Clinical Trial: Direction Modulation of Muscle Synergies After a Stroke

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Direction Modulation of Muscle Synergies After a Stroke

Brief Summary: The aim of the study is to investigate the capacity of post-stroke individual (study group) to modulate their EMG muscle activation pattern (MAP) compared to healthy individuals (control group), and to correlate these capacities with their motor impairments. Twenty post-stroke individuals and 12 healthy individuals will participate in this study. each participant will carry out hand-reaching movements in multiple directions, monitored by an EMG device. The modulation of the EMG signal will be compared between groups in terms of EMG-MAP and in terms of muscle-synergies. Additionally the MAPs and synergies of the study group will be correlated with their Fugl-Meyer (FM) assessment scores. Analysis of the muscle synergies underlying the EMG signal will be carried out by the Non-negative Matrix Factorization (NMF) algorithm.

Detailed Summary:

Introduction: Upper extremity function after a stroke is impaired and characterized by abnormal, stereotypical and uncoordinated movement pattern. Decreased neural drive in the damaged corticospinal system causing a decreased agonists motor units firing, spasticity, impaired motor coordination. A more comprehensive understanding of the way our brain controls and regulates limb-movements, through the spinal cord, may enhance more advanced rehabilitation techniques.

Current concept in motor control suggest that the brain-cortex modulates and synchronizes the activation of discrete number of functional units within the brainstem and spinal cord. These neural functional units i.e. muscle synergies, when linearly combined facilitate the production of diverse limb-movements. This control mechanism may in a large extent explain the way the CNS reduces the dimensionality of the vast number of degrees of freedom embedded in the CNS to a discrete number of muscle synergies. Therefore, execution of a movement may only requires to linearly combine these synergies and regulates its intensity of activation along the time domain.

The existence of such a control mechanism attracted the attention of both clinicians and scientists to use its properties to enhance motor recovery after a stroke. Therefore, studies emerged to investigate how cortical damage impact the synchronization of synergies, and also whether it changes the internal structure of the synergies. Despite numerous studies in this domain, there is lack of consensus regarding how stroke impact this control mechanism, and extent of correlation between the level of impairment and the synergy structure. The study objectives are to compare the synergy structure and the MAP in hand-reaching movements in multiple directions between post-stroke individuals and healthy individual, and
Sponsor: University of Haifa

Current Primary Outcome: Optimal number of synergies [ Time Frame: Between one week to one month after a stroke (study group). ]

The NMF will be applied, changing the number of synergies from 2-7. The highest VAF value for each participant will define the number of synergies for this participant.


Original Primary Outcome: Same as current

Current Secondary Outcome:

  • Muscle Activation Pattern (MAP) [ Time Frame: Between one week to one month after a stroke (study group). ]
    The EMG amplitude, during reaching movement, was normalized according to the 80% MVC of the same muscle. Therefore the MAP corresponded to the relative exertion that was applied during the execution of hand-reaching compared to the MVC of the same muscle. The MVC was measured by standard manual muscle testing, and monitored by the EMG device. The MAP represents an averaged-time value of EMG normalized amplitude during the execution of five reaching movements.
  • Similarity Index- Individual (SI-I) [ Time Frame: Between one week to one month after a stroke (study group). ]
    The extent of similarity between the average MAP of non-stroke individuals and each of the participants from both groups.
  • Similarity Index- Direction (SI-D) [ Time Frame: Between one week to one month after a stroke (study group). ]
    The extent of similarity between the average MAP of non-stroke individuals to the center of the reaching space and the MAP of all other movement-directions of each of the participants from both groups. The SI-D indicates the capacity to modulate the MAP for different movement-directions compared to representative hand-reaching movements that were carried out to the center of the reaching space.


Original Secondary Outcome: Same as current

Information By: University of Haifa

Dates:
Date Received: February 21, 2017
Date Started: February 14, 2016
Date Completion: February 2018
Last Updated: February 26, 2017
Last Verified: February 2017