Primary and secondary factors contributing to altered muscle morphology in children with spastic cerebral palsy

In the last decade, several investigations of altered muscle morphology demonstrated reduced muscle size and lengths in children with SCP in comparison to their typically developing (TD) peers. The morphological muscle deficits were already observed from a young age and with a more pronounced reduction in muscle size for children with more limited functional abilities as indicated by higher gross motor function classification system (GMFCS) levels. However, these cross-sectional studies, which included children from 2 years of age, did not capture the longitudinal trajectories of muscle growth. Consequently, the responsible mechanisms for the pathogenesis (i.e., onset, development and progression) of this altered muscle growth remained imprecise. Because of this, the rationale behind different treatment paradigms might be incomplete or even wrong. The general aim of this doctoral dissertation was to explore the primary and secondary factors contributing to altered muscle growth for children with SCP, using repeated muscle assessments over time and investigating the contribution of neural, biomechanical and treatment factors. This doctoral project established piecewise trajectories of MG morphological muscle growth in ambulant children with SCP, aged 6 months to 11 years. An infancy onset of muscle alterations was confirmed, indicating the contribution of altered neural input as a primary key factor. Altered muscle morphology involved further muscle size reduction with increasing age, especially for children with higher GMFCS levels. As a further consequence of the altered neural input, reduced levels of motor functioning were indicated to contribute to altered muscle growth as secondary factors. This project also showed that muscle growth was hampered after BoNT-A treatment. Overall, the results revealed that primary and secondary factors are contributing to altered muscle growth as a complex and interactive network. However, the multifactorial origin of altered muscle growth may not only be attributed to isolated contributors such as neural, biomechanical and treatment factors. Further investigations of the complex, continuing interactions in key factors of primary and secondary nature, as well as additional factors such as prematurity, nutrition and physical activity, are recommended to further understand the underlying mechanisms of altered muscle growth. In any case, early monitoring with close follow-up of the morphological muscle trajectory and treatment opportunities aiming to stimulate and maintain muscle growth, are advised.

Jaar van publicatie:2022

Toegankelijkheid:Open