></p

The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke-2

Tic groups. Group results ± SD.<p><b>Copyright information:</b></p><p>Taken from "The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/18</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():18-18.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2515334.</p><p></p

The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke-0

<p><b>Copyright information:</b></p><p>Taken from "The relation between Ashworth scores and neuromechanical measurements of spasticity following stroke"</p><p>http://www.jneuroengrehab.com/content/5/1/18</p><p>Journal of NeuroEngineering and Rehabilitation 2008;5():18-18.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2515334.</p><p></p