A1 Journal article (refereed)
Revising the stretch reflex threshold method to measure stretch hyperreflexia in cerebral palsy (2022)

Valadão, P., Bar-On, L., Cenni, F., Piitulainen, H., Avela, J., & Finni, T. (2022). Revising the stretch reflex threshold method to measure stretch hyperreflexia in cerebral palsy. Frontiers in Bioengineering and Biotechnology, 10, Article 897852. https://doi.org/10.3389/fbioe.2022.897852

JYU authors or editors

Frederico Valadao, Pedro
Cenni, Francesco
Piitulainen, Harri
Avela, Janne
Juutinen, Taija

Publication details

All authors or editors: Valadão, Pedro; Bar-On, Lynn; Cenni, Francesco; Piitulainen, Harri; Avela, Janne; Finni, Taija

Journal or series: Frontiers in Bioengineering and Biotechnology

eISSN: 2296-4185

Publication year: 2022

Publication date: 23/11/2022

Volume: 10

Article number: 897852

Publisher: Frontiers Media SA

Publication country: Switzerland

Publication language: English

DOI: https://doi.org/10.3389/fbioe.2022.897852

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/85120

Abstract

Hyper-resistance is an increased resistance to passive muscle stretch, a common feature in neurological disorders. Stretch hyperreflexia, an exaggerated stretch reflex response, is the neural velocity-dependent component of hyper-resistance, and has been quantitatively measured using the stretch reflex threshold (i.e., joint angle at the stretch reflex electromyographic onset). In this study, we introduce a correction in how the stretch reflex threshold is calculated, by accounting for the stretch reflex latency (i.e., time between the stretch reflex onset at the muscle spindles and its appearance in the electromyographic signal). Furthermore, we evaluated how this correction affects the stretch reflex threshold in children and young adults with spastic cerebral palsy. A motor-driven ankle dynamometer induced passive ankle dorsiflexions at four incremental velocities in 13 children with cerebral palsy (mean age: 13.5 years, eight males). The stretch reflex threshold for soleus and medial gastrocnemius muscles was calculated as 1) the joint angle corresponding to the stretch reflex electromyographic onset (i.e., original method); and as 2) the joint angle corresponding to the electromyographic onset minus the individual Hoffmann-reflex latency (i.e., latency corrected method). The group linear regression slopes between stretch velocity and stretch reflex threshold differed in both muscles between methods (p < 0.05). While the original stretch reflex threshold was velocity dependent in both muscles (p < 0.05), the latency correction rendered it velocity independent. Thus, the effects of latency correction on the stretch reflex threshold are substantial, especially at higher stretch velocities, and should be considered in future studies.

Keywords: cerebral palsy; neuromuscular activity; reflexes; neurophysiology; electromyography

Free keywords: hyperreflexia; neurophysiology; stretch reflex; electromyography; cerebral palsy

Fields of science: