Heterogeneity of muscle sizes in the lower limbs of children with cerebral palsy

INTRODUCTION: Cerebral palsy (CP) is associated with reduced muscle volumes, but previous studies have reported deficits in only a small number of muscles. The extent of volume deficits across lower limb muscles is not known. This study presents an imaging-based assessment of muscle volume and length deficits in 35 lower limb muscles. METHODS: We imaged and segmented 35 muscles in 10 subjects with CP and 8 typically developing (TD) controls using MRI. Muscle volumes were normalized, and Z-scores were computed using TD data. Volume Z-scores and percent deficits in volume, length, and cross-sectional area are reported. RESULTS: Muscle volumes are 20% lower, on average, for subjects with CP. Volume deficits differ significantly between muscles (12%-43%) and display significant heterogeneity across subjects. Distal muscles, especially the soleus, are commonly and severely small. CONCLUSIONS: Heterogeneity across muscles and across subjects reinforces the subject specificity of CP and the need for individualized treatment planning. Muscle Nerve 53: 933-945, 2016.