Ana Carolina de Campos

Development of reaching and grasping skills in infants with Down syndrome

Reaching and grasping skills have been described to emerge from a dynamic interaction between intrinsic and extrinsic factors. The aims of the study were to investigate the effect of such intrinsic factors as age and Down syndrome on the development of reaching and grasping skills and on overall gross motor skill, and to test the influence of the overall level of gross motor skill on the development of reaching and grasping. Seven infants with Down syndrome (DS) and seven infants with typical development were assessed at the ages of 4, 5 and 6 months. The following variables were analyzed: straightness index, mean velocity, movement units and deceleration time (for reaching movements), grasping frequency and AIMS scores. Intrinsic factors such as age and DS were found to influence the development of reaching, grasping, and of the overall level of gross motor skill. The overall level of gross motor skill was observed to influence grasping.

International Classification of Functioning, Disability and Health in children with cerebral palsy.

Purpose: We intended to describe how concepts from recent models of disability have been studied for evaluation of children with cerebral palsy (CP) and their clinical implications. Method: We revised studies that focused on the components of the International Classification of Functioning, Disability and Health (ICF) in children with CP. Results: Researchers have reported that children with CP exhibit impairments in various body functions/structures, limitations in functional activities performance and experience poorer participation outcomes than their typical peers. Moreover, it has been showed that participation of children with CP was affected by environmental factors. Conclusion: Therefore, evaluation and rehabilitation processes should be focused on the quality of life improvement by emphasizing what a child can and wants to execute within the environment. Also, environmental factors should be recognized so that barriers could be minimized and adaptations to the environment achieved. However, few studies have verified the interrelationship between contextual factors and the functioning and disability domains in children with CP. This would allow us to know about approaches specifically designed for these children’s needs. Implications for Rehabilitation Cerebral palsy is a disabling disease which impacts in body structures and functions, functional activities performance and social participation. ICF is a model of disability that focuses on the integration of these three dimensions. The knowledge about the concepts of ICF applied in children with CP allows an evidence-based practice.

Measuring changes in functional mobility in children with mild cerebral palsy

Objective: To support the use of TUG and TUDS to detect changes in functional mobility in children with mild cerebral palsy. Methods: Six children with spastic cerebral palsy and classified by GMFCS as level I or II were enrolled in the study. The gross motor function was measured by the GMFM and functional mobility by the TUG and TUDS. The participants were assessed before and after an 8-week follow-up. Results: After this period, increased GMFM scores were found at dimensions D (standing) and E (walking, running and jumping). The time to complete TUG and TUDS was shorter after the follow-up period. Negative correlations were found between GMFM dimension E and the TUG and TUDS tests. Conclusion: Changes in the gross motor skills measured by the GMFM may be accompanied by changes in the movement speed measured by TUG and TUDS. These tests may complement information provided by GMFM.

Induction of Motor Associative Plasticity in the Posterior Parietal Cortex–Primary Motor Network

There is anatomical and functional connectivity between the primary motor cortex (M1) and posterior parietal cortex (PPC) that plays a role in sensorimotor integration. In this study, we applied corticocortical paired-associative stimuli to ipsilateral PPC and M1 (parietal ccPAS) in healthy right-handed subjects to test if this procedure could modulate M1 excitability and PPC-M1 connectivity. One hundred and eighty paired transcranial magnetic stimuli to the PPC and M1 at an interstimulus interval (ISI) of 8 ms were delivered at 0.2 Hz. We found that parietal ccPAS in the left hemisphere increased the excitability of conditioned left M1 assessed by motor evoked potentials (MEPs) and the input-output curve. Motor behavior assessed by the Purdue pegboard task was unchanged compared with controls. At baseline, conditioning stimuli over the left PPC potentiated MEPs from left M1 when ISI was 8 ms. This interaction significantly attenuated at 60 min after left parietal ccPAS. Additional experiments showed that parietal ccPAS induced plasticity was timing-dependent, was absent if ISI was 100 ms, and could also be seen in the right hemisphere. Our results suggest that parietal ccPAS can modulate M1 excitability and PPC-M1 connectivity and is a new approach to modify motor excitability and sensorimotor interaction.

Efficient and reliable characterization of the corticospinal system using transcranial magnetic stimulation.

Purpose: The purpose of this study is to develop a method to reliably characterize multiple features of the corticospinal system in a more efficient manner than typically done in transcranial magnetic stimulation studies. Methods: Forty transcranial magnetic stimulation pulses of varying intensity were given over the first dorsal interosseous motor hot spot in 10 healthy adults. The first dorsal interosseous motor-evoked potential size was recorded during rest and activation to create recruitment curves. The Boltzmann sigmoidal function was fit to the data, and parameters relating to maximal motor-evoked potential size, curve slope, and stimulus intensity leading to half-maximal motor-evoked potential size were computed from the curve fit. Results: Good to excellent test–retest reliability was found for all corticospinal parameters at rest and during activation with 40 transcranial magnetic stimulation pulses. Conclusions: Through the use of curve fitting, important features of the corticospinal system can be determined with fewer stimuli than typically used for the same information. Determining the recruitment curve provides a basis to understand the state of the corticospinal system and select subject-specific parameters for transcranial magnetic stimulation testing quickly and without unnecessary exposure to magnetic stimulation. This method can be useful in individuals who have difficulty in maintaining stillness, including children and patients with motor disorders.

Infants with Down Syndrome and Their Interactions with Objects: Development of Exploratory Actions after Reaching Onset.

During infant development, objects and their functions are learned by means of active exploration. Factors that may influence exploration include reaching and grasping ability, object properties and the presence of developmental disorders. We assessed the development of exploratory actions in 16 typically-developing (TD) infants and 9 infants with Down syndrome (DS) after reaching onset. Infants with DS reached for and explored objects less frequently than TD infants, especially small objects. Over time, the amount of reaches increased in both groups, with no changes in the amount of exploration in the DS group. Pre-grasping actions were different across objects, but less efficient in generating action-relevant information in the DS group. These infants also performed fewer behaviors requiring complex motor skills. The results suggest that perceptual-motor abilities determine different exploratory behaviors in TD and DS infants. The reduced amount and complexity of exploratory actions may impact developmental outcome in DS.

Motor performance of children with Down syndrome and typical development at 2 to 4 and 26 months.

Purpose: To compare gross motor performance of children with Down syndrome (DS) and typical development (TD) at 2 to 4 months (Phase I) and at 2 years of age (Phase II) and to investigate the relation between early motor performance and later outcome. Methods: Seventeen infants (10 with TD and 7 with DS) were assessed in Phase I using the Test of Infant Motor Performance (TIMP); 25 children were assessed in Phase II using the gross motor scale of the Bayley Scales of Infant and Toddler Development (Bayley-III); 10 participants were enrolled in both phases. Results: TIMP and Bayley-III scores were lower in the DS group. In both groups, TIMP z scores were predictive of Bayley-III scores. Conclusions: Children with DS show difficulties in early postural control and activities requiring speed, postural control, and balance. The finding that early performance relates to later outcome reinforces the relevance of early and task-specific intervention.

Desempenho motor fino e funcionalidade em crianças com síndrome de Down

O objetivo do estudo foi comparar criancas com sindrome de Down (SD) e criancas tipicas quanto ao desempenho motor fino, avaliado pela Bayley Scales of Infant and Toddler Development - Third Edition (BSITD-III), e o desempenho em autocuidado segundo o Inventario Pediatrico de Avaliacao de Incapacidade (PEDI); e investigar associacao entre ambos os dominios. Participaram 12 criancas tipicas e 12 criancas com SD, avaliadas na idade de 2 anos. As criancas com SD apresentaram desempenho motor fino e funcionalidade inferior as criancas tipicas, possivelmente por dificuldades em desempenhar tarefas que exijam destreza e coordenacao manual, como as que compoem a BSITD-III. Apesar disso, sua pontuacao em autocuidado foi adequada para a faixa etaria, possivelmente porque as habilidades funcionais exigidas nesse periodo, como retirar calcados/vestimenta, impoem menor demanda motora fina do que tarefas da BSITD-III. Esse fato pode ter contribuido para o bom desempenho funcional das criancas com SD, e para a ausencia de associacao entre os dominios. Fatores como os cuidados oferecidos a crianca pelos cuidadores, bem como ambientes estimuladores provavelmente tambem contribuiram para os resultados.

Characteristics of Bilateral Hand Function in Individuals With Unilateral Dystonia Due to Perinatal Stroke Sensory and Motor Aspects

The authors assessed bilateral motor and sensory function in individuals with upper limb dystonia due to unilateral perinatal stroke and explored interrelationships of motor function and sensory ability. Reach kinematics and tactile sensation were measured in 7 participants with dystonia and 9 healthy volunteers. The dystonia group had poorer motor (hold time, reach time, shoulder/elbow correlation) and sensory (spatial discrimination, stereognosis) outcomes than the control group on the nondominant side. On the dominant side, only sensation (spatial discrimination, stereognosis) was poorer in the dystonia group compared with the control group. In the dystonia group, although sensory and motor outcomes were uncorrelated, dystonia severity was related to poorer stereognosis, longer hold and reach times, and decreased shoulder/elbow coordination. Findings of bilateral sensory deficits in dystonia can be explained by neural reorganization. Visual compensation for somatosensory changes in the nonstroke hemisphere may explain the lack of bilateral impairments in reaching.

Adaptive actions of young infants in the task of reaching for objects

Although several studies have investigated how movement trajectory and arm/hand configuration are adjusted to environmental affordances, the influence of specific object properties on early adjustments has not been studied. In this study, we aimed to determine the combined effect of object size and rigidity on reaching movements in young infants. Sixteen typically developing infants were assessed at 4, 5, and 6 months of age. The infants were presented with four objects: two soft and two rigid, which were either small or large. The results indicate that with age reaching movements became straighter, the arm control during the final phase was improved, and the grasping success increased. Object size and rigidity collectively influenced the proximal adjustments, grasping, adjustment time, and the number of movement units. The results suggest that early in the infants are able to modify their movement strategies based on object affordances.