Using the latency correction method to calculate the tonic stretch reflex threshold in spastic cerebral palsy pre and post exercise intervention: a case study
Abstract
ABSTRACT
Frick, J. 2024. Using the latency correction method to calculate the tonic stretch reflex threshold in spastic cerebral palsy pre and post exercise intervention: a case study, Faculty of Sport and Health Sciences, University of Jyväskylä, Master’s thesis, 75 pp. 0 appendices.
ABSTRACT
Cerebral palsy (CP) is the most common childhood disability, caused by brain lesions during early development, often leading to motor-related symptoms and spasticity. Exercise interventions focusing on strength, gait, flexibility, and balance are valuable for managing CP. Tailoring exercise programs to individual needs may maximise outcomes. This case study was a smaller project related to the EXECP project. The case study aimed to evaluate changes in the tonic stretch reflex threshold (TSRT) following a 12-week exercise intervention for stretch hyper-reflexia in spastic cerebral palsy (SCP), aiming to provide an insight into the potential benefits of exercise on the TSRT in SCP. One participant with spastic cerebral palsy was selected (N=1) for the case study and performed passive muscle stretching of the soleus and medial gastrocnemius using a motor-driven dynamometer (Neuromuscular Research Center, University of Jyväskylä, Finland). The dynamometer induced passive ankle dorsiflexion from 20° of plantarflexion to 0° at four angular velocities (55, 110, 210, and 291°/s) as part of the EXECP study. The EMG data was then provided for this case study, allowing the TSRT to be calculated and assessed at four time points (PRE1, PRE2, POST1, POST2) and four velocities (55°/s, 110°/s, 200°/s, 291°/s) for the medial gastrocnemius and soleus. This case study used the EMG burst activity data from the EXECP intervention, and TSRTcorrected was calculated in Spike2 from Cambridge Electronics Design, Cambridge, UK . An individualized Hoffman-reflex (H-reflex) latency correction method was used, based on suggestions from Valadão et al. (2022) The h-reflex EMG data also came from the EXECP intervention. The case study analysed a portion of the h-reflex EMG data using MATLAB (R2023a, The MathWorks Inc, Natick, United States). The primary research questions are 1) is the TSRT corrected velocity dependent in this case study subject for the soleus and medial gastrocnemius? 2) how does TSRT corrected for the soleus and medial gastrocnemius muscles vary across different stretch velocities (55, 110, 200, and 291°/s) and 3) pre vs post exercise intervention. The soleus showed higher variability and sensitivity to velocity changes compared to the medial gastrocnemius, suggesting its role in adaptive postural control. After exercise, reflex thresholds in the soleus decreased and variability was reduced, indicating modulation of reflex activation. In contrast, the medial gastrocnemius showed stable, higher reflex thresholds, indicating its role in high-speed dynamic movements. The study reveals the distinct behaviours of the soleus and medial gastrocnemius, highlighting their specialised functional roles and neuromechanical properties. These findings suggest that the soleus is specialized for postural stability, while the medial gastrocnemius is suited for dynamic movements, informing targeted rehabilitation approaches. The medial gastrocnemius shows stable reflex thresholds, suited for dynamic, high-speed tasks, while the soleus exhibits more variability, reflecting its role in postural stability and controlled movements. These findings highlight the distinct roles of these muscles and suggest targeted interventions could enhance motor control in individuals with cerebral palsy, especially those with spasticity. The results must be interpreted cautiously, and no generalisations should be made as this was a case study.
Key words: cerebral palsy, hyper-resistance, stretch reflex threshold, stretch hyper-reflexia, assessment, upper motor neuron syndrome, neuromuscular function.
Main Author
Format
Theses
Master thesis
Published
2024
The permanent address of the publication
https://urn.fi/URN:NBN:fi:jyu-202412077661Use this for linking
Language
English
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