Development of Postural Control in Healthy Children: A Functional Approach

From a set of experimental studies showing how intersegmental coordination develops during childhood in various posturokinetic tasks, we have established a repertoire of equilibrium strategies in the course of ontogenesis. The experimental data demonstrate that the first reference frame used for the organization of balance control during locomotion is the pelvis, especially in young children. Head stabilization during posturokinetic activities, particularly locomotion, constitutes a complex motor skill requiring a long time to develop during childhood. When studying the emergence of postural strategies, it is essential to distinguish between results that can be explained by biomechanical reasons strictly and those reflecting the maturation of the central nervous system (CNS). To address this problem, we have studied our young subjects in situations requiring various types of adaptation. The studies dealing with adaptation of postural strategies aimed at testing short and long-term adaptation capacity of the CNS during imposed transient external biomechanical constraints in healthy children, and during chronic internal constraints in children with skeletal pathologies. In addition to maintenance of balance, another function of posture is to ensure the orientation of a body segment. It appears that the control of orientation and the control of balance both require the trunk as an initial reference frame involving a development from egocentric to exocentric postural control. It is concluded that the first step for children consists in building a repertoire of postural strategies, and the second step consists in learning to select the most appropriate postural strategy, depending on the ability to anticipate the consequence of the movement in order to maintain balance control and the efficiency of the task

Orientation posturale et stratégies d'équilibre (développement et adaptation chez l'enfant et l'adolescent porteurs d'anomalies de torsion du squelette)

Ce travail étudie les conséquences d anomalies de torsion du squelette, chez l enfant et l adolescent, à partir d une approche du contrôle postural qui dissocie la fonction d orientation, de la fonction de stabilisation. Ces deux fonctions et l intégration sensorielle ont été étudiées avec des tâches locomotrices et un protocole d oscillations lentes du support. Que les anomalies de torsion touchent les membres inférieurs ou le rachis, les résultats montrent que la stabilisation du bassin est préservée alors que celle de la tête est affectée. De plus, l intégration sensorielle s effectue selon des processus graduels et linéaires qui sont lents à maturer au cours de l ontogenèse. En conclusion les adaptations posturales bénéficient de la redondance d un système en construction qui autorise des anomalies musculo-squelettiques locales sans remettre en cause les principes fonctionnels de la construction des référentiels spatiaux et sans mettre en échec les performances posturo-cinétique.This work studies the consequences of local musculo-skeletal abnormalities in children and adolescents, from a double perspective of postural control which dissociates the functions of orientation and stabilisation. Stabilisation, orientation and sensory integration have been studied using locomotors tasks and a paradigm of slow oscillations of a support. Whatever the level of torsion considered (lower part of the body or the spine), the results show that the pelvis stabilisation on space is preserved, while the head stabilisation is affected. Furthermore, sensory integration progresses according to gradual and linear processes, particularly slow to mature. The conclusion is that during ontogenesis, postural adaptations benefit from the redundancy of a system in construction which allows the existence of local musculo-skeletal abnormalities without challenging the functional principles of the construction of spatial reference frames and without defeating the posturo-kinetic performances.DIJON-BU Médecine Pharmacie (212312103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Postural Strategies and Sensory Integration: No Turning Point between Childhood and Adolescence

International audienceIn this study, we investigated the sensory integration to postural control in children and adolescents from 5 to 15 years of age. We adopted the working hypothesis that considerable body changes occurring during these periods may lead subjects to under-use the information provided by the proprioceptive pathway and over-use other sensory systems such as vision to control their orientation and stabilize their body. It was proposed to determine which maturational differences may exist between the sensory integration used by children and adolescents in order to test the hypothesis that adolescence may constitute a specific phase in the development of postural control. This hypothesis was tested by applying an original protocol of slow oscillations below the detection threshold of the vestibular canal system, which mainly serves to mediate proprioceptive information, to the platform on which the subjects were standing. We highlighted the process of acquiring an accurate sensory and anatomical reference frame for functional movement. We asked children and adolescents to maintain a vertical stance while slow sinusoidal oscillations in the frontal plane were applied to the support at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above the detection threshold of the semicircular canal system) with their eyes either open or closed. This developmental study provided evidence that there are mild differences in the quality of sensory integration relative to postural control in children and adolescents. The results reported here confirmed the predominance of vision and the gradual mastery of somatosensory integration in postural control during a large period of ontogenesis including childhood and adolescence. The youngest as well as the oldest subjects adopted similar qualitative damping and segmental stabilization strategies that gradually improved with age without reaching an adult's level. Lastly, sensory reweighting for postural strategies as assessed by very slow support oscillations presents a linear development without any qualitative turning point between childhood and adolescence

Postural Strategies and Sensory Integration: No Turning Point between Childhood and Adolescence

In this study, we investigated the sensory integration to postural control in children and adolescents from 5 to 15 years of age. We adopted the working hypothesis that considerable body changes occurring during these periods may lead subjects to under-use the information provided by the proprioceptive pathway and over-use other sensory systems such as vision to control their orientation and stabilize their body. It was proposed to determine which maturational differences may exist between the sensory integration used by children and adolescents in order to test the hypothesis that adolescence may constitute a specific phase in the development of postural control. This hypothesis was tested by applying an original protocol of slow oscillations below the detection threshold of the vestibular canal system, which mainly serves to mediate proprioceptive information, to the platform on which the subjects were standing. We highlighted the process of acquiring an accurate sensory and anatomical reference frame for functional movement. We asked children and adolescents to maintain a vertical stance while slow sinusoidal oscillations in the frontal plane were applied to the support at 0.01 Hz (below the detection threshold of the semicircular canal system) and at 0.06 Hz (above the detection threshold of the semicircular canal system) with their eyes either open or closed. This developmental study provided evidence that there are mild differences in the quality of sensory integration relative to postural control in children and adolescents. The results reported here confirmed the predominance of vision and the gradual mastery of somatosensory integration in postural control during a large period of ontogenesis including childhood and adolescence. The youngest as well as the oldest subjects adopted similar qualitative damping and segmental stabilization strategies that gradually improved with age without reaching an adult's level. Lastly, sensory reweighting for postural strategies as assessed by very slow support oscillations presents a linear development without any qualitative turning point between childhood and adolescence

Locomotor Skills and Balance Strategies in Adolescents Idiopathic Scoliosis

International audienceLocomotor balance control assessment was performed to study the effect of idiopathic scoliosis on head-trunk coordination in 17 patients with adolescent idiopathic scoliosis (AIS) and 16 control subjects

Left upper panel: Diagram of the shoulder roll angle with respect to the external axis, θ_a, and with respect to the supporting platform, θ_r.

<p>With x: lateral axis, y sagittal axis and z vertical axis. Right panel: angular roll displacement of the supporting platform (upper trace), the absolute angular displacement of the shoulders (middle trace) and the relative angular movement of the shoulders with respect to the supporting calculated every 8.33 ms during a trial using the formula: with , the angular orientation of the shoulders relative to the support, and and are the absolute shoulders and support angular orientations,s respectively. (Lower trace). Left lower panel: Diagram of the absolute (Sd Abs) and relative (Sd Rel) roll dispersions of the shoulders, according to the definition of the anchoring index (AI). Formula of the AI = (Sd Rel²−Sd Abs²)/(Sd Rel²+Sd Abs²) where Sd Abs is the standard deviation of the angular distribution about the roll of the segment under investigation with respect to the absolute allocentric reference (absolute vertical direction) value and Sd Rel is the corresponding standard deviation of the angular distribution with respect to the moving platform. In this example, AI is positive, which means that the shoulders are stabilized in space independently of platform movements.</p

Median and quartiles of sequential orientation (degrees) of head, shoulders, trunk, pelvis and support (top to down) with eyes open (top panel) and eyes closed (down panel) in subjects from 5 to 15 years at 0.01 Hz.

<p>Median and quartiles of sequential orientation (degrees) of head, shoulders, trunk, pelvis and support (top to down) with eyes open (top panel) and eyes closed (down panel) in subjects from 5 to 15 years at 0.01 Hz.</p

Subject's photography representing the markers' position.

<p>The 15 markers were placed symmetrically in pairs on the subject's back at the following sites: top of the head (1), mastoid (2, 3), acromion process (5, 6), spinal process of C7 (4), L2 (7) and T6 (8), on the sacrum (11), posterior-superior iliac crest (9, 10), lateral tibial plate (12, 13), external malleolus (14, 15). Two last markers were also placed on the platform (16, 17) to measure its lateral movements.</p

Median and quartiles of roll head, shoulders, trunk and pelvis (top to down) anchoring index, with eyes open (white) and eyes closed (black) in subjects from 5 to 15 years at 0.01 Hz (left panel) and at 0.06 Hz (right panel).

<p>Median and quartiles of roll head, shoulders, trunk and pelvis (top to down) anchoring index, with eyes open (white) and eyes closed (black) in subjects from 5 to 15 years at 0.01 Hz (left panel) and at 0.06 Hz (right panel).</p