Estimating medial gastrocnemius muscle volume in children with spastic cerebral palsy: a cross‐sectional investigation

Abstract

Aim This cross‐sectional investigation evaluates the reliability of estimating medial gastrocnemius anatomical cross‐sectional area (aCSA) in typically developing and spastic cerebral palsy (SCP) cohorts. It verifies whether muscle volume estimations based on aCSA improve when aCSA is multiplied by muscle–tendon unit (MTU) or muscle length, and whether the resulting errors in volume estimations are smaller than changes after intervention. Method Fifteen typically developing children (mean age 8y 2mo [SD 1y 5mo], six males, nine females) and 30 children with SCP (mean age 9y 2mo [SD 2y 5mo], 22 males, eight females, Gross Motor Function Classification System [GMFCS] level I=15, II=15) participated in the investigation. The SCP cohort was divided according to GMFCS level. A three‐dimensional freehand ultrasound technique was used to estimate medial gastrocnemius aCSA, muscle volume, MTU, and muscle length. Estimated muscle volume (aCSA×MTU or muscle length) was compared with the measured muscle volume. Results Anatomical cross‐sectional area, muscle volume, and muscle length significantly differed between the typically developing and two SCP cohorts (p≤0.050). aCSA multiplied by either MTU or muscle length improved estimations of medial gastrocnemius volume. Leave‐one‐out cross‐validation revealed an absolute difference with measured muscle volume of 3.77 ml (SD 2.90). Interpretation This investigation revealed that medial gastrocnemius muscle volume can be reliably estimated in a clinically feasible manner in typically developing children and those with SCP. What this paper adds Medial gastrocnemius anatomical cross‐sectional area (aCSA) can be reliably estimated in children with spastic cerebral palsy. The location of the anatomical cross‐section should be taken with respect to muscle and not bone length. Medial gastrocnemius volume can be reliably estimated by multiplying aCSA and muscle length. The errors in volume estimations are smaller than reported differences after interventions.

A comparison of 3D ultrasound to MRI for the measurement and estimation of gastrocnemius muscle volume in adults and young people with and without cerebral palsy

“…Freehand 3DUS has been used to provide reliable measures of MV and ML in both in vitro (Weide et al, ) and in vivo studies of typically developing (TD) children and those with CP (Schless et al, ). Dissected medial gastrocnemius MV and fascicle length from four cadavers showed significantly high correlations with MVs and fascicle lengths measured with 3DUS using a water submersion method and calipers (Weide et al, ).…”

Corrigendum

“…In the article by Schless et al., the ethical commission number was incorrect. It should have been s57384.…”

Estimating muscle volume from two‐dimensional measurements: a promising method for assessment

“…The work of Schless et al 5 suggests that muscle volume may be estimated from measurements made using a standard two-dimensional (2D) ultrasound scanner. Schless et al reported a strong linear relationship between muscle volume and the product of muscle length and cross-sectional area in the medial gastrocnemius.…”

“…Schless et al reported a strong linear relationship between muscle volume and the product of muscle length and cross-sectional area in the medial gastrocnemius. 5 This strong relationship has implications for the clinical feasibility of assessing muscle volume in this group. However, the work described is not a complete test of the utility and accuracy of estimating muscle volume by 2D ultrasound.…”

“…Despite these limitations, the findings of Schless et al 5 represent a significant stepping-stone towards the validation of a simple, low cost, clinically feasible method for estimating muscle volume that could potentially become a valuable clinic tool for assessing treatment outcome and aiding treatment selection in the future.…”