Aurélie Sarcher

Pathological and physiological muscle co-activation during active elbow extension in children with unilateral cerebral palsy

OBJECTIVE To address the roles and mechanisms of co-activation in two flexor/extensor pairs during elbow extension in children with cerebral palsy (CP). METHODS 13 Typically Developing (TD) and 13 children with unilateral spastic CP performed elbow extension/flexion at different speeds. Elbow angle and velocity were recorded using a 3D motion analysis system. The acceleration and deceleration phases of extension were analyzed. Co-activation of the brachioradialis/triceps and biceps/triceps pairs was computed for each phase from surface electromyographic signals. Statistical analysis involved linear mixed effects models and Spearman rank correlations. RESULTS During the acceleration phase, there was strong co-activation in both muscle pairs in the children with CP, which increased with speed. Co-activation was weak in the TD children and it was not speed-dependent. During the deceleration phase, co-activation was strong and increased with speed in both groups; co-activation of brachioradialis/triceps was stronger in children with CP, and was negatively correlated with extension range and positively correlated with flexor spasticity. CONCLUSIONS Abnormal patterns of co-activation in children with CP were found throughout the entire movement. Co-activation was specific to the movement phase and to each flexor muscle. SIGNIFICANCE Co-activation in children with CP is both physiological and pathological.

Patterns of upper limb muscle activation in children with unilateral spastic cerebral palsy: Variability and detection of deviations

Background: The aim of this study was two‐fold: (1) to quantify the variability of upper limb electromyographic patterns during elbow movements in typically developing children and children with unilateral spastic cerebral palsy, and to compare different amplitude normalization methods; (2) to develop a method using this variability to detect (a) deviations in the patterns of a child with unilateral spastic cerebral palsy from the average patterns of typically developing children, and (b) changes after treatment to reduce muscle activation. Methods: Twelve typically developing children ([6.7–15.9yo]; mean 11.0 SD 3.0yo) and six children with unilateral spastic cerebral palsy ([7.9–17.4yo]; mean 12.4 SD 4.0yo) attended two sessions during which they performed elbow extension‐flexion and pronation‐supination movements. Surface electromyography of the biceps, triceps, brachioradialis, pronator teres, pronator quadratus, and brachialis muscles was recorded. The Likelihood method was used to estimate the inter‐trial, inter‐session, and inter‐subject variability of the electromyography patterns for each time point in the movement cycle. Deviations in muscle patterns from the patterns of typically developing children and changes following treatment were evaluated in a case study of a child with cerebral palsy. Findings: Normalization of electromyographic amplitude by the mean peak yielded the lowest variability. The variability data were then used in the case study. This method detected higher levels of activation in specific muscles compared with typically developing children, and a reduction in muscle activation after botulinum toxin A injections. Interpretation: Upper limb surface electromyography pattern analysis can be used for clinical applications in children with cerebral palsy.

Methodology for the Assessment of Joint Efforts During Sit to Stand Movement

• children with cerebral palsy, for which the FRSTST was found a reliable and valid test to measure functional muscle strength in children with spastic diplegia in clinics [2, 3]; • older adults, for which the FRSTST test-retest reliability can be interpreted as good to high in most populations and settings [1]; • subjects with Parkinson’s disease [4]; • paraplegic subjects [5]; • subjects with multiple sclerosis [6]; • above knee amputees [7] and unilateral transtibial amputees [8]; • subjects with rheumatoid arthritis [9] or alterations in advanced knee osteoarthritis [10]; • post-stroke subjects [11].