Morphological Medial Gastrocnemius Muscle Growth in Ambulant Children with Spastic Cerebral Palsy: A Prospective Longitudinal Study

Abstract

Only cross-sectional studies have demonstrated muscle deficits in children with spastic cerebral palsy (SCP). The impact of gross motor functional limitations on altered muscle growth remains unclear. This prospective longitudinal study modelled morphological muscle growth in 87 children with SCP (age range 6 months to 11 years, Gross Motor Function Classification System [GMFCS] level I/II/III = 47/22/18). Ultrasound assessments were performed during 2-year follow-up and repeated for a minimal interval of 6 months. Three-dimensional freehand ultrasound was applied to assess medial gastrocnemius muscle volume (MV), mid-belly cross-sectional area (CSA) and muscle belly length (ML). Non-linear mixed models compared trajectories of (normalized) muscle growth between GMFCS-I and GMFCS-II&III. MV and CSA growth trajectories showed a piecewise model with two breakpoints, with the highest growth before 2 years and negative growth rates after 6–9 years. Before 2 years, children with GMFCS-II&III already showed lower growth rates compared to GMFCS-I. From 2 to 9 years, the growth rates did not differ between GMFCS levels. After 9 years, a more pronounced reduction in normalized CSA was observed in GMFCS-II&III. Different trajectories in ML growth were shown between the GMFCS level subgroups. These longitudinal trajectories highlight monitoring of SCP muscle pathology from early ages and related to motor mobility. Treatment planning and goals should stimulate muscle growth.

Reliability and validity of assessing lower‐limb muscle architecture of patients with cerebral palsy (CP) using ultrasound: A systematic review

“…This may be explained by the altered internal muscle architecture, containing declined muscle thickness, 20,21 muscle length, 22 cross‐sectional area, 20,23 muscle volume, 22,24 and fascicle length 20,21,24 . These abnormal alternations of muscle architecture are associated with altered muscle growth 25 . Besides, some muscle architecture alterations, such as the decreased volume of medial gastrocnemius and semitendinosus and the shorter medial gastrocnemius, can be more noticeable during low‐velocity stretches 26 .…”

“…When it comes to individuals with CP, numerous studies have applied ultrasound to assess muscle architecture over the past decade, 31–33,44–48 including muscle thickness, 20,21 muscle length, 22 cross‐sectional area, 20,23 muscle volume, 22,24 and fascicle length 20,21,24 . More recently, ultrasound has also been employed to monitor CP patients' muscle pathology from early age 25 . While many previous studies have investigated the reliability 20,21,32,44–49 and validity 31–33 of applying ultrasound to evaluate CP patients' muscle architectures, the findings have been inconsistent across different studies, making it difficult to draw a solid conclusion.…”

“…20,21,24 These abnormal alternations of muscle architecture are associated with altered muscle growth. 25 Besides, some muscle architecture alterations, such as the decreased volume of medial gastrocnemius and semitendinosus and the shorter medial gastrocnemius, can be more noticeable during low-velocity stretches. 26 Numerous interventions (e.g., physiotherapy, casting, botulinum toxin treatment, and surgery) have been developed and applied to treat the affected limb muscles in these patients.…”

“…20,21,24 More recently, ultrasound has also been employed to monitor CP patients' muscle pathology from early age. 25 While many previous studies have investigated the reliability 20,21,32,[44][45][46][47][48][49] and validity [31][32][33] of applying ultrasound to evaluate CP patients' muscle architectures, the findings have been inconsistent across different studies, making it difficult to draw a solid conclusion. More recently, a scoping review has reported that the most common muscle that been investigated previously was the medial gastrocnemius, the joint positioning for muscle assessment varied among the previous studies, and the assessed parameter(s) of muscle architecture was not common in the clinical setting due to the lack of supporting evidence.…”

Human lower leg muscles grow asynchronously

“…Knowledge of growth rates in typically developing children may have implications for understanding disordered growth, for example, in children with neurological disorders such as cerebral palsy. Currently, it is largely unknown if growth rates differ between muscles, because most studies of muscle growth in childhood have investigated only one muscle (Bell et al, 2021;Benard et al, 2011;Binzoni et al, 2001;De Beukelaer et al, 2023;D'Souza et al, 2019;Herskind et al, 2016;Morse et al, 2008;Walhain et al, 2023;Weide et al, 2015Weide et al, , 2020 or a few muscles (Böl et al, 2017;Handsfield et al, 2022;Modlesky & Zhang, 2020;Mogi & Wakahara, 2022;O'Brien et al, 2010;Peeters et al, 2023;Siebert et al, 2017;Williams et al, 2022;Yanagisawa et al, 2014). O'Brien et al (2010) reported that the four components of the quadriceps muscles undergo similar relative increases in volume from childhood to adulthood.…”