Correlations between motor performance and cognitive functions in children born < 1250 g at school age.

Very low birth weight born children manifest a higher prevalence of motor and cognitive impairments than term children. Seventy-four prospectively enrolled children born < 1250 g underwent testing of motor (Zurich neuromotor assessment ZNA: timed motor performances and associated movements) and cognitive functions (Kaufman-ABC) at age six years. Children with cerebral palsy or mental retardation were excluded. Adaptive motor tasks (pegboard and dynamic balance) and visuomotor cognitive functions were specifically impaired, and a distinct correlation pattern between motor and cognitive abilities was detected. The adaptive fine motor task (pegboard) correlated with visuomotor functions of the Kaufman-ABC ("triangles", r = 0.35; "matrix analogies", r = 0.39), while pure motor tasks of the ZNA (repetitive, alternating, and sequential movements) did not in spite of impaired motor performance. Timed motor performance below the 10th percentile correlated strongly with cognitive delay (IQ < 85: adaptive fine motor: OR 6.0 [95% CI] 4.7-7.3; adaptive gross motor: OR 7.0 [CI 5.6-8.4]; static balance: OR 9.6 [CI 8.2-11.0]). In conclusion, motor deficits in children born < 1250 g without severe disabilities correlate with specific cognitive impairments, in particular of the visuomotor domain. The correlation pattern may indicate specific dysfunction in visuomotor transformation, the intermediate process between visual-perceptual input and motor output. Early assessment of both motor and cognitive functions using standardized assessment tools is important to determine the extent and combination of specific developmental disturbances and to tailor therapeutic intervention.

Coordination training in individuals with incomplete spinal cord injury: consideration of motor hierarchical structures.

STUDY DESIGN: Clinical commentary. OBJECTIVE: To discuss the method of coordination training to enhance motor skills in persons after spinal cord injury (SCI). METHOD: From the literature and clinical experience, we learn that basic motor skills like walking are refined and maintained through the millions of repetitions that take place as part of normal development. These coordinated patterns function effectively as a form of training to the system because of the presence of neural pathways that mediate commands between higher and lower levels of the central nervous system (CNS). When these pathways are disrupted as a result of a lesion, the question that arises is whether retraining can be effective. RESULTS/DISCUSSION: The question is directed at the common practice among rehabilitation professionals to prescribe and carry out tireless repetitions of coordinated motor activities in people with SCI lesions. We discuss this fundamental question from the perspective of understanding differences in maturation and function of higher motor centres and lower motor centres.

TW3 bone age: RUS/CB and gender differences of percentiles for score and score increments.

BACKGROUND: Longitudinal data on bone age progression is scarce. AIM: The study aimed to present reference values for Tanner-Whitehouse 3 (TW3) bone age score and score increments, and to provide means and standard deviations of appearance time for all TW3 stages. Gender differences and differences between radio ulna and short bones (RUS) and carpal bone (CB) scores were studied. SUBJECTS AND METHODS: Bone age data collected for ages 3 months to 20 years in 232 subjects during the First Zurich Longitudinal Study (1954-1976) were used. Smoothed empirical percentiles of TW3 RUS and CB scores for age, of score increments for age and of score increments for attained score are presented. Means and standard deviations of the appearance times are calculated by parametric censored regression. RESULTS: There are clear differences between the RUS and CB scores and between the genders. Boys are delayed with respect to girls, with different delays for RUS and CB. For RUS, differences in maturation reflect the known differences of physical growth, with a later and more intense peak in boys. For CB, there is little difference in timing and intensity. However, girls reach the final score about 2 years earlier than boys. The consistently earlier mean appearance times in girls indicate that skeletal maturation is, already in childhood, more rapid in girls than in boys. There are significant gender differences in the sequence of appearance. CONCLUSION: Reference values for TW3 score and score increments and mean appearance times for stages add to existing knowledge and indicate important RUS/CB and gender differences, whose sources are largely unknown.

Neuromotor development from kindergarten age to adolescence: developmental course and variability.

The normal course of neuromotor development is described from 5 to 18 years of age. The data have been collected by use of the Zurich Neuromotor Assessment, a standardized testing procedure in which distinct motor tasks are judged with regard to timed performance and movement quality (associated movements of the contralateral and ipsilateral extremity, face, head and body). In the Zurich Growth and Development Studies, norms for these motor tasks have been established in 662 children and adolescents from middle class families. Neuromotor development is not a phenotypic entity, but evolves from motor functions of different complexity. With regard to timed performance and movement quality developmental course, gender differences and laterality vary considerably over age and among motor tasks. Thus, for a reliable assessment of the neuronotor developmental status in children, a standardized test instrument, well-trained examiners and normative data are required.

Impaired intellectual development in children with Type I diabetes: association with HbA(1c), age at diagnosis and sex.

AIMS/HYPOTHESIS: Good metabolic control in diabetic children is already crucial before puberty to prevent diabetic complications later in life. However, tight metabolic control could increase the risk of severe hypoglycaemia, which might be responsible for impaired intellectual performance later in life. The purpose of this prospective longitudinal study was to evaluate the relevance of long-term metabolic control and hypoglycaemia possibly affecting the intellectual development of young children with Type I (insulin-dependent) diabetes mellitus. METHODS: The intellectual development in 64 diabetic children between the ages of 7 and 16 years was assessed at least four times using the German version of the Hamburg Wechsler intelligence scale for preschool children, Children-Revised and by the "Adaptives Intelligenz Diagnostikum" (Adaptive Intelligence Diagnosticum). Data were analysed longitudinally compared with a control group. RESULTS: A significant decline in performance by age 7 and in verbal intelligence quotient between age 7 and 16 years was observed in diabetic boys diagnosed before the age of 6 but not in those diagnosed later and not in diabetic girls. The deterioration of intellectual performance in boys diagnosed at a very young age was not associated with the occurrence of severe hypoglycaemic episodes but was correlated with the degree of metabolic deterioration at diagnosis and with high long-term average of glycated haemoglobin. CONCLUSION/INTERPRETATION: Our study in diabetic children shows that the male sex, diagnosis at a young age, metabolic condition at diagnosis and long-term metabolic control, rather than experienced hypoglycaemic attacks are risk factors for intellectual development.

Statistical characterization of the pubertal growth spurt.

BACKGROUND: This is a methodical investigation into the problem of estimating parameters for the pubertal spurt (PS). The variability involved in determining the timing, intensity and duration of the PS for height, leg height and biiliac width is estimated via a realistic simulation. Further, a decomposition of adolescent growth into a component due to the pubertal peak and one due to ongoing prepubertal velocity is evaluated. METHODS: Data for 120 boys and 112 girls are available from 4 weeks to adulthood. The curve-fitting method is kernel estimation for distance, velocity and acceleration. RESULTS: The age of peak velocity and the age of stopping of the PS are well determined. In contrast, the age of onset of the PS is less well determined. Intensity is less variable for the parameter peak velocity than for maximal acceleration. It is feasible to decompose adolescent growth into a component due to the pubertal peak and one due to ongoing prepubertal growth. CONCLUSIONS: Nonparametric curve-fitting methods which do not rely on a parametric growth model can be successfully used to extract individual characteristics of the PS.

Neuromotor development from 5 to 18 years. Part 1: timed performance.

Timed performance in specific motor tasks is an essential component of a neurological examination applied to children with motor dysfunctions. This article provides centile curves describing normal developmental course and interindividual variation of timed performances of non-disabled children from 5 to 18 years. In a cross-sectional study (n=662) the following motor tasks were investigated: repetitive finger movements, hand and foot movements, alternating hand and foot movements, sequential finger movements, pegboard, and dynamic and static balance. Intraobserver, interobserver, and test-retest reliability for timed measurements were moderate to high. Timed performances improved throughout the entire prepubertal period, but differed among various motor tasks with respect to increase in speed and when the 'adolescent plateau' was reached. Centile curves of timed performance displayed large interindividual variation for all motor tasks. At no age were clinically relevant sex differences noted, nor did socioeconomic status significantly correlate with timed performance. Our results demonstrate that timed motor performances between 5 and 18 years are characterized by a long-lasting developmental change and a large interindividual variation. Therefore, a well standardized test instrument, and age-specific standards for motor performances are necessary preconditions for a reliable assessment of motor competence in school-age children.

Neuromotor development from 5 to 18 years. Part 2: associated movements.

Associated movements (AMs) are the most frequently assessed parameters of movement quality in children with motor dysfunctions. In this article, reference curves of duration and degree of AMs from 5 to 18 years are provided. In a cross-sectional study of non-disabled children (n=662) duration and degree of AMs were estimated at six specific ages while children performed repetitive finger, hand, and foot movements, alternating hand and foot movements, diadochokinesis, sequential finger movements, pegboard, stress gaits, and dynamic balance. Moderate-to-high intraobserver and interobserver reliability for the assessment of AMs were noted. Duration and degree of AMs displayed a non-linear developmental course that was a function of the motor task's complexity. AMs decreased most with age in repetitive movements, less in alternating and sequential movements, and least in the pegboard and dynamic balance. Reference curves demonstrated large interindividual variations for duration and degree of AMs. Both the variable developmental course and large interindividual variation need to be taken into account in the assessment of movement quality of school-age children. In contrast to timed performance, considerable sex differences for AMs were observed.

Growth processes leading to a large or small adult size.

BACKGROUND: The way in which a large size in anthropometric variables is achieved is a longstanding problem, since the pubertal spurt shows statistically and clinically little association with adult size (mostly studied for height). By analysing longitudinal growth of groups of subjects with a large or a small adult size separately for height, leg and sitting height, and bihumeral and biiliac width, we studied this problem in some detail. Of interest are growth patterns specific for these variables and for boys or girls. METHODS: The data consist of 120 boys and 112 girls followed longitudinally from 4 weeks until adulthood. Statistically, structural average velocity curves were computed for each variable and each subgroup separately for comparison. This velocity curve represents the average intensity and the average tempo of growth. Since the area under the velocity curve is adult size, differences in the growth process can be visualized. RESULTS: Both sexes show similar patterns in reaching a small or large adult size. The different variables, however, show marked differences. Only for legs is the pubertal spurt delayed for the large groups (with additional gains in prepubertal years). For sitting height and biiliac width, a slightly elevated velocity all along development (after 2 years) leads to a larger size and for bihumeral width the size of the pubertal peak is decisive. CONCLUSIONS: The steering of growth to a certain target size is qualitatively similar for boys and girls, but quite different for different anthropometric variables. This leads to questions about endocrinological control for various parts of the body and differential bone growth in development.

Growth of early and late maturers.

BACKGROUND: This is a study on the growth of subgroups of normal children, maturing early or late, in the variables height, leg and sitting height, arm length, biiliac and bihumeral width. While a longer growth period affects adult height only marginally, less is known about the other variables. It is also of interest to see in what way a shorter growth period is compensated by a higher velocity. METHODS: Out of 120 boys and 112 girls followed from 4 weeks until adulthood, subgroups of 40 boys and 37 girls were formed with respect to the average timing (across variables) of the pubertal spurt as an indicator of maturity. RESULTS: Only leg height shows a smaller adult size for early maturers. The shorter growth period is compensated by a higher prepubertal velocity and a higher level in pubertal years. The pubertal peak is a little larger for early maturing boys but not for girls. CONCLUSIONS: There is an inherent pacemaker for growth that leads to the same adult size for a shorter growth period via a higher basic intensity. Legs are an exception since late maturers have, on average, longer legs as adults.

Canalisation in human growth: a widely accepted concept reconsidered.

According to the concept of canalisation, infants and children stay within one or two growth channels, and therefore, any crossing of height centiles always warrants further evaluation. In view of evidence against this concept we re-investigated the variability of individual growth in the First Zürich Longitudinal Growth Study. The investigation is based on height measurements of 232 children (112 females, 120 males) measured at annual intervals during childhood and half-yearly during adolescence. Height data were transformed into height standard deviation scores (SDS) and canalisation defined by the width of an individual's growth channel, i.e., by the differences between maximum and minimum height SDS, in the individual series of measurements. Many subjects of the First Zürich Longitudinal Growth Study crossed numerous centiles with patterns that often seemed to show characteristic features. For approximately two thirds of the subjects, the SDS channel during the whole growth process covers more than one SDS. In childhood, between the age of two and age of minimal height velocity, only about one fourth of the subjects have an SDS channel below 0.5, indicating acceptable canalisation. During childhood, growth in boys appeared slightly more canalised than in girls (P = 0.02). Conclusion. The present investigation does not support the concept of strict canalisation of individual growth. We suggest to consider crossing of centiles a normal event in child development, though in a clinical setting crossing centiles should still be taken seriously, at least at first until a medical cause for this has been excluded.

Contribution of growth phases to adult size.

Based on the data of the First Zurich Longitudinal Growth Study we investigate how interindividual differences in adult size arise in the variables leg height, sitting height and standing height, arm length, bi-iliac width and bihumeral width. Specifically, we are also interested in the question of whether across sexes and variables the same growth phases and the same parameters are predictive for achieving a certain adult size. A rather complex pattern emerges, demonstrating that regulation of growth is not the same for boys and girls and moreover is not the same for the six anthropometric variables studied. Prepubertal growth is characterized by its intensity (average velocity) and by its duration. Whereas duration has by itself no appreciable influence on adult size, prepubertal intensity determines adult size to a high degree across all variables and both sexes. The intensity of prepubertal growth determines adult size to a larger degree for boys than for girls. For a given size at the end of the prepubertal period, a small duration enhances the chance of obtaining a large adult size. Compared with prepubertal growth, the amount of variance of adult size explained is small for pubertal parameters, and--with respect to linear measures--significant for girls only. A small duration of prepubertal growth is in the following mainly compensated by a stronger pubertal spurt (PS), to a varying degree across variables. The overall picture which emerges indicates that sitting height--and to a lesser extent bihumeral width--develop in a more irregular fashion than the variables bi-iliac width and leg height.

Phenotypic heterogeneity of growth and psychometric intelligence in Prader-Willi syndrome: variable expression of a contiguous gene syndrome or parent-child resemblance?

Phenotypic variability in children with Prader-Willi syndrome (PWS) was investigated with respect to variable expression of the contiguous gene syndrome and trait variance. In a prospective study, parent/child resemblance of anthropometric and psychometric measures was analyzed in 22 children with PWS (11 females and 11 males; 18 deletions, 4 uniparental disomy (UPD)) and in a control group (88 females and 88 males). The average child-midparent Z-score difference for height in females was -1.9 and in males -0.9, head circumference -1.7 and -1.0, and body mass index (BMI) 2.3 and 2.7, respectively. Intellectual performance of females and males was, on average, -2.7 and -2.6 below maternal performance. Range and standard deviation were moderately increased for height and head circumference, doubled for BMI, and unchanged for IQ. Parent/child correlations for anthropometric and psychometric measurements in the study group did not significantly differ from those of the control group. Exceptions were higher correlations between mothers and daughters for height (P < 0.05) and BMI (P < 0.01), and lower correlations for head circumference between midparent values and daughters (P < 0.05) than in the control group. In conclusion, parent-child resemblance in growth and intellectual development among children with PWS was found to be comparable to that noted in the normal population, indicating a strong determination by trait variance. Children with PWS differed significantly with respect to a lower trait level and-with the exception of IQ-a larger variability. The latter may indicate a variable expression of the contiguous gene syndrome.

Sex dimorphism in growth.

While there is agreement that sex differences in height are small up to the onset of the pubertal spurt in girls, there has been some debate about the question of which, and to what extent, various growth phases contribute to the average adult sex difference of about 13 cm. There has been no consistent agreement between authors as to what extent this difference is due to the late onset of the pubertal spurt (PS) for boys and to what extent it is due to their more intense PS. In this paper, we investigate this question for the variables height, sitting and leg height, arm length, bihumeral and biiliac width. Biiliac width is a special case since both sexes have roughly the same adult size, but girls still have a shorter growing period. The gains for boys, when compared to girls, show a very different pattern across variables: for the legs, the additional growth due to the later spurt is responsible for most of the adult sex difference (64%). On the other hand, for bihumeral width and sitting height, the more intense PS contributes almost 50% to the adult sex difference. An analysis across variables indicates that increments from 1.5 to 6 years largely compensate for deviations in infant morphology from adult morphology.

An analysis of variance of the pubertal and midgrowth spurts for length and width.

Using data from the first Zurich Longitudinal Growth Study characteristics of the growth of six variables--bihumeral width, biiliac width, standing height, sitting height, leg height and arm length--are studied. The main interest is in differences between boys and girls, and across variables and in particular in whether there are sex differences that are specific for some variables. For each child and variable, individual velocity and acceleration curves are estimated using a kernal smoother. From these curves, parameters characterizing the midgrowth spurt (MS) and the pubertal spurt (PS) are estimated: timings, durations and intensities. The level of childhood velocity is used for characterizing early growth. These parameters are analysed using a repeated measures analysis of variance (ANOVA) to assess the statistical significance of differences between boys and girls and across variables. This necessitates some kind of standardization and two types of standardization are used here. The MS shows negligible or small differences between boys and girls, and the same is true for velocity in childhood. Differences across variables during the MS are much more pronounced: with respect to intensity, bihumeral width has an MS about six times more intense than height. The PS is later for boys (as is well known), and there are significant differences across variables: bihumeral width and sitting height are late while legs are early. With the exception of biiliac width, the duration of the PS (which has been subdivided into three phases-early, middle and late) is slightly longer for boys for all variables: boys have a longer starting phase, the middle phase is about equal in length for both boys and girls, and girls have a slightly longer late phase. Leg height and height experience a PS of short duration while bihumeral and biiliac width experience a long one and these differences are highly statistically significant. For all variables, with the exception of biiliac width, boys have a more intense PS (in terms of maximal acceleration), even having adjusted for their larger adult size. Differences in intensity are also marked across variables, bihumeral width and sitting height having the highest intensity and legs the lowest. Differences between sexes and across variables are much smaller for the stopping intensity, characterized by maximal deceleration.

Development of bladder and bowel control: significance of prematurity, perinatal risk factors, psychomotor development and gender.

UNLABELLED: Development of bladder and bowel control from 6 months to 6 years was investigated in 140 preterm children and a control group of 349 healthy term children. Structured parental interviews and neurodevelopmental assessments were carried out when the child was 1, 3, 6, 9, 12, 18 and 24 months, and at yearly intervals thereafter. Even though preterm children were put on the potty at significantly earlier ages and significantly more frequently than term children, they expressed their need for evacuation and attained day and night bladder and bowel control at the same corrected age as term children. Initiation and intensity of toilet-training were not significantly correlated with the development of bladder and bowel control. Gestational age, being too small for gestational age, adverse perinatal conditions and mild to moderate neurological impairment did not affect the occurrence of the child's initiative and the development of bladder and bowel control. Neither developmental and intelligence quotients at the age of 1 to 3 years nor the socioeconomic status of the families influenced the age at which the child became clean and dry. Girls were significantly more advanced in expressing their needs and gaining bladder and bowel control than boys in both the preterm and term groups. CONCLUSION: Development of bladder and bowel control is largely a maturational process which cannot be accelerated by an early onset or a high intensity of training. It is not affected by prematurity, adverse perinatal events or mild to moderate neurological impairment, nor is it related to psychomotor development or actual Swiss socioeconomic conditions.

Bladder control a consequence of maturation: evidence after renal transplantation.

This report contains case studies on three children with early end-stage renal failure due to renal malformation or nephrotic syndrome, but without bladder involvement. All patients became anuric in the second year of life, before having obtained bladder control. They underwent successful cadaveric renal transplantation, having been anuric for almost 2 to 4 years. When the bladder catheter was removed 5 days after transplantation, all three children asked for the urine potty without ever having been prompted. Three weeks after transplantation, all three children achieved complete bladder control during the day, and two of them also at night. These observations add further evidence to the notion that the development of bladder control is a consequence of maturation and not of training.

Movement quality in preterm infants prior to term.

Quality of spontaneous movement behavior (fluency, spatio-temporal variation and sequencing) was studied from birth to term in high-risk preterm (n = 18), low-risk preterm (n = 18) and term (n = 20) infants. Cranial ultrasonography was performed during the first week of life and the child's general health was considered. The results were as follows: (1) In their first week of life, preterm infants displayed lower scores on all quality parameters when compared to term infants (p < 0.001). (2) Quality of spatiotemporal variation and sequencing decreased up to term (p < 0.01). These findings could be attributed to maturational differences, too early exposure to an extrauterine environment, and cerebral lesions.

Differences in movement quality at term among preterm and term infants.

Significant differences in movement quality at term are reported in high-risk preterm (n = 18), low-risk preterm (n = 21) and term (n = 20) infants. Movement quality was judged using 2-minute video collection of general movements; three parameters of movement quality could be assessed reliably in a semiquantitative way: fluency, spatiotemporal variability and sequencing. The parameters fluency and variability correlated highly with each other (r = 0.47-0.99) while their correlations with sequencing were less (r = 0.42-0.67). Significant differences on all quality parameters were noted between term, low-risk preterm and high-risk preterm infants (p < 0.001-0.05). The findings indicate a significant impact of prematurity per se and brain damage on movement quality.

Body proportionality in growth-retarded VLBW infants.

The aim of this study was to investigate how intrauterine growth retardation affects body proportions in VLBW infants. The cohort consisted of 135 surviving and 80 deceased preterm infants weighing less than 1250 grams at birth. Gestational age varied between 24 and 36 weeks (mean age 29.7 and 27.5 weeks, respectively). Birth weight was more than 2 SD below the mean birth standard values in 32% of the surviving, and in 27% of the deceased infants. Reduction of weight, length and head circumference at birth was analysed using Z scores based on Swedish birth standards. Z scores of weight, length and head circumference were highly correlated in the surviving and the deceased infants (r = 0.78 to 0.94 and 0.65 to 0.97, respectively). Length was significantly more affected by growth retardation than weight. Weight and head circumference were proportionately reduced. Intrauterine growth retardation influences body proportions in VLBW infants differently than in larger preterm and term infants.