MRI Findings at Term-Corrected Age and Neurodevelopmental Outcomes in a Large Cohort of Very Preterm Infants

BACKGROUND AND PURPOSE

Brain MR imaging at term-equivalent age is a useful tool to define brain injury in preterm infants. We report pragmatic clinical radiological assessment of images from a large unselected cohort of preterm infants imaged at term and document the spectrum and frequency of acquired brain lesions and their relation to outcomes at 20 months.

MATERIALS AND METHODS

Infants born at <33 weeks' gestation were recruited from South and North West London neonatal units and imaged in a single center at 3T at term-equivalent age. At 20 months' corrected age, they were invited for neurodevelopmental assessment. The frequency of acquired brain lesions and the sensitivity, specificity, and negative and positive predictive values for motor, cognitive, and language outcomes were calculated, and corpus callosal thinning and ventricular dilation were qualitatively assessed.

RESULTS

Five hundred four infants underwent 3T MR imaging at term-equivalent age; 477 attended for assessment. Seventy-six percent of infants had acquired lesions, which included periventricular leukomalacia, hemorrhagic parenchymal infarction, germinal matrix-intraventricular hemorrhage, punctate white matter lesions, cerebellar hemorrhage, and subependymal cysts. All infants with periventricular leukomalacia, and 60% of those with hemorrhagic parenchymal infarction had abnormal motor outcomes. Routine 3T MR imaging of the brain at term-equivalent age in an unselected preterm population that demonstrates no focal lesion is 45% sensitive and 61% specific for normal neurodevelopment at 20 months and 17% sensitive and 94% specific for a normal motor outcome.

CONCLUSIONS

Acquired brain lesions are common in preterm infants routinely imaged at term-equivalent age, but not all predict an adverse neurodevelopmental outcome.

Early postnatal maternal trait anxiety is associated with the behavioural outcomes of children born preterm <33 weeks

Maternal ante- and postnatal anxiety have been associated with children's socio-emotional development. Moreover, maternal anxiety has been studied as both a contributing factor and consequence of preterm birth, and children born preterm are more likely to develop behavioural problems compared to term-born controls. This study investigated the association between maternal anxiety measured soon after birth and mental health in 215 ex-preterm children, born at <33 weeks, who participated in the Evaluation of Preterm Imaging Study. Children were followed-up at a median age of 4.6 years (range 4.2-6.6), and received behavioural and cognitive evaluation. Maternal trait anxiety was assessed with the Spielberger State-Trait Anxiety Index at term corrected age. Primary outcome measures were children's Strengths and Difficulties Questionnaire (SDQ) and Social Responsiveness Scale 2 (SRS-2) scores, indicative of generalised psychopathology and autism symptomatology, respectively. IQ was assessed with the Wechsler Preschool and Primary Scales of Intelligence. The final sample, after excluding participants with missing data and multiple pregnancy (n = 75), consisted of 140 children (51.4% male). Results showed that increased maternal trait anxiety at term corrected age was associated with children's higher SDQ scores (β = 0.25, 95% CI 0.09-0.41, p = 0.003, f² = 0.08) and SRS-2 scores (β = 0.15, 95% CI 0.02-0.28, p = 0.03, f² = 0.04). Our findings indicate that children born preterm whose mothers are more anxious in the early postnatal period may show poorer mental health outcomes at pre-school age. Further research is needed to investigate preventative measures that can be offered to high-risk premature babies and their families.

Length of stay and cost analysis of neonates undergoing surgery at a tertiary neonatal unit in England

Introduction There is a lack of knowledge on the average length of stay (LOS) in neonatal units after surgical repair of common congenital anomalies. There are few if any publications reporting the activity performed by units undertaking neonatal surgery. Such activity is important for contracting arrangements, commissioning specialist services and counselling parents. The aim of this study was to describe postnatal LOS for infants admitted to a single tertiary referral neonatal unit with congenital malformations requiring surgery. Methods Data on nine conditions were collected prospectively for babies on the neonatal unit over a five-year period (2006-2011). For those transferred back to their local unit following surgery, the local unit was contacted to determine the total LOS. Only those babies who had surgery during their first admission to our unit and who survived to discharge were included in the study. Cost estimates were based on the tariffs agreed for neonatal care between our trust and the London specialised commissioning group in 2011-2012. Results The median LOS for the conditions studied was: gastroschisis 35 days (range: 19-154 days), oesophageal atresia 33 days (range: 9-133 days), congenital diaphragmatic hernia 28 days (range: 7-99 days), intestinal atresia 24 days (range: 6-168 days), Hirschsprung's disease 21 days (range: 15-36 days), sacrococcygeal teratoma 17 days (range: 12-55 days), myelomeningocoele 15.5 days (range: 8-24 days), anorectal malformation 15 days (range: 6-90 days) and exomphalos 12 days (range: 3-228 days). The total neonatal bed day costs for the median LOS ranged from £8,701 (myelomeningocoele) to £23,874 (gastroschisis). The cost of surgery was not included. Conclusions There is wide variation in LOS for the same conditions in a single neonatal unit. This can be explained by different types and severity within the same congenital anomalies, different surgeons and other clinical confounders (eg sepsis, surgical complications, associated anomalies). These data will enable us to give more detailed information to families following prenatal or postnatal diagnosis. They also allow more detailed planning of resource allocation for neonatal admissions.

Neonatal invasive fungal infection in England 2004-2010

Rates of invasive fungal infection are highest among neonates, especially those of low birthweight. This study aimed to describe the current epidemiology of invasive neonatal fungal infections in a UK neonatal infection surveillance network. From 2004 to 2010 prospective multicentre surveillance was conducted by 14 neonatal units using a web-based database. Clinicians then completed a standardized pro forma for each positive fungal blood and/or cerebrospinal fluid culture. The overall incidence was 2.4/1000 neonatal unit admissions and was highest among babies <1000 g (extreme low birthweight, 18.8/1000). Only five infants (6%) were >1500 g. The majority of infections were caused by Candida albicans (59; 69%) and Candida parapsilosis (17; 20%); 33% of infants had received antifungal prophylaxis. Known risk factors (use of central venous catheter, parenteral nutrition, previous antibiotic use) were common among cases. The attributable case fatality rate was 21% (18/84). Extreme low birthweight infants remain at highest risk of invasive fungal infection and prophylaxis should be particularly considered for this group. The number needing to receive prophylaxis to prevent one case varies significantly among units, hence unit-specific decisions are required. Further research is still needed into the optimal empiric and therapeutic strategies.

Infection control in United Kingdom neonatal units: variance in practice and the need for an evidence base

Infection prevention is a cornerstone of good neonatal care. There are, however, few research data to support infection control approaches in this population. Through a structured telephone interview we surveyed all neonatal units in the United Kingdom to identify infection control issues, practices and policies. Eighty seven percent of the 198 neonatal units participated. Twenty one units (12.2%) had closed with infection control issues in the last year; 14.1% had current infection control concerns; 81.5% of units decolonised MRSA positive infants, but over 15 regimens were used. Wide variations in hygiene measures were identified; 22.1% of units used theatre scrubs for all staff, 7.6% used aprons and 5.8% required gloves to be worn when entering clinical areas. Only 54% required hand washing and alcohol gel before entry to a patient care area; 11.6% required only the use of alcohol gel.

Although infection control issues are resulting in neonatal unit closures and risks to patients, there are considerable variations in hygiene and screening practices. There is little data to support the safety or efficacy of decolonisation in neonatal populations, but this is widely practised. Research needs to be carried out to evaluate the effectiveness of screening practices and decolonisation in order that a consistent evidence-based approach can be applied.

Perinatal cortical growth and childhood neurocognitive abilities

OBJECTIVE

This observational cohort study addressed the hypothesis that after preterm delivery brain growth between 24 and 44 weeks postmenstrual age (PMA) is related to global neurocognitive ability in later childhood.

METHODS

Growth rates for cerebral volume and cortical surface area were estimated in 82 infants without focal brain lesions born before 30 weeks PMA by using 217 magnetic resonance images obtained between 24 and 44 weeks PMA. Abilities were assessed at 2 years using the Griffiths Mental Development Scale and at 6 years using the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), the Developmental Neuropsychological Assessment (NEPSY), and the Movement Assessment Battery for Children (MABC). Analysis was by generalized least-squares regression.

RESULTS

Mean test scores approximated population averages. Cortical growth was directly related to the Griffiths Developmental Quotient (DQ), the WPPSI-R full-scale IQ, and a NEPSY summary score but not the MABC score and in exploration of subtests to attention, planning, memory, language, and numeric and conceptual abilities but not motor skills. The mean (95% confidence interval) estimated reduction in cortical surface area at term corrected age associated with a 1 SD fall in test score was as follows: DQ 7.0 (5.8-8.5); IQ 6.0 (4.9-7.3); and NEPSY 9.1 (7.5-11.0) % · SD(-1). Total brain volume growth was not correlated with any test score.

CONCLUSIONS

The rate of cerebral cortical growth between 24 and 44 weeks PMA predicts global ability in later childhood, particularly complex cognitive functions but not motor functions.

Detection of meticillin-resistant staphylococcus aureus (MRSA) colonization in newborn infants using real-time polymerase chain reaction (PCR)

OBJECTIVE

Meticillin-resistant staphylococcus aureus (MRSA) colonization on neonatal units is a common and important clinical problem. Effectiveness of polymerase chain reaction (PCR) for detecting MRSA nasal colonization of infants was evaluated and compared to culture-based methods. The effect of skin decolonization in affected infants was studied.

METHODS

Paired nasal swabs were collected from infants in our neonatal unit over a 12-month period (September 2007-2008). Colonization with MRSA was determined with a commercially available PCR method and compared to culture.

RESULTS

A total of 696 paired nasal swabs were taken. Three infants were colonized at the beginning and were included. There were positive PCRs in 12 infants. Five infants cultured MRSA from a nasal swab at the same time. No infants were culture-positive when PCR was negative (sensitivity 100%, specificity 99% compared to culture). PCR results were available within 24 h. Five infants were PCR+ and isolated meticillin-sensitive Staphylococcus aureus. This organism gave a false-positive PCR result. Two infants transferred in on broad-spectrum antibiotics were PCR+ and negative by culture. Decolonization led to negative nasal PCR and culture in 4/5 infants to discharge.

CONCLUSIONS

PCR methods are sensitive and specific for detection of MRSA colonization in newborn infants of all gestations with results 1-2 days before culture.

Early high C-reactive protein in infants with open abdominal wall defects does not predict sepsis or adverse outcome

AIM

To study CRP values and relate it to outcome in infants with antenatal diagnosis of gastroschisis, exomphalos and other surgical conditions.

METHODS

Over five years, infants admitted to our neonatal unit with gastroschisis, exomphalos and other surgical diagnoses were identified. Serum CRP measurements in first 5 days were studied. Group one included 33 gastroschisis patients, group two, 18 exomphalos patients, and group three, 38 patients with other surgical diagnoses. Outcome measures included TPN days, time to full feeds and duration of hospitalization.

RESULTS

Infants with gastroschisis were more premature (36.9 vs 38.1 weeks) with lower birth weights (2515 vs 3078 g), than infants with exomphalos. CRP values on admission in gastroschisis group were significantly higher than exomphalos and other diagnoses groups (33.7 +/- 6.4 vs 8.8 +/- 6.0 vs 5.7 +/- 2.0, respectively, p < 0.05). All blood cultures were sterile. There was no relationship between high CRP and death or adverse outcome (TPN days, time to full feeds or duration of hospitalization) in the gastroschisis group.

CONCLUSION

Infants with gastroschisis exhibit high early CRP, which may not indicate sepsis or adverse outcome. This increase can complicate the assessment of these infants. Clinicians should be aware of this finding as it could inform management decisions in this group.

Maturation of cerebral electrical activity and development of cortical folding in young very preterm infants

OBJECTIVE

The aim of this study was to examine the relationship between cortical development and cerebral electrical activity at early gestational ages.

METHODS

We obtained EEGs (7.2+/-3.8 days) and MR brain images (3.2+/-2.9 days) after birth in 17<30 week gestation infants without evidence of focal brain injury The EEGs were assessed for discontinuity and characteristic maturational features (delta brush, occipital and temporal sawtooth); cortical development was quantified from MR scans using a specially designed computer programme to measure cortical folding.

RESULTS

The inter-burst interval shortened and cortical folding increased with increasing post-menstrual age (PMA). In contrast, the minimum duration of bursts was independent of PMA and cortical folding. Delta brush (8-20 Hz activities) was seen at all PMAs; temporal and occipital sawtooth activities were always more prominent than delta brush but were seen less frequently with increasing PMA and complexity of cortical folding.

CONCLUSION

There was a positive correlation between some but not all maturational features of the preterm neonatal EEG and the complexity of whole brain cortical folding and PMA. These relationships were strong for the inter-burst interval, a global measure of maturation, but not strongly seen for regional features such as occipital and temporal sawtooth within this gestational age range.

SIGNIFICANCE

Combining neurophysiological examination with detailed neuroimaging gives insights into developmental changes occurring in the very preterm brains and suggests further comparative studies focusing on measures of focal brain development at different gestational ages.

Universal DNA primers amplify bacterial DNA from human fetal membranes and link Fusobacterium nucleatum with prolonged preterm membrane rupture

A large number of bacterial species have been identified in fetal membranes after preterm labour (PTL) associated with intrauterine infection by microbiological culture. In this study, we have investigated a molecular and bioinformatic approach to organism identification which surmounts the need for specific and diverse microbiological culture conditions required by conventional methods. Samples of fetal membranes were taken from 37 preterm infants, and 6 normal term controls delivered by caesarean section, in which bacteria had been detected by in situ hybridization of 16S ribosomal RNA using a generic probe. Degenerate primers were designed to amplify bacterial 16S ribosomal DNA by PCR and used to amplify bacterial DNA from human fetal membranes. Amplicons were cloned, sequenced and bacteria were identified bioinformatically by comparison of sequences with known bacterial DNA genomes. In situ hybridization using an organism specific probe was then used to confirm the presence of the commonest identified organism in tissue samples. Bacterial DNA amplified from 15/43 samples, all from preterm deliveries, and the bioinformatic approach identified organisms in all cases. Multiple bacteria were identified including Mycoplasma hominis, Pasturella multocida, Pseudomonas PH1, Escherichia coli and Prevotella bivia. The commonest organism Fusobacterium nucleatum was found in 9/15 (60%) of samples. Ten of the 12 samples obtained after prolonged membrane rupture were positive for bacterial DNA, and 7 of these (70%) contained DNA from F. nucleatum. Bacteria from fetal membranes may be identified by molecular and bioinformatic methods. Further work is warranted to investigate the apparent linkage between F. nucleatum, fetal membrane rupture and preterm delivery.

Fetal and neonatal gene therapy: benefits and pitfalls

The current approaches to gene therapy of monogenetic diseases into mature organisms are confronted with several problems including the following: (1) the underlying genetic defect may have already caused irreversible pathological changes; (2) the level of sufficient protein expression to ameliorate or prevent the disease requires prohibitively large amounts of gene delivery vector; (3) adult tissues may be poorly infected by conventional vector systems dependent upon cellular proliferation for optimal infection, for example, oncoretrovirus vectors; (4) immune responses, either pre-existing or developing following vector delivery, may rapidly eliminate transgenic protein expression and prevent future effective intervention. Early gene transfer, in the neonatal or even fetal period, may overcome some or all of these obstacles. The mammalian fetus enjoys a uniquely protected environment in the womb, bathed in a biochemically and physically supportive fluid devoid of myriad extra-uterine pathogens. Strong physical and chemical barriers to infection might, perhaps, impede the frenetic cell division. The physical support and the biochemical support provided by the fetal-maternal placental interface may, therefore, minimize the onset of genetic diseases manifest early in life. The fetal organism must prepare itself for birth, but lacking a mature adaptive immune system may depend upon more primordial immune defences. It is the nature of these defences, and the vulnerabilities they protect, that are poorly understood in the context of gene therapy and might provide useful information for approaches to gene therapy in the young, as well as perhaps the mature organism.

Maternal origin of inflammatory leukocytes in preterm fetal membranes, shown by fluorescence in situ hybridisation

The aim of this study was to determine the maternal or fetal origin of inflammatory leukocytes in fetal membranes from cases of chorioamnionitis. Fetal membranes were collected from male preterm infants and chorioamnionitis was diagnosed histologically. Fluorescence in situ hybridisation for X and Y chromosomes was used to determine the gender of infiltrating leukocytes in the chorion and amnion. Leukocytes, trophoblast and mesenchymal cells were identified using immunohistochemistry for CD45, cytokeratin-7 and vimentin, respectively. Leukocytes present in the chorion and amnion were labelled XX, indicating maternal origin, and these cells were immunoreactive for the leukocyte marker CD45 but not for vimentin or cytokeratin-7. All other cells in the chorion and amnion were labelled XY and of fetal origin. The results indicated that maternal leukocytes invade the amnion and chorion in chorioamnionitis and we suggest that this is part of the maternal inflammatory response to intrauterine infection.

The role of intrauterine bacteria in brain injury

Organisms appear to be present in human fetal membranes without any apparent impact on pregnancy maintenance or the fetal brain. A clear link between chorioamnionitis and fetal brain damage suggests that tissue responses at the feto-maternal interface may be the key determinant of whether preterm labour and brain damage occur.

Congenital microvillous inclusion disease presenting as antenatal bowel obstruction

Prenatal ultrasound has led to confidence in the antenatal diagnosis of intestinal obstruction allowing counseling and birth planning. We describe a male infant of a diabetic mother who had an antenatal diagnosis of distal bowel obstruction. This baby was subsequently found not to have bowel obstruction, but a congenital enteropathy - microvillous inclusion disease. The antenatal scans had demonstrated polyhydramnios as well as multiple fluid-filled dilated loops of bowel in the fetal abdomen. To our knowledge, similar prenatal ultrasound findings have not been previously described in this condition. The baby was delivered in a pediatric surgical center and postnatally there was no evidence of bowel obstruction either clinically or on abdominal X-ray. This baby initially fed well, but became collapsed and acidotic on his third day, having lost 26% of his birth weight due to excessive stool loss. The diagnosis of microvillous inclusion disease was made by electron microscopy of a small bowel biopsy. Congenital microvillous inclusion disease is a very rare inherited enteropathy with high mortality and morbidity. This condition, and other enteropathies, should be considered in cases in which antenatally diagnosed bowel obstruction is not confirmed after birth.