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Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

ABSTRACT: Individual joint deviations are often identified in the analysis of cerebral palsy (CP) gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient) of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.

SUBMITTER: Wang TM

PROVIDER: S-EPMC4667918 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundCongenital heart disease (CHD) is the most common birth defect, affecting 1% of children who are born in the United States each year. Children with hypoplastic left heart syndrome, a type of critical CHD, are at high risk for neurodevelopmental disabilities, which are conditions that can affect motor, language, and cognitive development. In children with critical CHD, the severity and prevalence of their motor delays is most pronounced in infancy.Case descriptionWe present a case of a former late preterm male with hypoplastic left heart syndrome and history of hypoxic ischemic encephalopathy, who was diagnosed with spastic diplegic cerebral palsy in the setting of periventricular leukomalacia. Like many children with critical CHD, this child had gross motor delays and tone abnormalities in infancy. However, unlike many children with CHD, he continued to have neurologic differences that prompted additional evaluation through a Cardiac Neurodevelopmental Program. He was diagnosed with spastic diplegic cerebral palsy based upon clinical history and physical examination. Ancillary testing showed periventricular leukomalacia on brain magnetic resonance imaging (MRI); this finding was consistent with his clinical diagnosis.ConclusionsThis is an interesting case report of spastic diplegic cerebral palsy in a late preterm infant with critical CHD. When making a diagnosis of cerebral palsy, it is important to consider the etiology of the motor impairment. Selective vulnerability may have played a factor in this child's condition. The most vulnerable part of the neonatal brain is the periventricular white matter; cerebral hypoxia can lead to periventricular leukomalacia. Children with CHD have brain dysmaturity beginning in-utero. Thus, it is possible that this child's brain dysmaturity may have increased his susceptibility to periventricular leukomalacia. Because most children with CHD have gross motor delays in infancy, it may be challenging to make a definitive diagnosis of cerebral palsy in an infant with critical CHD. Children with cerebral palsy have early motor delays that persist throughout life. It is the identification of persistent motor impairments through repeat evaluations that enabled this child's cerebral palsy diagnosis. This illustrates the importance of developmental surveillance in children with critical CHD.

Project description:AimTo compare anterior and posterior standing balance reactions, as measured by single-stepping thresholds, in children with and without spastic cerebral palsy (CP).MethodSeventeen ambulatory children with spastic CP (eight males, nine females) and 28 typically developing children (13 males, 15 females; age range 5-12y, mean [SD] 9y 2mo [2y 3mo]), were included in this cross-sectional, observational study. Balance reaction skill was quantified as anterior and posterior single-stepping thresholds, or the treadmill-induced perturbations that consistently elicited a step in that direction. In order to understand the underlying mechanisms of between-group differences in stepping thresholds, dynamic stability was quantified using the minimum margin of stability. Ankle muscle activation latency, magnitude, and co-contraction were assessed with surface electromyography.ResultsWe observed an age and group interaction for anterior thresholds (p=0.001, partial η2 =0.24). At older (≈11y; p<0.001, partial η2 =0.48), but not younger (≈7y; p=0.33, partial η2 =0.02) ages, typically developing children had larger anterior thresholds than those with CP. In response to near-threshold anterior perturbations, older typically developing children recovered from more instability than their peers with CP (p=0.004, partial η2 =0.18). Older children had no between-group differences in ankle muscle activity. No between-group differences were observed in posterior thresholds.InterpretationThe effects of CP on balance reactions are age- and direction-specific. Older typically developing children are more able or willing to withhold a step when unstable.What this paper addsChildren with spastic cerebral palsy have age- and direction-specific balance-reaction impairments. Lower anterior stepping thresholds were observed in older, but not younger children. Older typically developing children withheld a forward step at higher levels of instability. No between-group differences were seen in posterior stepping thresholds.

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Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

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