RELATIONSHIP BETWEEN NEURODEVELOPMENTAL STATUS OF VERY PRETERM INFANTS AT ONE AND FOUR YEARS

The neurodevelopmental status of 171 very preterm infants was assessed at one and four years of age. At one year 17 had major impairments and 14 had minor ones. At four years the numbers had increased to 25 with major and 25 with minor impairments. Infants with no impairments at one year had a 4 per cent probability of a major impairment at four years, whereas infants with a major impairment had a 94 per cent probability. Infants who later proved to have major neuromotor impairments had been accurately identified at one year, as had infants with sensorineural hearing-loss. Infants with minor impairments of tone and reflexes at one year did not develop cerebral movement disorder, but as a group their scores on tests of cognitive functioning were low. An additional group of infants with cognitive impairments was identified who were unimpaired at one year. The emergence of cognitive deficits largely accounted for the increase in impairments between one and four years.     

PROBABILITÉ OF NEURODEVELOPMENTAL DISORDERS ESTIMATED FROM ULTRASOUND APPEARANCE OF BRAINS OF VERY PRETERM INFANTS

The neurodevelopmental status of 342 very preterm infants who had undergone prospective ultrasound brainscans was assessed at a median corrected age of 52 weeks. The probabilities for neurodevelopmental disorders were calculated according to the ultrasound findings. The results showed that the probability of a major or minor disorder was low for infants whose scans did not show periventricular haemorrhage or markedly increased parenchymal echodensities in the first week of life, and for those whose scans at discharge gave no evidence of ventricular dilatation, hydrocephalus or cerebral atrophy. By contrast, the probability of a disorder was very high for infants with markedly increased parenchymal echodensities in the first week, and for infants with evidence of cerebral atrophy at discharge. The majority of the infants could be assigned, on the basis of the ultrasound scan at discharge, either to a large group who were at low risk of neurodevelopmental disorders or to a small group who were at high risk; the remainder were at intermediate risk. These findings may be used as a guide to the prognosis for other infants whose ultrasound scans show similar appearances.     

PREDICTION IN VERY PRETERM INFANTS OF SATISFACTORY NEURODEVELOPMENTAL PROGRESS AT 12 MONTHS

This study was performed to find out how well ultrasound brain-scanning and neurological examination of very preterm infants, together and separately, predicted normal neurodevelopmental progress at 12 months corrected age. 111 infants born at less than 33 weeks gestation were scanned at discharge from the neonatal unit, and neurological examinations were performed at a gestation-equivalent age at or near term. During the first year of life repeated neurological and developmental testing was carried out. At 12 months a diagnosis of normal progress or of major or minor neurodevelopmental disorders was made. 56 (50 per cent) infants with both a favourable ultrasound scan and normal neurological findings had a 98 per cent (90 to 99 per cent) probability of normal progress at 12 months, and a 100 per cent (93 to 100 per cent) probability of having no major disorder. Separately, ultrasound scanning and neurological examination were not such good predictors of normal outcome, although they selected larger groups of infants with high probabilities of progressing normally. Ultrasound brain-scanning and neurological examination can be used in combination to identify potentially normal preterm infants when they are discharged to their homes.     

LANGUAGE AND NEURODEVELOPMENTAL OUTCOME OF LOW-BIRTHWEIGHT INFANTS AT THREE YEARS

Forty low-birthweight (LBW) infants (28 AGA, 12 SGA) and 16 fullterm infants have been followed for three years with neurological, developmental, language, behavior and audiometric assessments. Only two (5 per cent) of the LBW infants were neurologically abnormal at three years. The AGA infants continued to lag cognitively and in receptive language in comparison with the fullterm infants. Socio-economic factors had a significant effect on the language development of all three groups. Short gestation and neurological status at eight months continued to have a significant effect on language performance. A variety of behavioral characteristics correlated with cognitive and language scores, and impaired middle-ear status was associated with lower cognitive function. These data support the concept that language development of LBW infants is influenced by perinatal, neurological and socio-economic factors, and by behavioral characteristics and middle-ear status.     

PRECISION OF ULTRASOUND DIAGNOSIS OF PATHOLOGICALLY VERIFIED LESIONS IN THE BRAINS OF VERY PRETERM INFANTS

Abnormalities detected by a mechanical sector scanner were compared 'blind' with autopsy findings in the brains of 56 infants born at less than 33 weeks gestation. Intraventricular haemorrhage was found in 53 of 112 hemispheres and had been accurately diagnosed by ultrasound (sensitivity 91 per cent; specificity 81 per cent). Isolated germinal layer haemorrhage was less successfully identified (sensitivity 61 per cent; specificity 78 per cent); false-positive diagnoses were partly due to difficulty in distinguishing haemorrhage from the normal choroid plexus in extremely preterm infants. Haemorrhagic parenchymal lesions were correctly identified in nine infants (sensitivity 82 per cent; specificity 97 per cent). Only 11 of 39 hemispheres with histological evidence of hypoxic-ischaemic injury, without marked bleeding, were correctly identified by ultrasound (sensitivity 28 per cent), mainly because of failure to detect small areas of periventricular leucomalacia and diffuse gliosis. 10 hemispheres with periventricular echodensities thought to represent leucomalacia showed no histological evidence of hypoxic-ischaemic injury (specificity 86 per cent). Ventricular dilatation in seven infants was always associated with evidence of hypoxic-ischaemic injury at autopsy.     

SHORT-LATENCY CORTICAL SOMATOSENSORY EVOKED RESPONSES OF PRETERM INFANTS WITH ULTRASOUND ABNORMALITY OF THE BRAIN

Somatosensory evoked response (SER) testing was carried out on 30 neonates with abnormality of the brain diagnosed by ultrasound, and the results were compared with previously defined normal ranges. The N1 peak latencies of the cortical SER were significantly different from normal, but peripheral nerve conduction velocities were not. Early neurological follow-up of these infants suggests that the cortical SER shows good correlation with neurological and developmental outcome, and may provide useful additional diagnostic information to cranial ultrasound for these high-risk infants.     

RELATIONSHIP BETWEEN TWO-YEAR BEHAVIOUR AND NEURODEVELOPMENTAL OUTCOME AT FIVE YEARS OF VERY LOW-BIRTHWEIGHT SURVIVORS

A prospective five-year follow-up of survivors of very low birthweight (less than or equal to 1500 g) born in 1979 was carried out at the Queen Victoria Medical Centre, Melbourne, between 1980 and 1985. Of the 57 children reported here, 23 had been identified during psychological testing at two years as having an attention deficit disorder (ADD). Although the number with ADD at five years had decreased to 18, the two-year diagnosis was retained to test its predictive value for outcome at school-age. Children with ADD at two years differed significantly from their peers at five years in verbal, performance and full-scale IQ and had significantly more minor physical disabilities. They also had poorer visual acuity, more tremor, poorer balance, and more deviations with arms extended in pronation. The ADD children had more minor, though chronic, physical illnesses such as tonsillitis and serous otitis media. Their mothers expressed greater concern than the other mothers about hearing and behaviour. The ADD children were rated as significantly more aggressive, difficult to manage and less able to cope with frustration. As a predictor of five-year IQ, behaviour at two years was more powerful than social class. ADD discriminated a subgroup of very low-birthweight children whose lower IQ and multiple physical, neurological and behavioural difficulties place them at very high risk of learning disabilities.     

IDENTIFICATION OF NEURODEVELOPMENTAL ABNORMALITY AT FOUR AND EIGHT MONTHS BY THE MOVEMENT ASSESSMENT OF INFANTS

The predictive validity of infant neuromotor evaluation by the Movement Assessment of Infants (MAI) was investigated in low-birthweight infants. Motor performance at four and eight months was examined in relation to neurodevelopmental outcome at 18 months of age. Correlations were equally strong between total MAI risk scores at four and eight months and performance on the Bayley Scales. Muscle tone observations were more discriminating at four months, and automatic reactions and volitional movement were most predictive at eight months. The MAI was highly sensitive to neurodevelopmental abnormality at four and eight months and more sensitive than the Bayley Motor Scale; both assessment tools had lower specificity at eight months. The high false-positive rate is attributed to transient neuromotor abnormalities and immaturity of motor function in low-birthweight infants with normal outcome.     

USING GROSS MOTOR MILESTONES TO IDENTIFY VERY PRETERM INFANTS AT RISK FOR CEREBRAL PALSY

The authors evaluated the efficacy of 10 gross motor milestones to screen for cerebral palsy in 173 high-risk, very preterm infants (less than or equal to 32 weeks gestation) followed for 18 to 24 months. Correcting for preterm birth and using population norms led to a better improvement in specificity and positive predictive values; race-specific norms did not contribute significantly. Incorporating a history of milestone attainment into the routine during sequential office visits will help health-care providers to monitor the development of high-risk infants.     

CEREBRAL BLOOD-FLOW VELOCITY DURING THE FIRST WEEK OF LIFE OF PRETERM INFANTS AND NEURODEVELOPMENT AT TWO YEARS

Disturbances in perinatal cerebral perfusion appear to be associated with unfavourable neurodevelopmental outcome. Using transcutaneous Doppler technique, the authors investigated cerebral blood-flow velocity patterns in the anterior cerebral artery (ACA) of an intensive care-unit population of preterm infants during the first week of life. The results were correlated with neurodevelopmental outcome at two years of age. Children with major disability at two years of age had significantly higher pulsatility index (PI) values, mainly increased peak systolic flow velocity (PSFV), compared with children with normal or more favourable outcome. End diastolic flow velocity and area under the velocity curve values of the ACA did not differ between the groups, indicating that cerebrovascular resistance and cerebral blood-flow were not different. It is thought that the higher PI and PSFV values were caused by increased compliance of the vascular bed supplied by the ACA, possibly induced by congestion and oedema of the periventricular white-matter due to ischaemic lesions, which also cause periventricular leukomalacia.     

SLEEP BEHAVIOR OF PRETERM CHILDREN AT THREE YEARS OF AGE

Caregivers of 50 preterm children completed a questionnaire relating to their child's sleep behavior at three years of age. Assessments of the children's EEGs at term and three months, medical status at birth and at four, nine and 24 months, caregiver-child interaction at one, eight and 24 months, the Bayley Scales at 25 months and the Stanford-Binet at five years of age were also obtained. Sleep disturbances were frequently noted at three years of age. However, by five years of age, the number of reported sleep-problem children was greatly reduced, and they were not the same children with sleep problems at three years. Surprisingly, children with the greatest difficulty falling asleep at night at three years were likely to have had fewer medical problems, higher scores on the Bayley scales, and more positive social interactions with their caregivers in the first two years. The relationships among early physical, psychological and social development and sleep behavior are discussed.     

LANGUAGE DEVELOPMENT OF LOW-BIRTHWEIGHT INFANTS AT TWO YEARS

Fifty low-birthweight (LBW) and 18 fullterm normal infants were prospectively evaluated at eight months and two years of age for language development and neurodevelopmental status. The LBW cohort was divided into those who were appropriate for gestational age (AGA) (N = 35) and small for gestational age (SGA) (N = 15) to assess the effect of intra-uterine growth retardation on language development within a premature population. LBW SGA infants lagged significantly behind term infants in both receptive and expressive language, but to a lesser degree than LBW AGA infants. Multiple regression analyses of gestational age, Hollingshead socio-economic status score, and eight-month neurological score as independent variables, and the receptive and expressive language scores as dependent variables, indicated that these three predictor variables had a significant cumulative effect on language development. Language was delayed in 28 per cent of the LBW children at two years.     

SIGNIFICANCE OF PRENATAL, PERINATAL AND POSTNATAL FACTORS IN THE DEVELOPMENT OF AGA PRETERM INFANTS AT FIVE TO SEVEN YEARS

The effects of prenatal, perinatal and postnatal events on developmental outcome at five to seven years of preterm infants with birthweights appropriate for gestational age were investigated in two separate cohorts: one a longitudinal study of 97 infants, the other a cross-sectional study of 249 infants. Among the prenatal variables, the number of minor congenital anomalies was negatively correlated with neurological development, as was the deformation score. The pregnancy optimality score was not significantly related to outcome. Among the perinatal variables, gestational age and birthweight had some significant correlations with development, but birth and neonatal optimality scores were only inconsistently significant in relation to outcome. Socio-economic status was strongly related to language and intellectual development. Infants with gestations of 32 to 36 weeks had a more favourable neurological and intellectual outcome than those born before 32 weeks: however, the former group comprised about 80 per cent of the population studied, so the majority of children with lower function were found in that group.