Periventricular leucomalacia and preterm birth have different detrimental effects on postural adjustments

Trunk postural reactions to the force perturbation intensity and frequency during sitting astride in children with cerebral palsy

The purpose of this study was to examine kinematic and neuromuscular responses of the head and body to pelvis perturbations with different intensities and frequencies during sitting astride in children with CP. Sixteen children with spastic CP (mean age 7.4 ± 2.4 years old) were recruited in this study. A custom designed cable-driven robotic horse was used to apply controlled force perturbations to the pelvis during sitting astride. Each participant was tested in four force intensity conditions (i.e., 10%, 15%, 20%, and 25% of body weight (BW), frequency = 1 Hz), and six force frequency conditions (i.e., 0.5 Hz, 1 Hz, 1.5 Hz, 2 Hz, 2.5 Hz, and 3 Hz, intensity = 20% of BW). Each testing session lasted for one minute with a one-minute rest break inserted between two sessions. Kinematic data of the head, trunk, and legs were recorded using wearable sensors, and EMG signals of neck, trunk, and leg muscles were recorded. Children with CP showed direction-specific trunk and neck muscle activity in response to the pelvis perturbations during sitting astride. Greater EMG activities of trunk and neck muscles were observed for the greater intensities of force perturbations (P < .05). Participants also showed enhanced activation of antagonistic muscles rather than direction-specific trunk and neck muscle activities for the conditions of higher frequency perturbations (P < .05). Children with CP may modulate trunk and neck muscle activities in response to greater changes in intensity of pelvis perturbation during sitting astride. Perturbations with too high frequency may be less effective in inducing direction-specific trunk and neck muscle activities.

Biological and environmental factors may affect children's executive function through motor and sensorimotor development: Preterm birth and cerebral palsy

Disruptive biological and environmental factors may undermine the development of children's motor and sensorimotor skills. Since the development of cognitive skills, including executive function, is grounded in early motor and sensorimotor experiences, early delays or impairments in motor and sensorimotor processing often trigger dynamic developmental cascades that lead to suboptimal executive function outcomes. The purpose of this perspective paper is to link early differences in motor/sensorimotor processing to the development of executive function in children born preterm or with cerebral palsy. Uncovering such links in clinical populations would improve our understanding of developmental pathways and key motor and sensorimotor skills that are antecedent and foundational for the development of executive function. This knowledge will allow the refinement of early interventions targeting motor and sensorimotor skills with the goal of proactively improving executive function outcomes in at-risk populations.

Development of postural control in infancy in cerebral palsy and cystic periventricular leukomalacia

BACKGROUND

Development of postural problems in Cerebral Palsy (CP) is largely unknown. Postural muscle activity is organized into two levels: 1) direction-specificity; 2) fine-tuning of direction-specific activity.

AIM

To study development of postural control until 21 months corrected age in subgroups of infants at very high-risk (VHR) of CP: a) with and without CP at 21 months; b) with and without cystic periventricular leukomalacia (cPVL), the brain lesion with highest risk of CP.

METHODS AND PROCEDURES

Longitudinal electromyography recordings of postural muscles during reaching were made in 38 VHR-infants (severe brain lesion or clear neurological signs) between 4.7 and 22.6 months (18 CP, of which 8 with cPVL). Developmental trajectories were calculated using linear mixed effect models.

OUTCOMES AND RESULTS

VHR-infants with and without CP showed virtually similar postural development throughout infancy. The subgroup of VHR-infants with cPVL improved performance in direction-specificity with increasing age, while they performed throughout infancy worse in fine-tuning of postural adjustments than infants without cPVL.

CONCLUSIONS AND IMPLICATIONS

VHR-infants with and without CP have a similar postural development that differs from published trajectories of typically developing infants. Infants with cPVL present from early age onwards dysfunctions in fine-tuning of postural adjustments; they focus on direction-specificity.

Discriminant ability and criterion validity of the Trunk Impairment Scale for cerebral palsy

Aims: To compare the performance of children with mild and moderate-to-severe cerebral palsy (CP) on the Trunk Impairment Scale (TIS), Gross Motor Function Measure (GMFM), and on center-of-pressure variables; to establish the discriminant ability of these tools to predict severity of motor impairment in CP; and to investigate the criterion validity of the TIS. Methods: Children with mild (n = 18, 11 males, 7 females, mean age = 9.5 ± 2.9 years, Gross Motor Function Classification System I-II) and moderate-to-severe (n = 18, 11 males, 7 females, mean age = 9.2 ± 229, Gross Motor Function Classification System III-IV) CP were tested using the TIS and the GMFM, and during static sitting on force-plate. Results: Children with mild CP showed better trunk (median; 95% confidence interval = 22.5; 21.29-22.59 vs. 13; 11.97-14.8; p < 0.001) and gross motor (60; 57.73-59.3 vs. 40; 38.96-46.25; p < 0.001) scores, and better postural control (lower center of pressure (CoP) displacement [anterior-posterior: (0.42; 0.32-1.11 vs. 0.89; 0.70-1.65; p = 0.022); medial-lateral: (0.42; 0.31-1.08 vs. 0.91; 0.65-1.17; p = 0.044)], and lower area of sway, (0.05; -0.15-0.97 vs. 0.44; 0.23-0.90; p = 0.008) than the moderate-to-severe group. Trunk control and gross motor function explained 81.5% of the variance in the severity of motor condition. Correlations between the TIS and the GMFM were excellent (ρ = 0.944, p < 0.001); correlations between the TIS and CoP variables were low (anterior-posterior displacement: ρ = -0.411, p < 0.05; medial-lateral displacement: ρ = -0.327, p < 0.05); area of sway: ρ = -0.430, p < 0.05; velocity of sway: ρ = -0.308, p < 0.05). Conclusions: The TIS is able to differentiate levels of trunk control across various levels of motor impairments in CP. It is a valid tool to assess trunk control, showing very high concurrent validity with the GMFM sitting dimension. Implications for Rehabilitation Trunk Impairment Scale (TIS) can be used by rehabilitation professionals to differentiate levels of trunk control across levels of motor impairment. TIS showed concurrent validity with Gross Motor Function Measure and should be used to assess trunk control in children with cerebral palsy (CP) in clinical settings. The use of TIS allows a reliable assessment of postural control in children with CP in clinical settings.

Influence of Sitting Positions and Level of Trunk Control During Reaching Movements in Late Preterm and Full-Term Infants

In order to acquire reaching and independent sitting, refinement of trunk control is needed by gradually and progressively incorporating the head, thoracic, lumbar, and sacral segments. Previous studies have evaluated trunk control in a segmental way, standardizing the level of manual support in the infants' trunk during reaching. The aim of this study was to identify the level of trunk control and to analyze the influence of the difference sitting positions in late preterm and full-term infants between 6 and 8 months of age during reaching. Therefore, 36 infants born full term (control group)-FTG and 20 late preterm infants at a corrected age (experimental group)-PTG were evaluated. Most of the infants started the study at 6 months and they were evaluated monthly until 8 months of age (longitudinal study) in a total of 1-3 visits. The Segmental Assessment of Trunk Control was used to identify the level of trunk control in a segmental way, as well as to verify the capacity of the infant to maintain or regain the vertical position while sitting. Kinematic analysis was used for reaching. The infants were in a ring sitting position and at 90° of flexion. To elicit reaching, an attractive object was presented at the infant's midline and at 45° to the right and left. We found that PTG infants presented lower trunk control scores, i.e., worse control. For both groups, the ring sitting position and at 90° of flexion did not influence most kinematic variables during reaching because accurate manual support was provided for the infants' trunk. The PTG group presented less trunk displacement when at 90° of flexion. Compared to the FTG, even with accurate trunk support, the PTG group presented more immature reaches. These results suggest that accurate manual trunk support favored more stability of the trunk during the reach. Thus, early intervention is suggested for PTG infants and reaching in this age group should be trained in the ring sitting position with their trunk accurately manually supported. SATCo is an effective tool for segmental trunk evaluation.

Are postural adjustments during reaching related to walking development in typically developing infants and infants at risk of cerebral palsy?

BACKGROUND

In typical development, postural adjustments during reaching change in the second half of infancy, including increasing rates of direction-specific adjustments. These changes are absent or different in infants at risk of cerebral palsy (CP). To discover whether these changes are related to acquisition of independent walking, we studied postural adjustments during reaching in infants before and after they learned to walk.

METHODS

Ten typically developing (TD) infants and 11 infants at very high risk (VHR) of CP were assessed before and after they learned to walk. Reaching movements were elicited during supported sitting, while surface electromyography was recorded of arm, neck, and trunk muscles. Percentages of direction-specific adjustments (first level of control), and recruitment patterns and anticipatory activation (second level of control) were calculated.

RESULTS

In both groups, postural adjustments during reaching were similar before and after acquisition of independent walking. Direction-specificity increased with age in typically developing infants but not in VHR-infants.

CONCLUSION

Increasing age rather than the transition to independent walking is associated with increasing direction-specificity of TD-infants during reaching while sitting, while infants at very high risk of CP show no increase in direction-specificity, suggesting that they gradually grow into a postural deficit.

Inter- and Intrarater Reliability of the Infant Motor Profile in 3- to 18-Month-Old Infants

PURPOSE

To investigate inter- and intrarater reliability scoring the Infant Motor Profile (IMP).

METHODS

A total of 20 infants at risk for motor developmental delay were assessed using the IMP. Six infants were born at term (gestational age: 38-42 weeks), and 14 infants were preterm (gestational age: 24-35 weeks). Videos were analyzed twice with an interval of 1 month by 4 assessors after 2 days of IMP training.

RESULTS

Spearman rank scores demonstrated strong interrater and intrarater reliability for total IMP scores (inter: r = 0.80-0.96; intra: r = 0.85-0.97) and the domain of performance (r = 0.95-0.99). Reliability for the domains of variation, variability, and fluency was satisfactory (inter: r = 0.15-0.85; intra: r = 0.30-0.92). The weakest agreement was found in the domain of symmetry (inter: r = 0.20-0.69; intra: r = 0.33-0.65).

CONCLUSION

Therapists naive to the IMP demonstrate good intra and interrater reliability (after 2 days of training) for most domains with the exception of symmetry.

Early diagnosis and early intervention in cerebral palsy

This paper reviews the opportunities and challenges for early diagnosis and early intervention in cerebral palsy (CP). CP describes a group of disorders of the development of movement and posture, causing activity limitation that is attributed to disturbances that occurred in the fetal or infant brain. Therefore, the paper starts with a summary of relevant information from developmental neuroscience. Most lesions underlying CP occur in the second half of gestation, when developmental activity in the brain reaches its summit. Variations in timing of the damage not only result in different lesions but also in different neuroplastic reactions and different associated neuropathologies. This turns CP into a heterogeneous entity. This may mean that the best early diagnostics and the best intervention methods may differ for various subgroups of children with CP. Next, the paper addresses possibilities for early diagnosis. It discusses the predictive value of neuromotor and neurological exams, neuroimaging techniques, and neurophysiological assessments. Prediction is best when complementary techniques are used in longitudinal series. Possibilities for early prediction of CP differ for infants admitted to neonatal intensive care and other infants. In the former group, best prediction is achieved with the combination of neuroimaging and the assessment of general movements, in the latter group, best prediction is based on carefully documented milestones and neurological assessment. The last part reviews early intervention in infants developing CP. Most knowledge on early intervention is based on studies in high-risk infants without CP. In these infants, early intervention programs promote cognitive development until preschool age; motor development profits less. The few studies on early intervention in infants developing CP suggest that programs that stimulate all aspects of infant development by means of family coaching are most promising. More research is urgently needed.

Prenatal methamphetamine exposure and neurodevelopmental outcomes in children from 1 to 3 years

BACKGROUND

Despite the evidence that women world-wide are using methamphetamine (MA) during pregnancy little is known about the neurodevelopment of their children.

DESIGN

The controlled, prospective longitudinal New Zealand (NZ) Infant Development, Environment and Lifestyle (IDEAL) study was carried out in Auckland, NZ. Participants were 103 children exposed to MA prenatally and 107 who were not exposed. The Mental Developmental Index (MDI) and the Psychomotor Developmental Index (PDI) of the Bayley Scales of Infant Development, Second Edition (BSID-II) measured cognitive and motor performances at ages 1, 2 and 3, and the Peabody Developmental Motor Scale, Second Edition (PDMS-II) measured gross and fine motor performances at 1 and 3. Measures of the child's environment included the Home Observation of Measurement of the Environment and the Maternal Lifestyle Interview. The Substance Use Inventory measured maternal drug use.

RESULTS

After controlling for other drug use and contextual factors, prenatal MA exposure was associated with poorer motor performance at 1 and 2 years on the BSID-II. No differences were observed for cognitive development (MDI). Relative to non-MA exposed children, longitudinal scores on the PDI and the gross motor scale of the PDMS-2 were 4.3 and 3.2 points lower, respectively. Being male and of Maori descent predicted lower cognitive scores (MDI) and being male predicted lower fine motor scores (PDMS-2).

CONCLUSIONS

Prenatal exposure to MA was associated with delayed gross motor development over the first 3 years, but not with cognitive development. However, being male and of Maori descent were both associated with poorer cognitive outcomes. Males in general did more poorly on tasks related to fine motor development.

Movement variation in infants born following IVF/ICSI with and without ovarian hyperstimulation

BACKGROUND

The effect of in vitro fertilisation (IVF) on neurodevelopment is not fully understood. Probably, IVF does not affect traditional measures of neurodevelopment in infancy. Recently, an instrument, the Infant Motor Profile (IMP), was developed that evaluates the quality of motor behaviour. It includes the evaluation of movement variation (i.e. movement repertoire size), a parameter reflecting the integrity of cortical connectivity.

AIM

To evaluate the effect of ovarian hyperstimulation and the in vitro procedure on movement variation during infancy.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

Singletons born following IVF or intracytoplasmic sperm injection (ICSI) with conventional controlled ovarian hyperstimulation (COH-IVF/ICSI, n=68), in a modified natural cycle (MNC-IVF/ICSI, n=57) and natural conception born to subfertile couples (Sub-NC, n=90).

OUTCOME MEASURES

Children were assessed with the IMP at 4, 10 and 18 months, resulting in a total IMP score and five domain scores: variation, variability, symmetry, fluency and performance. Primary outcome was the domain score variation.

RESULTS

A significant effect of study group was observed for the variation score up until 18 months of age (p=0.039). COH-IVF/ICSI children had a significantly lower mean variation score than MNC-IVF/ICSI children (mean difference [95% confidence interval] -1.010 [-1.766; -0.254]). Mean variation scores of COH-IVF/ICSI and Sub-NC children were similar; the same held true for the comparison between MNC-IVF/ICSI and Sub-NC. Total IMP scores and other domain scores of the three groups were similar.

CONCLUSION

The present study did not demonstrate a clear effect of ovarian hyperstimulation and the in vitro procedure on movement variation throughout infancy.

Influence of botulinum toxin therapy on postural control and lower limb intersegmental coordination in children with spastic cerebral palsy

Botulinum toxin injections may significantly improve lower limb kinematics in gait of children with spastic forms of cerebral palsy. Here we aimed to analyze the effect of lower limb botulinum toxin injections on trunk postural control and lower limb intralimb (intersegmental) coordination in children with spastic diplegia or spastic hemiplegia (GMFCS I or II). We recorded tridimensional trunk kinematics and thigh, shank and foot elevation angles in fourteen 3-12 year-old children with spastic diplegia and 14 with spastic hemiplegia while walking either barefoot or with ankle-foot orthoses (AFO) before and after botulinum toxin infiltration according to a management protocol. We found significantly greater trunk excursions in the transverse plane (barefoot condition) and in the frontal plane (AFO condition). Intralimb coordination showed significant differences only in the barefoot condition, suggesting that reducing the degrees of freedom may limit the emergence of selective coordination. Minimal relative phase analysis showed differences between the groups (diplegia and hemiplegia) but there were no significant alterations unless the children wore AFO. We conclude that botulinum toxin injection in lower limb spastic muscles leads to changes in motor planning, including through interference with trunk stability, but a combination of therapies (orthoses and physical therapy) is needed in order to learn new motor strategies.

Sitting postural control in infants with typical development, motor delay, or cerebral palsy

PURPOSE

To determine whether infants born full-term, infants born preterm with motor delays, and infants born preterm who have a diagnosis of cerebral palsy (CP) differed in postural control at the emergence of early sitting.

METHODS

Thirty infants born at term who were developing typically, 6 infants born preterm who were later diagnosed with CP, and 5 infants born preterm who were delayed in motor development participated in this study. Center-of-pressure data from unsupported sitting were recorded and analyzed using measures of both amount and temporal organization of center-of-pressure variability.

RESULTS

Infants born full-term, infants born preterm with motor delays, and infants born preterm who have a diagnosis of CP exhibited dissimilar movement-control strategies at the onset of sitting.

CONCLUSIONS

The present findings may be helpful in directing and testing intervention protocols for infants born preterm.

Cerebral palsy: definition, assessment and rehabilitation

Over the last 25 years the definition and classification of cerebral palsy (CP) have evolved, as well as the approach to rehabilitation. CP is a disorder of the development of movement and posture, causing activity limitations attributed to nonprogressive disturbances of the fetal or infant brain that may also affect sensation, perception, cognition, communication, and behavior. Motor control during reaching, grasping, and walking are disturbed by spasticity, dyskinesia, hyperreflexia, excessive coactivation of antagonist muscles, retained developmental reactions, and secondary musculoskeletal malformations, together with paresis and defective programing. Weakness and hypoextensibility of the muscles are due not only to inadequate recruitment of motor units, but also to changes in mechanical stresses and hormonal factors. Two methods, the General Movements Assessment and the Test of Infant Motor Performance, now permit the early detection of CP, while the development of valid and reliable outcome measures, particularly the Gross Motor Function Measure (GMFM), have made it possible to evaluate change over time and the effects of clinical interventions. The GMFM has further led to the development of predictive curves of motor function while the Gross Motor Classification System and the Manual Ability Classification System provide standardized means to classify the severity of the movement disability. With the emergence of the task-oriented approach, the focus of therapy in rehabilitation has shifted from eliminating deficits to enhancing function across all performance domains by emphasizing fitness, function, participation, and quality of life. There is growing evidence supporting selected interventions and interest for the therapy and social integration of adults with CP.

Infant Motor Profile and cerebral palsy: promising associations

AIM

The Infant Motor Profile (IMP) is a novel qualitative assessment of motor behaviour in infancy. The aim of this study was to determine whether IMP scores throughout infancy differ between children with and without cerebral palsy (CP) at 18 months. Furthermore, we evaluated the predictive ability of IMP scores throughout infancy for CP.

METHOD

Fifty-nine preterm (median gestational age 29.7 wk, median birthweight 1285 g) and 30 term infants (median gestational age 40.1 wk, median birthweight 3588 g) were included. IMP assessments were longitudinally performed at (corrected) ages of 4, 6, 10, and 12 months. Neurological outcome was determined at 18 months with the neurological examination according to Hempel. We compared total and domain IMP scores throughout infancy between infants with and without CP.

RESULTS

In the term group none of the children was diagnosed with CP at the age of 18 months, in the preterm group eight had CP at 18 months (14%). Three had unilateral spastic CP, and five bilateral spastic CP. Children with CP (n=8) at 18 months had lower IMP scores throughout infancy than children without. These differences were most pronounced for the domains variation and performance. The predictive ability of the total IMP scores throughout infancy for CP was high (area under receiver operating characteristic curve 0.89-0.99) and most pronounced for the variation and performance domains.

INTERPRETATION

IMP scores throughout infancy and CP at 18 months are strongly related. In particular, low scores on the variation and performance domains were important indicators for CP. To determine the exact predictive ability of the IMP, further research is needed.

A descriptive analysis of abnormal postural patterns in children with hemiplegic cerebral palsy

BACKGROUND

Functional classification systems generally divide children with cerebral palsy (CP) into mild, moderate, and severe types. Although depending on functional limitations, they do not seem to evaluate abnormal postural patterns in standing. Since the most asymmetrical patterns can be observed in hemiplegia, the goal of this case series study was to provide their objective analysis and to establish any potential clinical value for evaluation and management of CP.

MATERIAL/METHODS

A group of 36 children (aged 5-10 years) with spastic hemiplegic CP, who could stand and ambulate independently, were selected. The photogrammetric and pedobarographic studies were obtained for the postural analysis in standing.

RESULTS

Two different anti- and pro- gravitational postural patterns were identified. They seem not only to affect functional status and rehabilitation potential, but also clinical value for evaluation and management of CP hemiplegia.

CONCLUSIONS

The importance of strong study design cannot be overemphasized. The 2 different postural patterns indicate dissimilar compensatory tendencies, which may help in prognosis of deformity and functional outcomes of rehabilitation. The use of objective photogrammetric and the pedobarographic studies may also help to develop a more specific therapeutic intervention in order to facilitate the pattern leading towards better outcome (orthosis in the anti-gravitational postural pattern vs focal spasticity management in the pro-gravitational postural pattern).

Variation and variability: key words in human motor development

This article reviews developmental processes in the human brain and basic principles underlying typical and atypical motor development. The Neuronal Group Selection Theory is used as theoretical frame of reference. Evidence is accumulating that abundance in cerebral connectivity is the neural basis of human behavioral variability (ie, the ability to select, from a large repertoire of behavioral solutions, the one most appropriate for a specific situation). Indeed, typical human motor development is characterized by variation and the development of adaptive variability. Atypical motor development is characterized by a limited variation (a limited repertoire of motor strategies) and a limited ability to vary motor behavior according to the specifics of the situation (ie, limited variability). Limitations in variation are related to structural anomalies in which disturbances of cortical connectivity may play a prominent role, whereas limitations in variability are present in virtually all children with atypical motor development. The possible applications of variation and variability in diagnostics in children with or at risk for a developmental motor disorder are discussed.

Gastrocnemius-soleus muscle tendon unit changes over the first 12 weeks of adjusted age in infants born preterm

BACKGROUND AND PURPOSE

Differences in the gastrocnemius-soleus muscle and tendon have been documented shortly after birth in infants born preterm compared with infants born at term. Knowledge of muscle tendon unit lengths at term age to 12 weeks of age in infants born preterm may be useful in understanding motor development.

PARTICIPANTS AND METHOD

Gastrocnemius-soleus muscle tendon unit lengths were compared at term age, at 6 weeks of age, and at 12 weeks of age (preterm adjusted age) in 20 infants born full term and 22 infants born preterm.

RESULTS

Significant differences were found between the 2 groups on taut tendon, relaxed muscle length (A(O)); taut tendon, stretched muscle length (A(Max)); and muscle stretch (A(O) to A(Max)). Infants born preterm demonstrated measures of A(O) and A(Max) in positions of greater plantar flexion compared with infants born full term. Significant differences in measurements of A(O) were found between term age and 12 weeks of age, indicating that the tendon lengthens during this period for both groups.

DISCUSSION AND CONCLUSION

These results provide knowledge of musculoskeletal development of the gastrocnemius-soleus muscle and tendon. Differences in musculoskeletal measurements are consistent with uterine confinement in the last weeks of full-term gestation. These findings have implications when examining the musculoskeletal system in infants born preterm who are demonstrating functional changes.

Reduced variability in motor behaviour: an indicator of impaired cerebral connectivity?

Evidence is accumulating that abundance in cerebral connectivity is the neural basis of human behavioural variability, i.e., the ability to select adaptive solutions from a large repertoire of behavioural options. Recently it was demonstrated that variability in motor behaviour- the hallmark of typical development--emerges coincident with the onset of synaptic activity in the embryonic cortex. This inspired the hypothesis that variability results from cortical activity and that its expression depends on integrity of cortical connectivity. Recent findings in preterm infants with cerebral white matter injury and in children with autism spectrum disorder (ASD) allow the elaboration of this hypothesis: diffuse damage of the cerebral white matter is associated with an overall reduction in variability, i.e., in a reduction of movement complexity and variation, whereas reduction in long-distance cortical connectivity, as described in children with ASD, is associated with reduced variability, in which movement complexity may be conserved.

Effect of seat surface inclination on postural control during reaching in preterm children with cerebral palsy

BACKGROUND AND PURPOSE

Because it is debatable whether seat surface inclination improves motor function in children with cerebral palsy (CP), the effect of seat surface tilting on postural control and quality of reaching was studied.

SUBJECTS

The subjects were 58 children with CP aged 2 to 11 years (34 with unilateral spastic CP, 24 with bilateral spastic CP).

METHODS

During the task of reaching movements, surface electromyographic and kinematic data were recorded for posture and reaching with the dominant arm in 3 sitting conditions: horizontal seat surface, seat surface tilted forward 15 degrees, and seat surface tilted backward 15 degrees.

RESULTS

In the children with unilateral spastic CP, forward tilting improved postural efficiency and quality of reaching. In the children with bilateral spastic CP, both forward and backward tilting of the seat surface was associated with more postural instability and did not affect the quality of reaching.

DISCUSSION AND CONCLUSION

The results suggest that, in terms of postural control and quality of reaching, children with unilateral spastic CP benefit from a forward-tilted position and children with bilateral spastic CP benefit from a horizontal sitting position.

Ontogeny of the human central nervous system: what is happening when?

The present paper reviews current data on the structural development of the human nervous system. Focus is on the timing of ontogenetic events in the telencephalon. Neuronal proliferation and migration especially occur during the first half of gestation; the second half of gestation is the period of the existence of the functionally important transient structure 'subplate' and the major period of glial cell proliferation and programmed cell death. Axon and dendrite sprouting and synapse formation bloom during the last trimester of gestation and the first postnatal year. Major part of telencephalic myelination occurs during the first year after birth. Many developmental processes, such as myelination, synapse formation and synapse elimination continue throughout childhood and adolescence. Evidence is emerging that the peak of synapse elimination occurs between puberty and the onset of adulthood. Neurotransmitter systems are present from early foetal life onwards and their pre- and perinatal development is characterized by periods of transient overexpression. The latter is for instance true for the acetylcholinergic, catecholaminergic and glutamate systems. Thus, the development of the human brain is characterized by a protracted, neatly orchestrated chain of specific ontogenetic events. The continuous changes of the nervous system have consequences for vulnerability to adverse conditions, for diagnostics and for physiotherapeutical intervention.

Kinematic characteristics of reaching movements in preterm children with cerebral palsy

Kinematic characteristics of reaching movements of the dominant arm were assessed in 51 sitting preterm children who were aged 2-11 y and had cerebral palsy (CP), including 33 with spastic hemiplegia and 18 with bilateral CP (Bi-CP). Reference data of 29 typically developing children were present. The results indicated that the quality of reaching movements from the dominant arm of children with CP was significantly worse than that of typically developing children. This held true in particular for the children with Bi-CP. For example, reaching movements of children with CP took more time and consisted less often of one movement unit. The quality of reaching was related to the severity of lesion present on the neonatal ultrasound scan of the brain, the severity of motor disorder, the degree of spasticity, and the ability to perform activities of daily life. The last indicates that movements of the dominant arm in children with spastic hemiplegia and Bi-CP deserve clinical attention.

Trunk position in supine of infants born preterm and at term: an assessment using a computerized pressure mat

PURPOSE

Trunk position may influence motor, cognitive, and social development during infancy and early childhood and has not been quantitatively assessed. The purpose of this study was to assess the trunk positions of infants born at term and preterm in supine using a computerized pressure mat.

METHODS

Trunk position was represented as a ratio of head and pelvis to trunk pressure. Eighteen healthy infants born preterm with a mean gestational age of 31.9 weeks (25.0-34.6) and fifteen healthy infants born at term with a mean gestational age of 38.9 weeks (37.3-40.6) were assessed at 38 to 43 weeks gestational age.

RESULTS

Infants born at term spent more than two-thirds of the time in either flexed or neutral trunk positions. No significant differences were found between infants born preterm and those born at term in total duration of flexion or extension or in flexion event duration.

CONCLUSION

This study provides evidence that infants born preterm may not exhibit greater trunk extension tendencies in supine than infants born at term. Results should be interpreted with caution, however, because of the small sample size and large variability observed within the subject groups. Infants born at less than 30 weeks of gestation may demonstrate greater extension tendencies than those born at more than 30 weeks of gestation.

Quality of general movements and the development of minor neurological dysfunction at toddler and school age

OBJECTIVE

To evaluate the reliability of assessing infants' general movements (GMs) using a new classification and its validity in predicting complex minor neurological dysfunction (MND) at toddler and at school age.

DESIGN

Prospective study of two groups of infants, each consisting of a mix of low-risk and high-risk infants.

SETTING

University Hospital Groningen, the Netherlands.

SUBJECTS

Group A consisted of 16 low-risk and 21 high-risk infants; group B of 28 low-risk and 24 high-risk infants.

MAIN OUTCOME MEASURES

Between term age and four months post term: multiple assessments of neurological condition by means of (a) assessment of GMs, and (b) a traditional neurological examination. GMs were classified into four classes using a standardized qualitative description: two classes of normal movements (normal-optimal and normal-suboptimal) and two classes of abnormal movements (mildly and definitely abnormal movements). Follow-up neurological examination with special attention to presence of MND was carried out in group A at 1 1/2 years, in group B at 4-9 years.

RESULTS

GMs could be assessed reliably. They were stable over age in about 60% of the infants. Both the condition of the GMs and the infant neurological condition were significantly related to neurological condition at follow-up. Best prediction of complex MND was achieved when both types of infant assessment at the age of 2-4 months post term were combined.

CONCLUSIONS

The assessment of GMs is a valuable tool, in particular when combined with the traditional neurological examination, to predict at early age the development of complex MND.

Postural adjustments in preterm infants at 4 and 6 months post-term during voluntary reaching in supine position

Gradually it is getting clear that motor development - in particular balance control - in so-called "low-risk" preterm infants often differs from that in full-term infants. However, little is known on the etiology and pathophysiology of these problems. The aim of this study was to evaluate postural behavior during reaching by means of kinetic and kinematic measurements. Preterm infants (n = 32) without cerebral palsy were investigated longitudinally at the corrected ages of 4 and 6 mo. Thirteen age-matched full-term infants served as controls. Cognitive and motor development were assessed by means of the quality of General Movements (GMs) at 4 mo and Bayley scales at 6 and 12 mo. The infants were lying supine on a forceplate reaching for a toy and the kinetics of the total body's Center of Pressure (COP) was measured in cranial-caudal and medial-lateral direction. The analysis focused on COP displacement, Vmax and oscillatory changes of the COP displacement during reaching. The kinematic analysis of reaching focused on movement units, Vmax and a compound kinematic variable reflecting the quality of reaching. The results showed that preterm infants showed a remarkable "still" postural behavior, which differed significantly from the mobile COP behavior of the full-term infants. More "still" postural behavior at 6 mo was associated with a better quality of reaching movements and with normal GMs at 4 mo. We concluded that "still" postural behavior is an adequate postural strategy of preterm infants. But it might be that this postural behavior is an indicator of later dysfunction.

Kinematic quality of reaching movements in preterm infants

Many preterm infants may experience so-called minor developmental disorders; however, in general, the problems in motor behavior are not detected until school age. To introduce therapies aimed at the prevention of these problems, we need to increase our knowledge of motor function and dysfunction at early age. The present study focused on the organization of reaching movements in full-term and preterm infants without cerebral palsy. The reaching behavior of premature infants (n = 63) was assessed longitudinally at the corrected ages of 4 and 6 mo. Clinical assessments were made at 6 and 12 mo of age. On the basis of the infant's morbidity during the early stay in the neonatal intensive care unit, the preterm infants were allocated into a high-risk and a low-risk group. Results from a previous study in full-term infants (n = 13) were included. Kinematics of reaching movements in supine position were measured, and the analysis focused on movement velocity and movement units. A compound parameter of kinematic variables was created, reflecting the quality of reaching movements. The present study showed that at the age of 4 mo, low-risk preterm infants showed more often optimal reaching behavior than full-term and preterm high-risk infants. This better reaching performance was related to a better general motor and behavioral development during the first year of life. At the age of 6 mo, the advantage of the low-risk group in reaching behavior had disappeared and a disadvantage in the form of nonoptimal reaching behavior of the high-risk group emerged.

Patterns of motor disability in very preterm children

Motor development in very preterm children differs in several important ways from that of children born at full term. Variability is common, although the anatomic and physiologic bases for that variability are often poorly understood. Motor patterns over the first postnatal year may depend on behaviours learned during often long periods of neonatal intensive care. The normal pattern of development may be modified by disturbances of brain function caused both by the interruption of normal brain maturation ex-utero and the superimposition of focal brain injuries following very preterm birth. Abnormal patterns of development over the first year may evolve into clear neuromotor patterns of cerebral palsy or resolve, as "transient dystonias." Cerebral palsy is associated with identified patterns of brain injury secondary to ischaemic or haemorrhagic lesions, perhaps modified by activation of inflammatory cytokines. Cerebral palsy rates have not fallen as might be expected over the past 10 years as survival has improved, perhaps because of increasing survival at low gestations, which is associated with the highest prevalence of cerebral palsy. Children who escape cerebral palsy are also at risk of motor impairments during the school years. The relationship of these impairments to perinatal factors or to neurological progress over the first postnatal year is debated. Neuromotor abnormalities are the most frequent of the "hidden disabilities" among ex-preterm children and are thus frequently associated with poorer cognitive ability and attention deficit disorders. Interventions to prevent cerebral palsy or to reduce these late disabilities in very preterm children are needed.

Development of postural adjustments during reaching in preterm infants

Preterm infants often show postural abnormalities, such as hyperextension of neck and trunk, which can interfere with motor and cognitive development. Little is, however, known on the pathophysiology of postural development in preterm infants. Therefore, we longitudinally studied the development of postural adjustments during reaching movements in 12 preterm infants between the (corrected) ages of 4 and 18 mo. Five infants showed minor neurological dysfunctions at 18 mo, such as a mild diffuse hypotonia, a mild hypertonia of the legs, or a mild asymmetry in posture and motility, and seven infants were neurologically normal. Each assessment consisted of a simultaneous recording of video-data and surface electromyograms of arm, neck, trunk, and leg muscles during reaching in various lying and sitting positions. Comparable data on postural development in ten full-term infants were available. The preterm infants showed an excessive amount of postural activity during reaching movements at all ages studied. Moreover, the postural adjustments were temporally disorganized and could not be modulated with respect to the velocity of the arm movement and the initial sitting position. We hypothesized that the preterms' disability to modulate their postural adjustments might be due to a reduced capacity to learn from prior experience. In our small group the postural dysfunctions were not related to the presence of hyperextension at early ages, to the neurological outcome at 18 mo, or to the lesions found on the neonatal brain ultrasound scans.