Neuropsychological consequences of very low birth weight and asphyxia at term: follow-up until school-age

Use and completion of partograph during labour is associated with a reduced incidence of birth asphyxia: a retrospective study at a peri-urban setting in Ghana

BACKGROUND

Morbidity of birth asphyxia has been estimated to be 42 million disability-adjusted life years. The study sought to assess the impact of the use and completion of partograph during labour on reducing birth asphyxia at the St Anthony's Hospital, Dzodze, in the Volta Region of Ghana.

METHODS

A retrospective study design using a quantitative approach was adopted for the study. A simple random sampling technique was used to select a total of 200 folders of labouring women who were admitted and delivered at St Anthony's Hospital, Dzodze, between 1st May 2015 and 30th April 2016. A structured checklist, which was developed by using labour and foetal monitoring parameters based on the standards of the World Health Organization partograph usage, was used to review all the 200 existing maternal records.

RESULTS

The findings revealed that partographs were used by midwives at St Anthony's Hospital with the majority of the maternal folders fully completed. The use and completion of partograph were found to be associated with less non-asphyxiated birth outcomes. Labours which were monitored with partograph were 4.29 times less likely to result in birth asphyxia [AOR (95% CI) 4.29 (1.35-14.81)], and those that were monitored with a completed partograph were 5.3 times less likely to result in birth asphyxia [AOR (95% CI) 5.31 (2.011-16.04)].

CONCLUSION

Midwives used partographs during labour at St Anthony's Hospital. The use and completion of partograph were significantly associated with a reduced incidence of birth asphyxia at the hospital. Birth asphyxia could be reduced if partographs are used and completed by midwives during labour in all cases.

Impaired prospective memory but intact episodic memory in intellectually average 7- to 9-year-olds born very preterm and/or very low birth weight

Relatively little is known about episodic memory (EM: memory for personally-experienced events) and prospective memory (PM: memory for intended actions) in children born very preterm (VP) or with very low birth weight (VLBW). This study evaluates EM and PM in mainstream-schooled 7- to 9-year-olds born VP (≤ 32 weeks) and/or VLBW (< 1500 g) and matches full-term children for comparison (n = 35 and n = 37, respectively). Additionally, participants were assessed for verbal and non-verbal ability, executive function (EF), and theory of mind (ToM). The results show that the VP/VLBW children were outperformed by the full-term children on the memory tests overall, with a significant univariate group difference in PM. Moreover, within the VP/VLBW group, the measures of PM, verbal ability and working memory all displayed reliable negative correlations with severity of neonatal illness. PM was found to be independent of EM and cognitive functioning, suggesting that this form of memory might constitute a domain of specific vulnerability for VP/VLBW children.

Examination of the Underlying Structure of the Nepsy: A Developmental Neuropsychological Assessment

The internal structure of the NEPSY, a developmental neuropsychological instrument, was investigated with exploratory principal axis factor analyses using the correlation matrix for the 5- to 12-year-old children of the standardization sample. Additionally, a review of the psychometric properties of the NEPSY was conducted. The concurrence of multiple criteria indicated that a one-factor solution best describes the NEPSY (5-12) core domain structure. The five core domains specified in the test manual may significantly overdefine the NEPSY structure. Estimates of the unique variance accounted for by NEPSY subtests were also calculated. Most of the subtests have adequate or moderate specificity. Three subtests met the criteria for ample or excellent specificity. The subtest data should not be interpreted as if they reflect unique neuropsychological processing skills. Practitioners should be cautious in interpreting the core domain and subtest profiles of children's performance on the NEPSY. Further research of the utility of the NEPSY is needed.

Measuring the development of inhibitory control: The challenge of heterotypic continuity

Inhibitory control is thought to demonstrate heterotypic continuity, in other words, continuity in its purpose or function but changes in its behavioral manifestation over time. This creates major methodological challenges for studying the development of inhibitory control in childhood including construct validity, developmental appropriateness and sensitivity of measures, and longitudinal factorial invariance. We meta-analyzed 198 studies using measures of inhibitory control, a key aspect of self-regulation, to estimate age ranges of usefulness for each measure. The inhibitory control measures showed limited age ranges of usefulness owing to ceiling/floor effects. Tasks were useful, on average, for a developmental span of less than 3 years. This suggests that measuring inhibitory control over longer spans of development may require use of different measures at different time points, seeking to measure heterotypic continuity. We suggest ways to study the development of inhibitory control, with overlapping measurement in a structural equation modeling framework and tests of longitudinal factorial or measurement invariance. However, as valuable as this would be for the area, we also point out that establishing longitudinal factorial invariance is neither sufficient nor necessary for examining developmental change. Any study of developmental change should be guided by theory and construct validity, aiming toward a better empirical and theoretical approach to the selection and combination of measures.

Development of neuromotor functions in very low birth weight children from six to 10 years of age: patterns of change

AIM

To assess patterns of change for different neuromotor functions in very low birth weight (VLBW) children during school age and to identify factors associated with improvement.

METHODS

In a longitudinal study, we examined 65 prospectively enrolled VLBW children (38 female, 59%) without cerebral palsy at age six and 10 years. Measures included the evaluation of timed motor performance and motor overflow (MO) for the motor components of the Zurich Neuromotor Assessment (pure motor-, adaptive fine- and gross motor tasks, static balance) and a standardized neurological examination. Variables associated with improvement were assessed by multiple regression analyses.

RESULTS

Between six and 10 years, adaptive fine motor tasks (40% vs. 17% of children scoring below 10th percentile) and MO (77% vs. 55%) improved significantly (both p<0.01), while all other components remained stable (pure motor 23% vs. 25%, adaptive gross motor 26% vs. 34%, static balance 18% vs. 20%, respectively). Mild neurological abnormalities at 6 years of age were associated with less improvement.

CONCLUSION

Neuromotor functions improve in some children potentially reflecting catch up of maturational delay. However, the majority of neuromotor functions remain abnormal in a significant proportion of VLBW children.

Maternal factors predicting cognitive and behavioral characteristics of children with fetal alcohol spectrum disorders

OBJECTIVE

To provide an analysis of multiple predictors of cognitive and behavioral traits for children with fetal alcohol spectrum disorders (FASDs).

METHOD

Multivariate correlation techniques were used with maternal and child data from epidemiologic studies in a community in South Africa. Data on 561 first-grade children with fetal alcohol syndrome (FAS), partial FAS (PFAS), and not FASD and their mothers were analyzed by grouping 19 maternal variables into categories (physical, demographic, childbearing, and drinking) and used in structural equation models (SEMs) to assess correlates of child intelligence (verbal and nonverbal) and behavior.

RESULTS

A first SEM using only 7 maternal alcohol use variables to predict cognitive/behavioral traits was statistically significant (B = 3.10, p < .05) but explained only 17.3% of the variance. The second model incorporated multiple maternal variables and was statistically significant explaining 55.3% of the variance. Significantly correlated with low intelligence and problem behavior were demographic (B = 3.83, p < .05) (low maternal education, low socioeconomic status [SES], and rural residence) and maternal physical characteristics (B = 2.70, p < .05) (short stature, small head circumference, and low weight). Childbearing history and alcohol use composites were not statistically significant in the final complex model and were overpowered by SES and maternal physical traits.

CONCLUSIONS

Although other analytic techniques have amply demonstrated the negative effects of maternal drinking on intelligence and behavior, this highly controlled analysis of multiple maternal influences reveals that maternal demographics and physical traits make a significant enabling or disabling contribution to child functioning in FASD.

Outcome of extremely low birth weight infants: what's new in the third millennium? Neuropsychological profiles at four years

BACKGROUND

Extremely low birth weight (ELBW) infants, even those not presenting severe neuromotor sequelae, continue to be at risk of developing multiple, complex disorders involving the cognitive, emotional and behavioural domains. Follow-up protocols are able, in the short term, to identify subjects at risk of developing major sequelae, however they fail to identify all children at risk of developing disorders.

AIMS

To investigate the cognitive, neuropsychological and behavioural outcomes of a sample of ELBW children at the age of four years in order to identify characteristic profiles.

STUDY DESIGN

Longitudinal study.

SUBJECTS

16 healthy ELBW children born in 2005 and followed up until the age of four.

OUTCOME MEASURE

Performances on standardised tests evaluating intelligence, memory, cognitive visual functions, attention, and executive functions.

RESULTS

General intelligence was within normal range. Cognitive profile showed mild or moderate deficits with different levels of involvement in many of the examined functions, in particular executive functions, attention and naming.

CONCLUSION

There emerged a wide-ranging spectrum of weaknesses and deficits involving all the functions examined, which together give rise to a dysexecutive syndrome. Analysis of cognitive profiles showed that the sample could be divided into two subgroups of subjects that differ in the quality of their global cognitive and behavioural functioning. Our results confirm the need to continue follow up of ELBW children until school age, as this will allow early detection of at-risk children and the planning of timely preventive interventions.

Impaired neuromotor outcome in school-age children with congenital hypothyroidism receiving early high-dose substitution treatment

Congenital hypothyroidism (CH) can lead to intellectual deficits despite early high-dose treatment. Our study aimed to determine whether motor impairments can occur despite early high-dose treatment. Sixty-three children with CH and early (median age of onset of treatment 9 d), high-dose treatment (median starting dose of levothyroxine 14.7 μg/kg/d) were tested with the Zurich Neuromotor Assessment (ZNA) at a median age of 13.8 y (range 7.0-14.2 y). Median z-scores in the children with CH were -0.95 in the pure and -0.56 in the adaptive fine motor component, significantly lower than in the ZNA test norms (p < 0.001 and p = 0.01, respectively). The 26 children with athyreosis were more affected than the 33 children with dysgenesis, particularly in the pure motor (-1.55 versus -0.76, p = 0.03), adaptive fine motor (-1.31 versus 0.13, p < 0.01), and static balance task (-0.47 versus 0.67, p = 0.01). Boys performed worse than girls. Older age at onset of treatment was related to poorer adaptive fine motor performance. Movement quality (assessed by associated movements) was not affected. We conclude that severe CH can cause neuromotor deficits persisting into adolescence. These deficits cannot completely be reversed by postnatal treatment, but earlier age at treatment may reduce the degree of impairment.

Psychopathology in young adults born at extremely low birth weight

BACKGROUND

Little is known about the long-term mental health of extremely low birth weight (ELBW) (<1000 g) survivors. We test whether young adults aged 22 to 26 years born at ELBW differ from normal birth weight (NBW) controls in self-reported levels of psychopathology.

METHOD

Participants included 142 ELBW survivors (86% response) born between 1977 and 1982 to residents of central-west Ontario, Canada and 133 NBW control subjects (92% response). The Young Adult Self-Report measure was used to create five DSM-IV oriented scales aggregated to form internalizing (depressive problems, anxiety problems, avoidant personality problems) and externalizing (attention deficit-hyperactivity disorder problems and antisocial personality problems) scales.

RESULTS

After adjusting for family background characteristics, mean scores for ELBW survivors were 3.02 [95% confidence interval (CI) 0.78-5.26] points higher for internalizing problems and no different, i.e. 0.00 (95% CI -1.17 to 1.17), for externalizing problems. There was a sex × group statistical interaction such that being male muted the risk for externalizing problems among those born at ELBW: -2.11 (95% CI -4.21 to -0.01). Stratifying ELBW adults as born small for gestational age (SGA) versus appropriate weight for gestational age (AGA) revealed a significant gradient of risk for levels of internalizing problems that was largest for SGA, i.e. 4.75 (95% CI 1.24-8.26), and next largest for AGA, 2.49 (95% CI 0.11-4.87), compared with NBW controls.

CONCLUSIONS

Depression, anxiety and avoidant personality problems (internalizing problems) are elevated in young adulthood among ELBW survivors. This effect is relatively small overall but noticeably larger among ELBW survivors born SGA.

Basic Information Processing Abilities at 11 years Account for Deficits in IQ Associated with Preterm Birth

Although it is well established that preterms as a group do poorly relative to their full-term peers on tests of global cognitive functioning, the basis for this relative deficiency is less understood. The present paper examines preterm deficits in core cognitive abilities and determines their role in mediating preterm/full-term differences in IQ. The performance of 11-year-old children born preterm (birth weight <1750g) and their full-term controls were compared on a large battery of 15 tasks, covering four basic cognitive domains -- memory, attention, speed of processing and representational competence. The validity of these four domains was established using latent variables and confirmatory factor analysis (CFA). Preterms showed pervasive deficits within and across domains. Additionally, preterm deficits in IQ were completely mediated by these four cognitive domains in a structural equation model involving a cascade from elementary abilities (attention and speed), to more complex abilities (memory and representational competence), to IQ. The similarity of findings to those obtained with this cohort in infancy and toddlerhood suggest that preterm deficits persist - across time, across task, and from the non-verbal to the verbal period.

Sensorimotor skills associated with motor dysfunction in children born extremely preterm

BACKGROUND

Children born prematurely, despite being free of intellectual and sensorineural deficits, are at risk of motor dysfunction.

AIM

To investigate the association of sensorimotor processing skills and Developmental Coordination Disorder (DCD) in "apparently normal" extreme preterm children.

STUDY DESIGN

In a matched case-control study, 50 preterm children born less than 29 weeks or birthweight <1000 g, with an IQ>85 and no identified sensorineural disability, were assessed at 8 years of age along with 50 gender and birth date matched classroom controls born at full term. A battery of sensorimotor tests was administered, which examined visual-motor, visual perception, tactile perception, kinaesthesia, and praxis.

RESULTS

For preterm children with DCD (n=21), significantly lower scores were found for the visual processing and praxis tests, with the exception of verbal command, in comparison to those 29 preterm children without DCD and term controls (median visual perception scores were 92, 96 and 108 respectively; design copying was 0.07, 0.46 and 0.95; constructive praxis was 0.09, 0.27 and 0.63; and sequencing praxis was 0.14, 0.73 and 0.96). There were no difference on the tactile sensitivity and kinaesthetic processing tests.

CONCLUSIONS

Preterm children with DCD have difficulty with visual processing tasks. Praxis or motor planning poses a particular challenge for them. Motor dysfunction in extremely preterm children was related to poorer visual processing and motor planning and may relate to a cognitive processing problem.

Neurodevelopment of preterm infants born at 28 to 36 weeks of gestational age: the role of hypothyroxinemia and long-term outcome at 4 years

CONTEXT

Hypothyroxinemia in premature neonates may affect long-term neurodevelopment.

OBJECTIVE

This study aimed to examine the effects of hypothyroxinemia of the newborn preterm infants born at 28-36 weeks of gestational age (GA) on the neurodevelopment at 4 years of age.

PATIENTS

Prospective observational cohort study conducted in Madrid, Spain. Forty-six preterm infants were included in the study.

MAIN OUTCOME

The effects of the exposure to neonatal hypothyroxinemia on mental development were examined.

RESULTS

Using regression analyses we found that neonatal T4 had a positive association with general cognitive index and Verbal index, and neonatal FT4 with general cognitive and Memory indexes at 4 years of age.

CONCLUSIONS

The exposure to hypothyroxinemia during the neonatal period of late preterm infants may play role in neurodevelopmental delays. Higher T4 level means a trend to higher indexes and low T4 level means a lower neurodevelopmental indexes at 4 years of age.

Neurocognitive test profiles of extremely low birth weight five-year-old children differ according to neuromotor status

The neurocognitive outcome of children born with extremely low birth weight (ELBW) is highly variable due to the complexity of morbidity. So far, no study has compared comprehensive neuropsychological test profiles in groups with different neuromotor status. In a national cohort of ELBW children neuropsychological test profiles were assessed in 4 groups defined according to a neurological examination at 5 years of age: normal neuromotor status (N = 56), motor coordination problems (N = 32), multiple subtle neuromotor signs including both motor coordination problems and deviant reflexes (N = 20), and spastic diplegia (N = 12). The neurocognitive assessment included a test of intelligence, the Wechsler Primary and Preschool Scale of Intelligence-Revised (WPPSI-R) and 14 subtests of attention and executive functions, verbal functions, manual motor functions, visuoconstructional functions and verbal learning (NEPSY). The children with normal neuromotor status performed within the average range; children with motor coordination problems had widespread impairment; and children with spastic diplegia and children with multiple minor neuromotor signs had uneven test profiles with stronger verbal results but weaknesses in attention and executive functions, and in manual motor and visuoconstructional tasks. In conclusion, very preterm children with neuromotor signs, including motor coordination problems, are at risk for neurocognitive impairment, in spite of average intelligence. More impaired children have more irregular test profiles. Follow-up and neuropsychological assessment of very preterm children with minor neuromotor signs are therefore indicated.

General background on the hypothalamic-pituitary-thyroid (HPT) axis

This article reviews the thyroid system, mainly from a mammalian standpoint. However, the thyroid system is highly conserved among vertebrate species, so the general information on thyroid hormone production and feedback through the hypothalamic-pituitary-thyroid (HPT) axis should be considered for all vertebrates, while species-specific differences are highlighted in the individual articles. This background article begins by outlining the HPT axis with its components and functions. For example, it describes the thyroid gland, its structure and development, how thyroid hormones are synthesized and regulated, the role of iodine in thyroid hormone synthesis, and finally how the thyroid hormones are released from the thyroid gland. It then progresses to detail areas within the thyroid system where disruption could occur or is already known to occur. It describes how thyroid hormone is transported in the serum and into the tissues on a cellular level, and how thyroid hormone is metabolized. There is an in-depth description of the alpha and beta thyroid hormone receptors and their functions, including how they are regulated, and what has been learned from the receptor knockout mouse models. The nongenomic actions of thyroid hormone are also described, such as in glucose uptake, mitochondrial effects, and its role in actin polymerization and vesicular recycling. The article discusses the concept of compensation within the HPT axis and how this fits into the paradigms that exist in thyroid toxicology/endocrinology. There is a section on thyroid hormone and its role in mammalian development: specifically, how it affects brain development when there is disruption to the maternal, the fetal, the newborn (congenital), or the infant thyroid system. Thyroid function during pregnancy is critical to normal development of the fetus, and several spontaneous mutant mouse lines are described that provide research tools to understand the mechanisms of thyroid hormone during mammalian brain development. Overall this article provides a basic understanding of the thyroid system and its components. The complexity of the thyroid system is clearly demonstrated, as are new areas of research on thyroid hormone physiology and thyroid hormone action developing within the field of thyroid endocrinology. This review provides the background necessary to review the current assays and endpoints described in the following articles for rodents, fishes, amphibians, and birds.

Auditory processing deficits in growth restricted fetuses affect later language development

An increased risk for language deficits in infants born growth restricted has been reported in follow-up studies for more than 20 years, suggesting a relation between fetal auditory system development and later language learning. Work with animal models indicate that there are at least two ways in which growth restriction could affect the development of auditory perception in human fetuses: a delay in myelination or conduction and an increase in sensorineural threshold. Systematic study of auditory function in growth restricted human fetuses has not been reported. However, results of studies employing low-risk fetuses delivering as healthy full-term infants demonstrate that, by late gestation, the fetus can hear, sound properties modulate behavior, and sensory information is available from both inside (e.g., maternal vascular) and outside (e.g., noise, voices, music) of the maternal body. These data provide substantive evidence that the auditory system is functioning and that environmental sounds are available for shaping neural networks and laying the foundation for language acquisition before birth. We hypothesize that fetal growth restriction affects auditory system development, resulting in atypical auditory information processing in growth restricted fetuses compared to healthy, appropriately-grown-for-gestational-age fetuses. Speech perception that lays the foundation for later language competence will differ in growth restricted compared to normally grown fetuses and be associated with later language abilities.

Intellectual development in a Danish cohort of prematurely born preschool children: specific or general difficulties?

A national cohort of extremely low birth weight (ELBW) and/or extremely preterm (EPT) children and a term control group was followed up at the age of 5 years. The primary objective was to investigate whether premature birth had a global impact on cognitive functions or affected specific functions only. Assessment tools were Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), Movement Assessment Battery for Children (M-ABC), and subtests from the Neuropsychological Assessment 4-7 years (NEPSY). The mean Full Scale IQ (FSIQ) and M-ABC score of the index children were 1.1 and 1.2 SDs lower than that of the control children (p <.001). Most WPPSI-R subtests showed medium to large differences between index and control children, suggesting a global impact of premature birth on cognitive functions. For both unadjusted and FSIQ adjusted means, no significant group differences on tests of memory or executive function were observed (p >.1), suggesting little impact of premature birth on these specific functions. In this sample, cognitive difficulties in 5-year-old ELBW and/or EPT children tended to be associated with general intellectual difficulties rather than with specific dysfunctions; however, the implications of this finding are ambiguous due to substantial attrition on the NEPSY subtests.

Neuropsychological outcome of children with intrauterine growth restriction: a 9-year prospective study

OBJECTIVE

The aim was to evaluate the effect of late-onset intrauterine growth restriction on the neuropsychological profile and on academic achievements at 9 years of age using a large-scale prospective paradigm.

STUDY DESIGN

We followed up 123 infants diagnosed with late-onset intrauterine growth restriction yearly for 9 years. They were matched with 63 children for gestation age and multiple socioeconomic factors and evaluated by an extensive neuropsychological battery to assess intelligence quotient, academic achievements, learning and memory, visuomotor skills, visuospatial integration, attention, language, executive functions, and creativity.

RESULTS

Children with intrauterine growth restriction had lower intelligence quotient and more frequent neuropsychological difficulties. Difficulties in executive functioning, inflexibility-creativity, and language, indicative of frontal lobe dysfunction, were typically affected by intrauterine growth restriction and were rarely identified in the control group. Learning difficulties accompanied by lower academic achievements were more prevalent in the intrauterine growth restriction group, particularly when anthropometric catch-up was incomplete.

CONCLUSIONS

The longitudinal findings reaffirm that functional coherence depends on preestablished structural growth and reorganization of the central nervous system. The neuropsychological profile at 9 years of age indicates that late-onset intrauterine growth restriction compromises frontal network functioning.

Naming skills of children born preterm in comparison with their term peers at the ages of 9 and 16 years

The linguistic abilities of children born preterm at 32 weeks' gestation or earlier at Kuopio University Hospital during 1984 to 1986 were evaluated during successive phases of a prospective study. The study protocol included the Rapid Automatic Naming test and Wechsler Intelligence Scale for Children - Revised at 9 years of age and a modified Stroop Color-Word test and the Wechsler Intelligence Scale - Revised at the age of 16 years. Fifty-one children born preterm (26 males, 25 females) and 51 age-matched and sex-matched term controls (26 males, 25 females) were studied at the age of 9 years. At the age of 16 years, 40 children born preterm (19 males, 21 females) and 31 term controls (14 males, 17 females) participated in the study. The children born preterm scored significantly lower in two naming tasks than the controls at the age of 9 years. However, there was no difference between the study groups in naming skills at the age of 16 years or in verbal IQ in either study phase. Maternal education level was not associated with naming skills. Thus, the consequences of preterm birth seem to be minor in relation to linguistic skills during school age and diminish by adolescence.

Comparison of fetal behavior in low- and high-risk pregnancies

Meta-analyses were conducted on archival data of human fetal behavior to identify differential behavior among high-risk fetuses in pregnancies complicated by threatened preterm delivery, maternal hypertension or diabetes compared with low-risk fetuses in uneventful pregnancies, delivering as healthy, full-term infants. Data for a total of 493 fetuses (260 high risk, 233 low risk) from 23 weeks' gestation to term who participated in a study using a standardized protocol including observations of spontaneous and auditory-induced behavior were retrieved from our laboratory database. There were no differences in spontaneous behaviors when scored using clinical criteria for the nonstress test and biophysical profile; however, there were differences in the magnitude of the behaviors measured in the tests. Developmental differences were observed between those threatening to deliver early and the fetuses of hypertensive and diabetic mothers. The latter two groups differed little from one another but differed from low-risk fetuses in their response to auditory stimulation. We concluded that differences in behavior among high-risk groups suggest that atypical fetal behaviors may represent adaptation to condition specific insult rather than a generalized response to insult per se. The finding that high-risk fetuses showed atypical responses to auditory stimuli indicates a need to examine the relation between fetal auditory function and later language acquisition.

Long-term neuropsychological outcomes of very low birth weight: associations with early risks for periventricular brain insults

Few follow-up studies of children with very low birth weight (VLBW, <1,500 g) have examined neuropsychological sequelae at later ages or neonatal risks as predictors of these outcomes. The present study assessed cognitive skills at mean age 16 years in 48 participants with <750 g birth weight, 47 with 750-1,499 g birth weight, and 52 term-born controls. Our major objectives were to delineate the long-term cognitive consequences of VLBW, and to determine if risks for periventricular brain insults accounted for variations in outcomes. Analysis revealed poorer outcomes for the <750 g group than for term-born controls on nearly all measures, with specific impairments in visual-motor skills, spatial memory, and executive function. Predictors of outcome for participants with VLBW included lower birth weight, lower weight for gestational age, and a longer period of oxygen requirement for chronic lung disease. The longer-term consequences of VLBW are consistent with expectations based on early brain pathology and suggest limitations to functional plasticity.

Atypical auditory event-related potentials in preterm infants during the first year of life: a possible sign of cognitive dysfunction?

We assessed auditory event-related potentials in small-for-gestational-age (SGA; 850 +/- 258 g, 28.9 +/- 3.3 gestational wk; n = 15) and appropriate for gestational age (AGA; 1014 +/- 231 g, 26.9 +/- 1.9 gestational wk; n = 20) preterm infants and healthy term infants (n = 22). An oddball paradigm was used with a harmonic tone of 500-Hz frequency as the standard and of 750-Hz frequency as the deviant stimulus. The preterm infants were studied at 40 gestational wk and at 6 and 12 mo of corrected age, and the control subjects were studied at 2-4 d and at 3, 6, 9, 12, and 15 mo of age. The peaks of interest were the main positive peak (P350), the negative peaks at 250 ms (N250) and 650 ms (Nc), and the mismatch negativity at 200 ms (MMN). At term, the P350 in the preterm infants was similar to that of the newborn control subjects. In response to the deviant, the Nc was smaller in the SGA than in the AGA (P < 0.02) and control (P < 0.005) infants. The N250 amplitude was also lower in the SGA infants. At 12 mo, the MMN was observed in the control but not in the preterm infants, whose broad difference positivity correlated with the Bayley developmental index. The decreased Nc and N250 peaks in the SGA infants may suggest an increased risk for cognitive dysfunction. The broad difference positivity at 1 y of age may indicate atypical cortical auditory processing. Whether cognitive dysfunction can be predicted by these findings needs to be assessed in a study with extended follow-up.

Large variability in performance IQ associated with postnatal morbidity, and reduced verbal IQ among school-aged children born preterm

AIM

To assess cognitive ability in a population-based group of prematurely born school-aged children and to relate these findings to postnatal morbidity.

METHOD

The study group consisted of a cohort of 51 children born preterm, 43 (26 boys, 17 girls) of whom were available for psychological evaluation At evaluation, their median age was 10 y (range 8-11 y). They were all born between 1988 and 1991, with gestational age less than 29 wk (median 27, range 24-28). Their median birthweight was 1060g (range 450-1450). The Wechsler Intelligence Scale for Children (WISC-III) was used, and the test results were compared with those of a standardized, age-matched, normative group of children.

RESULTS

Thirteen children (30%) performed below average [intelligence quotient (IQ) < 80] for Full Scale IQ (FSIQ). Thirty-six children had a Verbal IQ (VIQ) below the mean value of 100 [84%, 95% confidence interval 73-95%], p < 0.0001. The Performance IQ (PIQ) was within the expected range of a normal population, although a large variability was observed. Discrepancies between VIQ and PIQ of more than 15 IQ units were found in 42% of the children. High postnatal morbidity (days with assisted ventilation, number of blood transfusions) and low birthweight standard deviation scores (SDS) were associated with lower PIQ than VIQ, while low postnatal morbidity and high birthweight were associated with higher PIQ than VIQ.

CONCLUSION

This cohort of preterm children had reduced overall verbal capacity independent of morbidity, and a large variability in performance capacity that was associated with postnatal morbidity. The findings suggest that there are different mechanisms influencing the outcome of verbal and performance capacity in preterm children.

Cognitive development at 5.5 years of children with chronic lung disease of prematurity

BACKGROUND

Preterm infants with chronic lung disease (CLD) had impaired cognitive development and poorer eye-hand coordination at 10 months of age.

AIMS

To study whether this effect of CLD persisted until school age and whether the severity of CLD affected outcome.

METHOD

Cognition and visual-motor skills were examined (Wechsler preschool and primary scale of intelligence, and tests from the Nepsy scale) in 60 very preterm children, without intraventricular haemorrhage or periventricular leucomalacia, at 5.5 years of age. Thirty two children suffered from CLD and 28 were controls.

RESULTS

The groups did not differ significantly in cognitive outcome. Children with CLD and controls attained a full scale intelligence quotient (IQ) of 94.4 and 99.1, a verbal IQ of 99.6 and 101.5, and a performance IQ of 90.9 and 96.7 respectively. Similarly, no difference was found in tests of eye-hand control. However, the children with the most severe form of CLD had significantly lower performance (84.8) and full scale(87.6) IQs and worse visual-motor performance than the controls. CLD grade III, together with the need for glasses or lenses, had a significant impact on the explained variance.

CONCLUSIONS

At school age, children born very preterm and who experienced severe CLD had deficits in cognition, visual-motor perception, and performance. The findings suggest a need to consider intervention programmes for such infants.

Brainstem auditory-evoked potentials of 8-year-old preterm children in relation to their psycholinguistic abilities and MRI findings

BACKGROUND

Brainstem auditory potential (BAEP) has been used to demonstrate brainstem damage and to provide prognosis for the outcome for newborn children. There are contradictory results of its power to predict problems in language development or problems at school. It is well known that preterm children experience an excess of these problems.

AIM

To study if BAEP findings of 8-year-old preterm children differ from those of the full-term born control children and whether there is correlation to their linguistic problems or to the findings in magnetic resonance imaging (MRI).

STUDY DESIGN

Population-based cohort study.

SUBJECTS

Forty-two preterm children aged 8 years born with birth weight <1750 g and their matched full-term control children with birth weight >2500 g, 24 of whom had BAEP recordings and MRI.

OUTCOME MEASURES

Differences in BAEPs between the preterm and the control children. Correlation of BAEPs with linguistic problems and with MRI findings.

RESULTS

No differences were found in the absolute latencies nor in the interpeak intervals and in the I/V amplitude ratio. Nor did the results differ even when cerebral palsy disabled preterm children, preterm children with mild neurodevelopmental dysfunction or healthy preterm children were compared to each other or to the control children. No correlation to the linguistic problems or to the findings of periventricular leukomalacia (PVL) in MRI or to the different measurements of the brainstem were found.

CONCLUSION

If hearing impairment does not exist, BAEP does not give further information on neurodevelopmental nor linguistic problems of the preterm children.

Long-term developmental outcome of asphyxiated term neonates

Asphyxia remains one of the main causes of later disability in term infants. Despite many publications identifying possible predictors of outcome in this population of interest, little is known of the long-term developmental outcome of asphyxiated term neonates. Observational studies have largely focused on short-term outcomes, with an emphasis on significant neurologic sequelae and intellectual impairments. This article reviews the literature that has described the developmental outcome of asphyxiated term newborns. As part of this review, we have also highlighted the evolution of the definition of asphyxia and delineated appropriate markers that should be used in future research on this population.

Cognitive development, temperament and behavior at 2 years as indicative of language development at 4 years in pre-term infants

This study focuses on the early temperamental (TTQ = toddler temperament questionnaire), behavioral (IBR = infant behavior record), and cognitive precursors of impaired language functioning in preschool-age pre-terms infants. The study group consisted of 63 pre-term infants with a mean birth weight of 1246 +/- 437 g born in 1989-1991 in the University Central Hospital of Helsinki. Children with major disabilities (CP or mental retardation) were excluded. At the age of 4 years, 22% showed impaired language function. Logistic regression analysis showed that the Bayley MDI score was the best predictor in identifying an increased risk for language impairment. Behavioral characteristics were more strongly associated with subsequent language impairment than temperament.

Applying Luria's diagnostic principles in the neuropsychological assessment of children

The first part of this article examines the theoretical justification for applying Luria's approach in the assessment of children. It is concluded that Luria's concepts of functional systems and the principle of specifying primary and secondary deficits may be applied to children. However, the selection of functional components to assess should be based on traditions of child neuropsychology rather than on Luria's assessment of adults. In addition, the tendency for comorbid disorders, mechanisms of neural adaptation to damage, and the prevalent types of brain abnormality in children render brain-behavior relationships more complex in children than in adults. The second part of the article describes how Luria's methods were adapted for use with children. An assessment, NEPSY, was developed by integrating Luria's views with contemporary child neuropsychological traditions. The NEPSY includes 27 homogeneous and psychometrically developed subtests, standardized in the United States and Finland for the age range of 3 to 12 years. The rationale of analyzing disorders of cognitive processes through a comprehensive and systematic assessment of their components, characteristic of Luria's approach, was preserved, but more specific principles of diagnosis were modified. Research findings obtained with a previously published, Finnish NEPSY version are presented.

Psychological findings in preterm children related to neurologic status and magnetic resonance imaging

OBJECTIVE

Preterm children experience learning disabilities more often than full-term children, but detailed information on their neuropsychological and neurologic determinants is lacking. We therefore examined these problems more closely and also studied if clinical neurologic examination and/or magnetic resonance imaging (MRI) can be used as tools to screen the preterm children at risk for these problems.

METHODS

In a population-based study, the psychological performance of 42 preterm children with a birth weight <1750 g and of their matched controls was assessed at 8 years of age and the findings were then related to clinical neurologic examination and MRI. Learning disabilities of these children, reported by the teachers, were also studied.

RESULTS

The cognitive ability of the preterm children, although in the normal range, was significantly lower than that of the control children. They performed particularly poorly in tasks requiring spatial and visuoperceptual abilities, which were associated with the finding of periventricular leukomalacia in MRI, especially with posterior ventricular enlargement. The preterm children with minor neurodevelopmental dysfunction (MND) had the most problems in neuropsychological tests, whereas the clinically healthy preterm children and those with cerebral palsy had fewer problems. The problems of MND children emerged in the domain of attention. They also experienced the most problems at school.

CONCLUSIONS

Visuospatial problems were associated with periventricular leukomalacia in MRI, but learning disabilities were most frequent among the preterm children with minor neurologic abnormalities. We recommend closer follow-up of preterm children with MND.