Intersegmental coordination in children with cerebral palsy

Cerebral Palsy (CP) is the most common physical disability in the paediatric population. It is produced by a lesion in the developing brain and may generate deficits in movement planning, execution as well as coordination, i.e. motor control impairments. These may be encountered in everyday life, for instance when opening a door or when transporting a tray. In research, these alterations can be evidenced during precision grip grasping tasks. This thesis aims to better understand the altered motor control in children with unilateral CP using the precision grip during a discrete, intersegmental task of going down a step. It also aims to determine whether is possible to improve the motor control during this task after a specific intensive training (HABIT-ILE).La paralysie cérébrale (PC) est le handicap physique le plus courant en pédiatrie. Elle est secondaire à une lésion dans le cerveau en développement pouvant générer des déficits dans la planification, l’exécution ainsi que la coordination des mouvements, c.-à-d. des déficiences du contrôle moteur. Ceux-ci peuvent être rencontrés dans la vie quotidienne par exemple lors de l’ouverture d’une porte ou du transport d’un plateau. Ces altérations peuvent être mises en évidence lors des tâches de préhension fine. Cette thèse vise à mieux comprendre le contrôle moteur altéré chez les enfants atteints de PC unilatérale utilisant la préhension fine lors d’une tâche discrète, intersegmentaire de descente d’une marche. Elle vise également à déterminer s’il est possible d’améliorer le contrôle moteur dans cette tâche suite à une thérapie intensive spécifique (HABIT-ILE).(MOTR - Sciences de la motricité) -- UCL, 202

Precision Grip Control while Walking Down a Stair Step

The aim of this study was to determine whether the internal model regulating grip force (GF)/load force (LF) coordination during a brisk load increase is preserved when the lower extremities produce a perturbation during a single step-down task. We observed the coordination of the vertical ground reaction force (vGRF), GF and LF while holding a handheld object during a single step-down task. The 3 forces (vGRF, GF and LF) decreased during the start of the task. While the subject was descending, LF and GF became dissociated from vGRF and increased in value, probably to anticipate the first foot contact. Coordination of LF and GF was maintained until the maximal vGRF (knee extension). LF peaked in the same time window as vGRF, whereas GF peaked about 70 ms later. This desynchronization, which was previously observed in direct load increase on a handheld object, was interpreted to be a predictive action to ensure the smooth management of the brisk increase in load induced by the lower extremities. Incidentally, in this group, kinematic and dynamic differences were observed between men and women, which may highlight a gender-specific strategy to perform the step-down task. In conclusion, these results suggest that the internal model of precision grip is able to integrate a brisk load change, whatever its origin, and regulate the forces to provide an ideal GF to dampen a brisk load increase and secure the object

Mean values (SD) of kinematic and dynamic variables at the different events of the task.

<p>Mean values (SD) of kinematic and dynamic variables at the different events of the task.</p

Comparison of kinematic and dynamic variables between female and male groups.

<p>Comparison of kinematic and dynamic variables between female and male groups.</p

Mean values (SD) of temporal variables of the whole sample during the task.

<p>Mean values (SD) of temporal variables of the whole sample during the task.</p

Tables and figure 2 data.

excel sheets containing the data of both tables and of the plots in figure 2

Example of two subjects’ traces corresponding to each groups mean values.

<p>Female subject (S5) is presented in grey and male subject (S7) in black. The traces display the vertical position of the hand (straight traces) and the sacrum (line-dot-dot traces) as function of time, starting from t₀, showing the difference in the vertical displacement of the hands and the sacrum between groups. The vertical cut lines mark vGRF_fc and LF_max events in each subject’s trial.</p

Data from: Precision grip control while walking down a step in children with unilateral cerebral palsy

Aim. To compare grip force (GF) and load force (LF) coordination while walking down a step between children with unilateral cerebral palsy (UCP) and typically developing (TD) children. Methods. Twenty-five children with UCP (age 9.3±1.7 y) and 25 TD controls (age 9.4±2.1 y) walked down a step while holding a grip-lift manipulandum. Dynamic and temporal variables were analyzed. The maximum voluntary contraction (MVC) was also assessed. Results. The temporal course was perturbed mainly in the more affected hand of children with UCP when compared to TD children because the increases in GF and LF onset occurred in a reversed order. Compared with the TD controls, the children with UCP presented higher LF values on both hands and a higher GF on the less affected hand. In children with UCP, the GF to LF adaptation was adequate on the less affected hand but overestimated on the more affected hand. Furthermore, children with UCP presented a lower MVC in the more affected hand, leading to a higher percentage of MVC used during the task. Interpretation. Our findings highlight an anticipatory control of precision grip during a stepping down task in children with UCP that is adequate for the less affected hand but altered for the more affected hand