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Background: The pronator teres and pronator quadratus muscles are frequently injected with neuromuscular blocking agents to improve supination in children with spastic cerebral palsy and limited active elbow supination. However, determining by simple clinical examination whether these muscles are overactive during active movement is difficult., Objective: This study aimed to develop a semi-automatic method to detect pronator muscle overactivity by using surface electromyography (EMG) during active supination movements in children with cerebral palsy., Methods: In total, 25 children with unilateral spastic cerebral palsy (10 males; mean [SD] age 10.6 [3.0] years) and 12 typically developing children (7 males; mean age 11.0 [3.0] years) performed pronation-supination movements at 0.50Hz. Kinematic parameters and surface EMG signals were recorded for both pronator muscles. Three experts visually assessed muscle overactivity in the EMG signals of the children with cerebral palsy, in comparison with the reference group. The reliability and discrimination ability of the visual assessments were analysed. Overactivity detection thresholds for the semi-automatic method were adjusted by using the visual assessment by the EMG experts. The positive and negative predictive values of the semi-automatic detection method were calculated., Results: Intra-rater reliability of visual assessment by EMG experts was excellent and inter-rater reliability was moderate. For the 25 children with unilateral spastic cerebral palsy, EMG experts could discriminate different profiles of pronator overactivity during active supination: no pronator overactivity, one overactive pronator, or overactivity of both pronators. The positive and negative predictive values were 96% and 91%, respectively, for this semi-automatic detection method., Conclusions: Detection of pronator overactivity by using surface EMG provides an important complement to the clinical examination. This method can be used clinically, with the condition that clinicians be aware of surface EMG limitations. We believe use of this method can increase the accuracy of treatment for muscle overactivity, resulting in improved motor function and no worsening of paresis., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Abstract 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. Highlights • Three techniques of electromyography amplitude normalization are compared. • Normalization using the mean peak value during dynamic trials is appropriate. • Variability of upper limb electromyographic patterns is quantified in children. • Inter-trial and inter-session variability are equivalent. • Variability is similar between children with cerebral palsy and typical development. [ABSTRACT FROM AUTHOR]

Background The theoretical role of muscle coactivation is to stiffen joints. The aim of this study was to assess the relationship between muscle coactivation and joint excursions during gait in children with and without hemiplegic cerebral palsy. Methods Twelve children with hemiplegic cerebral palsy and twelve typically developing children underwent gait analysis at three different gait speeds. Sagittal hip, knee, and ankle kinematics were divided into their main components corresponding to joint excursions. A coactivation index was calculated for each excursion from the electromyographic envelopes of the rectus femoris/semitendinosus, vastus medialis/semitendinosus, or tibialis anterior/soleus muscles. Mixed linear analyses of covariance modeled joint excursions as a function of the coactivation index and limb. Findings In typically developing children, increased coactivation was associated with reduced joint excursion for 8 of the 14 linear models (hip flexion, knee loading, knee extension in stance, knee flexion in swing, ankle plantarflexion from initial contact to foot-flat, ankle dorsiflexion in stance and in swing). Conversely, ankle plantarflexion excursion at push-off increased with increasing tibialis anterior/soleus coactivation. In the involved limbs of the children with cerebral palsy, knee loading, ankle plantarflexion at push off, and ankle dorsiflexion in swing decreased, while hip extension increased, with increasing muscle coactivation. Interpretation The relationships between muscle coactivation and joint excursion were not equally distributed in both groups, and predominant in typically developing children. The results suggest that excessive muscle coactivation is not a cause of stiff-knee gait in children with hemiplegic cerebral palsy, but appears to be related to spastic drop foot. [ABSTRACT FROM AUTHOR]

Abstract: Background: Physiological co-activation of antagonistic muscles during gait allows stability of loaded joints. Excessive co-activation restrains motion and increases energy expenditure. Co-activation is increased by gait speed and in the case of upper motor neuron lesions. This study aimed to assess the pathological component of co-activation in children with unilateral cerebral palsy. Methods: 10 children with unilateral cerebral palsy and 10 typically developing children walked at spontaneous, slow and fast speeds. The spatio-temporal parameters and electromyographic activity of the rectus femoris, vastus medialis, semi-tendinosus, tibialis anterior and soleus of both lower limbs were recorded. A co-activation index was computed from the EMG envelopes. A mixed linear model was used to assess the effect of walking speed on the index of the antagonistic muscle couples (rectus femoris/semi-tendinosus, vastus medialis/semi-tendinosus and tibialis anterior/soleus) in the different limbs. Findings: A greater effect of walking speed on co-activation was found in the involved limbs of children with cerebral palsy for all muscle couples, compared with their uninvolved limbs and the limbs of typically developing children. In typically developing children, but not in children with cerebral palsy, the effect of gait speed on the co-activation index was lower in the rectus femoris/semi-tendinosus than in the other agonist/antagonist muscle couples. Interpretations: In children with cerebral palsy, a pathological component of muscle activation might be responsible for the greater increase in co-activation with gait speed in the involved limb. Altered motor control could explain why the co-activation in the rectus femoris/semi-tendinosus couple becomes more sensitive to speed. [Copyright &y& Elsevier]

Objective Children with spastic unilateral cerebral palsy (SUCP) have an involved upper limb (IUL) restricted in active range of motion and in velocity when performing elbow extension, due to a combination of muscle impairments. One of them is excessive muscle co-activation (CA). CA usually has a functional role, particularly in joint stabilization. The aim of this study is to identify when pathological CA occurs during active elbow extension of the IUL to highlight its impact on movement restriction and to discriminate impaired muscles. Material/patients and methods Thirteen typically developing (TD) children and 13 children with SUCP performed active elbow extension/flexions at 3 externally paced frequencies. Elbow angle and velocity were computed using a subject-specific model tracking the position of 29 upper limb markers. With these data, the extension movement was decomposed into the Extension Acceleration Phase (EAP) (velocity increase) and the Extension Deceleration Phase (EDP) (velocity decrease). The percentage of CA for the brachioradialis (BR)/triceps and biceps/triceps couples for each phase was extracted from the surface electromyographic signals. Statistical analysis was conducted using linear mixed effects models. Results During the EAP, excessive and positive frequency-dependent CA was found in the SUCP group, whereas CA in the TD group was low and invariant. These results point to pathological CA in the SUCP group, probably linked to restricted velocity. During the EDP, only excessive BR/triceps CA was found in the SUCP group. CA was positive frequency-dependent in both groups. These results point to mostly functional CA, for joint stabilization at the end of the movement. However, BR seems to stand out in its possible involvement in extension active range of motion restriction. Discussion–conclusion This study provides insight into pathological CA in children with SUCP. Perspectives include individual clinical interpretation of the results, to assist in each child's therapeutic decision. [ABSTRACT FROM AUTHOR]