Measuring skeletal muscle morphology in children with cerebral palsy – A scoping review update of the last 4 years

Skeletal muscle is among the most plastic tissues in the human body, adapting to both positive and negative stimuli [1]. In cerebral palsy (CP), the primary injury is located in the central nervous system, but the clinical symptoms are most often in the peripheral neuromuscular system [2]. The characteristics of skeletal muscle determine to a large extent the functional capacities of the child with CP, and many clinical interventions are aimed at optimizing muscular function [3]. Therefore, it is important to accurately assess muscle morphology in CP. In 2020, Williams et al. published a scoping review on the measurement of muscle morphology in children with CP[4]. Recent years showed a continued flow of studies describing muscle morphology in CP, therefore this investigation aimed to update the current state of evidence and explore the possibilities for implementation in clinical care. How have muscle imaging approaches been applied in CP in the past 2 decades, and especially in the last 4 years? An update of the scoping review[4] was performed, including all articles utilizing ultrasound (US) or magnetic resonance imaging (MRI) to determine lower limb muscle morphology in children (0-18 y) with CP. Hereto, 5 databases were sought (Pubmed, Web of Science, Embase, Scopus, and PsycInfo) between February 2019 and 2023. Forty-seven articles were identified in 2019-2023 (=update) in comparison to 82 articles between 2002-2019 (=original). In the update, 2D US, 3D US, and MRI were more evenly applied than in the original review (Fig. 1A). The median sample size was similar (update: n=18, original: n=15), with a wider range in the update (update: n=1-87, original: n=1-50). The majority of studies still focused on ambulant children with CP (gross motor function classification system level I/II/III/IV/V; update: n=43/38/25/4/3, original: n=62/65/29/14/4). There was a relative increase in methodological studies and a relative decrease in observational studies, whilst the percentage of experimental studies remained constant (Fig. 1B). The most investigated muscle remains the medial gastrocnemius (update: 87%, original: 72%, Fig. 1C) and a large variability is still present in the normalization to anthropometric measures, including (combinations of) body mass, height, and bone lengths. A similar percentage of studies reported morphological outcomes between different groups (update: 17%, original: 22%), but an increase was present in associations of morphological outcomes with levels of the International Classification of Functioning, Disability and Health model (update: 49%, original: 21%).Download : Download high-res image (175KB)Download : Download full-size image The majority of current knowledge results from the medial gastrocnemius in ambulant children, whereas imaging methodologies and normalization procedures vary highly between studies. Further analysis of all 129 articles are conducted to determine standardized effect sizes between groups and the strength of correlations. Yet, additional scientific approaches might be necessary to reach consensus on the implementation of morphological outcomes in the clinical decision-making process.