Use of ultrasound shear wave to measure muscle stiffness in children with cerebral palsy.

ABSTRACT

PURPOSE: Cerebral palsy (CP) is a disorder characterized by an increased muscle stiffness that can be contingent on both neurological and biomechanical factors. The neurological aspects are related to hyper-excitability of the stretch reflex, while the biomechanical factors are related to modifications in muscle structure. We used smart-shear wave elastography (S-SWE) to analyze muscle properties and to compare shear wave speed in soleus muscles of patients affected by CP and typically developing children. METHODS: We enrolled 21 children (15 males and 6 females; age range 3-16) with spastic hemiplegia CP and 21 healthy children (11 males and 10 females; age range 3-14). Measurements of soleus S-SWE were performed using a Samsung RS80A ultrasound scanner with Prestige equipment (Samsung Medison Co. Ltd., Seoul, Korea), with a convex array transducer (CA1-7; Samsung Medison Co. Ltd., Seoul, Korea). For each CP child clinical assessment included Modified Ashworth Scale (MAS) score. RESULTS: Children with CP showed greater S-SWE values than the healthy ones (p < 0.001). Our data suggest a significant correlation between the S-SWE values and the MAS scores (Spearman correlation coefficient 0.74; p < 0.001 at Kruskal-Wallis test) in children with CP. CONCLUSIONS: Measuring muscle properties with SWE, a non-invasive and real-time technique, may integrate the physical exam. SWE may be a reliable clinical tool for diagnosis and longitudinal monitoring of muscle stiffness, as well as particularly suitable for grading and for assessing the response to treatments.