Projects

N Mehrabi, MH Schwartz, KM Steele (2019) “Can altered muscle synergies control unimpaired gait?” Journal of Biomechanics

Nicole JournalArticle, MotorControl, Publications , , , , ,

Journal Article in Journal of Biomechanics:

Musculoskeletal models of gait with lower dimensional control spaces showed that an individual with reduced number of synergies could not produce an unimpaired gait

Background: Recent studies have postulated that the human motor control system recruits groups of muscles through low-dimensional motor commands, or muscle synergies. This scheme simplifies the neural control problem associated with the high-dimensional structure of the neuromuscular system. Several lines of evidence have suggested that neurological injuries, such as stroke or cerebral palsy, may reduce the dimensions that are available to the motor control system, and these altered dimensions or synergies are thought to contribute to impaired walking patterns. However, no study has investigated whether impaired low-dimensional control spaces necessarily lead to impaired walking patterns.

Methods: In this study, using a two-dimensional model of walking, we developed a synergy-based control framework that can simulate the dynamics of walking.

Results: The simulation analysis showed that a synergy-based control scheme can produce well-coordinated movements of walking matching unimpaired gait. However, when the dimensions available to the controller were reduced, the simplified emergent pattern deviated from unimpaired gait. A system with two synergies, similar to those seen after neurological injury, could not produce an unimpaired walking pattern.

Conclusions: These findings provide further evidence that altered muscle synergies can contribute to impaired gait patterns and may need to be directly addressed to improve gait after neurological injury.

HA Feldner, D Howell, VE Kelly, S Westcott McCoy, KM Steele (2019) “‘Look, Your Muscles Are Firing!’: A Qualitative Study of Clinician Perspectives on the Use of Surface Electromyography in Neurorehabilitation.” Archives of Physical Medicine and Rehabilitation

Nicole JournalArticle, Projects, Publications, UbiquitousRehabilitation

Journal Article in Archives of Physical Medicine and Rehabilitation:

We collaborated with rehabilitation clinicians across the Seattle region to understand the barriers and facilitators of using wireless electromyography sensors to track motor recovery in the clinic and community

Objective: To examine the perceived value, benefits, drawbacks, and ideas for technology development and implementation of surface electromyography recordings in neurologic rehabilitation practice from clinical stakeholder perspectives.

Design: A qualitative, phenomenological study was conducted. In-depth, semistructured interviews and focus groups were completed. Sessions included questions about clinician perspectives and demonstrations of surface electromyography systems to garner perceptions of specific system features.

Setting: The study was conducted at hospital systems in a large metropolitan area.

Participants: Adult and pediatric physical therapists, occupational therapists, and physiatrists from inpatient, outpatient, and research settings (N=22) took part in the study.

Interventions: Not applicable.

Main Outcome Measures: Interviews and focus groups were audio-recorded, transcribed verbatim, then coded for analysis into themes.

Results: Four major themes emerged: (1) low-tech clinical practice and future directions for rehabilitation; (2) barriers to surface electromyography uptake and potential solutions; (3) benefits of surface electromyography for targeted populations; and (4) essential features of surface electromyography systems.

Conclusions: Surface electromyography systems were not routinely utilized for assessment or intervention following neurologic injury. Despite recognition of potential clinical benefits of surface electromyography use, clinicians identified limited time and resources as key barriers to implementation. Perspectives on design and surface electromyography system features indicated the need for streamlined, intuitive, and clinically effective applications. Further research is needed to determine feasibility and clinical relevance of surface electromyography in rehabilitation intervention.

Congratulations – Makoto Eyre is awarded a UWIN WRF Innovation Undergraduate Fellowship in Neuroengineering

Nicole Awards, News, Orthoses

Makoto Eyre has been selected as a WRF Innovation Undergraduate Fellow in Neuroengineering for the UW Institute for Neuroengineering. The UWIN fellowship provides funding and is a highly prestigious and selective competition. Congratulations, Makoto!

Makoto’s research seeks to use muscle synergies, a clinically-useful, low-dimensional representation of motor coordination, to quantify and compare the effects of AFOs on motor control strategies employed during SS and nSS gait. Ankle foot orthoses (AFOs) are a common intervention for cerebral palsy and stroke survivors, with most research on the impacts of AFOs on impaired locomotion and motor control focuses on steady state (SS) gait despite a large portion of locomotion being non-steady state (nSS). As nSS locomotion may rely on different neuromuscular control strategies, AFOs optimized for SS may be suboptimal to nSS locomotion.

BR Shuman, M Goudriaan, K Desloovere, MH Schwartz, KM Steele (2019) “Muscle synergies demonstrate only minimal changes after treatment in cerebral palsy.” Journal of NeuroEngineering and Rehabilitation

Nicole JournalArticle, MotorControl, Projects, Publications , , , , , , ,

Journal Article in Journal of NeuroEngineering and Rehabilitation:

In collaboration with University Hospital Pellenberg we examined whether muscle synergies change following common treatments in CP.

Background: Children with cerebral palsy (CP) have altered synergies compared to typically-developing peers, reflecting different neuromuscular control strategies used to move. While these children receive a variety of treatments to improve gait, whether synergies change after treatment, or are associated with treatment outcomes, remains unknown.

Methods: We evaluated synergies for 147 children with CP before and after three common treatments: botulinum toxin type-A injection (n = 52), selective dorsal rhizotomy (n = 38), and multi-level orthopaedic surgery (n = 57). Changes in synergy complexity were measured by the number of synergies required to explain > 90% of the total variance in electromyography data and total variance accounted for by one synergy. Synergy weights and activations before and after treatment were compared using the cosine similarity relative to average synergies of 31 typically-developing (TD) peers.

Results: There were minimal changes in synergies after treatment despite changes in walking patterns. Number of synergies did not change significantly for any treatment group. Total variance accounted for by one synergy increased (i.e., moved further from TD peers) after botulinum toxin type-A injection (1.3%) and selective dorsal rhizotomy (1.9%), but the change was small. Synergy weights did not change for any treatment group (average 0.001 ± 0.10), but synergy activations after selective dorsal rhizotomy did change and were less similar to TD peers (− 0.03 ± 0.07). Only changes in synergy activations were associated with changes in gait kinematics or walking speed after treatment. Children with synergy activations more similar to TD peers after treatment had greater improvements in gait.

Conclusions: While many of these children received significant surgical procedures and prolonged rehabilitation, the minimal changes in synergies after treatment highlight the challenges in altering neuromuscular control in CP. Development of treatment strategies that directly target impaired control or are optimized to an individual’s unique control may be required to improve walking function.