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Published on: April 18, 2011
Muscle Synergies in Response to Biofeedback-Driven Gait Adaptations in Children With Cerebral Palsy
Adam T C Booth1,2, Marjolein M van der Krogt1, Jaap Harlaar1,3
1Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.
Insights
Children with cerebral palsy (CP) showed immediate gait improvements with biofeedback, but neural control of selective motor control (SMC) remained largely unchanged, suggesting limited short-term plasticity.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Pediatrics
Background:
- Children with cerebral palsy (CP) often exhibit impaired selective motor control (SMC), impacting motor function and gait.
- While visual biofeedback can immediately improve pathological gait in children with CP, the underlying neural mechanisms and extent of SMC plasticity remain unclear.
Purpose of the Study:
- To investigate the neural basis of selective motor control (SMC) in children with CP.
- To examine changes in SMC during gait adaptation using real-time biofeedback.
Main Methods:
- Twenty-three children with CP underwent gait analysis using an instrumented treadmill in a virtual reality environment.
- Electromyograms of leg muscles were analyzed using non-negative matrix factorization (NNMF) to quantify SMC and synergy complexity (tVAF).
- Comparisons of muscle synergies were made between baseline and biofeedback conditions.
Main Results:
- While gait patterns changed, muscle synergies showed limited adaptation to biofeedback.
- The number of synergies needed to explain muscle activation increased, but the complexity (tVAF) and similarity of synergies remained largely consistent with baseline.
- Within-subject similarity of synergies was high across biofeedback trials.
Conclusions:
- Immediate gait adaptations in children with CP using biofeedback may not reflect significant changes in underlying selective motor control (SMC) at the neural level.
- The observed subtle changes in synergies may not be clinically significant for individual patients.
- Further research is needed to determine if long-term biofeedback training can induce meaningful adaptations in SMC in children with CP.
Background:
Children with cerebral palsy (CP) often show impaired selective motor control (SMC) that induces limitations in motor function. Children with CP can improve aspects of pathological gait in an immediate response to visual biofeedback. It is not known, however, how these gait adaptations are achieved at the neural level, nor do we know the extent of SMC plasticity in CP.
Aim:
Investigate the underlying SMC and changes that may occur when gait is adapted with biofeedback.
Methods:
Twenty-three ambulatory children with CP and related (hereditary) forms of spastic paresis (Aged: 10.4 ± 3.1, 6-16 years, M: 16/F: 9) were challenged with real-time biofeedback to improve step length, knee extension, and ankle power while walking on an instrumented treadmill in a virtual reality environment. The electromyograms of eight superficial muscles of the leg were analyzed and synergies were further decomposed using non-negative matrix factorization (NNMF) using 1 to 5 synergies, to quantify SMC. Total variance accounted for (tVAF) was used as a measure of synergy complexity. An imposed four synergy solution was investigated further to compare similarity in weightings and timing patterns of matched paired synergies between baseline and biofeedback trials.
Results:
Despite changes in walking pattern, changes in synergies were limited. The number of synergies required to explain at least 90% of muscle activation increased significantly, however, the change in measures of tVAF1 from baseline (0.75 ± 0.08) were less than ±2% between trials. In addition, within-subject similarity of synergies to baseline walking was high (>0.8) across all biofeedback trials.
Conclusion:
These results suggest that while gait may be adapted in an immediate response, SMC as quantified by synergy analysis is perhaps more rigidly impaired in CP. Subtle changes in synergies were identified; however, it is questionable if these are clinically meaningful at the level of an individual. Adaptations may be limited in the short term, and further investigation is essential to establish if long term training using biofeedback leads to adapted SMC.
