scholarly journals The Impact of Shoulder Abduction Loading on Volitional Hand Opening and Grasping in Chronic Hemiparetic Stroke

2017 ◽  
Vol 31 (6) ◽  
pp. 521-529 ◽  
Author(s):  
Yiyun Lan ◽  
Jun Yao ◽  
Julius P. A. Dewald
Keyword(s):  
Shoulder Abduction ◽  
Grasping Forces ◽  
Finger Flexion ◽  
Enhanced Expression ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke ◽  
And Control ◽  
The Impact ◽  
Hand Opening ◽  
Flexion Synergy

Background. Up to 60% of individuals with moderate to severe chronic hemiparetic stroke experience excessive involuntary wrist/finger flexion that constrains functional hand movements including hand opening. It’s not known how stroke-induced brain injury impacts volitional hand opening and grasping forces as a result of the expression of abnormal coupling between shoulder abduction and wrist/finger flexion or the flexion synergy. Objective. The goal of this study is to understand how shoulder abduction loading affects volitional hand opening and grasping forces in individuals with moderate to severe chronic hemiparetic stroke. Methods. Thirty-six individuals (stroke, 26; control, 10) were recruited for this study. Each participant was instructed to perform maximal hand opening and grasping forces while the arm was either fully supported or lifted with a weight equal to 25% or 50% of the participant’s maximal shoulder abduction torque. Hand pentagon area, defined as the area formed by the tips of thumb and fingers, was calculated during hand opening. Forces were recorded during grasping. Results. In individuals with moderate stroke, increasing shoulder abduction loading reduced the ability to maximally open the hand. In individuals with severe stroke, who were not able to open the hand, grasping forces were generated and increased with shoulder abduction loading. Stroke individuals also showed a reduced ability to control volitional grasping forces due to the enhanced expression of flexion synergy. Conclusions. Shoulder abduction loading reduced the ability to volitionally open the hand and control grasping forces after stroke. Neural mechanisms and clinical implications of these findings are discussed.

scholarly journals Limited Capacity for Ipsilateral Secondary Motor Areas to Support Hand Function Post-Stroke

2019 ◽  
Author(s):  
Kevin B. Wilkins ◽  
Jun Yao ◽  
Meriel Owen ◽  
Haleh Karbasforoushan ◽  
Carolina Carmona ◽  
...  
Keyword(s):  
Hand Function ◽  
Shoulder Abduction ◽  
Limited Capacity ◽  
Post Stroke ◽  
Backup System ◽  
Reticulospinal Tract ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke ◽  
Hand Opening ◽  
Motor Areas

AbstractRecent findings have shown connections of ipsilateral cortico-reticulospinal tract (CRST), predominantly originating from secondary motor areas, to not only proximal but also distal portions of the arm. In unilateral stroke, CRST from the ipsilateral side is intact and thus has been proposed as a possible backup system for post-stroke rehabilitation even for the hand. We argue that although CRST from ipsilateral secondary motor areas can provide control for proximal joints, it is insufficient to control either hand or coordinated shoulder and hand movements due to its extensive branching compared to contralateral corticospinal tract. To address this issue, we combined MRI, high-density EEG, and robotics in 17 individuals with severe chronic hemiparetic stroke and 12 age-matched controls. We tested for changes in structural morphometry of the sensorimotor cortex and found that individuals with stroke demonstrated higher gray matter density in secondary motor areas ipsilateral to the paretic arm compared to controls. We then measured cortical activity while participants attempted to generate hand opening either supported on a table or while lifting against a shoulder abduction load. The addition of shoulder abduction during hand opening increased reliance on ipsilateral secondary motor areas in stroke, but not controls. Crucially, increased use of ipsilateral secondary motor areas was associated with decreased hand opening ability while lifting the arm due to involuntary coupling between the shoulder and wrist/finger flexors. Together, this evidence implicates a compensatory role for ipsilateral (i.e., contralesional) secondary motor areas post-stroke, but with limited capacity to support hand function.

Investigation of the effects of mirror therapy on the spasticity, motor function and functionality of impaired upper limbs in chronic stroke patients

2019 ◽  
Vol 26 (7) ◽  
pp. 1-9
Author(s):  
Luciana Protásio de Melo ◽  
Valton da Silva Costa ◽  
Júlio César Cunha da Silveira ◽  
Tatiana Catarina Albuquerque Clementino
Keyword(s):  
Motor Function ◽  
Upper Limb ◽  
Functional Independence ◽  
Mirror Therapy ◽  
Stroke Patients ◽  
Number Of Patients ◽  
Limb Spasticity ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke ◽  
The Impact

Background/Aims Strokes lead to different levels of disability. During the chronic stage, hemiparesis, spasticity and motor deficits may cause loss of functional independence. Mirror therapy aims to reduce deficits and increase functional recovery of the impaired upper limb. This study aimed to evaluate the effects of mirror therapy on upper limb spasticity and motor function, as well as its impact on functional independence in chronic hemiparetic patients. Methods In this quasi-experimental study, eight chronic hemiparetic patients (age 55.5 ± 10.8 years) were assessed to determine their degree of spasticity (Modified Ashworth Scale), level of upper limb motor function (Fugl-Meyer Assessment) and functionality (Functional Independence Measure). All participants received 12 sessions of mirror therapy delivered three times per week, over a period of 4 weeks. Participants were re-evaluated post-intervention and these results were compared to their pre-intervention scores to determine the impact of mirror therapy. Results A decrease in spasticity was observed, with significant improvements in shoulder extensors (P=0.033) and a significant increase in motor function (P=0.002). The therapeutic protocol adopted did not have a significant effect on functional independence (P=0.105). Conclusions Mirror therapy led to improvements in upper limb spasticity and motor function in chronic hemiparetic stroke patients. No effects on functional independence were observed. Further research with a larger number of patients is needed to provide more robust evidence of the benefits of mirror therapy in chronic hemiparetic stroke patients.

scholarly journals Assessing the usage of indirect motor pathways following a hemiparetic stroke

2020 ◽  
Author(s):  
Runfeng Tian ◽  
Julius P.A. Dewald ◽  
Yuan Yang
Keyword(s):  
Model Simulation ◽  
Brain Activity ◽  
Shoulder Abduction ◽  
Joint Control ◽  
Motor Pathways ◽  
Co Activation ◽  
Shoulder Abductor ◽  
Hemiparetic Stroke ◽  
Muscle Connectivity ◽  
Flexion Synergy

AbstractA hallmark impairment in a hemiparetic stroke is a loss of independent joint control resulting in abnormal co-activation of shoulder abductor and elbow flexor muscles in their paretic arm, clinically known as the flexion synergy. The flexion synergy appears while generating shoulder abduction (SABD) torques as lifting the paretic arm. This likely be caused by an increased reliance on contralesional indirect motor pathways following damage to direct corticospinal projections. The assessment of functional connectivity between brain and muscle signals, i.e., brain-muscle connectivity (BMC), may provide insight into such changes to the usage of motor pathways. Our previous model simulation shows that multi-synaptic connections along the indirect motor pathway can generate nonlinear connectivity. We hypothesize that increased usage of indirect motor pathways (as increasing SABD load) will lead to an increase of nonlinear BMC. To test this hypothesis, we measured brain activity, muscle activity from shoulder abductors when stroke participants generate 20% and 40% of maximum SABD torque with their paretic arm. We computed both linear and nonlinear BMC between EEG and EMG. We found dominant nonlinear BMC at contralesional/ipsilateral hemisphere for stroke, whose magnitude increased with the SABD load. These results supported our hypothesis and indicated that nonlinear BMC could provide a quantitative indicator for determining the usage of indirect motor pathways following a hemiparetic stroke.

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