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Biomedical subjects

L M Dubowitz

Publications and source records attributed to L M Dubowitz.

At least 19 recordsLinked to original sources
PubMed2000

Head growth in infants with hypoxic-ischemic encephalopathy: correlation with neonatal magnetic resonance imaging.

OBJECTIVES: The aims of the study were to establish the relationship between head growth in the first year of life with the pattern on injury on neonatal magnetic resonance imaging (MRI) in infants with hypoxic-ischemic encephalopathy (HIE) and to relate these to the neurodevelopmental outcome. METHODS: Fifty-two term infants who presented at birth with a neonatal encephalopathy consistent with HIE and who had neonatal brain MRI were entered into the study. Head circumference charts were evaluated retrospectively and the head growth over the first year of life compared with the pattern of brain lesions on MRI and with the neurodevelopmental outcome at 1 year of age. Suboptimal head growth was classified as a drop of >2 standard deviations across the percentiles with or without the development of microcephaly, which was classified as a head circumference below the third percentile. RESULTS: There was no statistical difference between the neonatal head circumferences of the infants presenting with HIE and control infants. At 12 months, microcephaly was present in 48% of the infants with HIE, compared with 3% of the controls. Suboptimal head growth was documented in 53% of the infants with HIE, compared with 3% of the controls. Suboptimal head growth was significantly associated with the pattern of brain lesions, in particular to involvement of severe white matter and to severe basal ganglia and thalamic lesions. Suboptimal head growth predicted abnormal neurodevelopmental outcome with a sensitivity of 79% and a specificity of 78%, compared with the presence of microcephaly at 1 year of age, which had a sensitivity of only 65% and a specificity of 73%. The exceptions were explained by infants with only moderate white matter abnormalities who had suboptimal head growth but normal outcome at 1 year of age and by infants with moderate basal ganglia and thalamic lesions only who had normal head growth but significant motor abnormality.

Apgar Score↗
PubMed1998

Abnormal magnetic resonance signal in the internal capsule predicts poor neurodevelopmental outcome in infants with hypoxic-ischemic encephalopathy.

OBJECTIVE: The aim of this study was to establish whether abnormal signal intensity in the posterior limb of the internal capsule (PLIC) on magnetic resonance imaging is an accurate predictor of neurodevelopmental outcome at 1 year of age in infants with hypoxic-ischemic encephalopathy (HIE). METHODS: We have examined 73 term neonates with HIE between 1 and 17 days after birth with cranial magnetic resonance imaging and related the magnetic resonance imaging findings to neurodevelopmental outcome at 1 year of age. RESULTS: All infants with an abnormal signal intensity in the PLIC developed neurodevelopmental impairment although in 4 infants with very early scans the abnormal signal was not apparent until up to 4 days after birth. A normal signal intensity was associated with a normal outcome in all but 4 cases; 3 of these infants had minor impairments and all had persistent imaging changes within the white matter. The 4th infant with a normal signal intensity on day 2 died before a further image could be obtained. The absence of normal signal predicted abnormal outcome in term infants with HIE with a sensitivity of 0.90, a specificity of 1.0, a positive predictive value of 1.0, and a negative predictive value of 0.87. The test correctly predicted outcome in 93% of infants with grade II HIE, according to the Sarnat system. Applying a Bayesian approach, the predictive probability of the test (the probability that the test would predict an outcome correctly) was distributed with a mean of 0.94 and 95% confidence limits of 0.89 to 1.0. CONCLUSION: Abnormal signal intensity in the PLIC is an accurate predictor of neurodevelopmental outcome in term infants suffering HIE.

Basal Ganglia↗
PubMed1997

Cerebellar infarction and atrophy in infants and children with a history of premature birth.

BACKGROUND AND OBJECTIVE: We wished to determine the pattern of cerebellar disease in children with a history of premature birth and early ultrasound evidence of intraventricular haemorrhage and/or parenchymal lesions of the cerebral hemispheres. MATERIALS AND METHODS: MRI findings for all premature infants examined in a 3-year period (73 patients) were reviewed to determine the nature and frequency of lesions of the cerebellum and the results were correlated with clinical data. RESULTS: Six cases of unilateral cerebellar infarction were identified. These involved the posterior inferior cerebellar territory in each case (as well as other territories in two cases). A case of generalised cerebellar atrophy and three cases of unilateral cerebellar hemisphere atrophy were identified as well. In nine of these ten cases abnormalities were also seen elsewhere in the brain. CONCLUSION: The literature describes cerebellar infarction in infants and children as rare, but this study shows that it is not unusual following perinatal haemorrhagic/ischaemic anoxic injury. It is suggested that cerebellar atrophy may also occur as a result of vascular disease.

Arteries↗
PubMed1997

Does the brain regenerate after perinatal infarction?

We have used registered serial magnetic resonance scans to assess the growth of the brain after perinatal infarction in six infants. The initial scans were performed at ages of 4 days to 8 weeks and follow-up studies were performed from 4 days to 21 weeks later. A three-dimensional volume acquisition was performed on each occasion. Rigid body translations and rotations were used to match the images obtained on each occasion. Subtraction of the first image from the second then provided an assessment of the growth of the brain that had occurred between the two examinations. In the early phase of infarction (up to 2 months) low signal areas with clearly defined margins developed at the site of infarction. In the late phase (2 months onwards) growth was seen in the brain at the margins of the infarct in each case, and the size of the infarcted region showed a marked decrease in size. The rate of growth of the brain into the infarcted area exceeded that of the surrounding brain in some cases and was less in others. Growth of undamaged tissue may provide an important mechanism for recovery of the developing brain.

Brain↗
PubMed1997

Chiari I malformation in asymptomatic young children with Williams syndrome: clinical and MRI study.

We report clinical and magnetic resonance imaging findings in two young children, aged 2 years 4 months and 3 years, with Williams syndrome. Both showed a mild global delay, although their neurological examination was completely normal. Their magnetic resonance imaging, however, showed Chiari I malformation and some non-specific changes in the centrum semiovale and in the white matter posterior to the lateral ventricles. Cerebellar tonsils were displaced through the foramen magnum 8.5 and 7.5 mm respectively. Our results suggest that Chiari I malformation can also be a frequent feature in subjects with Williams syndrome even in the absence of overt neurological signs suggestive of it. Whether these children might develop acute signs later is not known at present. Further studies are needed not only to evaluate the incidence of these findings in the global population of subjects with Williams syndrome but also to identify the children who are at risk for developing acute neurological signs.

Arnold-Chiari Malformation↗
PubMed1996

Effect of cerebral lesions on continuous performance test responses of school age children born prematurely.

Examined attention skills, as measured by the Continuous Performance Test (CPT), in a group of 64 children born premature and 40 full-term children, ages 6 to 8 years. Premature children were classified by neonatal cerebral lesions into no lesion, mild lesion, and severe lesion groups. It was predicted that severity of lesion would be associated with CPT performance. While mean differences among the groups of prematures did not reach significance, children with severe lesions made significantly more errors of omission and commission than the full-term comparison group. Children with mild lesions were poorer than full terms in errors of commission. Children with no lesions also made more errors of omission and commission than full terms, suggesting attention deficits secondary to prematurity even in the absence of identified brain lesion. With increasing severity of lesion, increasing percentages of each group were found to perform more than 2 SD below the mean in errors of commission. Results suggest that premature children, with and without identified lesions, are at risk for attention deficits.

Attention↗
PubMed1995

Hypoxic ischaemic encephalopathy: early magnetic resonance imaging findings and their evolution.

Eighteen term infants with hypoxic ischaemic encephalopathy (HIE) were studied with serial magnetic resonance imaging of the brain for up to two months following birth. Important early findings included brain swelling, cortical highlighting, diffuse loss of grey/white differentiation and loss of signal in the posterior limb of the internal capsule (PLIC). These signs were easier to identify on T1-weighted spin echo or inversion recovery sequences than on T2-weighted spin echo sequences. Brain swelling was only seen in the first seven days and was present in all grades of HIE. All other signs persisted and were associated with the subsequent development of major structural changes in the brain. The exact pattern of injury was best identified after the first week of life once the signs of brain swelling had cleared.

Asphyxia Neonatorum↗
PubMed1995

Neonatal neurology, past present and future. A window on the brain.

Interest in the neurology of the newborn has been largely stimulated by the new advances of imaging; CT, cranial ultrasonography and MRI which for the first time allowed diagnosis of brain lesions in the live infant which in the past could only be made by post mortem examinations. (Ultrasound in particular, as it is safe, cheap and portable has been eminantly suitable for routine use in the nurseries to study the incidence, timing and evolution of the lesions in the neonatal period. While MRI is expensive and more difficult to perform it gives superb anatomical definition and is also safe for repeated examinations. It is thus very suitable to follow the evolution of the lesions into infancy). The aim of this presentation is to illustrate how an integrated approach with the combined use of imaging and clinical evaluations lead to a better understanding of antenatal and perinatal factors which may be responsible for the production of these lesions on one hand and the impact of these lesions on later development on the other.

Brain Diseases↗
PubMed1994

Prediction of outcome in children with congenital hemiplegia: a magnetic resonance imaging study.

The degree of Wallerian degeneration (WD) in the corticospinal tracts seen with magnetic resonance imaging (MRI) was correlated with the distribution and severity of congenital hemiplegia in 20 children aged nine months to nine years. All the children had hemispheric lesions diagnosed with ultrasound in the neonatal period: MRI and clinical assessment were performed from nine months to nine years of age. Hemiplegia was graded as mild, moderate or severe and into predominantly upper or lower limb distribution. WD was assessed by the presence or absence of signal intensity changes in the internal capsule on inversion recovery and spin echo sequences and by the asymmetry of the upper brainstem. The degree of asymmetry was estimated by measuring the cross sectional area (CSA) of the brainstem at three levels and calculating the ratio of the measurements between the side of the lesion and the unaffected side. Infarct size was estimated from the CSA of the infarct at the maximum site of the lesion. Both measurements were correlated with the severity of outcome and the site of involvement. There was a better correlation between severity of outcome and brainstem asymmetry (p = 0.003) than severity of outcome and infarct size (p = 0.02). There was also a significant correlation between upper limb involvement and brainstem asymmetry (p = 0.01). As WD estimated by brainstem asymmetry appears early and is easy to measure, it may be a good marker to estimate later impairment in infants with predominantly unilateral hemispheric haemorrhagic/ischaemic lesions diagnosed in the neonatal period.

Brain Stem↗
PubMed1994

Evolution of early hemiplegic signs in full-term infants with unilateral brain lesions in the neonatal period: a prospective study.

Neonates with unilateral hemispheric lesions detected by imaging in the newborn period are at risk for developing hemiplegia. Five full-term infants with predominantly unilateral lesions identified by cranial ultrasound in the neonatal period and confirmed with MRI were examined clinically at regular intervals in order to establish the development, incidence and evolution of later hemiplegia and the evolution of hemiplegic signs. In the neonatal period the infants had either a normal examination or subtle transient abnormalities. Abnormalities were not seen until 6 months of age in infants who developed hemiplegia. The number of hemiplegic signs in each child increased with time, the earlier the signs appeared the more severe the hemiplegia. In some infants deterioration with loss of preexisting skills was observed. At 24 months two of the infants were normal, one had a mild and two a moderate hemiplegia.

Brain Damage, Chronic↗
PubMed1994

Cranial ultrasound and magnetic resonance imaging in hypoxic-ischaemic encephalopathy: a comparison with outcome.

Forty term infants with hypoxic-ischaemic encephalopathy were assessed during the neonatal period with cranial ultrasound and MRI, and the findings were compared with outcome at one year of age. 38 had abnormalities on ultrasound and all had changes on MRI. The incidence of changes in the basal banglia/thalami and periventricular white matter was much greater with MRI than with ultrasound. Changes in the basal ganglia and thalami on MRI were associated with a poor outcome if they had also been detected with ultrasound. However, MRI identified four small infarcts which were not detected by ultrasound. There was no consistent association between periventricular white matter change on MRI and outcome. Regular ultrasound scanning identified all infants with a poor outcome. A normal ultrasound or isolated findings of intraventricular haemorrhage, subarachnoid haemorrhage or transient flares were associated with a normal outcome in 13 of 14 infants.

Brain Ischemia↗
PubMed1994

Patterns of visual impairment associated with lesions of the preterm infant brain.

The visual function of 42 children with haemorrhagic and/or ischaemic cerebral lesions acquired before a gestational age of 35 weeks was examined and related to cranial ultrasound in the neonatal period and to MRI and neurodevelopmental status at follow-up. All 37 children with abnormal ultrasound scans and one of the five with normal ultrasound scans showed impairment of one or more aspects of visual function. While impaired acuity was more frequent among infants with MRI evidence of visual pathway damage, this was not an invariable finding. Normal or near-normal visual acuity did not preclude the presence of other functional visual deficits. The authors conclude that preterm cerebral insults may produce a variety of visual difficulties, the pattern and severity of which cannot be predicted on imaging. Each child therefore requires individual assessment of multiple aspects of visual function.

Brain↗
PubMed1994

Late magnetic resonance imaging and clinical findings in neonates with unilateral lesions on cranial ultrasound.

Twenty-two neonates (11 term and 11 preterm) with predominantly unilateral hemispheric lesions on ultrasound were re-examined clinically and by magnetic resonance imaging (MRI) at between two and nine years of age. The aim was to correlate early ultrasound and late MRI findings with the development of hemiplegia. At follow-up, five children were normal and 15 had hemiplegia, which was mild in seven and moderate in 10. The presence or absence of hemiplegia, or its severity, could not be predicted from either early ultrasound or later MRI appearances.

Brain Diseases↗
PubMed1994

Reversible changes in cerebral activity associated with acidosis in preterm neonates.

Computerized online EEG monitoring in ventilated preterm infants less than 32 weeks' gestation enabled evaluation of the effect of acidosis on cerebral function. All episodes of acidosis were found to be associated with changes in the levels of cerebral activity. In 21 of the 32 episodes, EEG activity returned to pre-acidosis levels after therapeutic intervention. The duration of EEG abnormality was related to the severity of acidosis. However, the time to recovery of the EEG after therapeutic procedures was not related to duration of the EEG change.

Acidosis↗
PubMed1993

Some aspects of the reliability of Touwen's examination of the child with minor neurological dysfunction.

Three studies concerning the inter-rater and test-retest reliability of the Touwen examination are presented. The results of the first study showed that it was not possible to achieve acceptable levels of reliability using the manual as the only reference for instruction. Although the reliability estimates of the total scores were good, inter-rater reliability for the nine groups of items and the individual tasks within them was poor. When methodology and interpretation of performance was agreed between observers, a second study showed that these disagreements diminished. The third study demonstrated that the short-term stability of total scores is good, but reliability for group and individual item scores remained poor.

Child↗
PubMed1993

Proton spectroscopy of the neonatal brain following hypoxic-ischaemic injury.

Proton magnetic resonance spectroscopy was used to examine, within the first month of life, the brains of 11 infants born at term--10 with signs of hypoxic-ischaemic encephalopathy (HIE) and one who was neurologically normal at birth. All the infants had peak resonances on their spectra which could be assigned to N-acetyl-aspartase (NAA), choline-containing compounds (Cho) and creatine plus phosphocreatine (Cr). When neurodevelopmental outcome at one year was correlated with initial spectroscopy findings, the NAA/Cho and NAA/Cr ratios reflected clinical outcome. This study suggests that proton spectroscopy not only provides new information about biochemical changes occurring in the brains of infants with HIE, but also may help to predict outcome within the first month of life.

Brain↗
PubMed1992

The spectrum of leukomalacia using cranial ultrasound.

The spectrum of leukomalacia using cranial ultrasound is discussed. Transient densities not evolving into cystic lesions may represent a mild degree of leukomalacia when persisting for at least a week. A unilateral parenchymal density may be due to bleeding into an ischaemic area, but can also be due to a venous infarction. Cystic leukomalacia can be confidently diagnosed using appropriate equipment and performing sequential scans. A distinction should be made between cysts in the periventricular white matter and cysts in the deep white matter, as the latter carries a higher risk for cerebral visual impairment. Careful ophthalmological examination of these infants will enable us to identify infants with cerebral visual impairment during the first few months of life, allowing the use of special programs aimed at promoting visual development.

Echoencephalography↗