The gap between clinical gaze and systematic assessment of movement disorders after stroke

Abstract Background Movement disorders after stroke are still captured by clinical gaze and translated to ordinal scores of low resolution. There is a clear need for objective quantification, with outcome measures related to pathophysiological background. Neural and non-neural contributors to joint behavior should be separated using different measurement conditions (tasks) and standardized input signals (force, position and velocity). Methods We reviewed recent literature for the application of biomechanical and/or elektromyographical (EMG) outcome measures under various measurement conditions in clinical research. Results Since 2005, 36 articles described the use of biomechanical and/or EMG outcome measures to quantify post-stroke movement disorder. Nineteen of the articles strived to separate neural and non-neural components. Only 6 of the articles measured biomechanical and EMG outcome measures simultaneously, while applying active and passive tasks and multiple velocities. Conclusion The distinction between neural and non-neural components to separately assess paresis, stiffness and muscle overactivity is not commonplace yet, while a large gap is to be bridged to attain reproducible and comparable results. Pathophysiologically clear concepts, substantiated with a comprehensive and concise measuring protocol will help professionals to identify and treat limiting factors in movement capabilities of post-stroke patients.</p

Selective activity of flexor and extensor wrist muscles is reduced in post-stroke patients

Introduction: Loss of selective muscle activation after stroke contributes to poor arm function but is difficult to quantify. The objective of this study was to quantify selective activity of flexor and extensor wrist muscles in post-stroke patients. Methods: 31 Patients in the chronic phase after stroke and 14 matched healthy controls exerted a flexion and extension torque onto a haptic wrist manipulator. EMG of the flexor and the extensor carpi radialis muscles was stratified for equal flexion and extension torques. The Activation Ratio per muscle was determined, i.e. ratio of the difference of EMG activity during flexion and extension over summed EMG activity. A ratio close to one indicates selective activation while a ratio close to zero indicates indifferent activation. Results: Control subjects could exert higher (p&lt;0.001) flexion and extension torques (25.42 Nm and 14.32 Nm) compared to post-stroke subjects (14.45Nm and 6.69Nm). The Activation Ratio’s for flexor and extensor muscle were significantly lower (p&lt;0.001) in post-stroke subjects (ARflex: 0.72 – 0.54, ARext:0.79 – 0.64). Discussion and conclusion: Activation Ratio’s allow for muscle specific determination of selective activity which is advantageous in case of diverging muscle features. In post-stroke patients the loss of selective activity has to be accounted for when explaining and intervening on loss of function. Clinical message: Quantification of muscle specific selective activation in post stroke hemiparesis allows for assessment of contribution of the muscle to co-contraction and functional loss and evaluation of therapeutic options