Predictors of neonatal encephalopathy in full-term infants

Myasthenia gravis in pregnancy and birth: identifying risk factors, optimising care

Women with myasthenia gravis (MG) have increased risk of pregnancy complications and an adverse pregnancy outcome. This study examined risk factors for such complications in order to improve the care for pregnant MG women. Through the Medical Birth Registry of Norway, 73 MG mothers with 135 births were identified. Their obstetrical and clinical records were examined. Data on pregnancy, delivery and the newborn were combined with information on mother's disease. The risk for neonatal MG was halved if the mother was thymectomized (P = 0.03). Children with neonatal MG were more likely to display signs of foetal distress during delivery (P = 0.05). Only in one-third of the pregnancies did the patient see a neurologist during pregnancy. These patients used MG medication more often during pregnancy (P = 0.001), and were more likely to be thymectomized (P = 0.007). They also had a higher rate of elective sections (P = 0.009). Thymectomy may have a protective effect against neonatal MG. Neonatal MG can cause foetal distress during delivery. Most MG women benefit from being examined by a neurologist during pregnancy, to minimize risks and select the best delivery mode in collaboration with obstetricians.

The chasm in neonatal outcomes in relation to time of birth in Lebanon

PURPOSE

The purpose of this study was to investigate the relationship between the time of birth and the mortality and morbidity of infants admitted to neonatal intensive care units.

DESIGN

This prospective, cohort study examined the records of women and infants admitted to the NICUs of four hospitals in Beirut, Lebanon, between July 1, 2002, and June 30, 2003. The hospitals selected were university affiliated and had a large number of deliveries (5,152 total for the year 2002-2003).

MAIN OUTCOME VARIABLES

Neonatal mortality and morbidity for infants admitted to the NICU were evaluated in relation to time of birth.

RESULTS

For the whole sample, mortality was higher for infants born during the night shift than for those born during the day shift. Mortality, morbidity, and brain asphyxia rates were also higher for infants born during the night shift and admitted to the NICU. Maternal risk factors and delivery complications were nor consistently higher on the night shift.

Placental pathology and cerebral palsy

Recent classification systems of cerebral palsy call for an assessment of the timing and etiology of brain injury. The placenta is an underused resource for addressing these important questions. An expert assessment of the placental pathology can provide temporally and mechanistically specific data not available from any other source. Key concepts for an understanding of the role of placental pathology are the "sentinel lesion," the high prevalence of thromboinflammatory lesions affecting large fetal placental vessels, the significance of underlying placental reserve, and the realization that placental findings can serve as markers for processes occurring in the mother or fetus.

Does training in obstetric emergencies improve neonatal outcome?

OBJECTIVES

To determine whether the introduction of Obstetrics Emergency Training in line with the recommendations of the Clinical Negligence Scheme for Trusts (CNST) was associated with a reduction in perinatal asphyxia and neonatal hypoxic-ischaemic encephalopathy (HIE).

DESIGN

A retrospective cohort observational study.

SETTING

A tertiary referral maternity unit in a teaching hospital.

POPULATION

Term, cephalic presenting, singleton infants born at Southmead Hospital between 1998 and 2003 were identified; those born by elective Caesarean sections were excluded.

METHOD

Five-minute Apgar scores were reviewed. Infants that developed HIE were prospectively identified throughout this period. The study compared the period 'pre-training' (1998-1999), with the period 'post-training' (2001-2003).

MAIN OUTCOME MEASURES

Five-minute Apgar scores and HIE.

RESULTS

Infants (19,460) were included. Infants born with 5-minute Apgar scores of <or=6 decreased from 86.6 to 44.6 per 10,000 births (P<0.001) and those with HIE decreased from 27.3 to 13.6 per 10,000 births (P=0.032) following the introduction of the training courses in 2000. Antepartum and intrapartum stillbirth at term rates remained unchanged, at about 15 and 4 per 10,000 births, respectively.

CONCLUSION

The introduction of obstetric emergencies training courses was associated with a significant reduction in low 5-minute Apgar scores and HIE. This improvement has been sustained as the training has continued. This is the first time an educational intervention has been shown to be associated with a clinically important, and sustained, improvement in perinatal outcome.

Hyperthermia in the delivery: potential impact on neonatal mortality and morbidity

In recent years, it has become apparent that temperature can modify the extent of hypoxic-ischemic brain injury. There is an increasing body of experimental and clinical data showing a reduction in the extent of brain injury after intrapartum hypoxia-ischemia with induced hypothermia. Conversely, there is experimental evidence indicating a worsening of cerebral injury during or after ischemia under conditions of elevations in temperature in a variety of animal species. Neonatal experimental studies are limited, and the data are conflicting. This article addresses the available evidence concerning the potential impact of hyperthermia in the delivery on neonatal mortality and morbidity.

Autism following a history of newborn encephalopathy: more than a coincidence?

Between June 1993 and December 1996, 276 term newborn infants with encephalopathy and 564 randomly selected term controls were enrolled in a population-based study of moderate and severe term newborn encephalopathy (NE) in Western Australia. During comprehensive neurobehavioural and cognitive follow-up of all patients and controls at 3 years and again at 5 years of age we found an unexpected but strong association between NE and autism spectrum disorders (ASDs). A diagnosis of ASD by age 5 years was reached using criteria according of the Diagnostic Statistical Manual, 4th edition. Linking records to the Western Australian Disability Services Commission Register ensured that no child in the study with ASD was missed. By age 5 years, 37 (13.4%) infants with NE and one (0.2%) control had died. Among the 239 survivors of NE, 12 (5%) were diagnosed with an ASD. Of these, 10 (4.2%) met the full criteria for autism, one had pervasive developmental disorder-not otherwise specified, and one had Asperger syndrome. Among the 563 surviving controls, five (0.8%) were diagnosed with an ASD: three with autism, one with autism/possible Asperger syndrome, and one with Asperger syndrome. Compared with the controls, the children who had experienced NE were 5.9 times (95% confidence interval 2.0-16.9) more likely to have been diagnosed with an ASD.

Xenon preconditioning reduces brain damage from neonatal asphyxia in rats

Xenon attenuates on-going neuronal injury in both in vitro and in vivo models of hypoxic-ischaemic injury when administered during and after the insult. In the present study, we sought to investigate whether the neuroprotective efficacy of xenon can be observed when administered before an insult, referred to as 'preconditioning'. In a neuronal-glial cell coculture, preexposure to xenon for 2 h caused a concentration-dependent reduction of lactate dehydrogenase release from cells deprived of oxygen and glucose 24 h later; xenon's preconditioning effect was abolished by cycloheximide, a protein synthesis inhibitor. Preconditioning with xenon decreased propidium iodide staining in a hippocampal slice culture model subjected to oxygen and glucose deprivation. In an in vivo model of neonatal asphyxia involving hypoxic-ischaemic injury to 7-day-old rats, preconditioning with xenon reduced infarction size when assessed 7 days after injury. Furthermore, a sustained improvement in neurologic function was also evident 30 days after injury. Phosphorylated cAMP (cyclic adenosine 3',5'-monophosphate)-response element binding protein (pCREB) was increased by xenon exposure. Also, the prosurvival proteins Bcl-2 and brain-derived neurotrophic factor were upregulated by xenon treatment. These studies provide evidence for xenon's preconditioning effect, which might be caused by a pCREB-regulated synthesis of proteins that promote survival against neuronal injury.

Retrospective review of the epidemiology of epilepsy in special schools for children with cerebral palsy, learning difficulties, and language and communication difficulties

PURPOSE OF THE STUDY

To determine in children the proportion and characteristics of epilepsy associated with cerebral palsy, learning difficulties and language and communication difficulties in a specific population of two special schools.

BASIC PROCEDURES

Retrospective review of case notes for 142 children in two special schools (school A and school B) in Newcastle, UK MAIN FINDINGS: School A had more children with learning difficulties (X2=32.41, p<0.01) and active epilepsy (X2=3.03, p=0.08) than school B. There were more children with cerebral palsy (X2=9.56, p<0.01) and language and communication problems (X2=4.25, p=0.03) at school B compared to school A. Active epilepsy is significantly more common in children with cerebral palsy (X2=7.58, p=0.01). All children with cerebral palsy and learning difficulties had epilepsy (n=6). Although not statistically significant, those children who developed epilepsy within the first 24 hours of life were more likely to have cerebral palsy than those who developed epilepsy later in life (X2=3.10, p=0.08). Those children with cerebral palsy tended to have a lower birth weight (t=3.15, p<0.01) and a shorter gestation (t=3.17, p<0.01) than children without cerebral palsy.

PRINCIPAL CONCLUSIONS

The data supports evidence from previous studies, demonstrating that epilepsy commonly accompanies cerebral palsy, thus complicating this difficult chronic condition. We show an association between both low birth weight and gestational age, and early age of onset of seizures, in children with cerebral palsy. This illustrates the importance, in these children, of past medical history from birth to determine risk factors for epilepsy later in life.

Perinatal asphyxia pathophysiology in pig and human: A review

In utero fetuses are evidently exposed to several factors that cause an interruption of the oxygen flow through the umbilical cord causing asphyxia leading to hypoxia and metabolic acidosis. These conditions are important causes of intra-partum and neonatal mortality. The main objective of this review is to provide current information regarding the pathophysiology of asphyxia in piglets around parturition; the physiological mechanisms invoked by affected piglets to compensate perinatal hypoxemia are discussed. This review also addresses some similarities and differences of asphyxia between piglets and other mammals, including human neonates. Metabolic acidosis and hypoxia are sequela to asphyxia and can cause profound health effects in postnatal performance because of an abnormal suckling, a reduced absorption of colostrum and inadequate passive transfer of neonatal immunity. Acidosis also cause hypothermia, increased mortality and reduced survival in neonates. One of the first deleterious effects of intrauterine hypoxia is the expulsion of meconium into the amniotic sac leading to meconium staining of the skin, and in severe cases, meconium aspiration into the lungs. Even though there have been technological changes and improvements in husbandry, piglet mortality due to asphyxia remains a major problem. One potential alternative to reduce neonatal mortality in pigs is the monitoring of fetal stress during birth and the implemention of strategies such as the Apgar score, that is often used in human pediatrics. It is also important to consider the physiological, behavioral and biochemical changes that take place during parturition which subsequently impact the vitality, maturity and development of neonatal pigs. Understanding the pathophysiology of fetal hypoxia should help practitioners and farmers implement more effective delivery techniques aimed at reducing neonatal mortality and improving postnatal performance.

Neonatal encephalopathy and cerebral palsy revisited: the current state of knowledge and the impact of american college of obstetricians and gynecologists task force report

OBJECTIVES

To re-assess obstetrician-gynecologists' knowledge of neonatal encephalopathy and cerebral palsy after publication of the ACOG/AAP Task Force report.

STUDY DESIGN

A questionnaire investigating knowledge of neonatal encephalopathy and cerebral palsy was mailed to 1060 members of ACOG, 337 of whom participated in a similar study in 2001.

RESULTS

There was a strong association between familiarity with ACOG documentation and knowledge of neonatal encephalopathy (NE) and cerebral palsy (CP) (p<0.001). As with obstetricians surveyed in 2001, knowledge gaps remain. Performance was better on practices questions than knowledge questions. About one-third (34.2%) of the physicians said their knowledge of neonatal encephalopathy was poor or deficient; the majority (76%) rated their residency training as inadequate to marginal.

CONCLUSION

The results indicate better knowledge of neonatal encephalopathy and cerebral palsy among physicians more familiar with the Task Force report. There is a clear need for emphasis on these topics during training and continuing medical education.

Intrapartum complications associated with malformations of cortical development

Birth asphyxia can be an early sign of cerebral palsy, the effect of an antenatal anomaly rather than its cause. The objective of this study was to evaluate the occurrence of intrapartum complications in patients with malformation of cortical development. The data were retrospectively assessed and compared with a control group of children with idiopathic epilepsy. Intrapartum complications were reported in 22 (31.5%) patients, as opposed to only 2 in the control group (p < 0.001). Patients with cortical malformations frequently present intrapartum complications, which could lead to the misdiagnosis of hypoxic-ischemic encephalopathy.

Cesarean section upon request: is it appropriate for everybody?

The request for cesarean section without medical indication has become one of the dilemmas faced by the obstetrician. Most recent studies that compare vaginal delivery with elective cesarean section find them equally safe. This comparison is lacking in the option of trial of labor, which may result in an assisted vaginal delivery or intrapartum cesarean section, both with increased morbidity and mortality for the mother and newborn. When considering elective cesarean section, the obstetrician has to take into account improved anesthetic techniques and the decrease in morbidity and mortality after cesarean section with the trend toward patient autonomy to decide on her own treatment. On the other hand, the obstetrician has to advise his patient of the best treatment with respect to possible complications in future pregnancies, such as placental complications and increased morbidity and mortality resulting from repeated cesarean sections. The advantage of cesarean section for pelvic floor protection does not exist after three consecutive cesarean sections and equals the rate of urinary incontinence after consecutive three vaginal deliveries. In countries such as ours, where most women wish for several children, the risk-benefit balance is toward repeated spontaneous vaginal deliveries.

Choline exposure reduces potentiation of N-methyl-D-aspartate toxicity by corticosterone in the developing hippocampus

Exposure to high levels of glucocorticoids (GCs) may adversely affect neuronal viability, particularly in the developing hippocampus, via increased function or sensitivity of N-methyl-D-aspartate (NMDA)-type glutamate receptors. Conversely, choline supplementation in the developing brain may reduce the severity of subsequent insult. The present studies aimed to examine the extent to which short-term exposure to high concentrations of corticosterone would produce neuronal injury mediated by NMDA receptor activity. These studies also assessed the ability of choline to prevent this form of injury via interactions with nicotinic acetylcholine receptors (nAChRs) expressing the alpha7 subunit. Organotypic hippocampal slice cultures derived from neonatal rat were pre-treated for 72 h with corticosterone (100 nM) alone or with choline (0.1-10 mM), prior to a brief (1 h) NMDA exposure (5 microM). NMDA exposure produced significant cellular damage, reflected as increased fluorescence of the non-vital marker propidium iodide, in the CA1 region. While exposure to corticosterone alone did not produce damage, pre-treatment of cultures with corticosterone markedly exacerbated NMDA-induced toxicity. Pre-treatment with choline (> or =1 mM) alone or in combination with corticosterone markedly reduced subsequent NMDA toxicity, effects blocked by co-exposure to methyllycaconitine (100 nM), an antagonist active at nAChRs expressing the alpha7 subunit. These data suggest that even short-term exposure to high concentrations of GCs may adversely affect neuronal viability and that choline supplementation protects the brain from NMDA receptor-mediated damage, including that associated with hypercortisolemia.

The Scottish perinatal neuropathology study: clinicopathological correlation in early neonatal deaths

BACKGROUND

A proportion of neonatal deaths from asphyxia have been shown to be associated with pre-existing brain injury.

OBJECTIVES

(a) To compare the epidemiology of infants displaying signs of birth asphyxia with those not showing signs; (b) to examine the neuropathology and determine if possible the timing of brain insult comparing asphyxiated with non-asphyxiated infants; (c) to compare the clinical features of those born with birth asphyxia with and without pre-labour damage.

METHODS

Over a two year period, all 22 Scottish delivery units collected clinical details on early neonatal deaths. Requests for post mortem included separate requests for detailed neuropathological examination of the brain. Infants were classified into two groups: birth asphyxia and non-birth asphyxia. Clinicopathological correlation was used to attempt to define the time of brain insult.

RESULTS

Detailed clinical data were available on 137 of 174 early neonatal deaths that met the inclusion criteria. Seventy of 88 parents who had agreed to post mortem examination consented to a detailed examination of additional samples from the brain; in 53 of these cases the infant was born in an asphyxiated condition. All asphyxiated and encephalopathic infants, 38% of mature and 52% of preterm infants with features of birth asphyxia but without encephalopathy, and only one of 12 infants without any signs of birth asphyxia showed damage consistent with onset before the start of labour.

CONCLUSIONS

In a large proportion of neonatal deaths, brain injury predates the onset of labour. This is more common in infants born in an asphyxiated condition.

Visual function at school age in children with neonatal encephalopathy and low Apgar scores

OBJECTIVE

To assess different aspects of visual function at school age in children who suffered from neonatal encephalopathy.

METHOD

Thirty nine full term infants with neonatal encephalopathy, low Apgar scores, and early neonatal imaging were studied using a battery of tests assessing different aspects of visual function (crowding acuity, stereopsis, visual fields) at school age. The results were compared with brain magnetic resonance imaging (MRI) findings and, when possible, with the results of the assessment of visual function performed at 5 and 12 months, available in 24 of the 39 children examined at school age.

RESULTS

Sixteen of the 39 children (41%) had abnormal results at school age in at least one of the visual tests used. Seven of these 16 were untestable on all tests. The remaining 23 children (59%) had normal results.

CONCLUSIONS

The presence and severity of visual impairment was related to the severity of brain lesions. Moderate or severe basal ganglia lesions and severe white matter changes were always associated with abnormal visual function. Infants with normal MRI, minimal basal ganglia lesions, and minimal or moderate white matter involvement tended to have normal vision. It was also found that the assessment of visual function performed in the first year was a reliable indicator of visual function at school age. With two exceptions, the results on the 5 month visual assessment were predictive of visual outcome at school age. In the remaining two cases, a normal visual outcome at 5 years was associated with visual abnormalities at 5 months but these had already normalised by the age of 1 year.

One-year neurodevelopmental outcome after moderate newborn hypoxic ischaemic encephalopathy

OBJECTIVES

To define the 1-year neurodevelopmental outcome for survivors of moderate (Sarnat stage 2) neonatal hypoxic-ischaemic encephalopathy (HIE) to facilitate appropriate parental counselling.

METHODS

Hospital-based retrospective review of admissions to a tertiary newborn intensive care unit between 1988 and 2000. All babies admitted for seizures were reviewed and those in whom the probable diagnosis was moderate HIE were identified from chart review. Perinatal variables, number of anticonvulsants, duration of hospital stay and 1-year neurodevelopmental outcome was recorded in survivors.

RESULTS

Fifty-three babies who survived probable moderate HIE were identified. Forty-two of these were seen at 1 year of age. Of these, 22 (52%) had normal development and neurological examination and four (9.5%) had mild developmental delay with normal neurological examination. Thirteen babies (31%) had cerebral palsy, 11 of whom also had developmental delay. Two infants (5%) who had been severely impaired at 6 months died before 1 year of age. Overall, 36% of survivors of the neonatal period had significant disability and or had died by 1 year of age. Duration of anticonvulsant treatment and length of hospital stay were significantly related to adverse outcome.

CONCLUSIONS

These data suggest morbidity rates after moderate HIE in the upper end of the range previously described in the literature. Systematic longer-term follow up of this high-risk group of infants is needed.

Thyroid hormone supplementation for the prevention of morbidity and mortality in infants undergoing cardiac surgery

BACKGROUND

Paediatric studies have demonstrated that cardiopulmonary bypass is associated with a decline in thyroid hormone levels. Adult patients who undergo open heart surgery and receive triiodothyronine supplementation have demonstrated a dose-dependent increase in cardiac output which has been associated with an improved clinical outcome. Thyroid hormone supplementation in infants may also reduce post-operative morbidity and mortality.

OBJECTIVES

To determine if peri-operative thyroid hormone supplementation or replacement in infants undergoing cardiac surgery on cardiopulmonary bypass improves post-operative and longer term morbidity and mortality.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of The Oxford Database of Perinatal Trials, MEDLINE (1966 - December 2003), EMBASE (1980 - December 2003), CINAHL (1982 - December 2003), The Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2003), previous reviews including cross references, abstracts, conferences, symposia proceedings, expert informants and journal handsearching in the English language.

SELECTION CRITERIA

All trials using random allocation to peri-operative thyroid hormone therapy (supplementation or replacement) compared to control (placebo or no therapy) in infants (birth to one year of age) undergoing cardiac surgery requiring cardiopulmonary bypass. Thyroid hormone therapy must be tri-iodothyronine.

DATA COLLECTION AND ANALYSIS

Primary clinical outcomes included measures of post-operative morbidity and mortality. The standard methods of the Cochrane Neonatal Review Group were used in the assessment of trial quality. Treatment effects were expressed using relative risk (RR) and mean difference (MD).

MAIN RESULTS

Two very small studies were identified that tested peri-operative thyroid hormone supplementation or replacement in infants aged less than one year undergoing cardiac surgery (Chowdhury 2001; Portman 2000). In the Chowdhury 2001 study, a subgroup of nine neonates was eligible for this review. No deaths occurred during either study. Chowdhury 2001 found no significant effect of peri-operative thyroid hormone supplementation in neonates on either length of hospital stay or duration of mechanical ventilation. Portman 2000 found no significant difference in dopamine requirements for the treatment versus control groups for the first 24 hours post operatively, while in the Chowdhury neonatal subgroup, inotrope requirements were significantly lower in the treatment group. Portman 2000 reported significant differences between the two groups at 1 and 24 hours post operatively for free T3 and at 1 hour post operatively for total T3 levels. Total T4 levels showed no significant difference between groups, either pre-cardiopulmonary bypass or up to 72 hours post operatively.

REVIEWERS' CONCLUSIONS

At present, there is a lack of evidence concerning the effects of tri-iodothyronine supplementation in infants undergoing cardiac surgery. Further randomised controlled trials which include sufficiently large subject numbers in a variety of different age strata (neonates, infants and older children) need to be undertaken.

Unselected low-risk pregnancies and the effect of continuous intrapartum fetal heart rate monitoring on umbilical blood gases and cerebral palsy

OBJECTIVE

Our purpose was to evaluate the clinical validity of electronic fetal heart rate monitoring to detect fetal acidemia and to evaluate the prevalence of cerebral palsy in unselected low-risk pregnancies.

STUDY DESIGN

We selected two secondary and two tertiary level institutions in which 10,030 infants were born. Among them, 5546 of the pregnancies were low-risk pregnancies by antepartum evaluation. The fetal heart rate patterns were interpreted according to the guidelines of the National Institute of Child Health and Human Development. The correlations between the fetal heart rate pattern and umbilical blood gases and the fetal heart rate pattern and cerebral palsy were studied. Spastic cerebral palsy was diagnosed at > or =1 year by pediatric neurologists. Statistics included unpaired t test, contingency table with chi(2) and Fisher tests, and one-way analysis of variance with Bonferroni/Dunn test.

RESULTS

On the basis of the severity of decelerations, frequency of decelerations, and decreased variability, umbilical pH, and Po(2) level were decreased accordingly, and incidence of pH<7.1 was increased. Sensitivity and false-positive rate of nonreassuring fetal heart rate patterns for fetal acidemia were 63% and 89%. There were nine cerebral palsy cases: six of the cases were preexisting asphyxia before monitoring was initiated, two of the cases were cytomegaloviral infections, and one of the cases was a maternal amniotic fluid embolism.

CONCLUSION

In low-risk pregnancies, intrapartum fetal heart rate monitoring was useful to detect fetal acidemia. Cerebral palsy caused by intrapartum asphyxia was restricted to unavoidable accidents under continuous fetal heart rate monitoring.

Etiology of cerebral palsy

Cerebral palsy has a complex and multifactorial etiology. Approximately 5%-10% of cases can be ascribed to perinatal hypoxia, but the vast majority of cases are caused by the interplay of several risk factors and antenatal, perinatal, and neonatal events. The strongest risk factors include prematurity and low birth weight. The prevalence of cerebral palsy has remained constant despite improvements in obstetric and neonatal care. For a long time, the only causal factors explored to account for risk for cerebral palsy were complications of labor and delivery. As other periods have been investigated, new associations have come to light. The current understanding of contributors to the risk for cerebral palsy is still incomplete. Multiple causes may interact by way of excitotoxic, oxidative, or other converging pathophysiologic pathways. A single factor, unless present to an overwhelming degree, often may be insufficient to produce cerebral damage, whereas two or three interacting pathogenic assaults may overwhelm natural defenses and produce irreversible brain injury. The low prevalence of cerebral palsy makes the formal testing of preventative strategies difficult. There is a need for such strategies to be carefully assessed in well designed, multicenter, randomized, controlled trials before becoming part of clinical practice, however, so that the balance between harm and benefit is known in advance.

Neonatal seizures and brain damage

There are four unresolved clinical issues at bedside with respect to the recognition, differential diagnosis, prognosis, and treatment of infants who present with seizures. There is also an overriding fifth question which bridges these four clinical issues, based on a laboratory researcher's perspective at the "bench". Given the increasing understanding of the neurobiologic and pathophysiologic explanations for seizures in animal models, one must consider the question of whether neonatal seizures cause brain injury or are a surrogate of injury resulting from other etiologies.

Challenge of conducting trials of neuroprotection in the asphyxiated term infant

There has been much progress in understanding the pathogenesis of hypoxic-ischemic brain injury in the near-term and term infant. Although gaps in our knowledge base persist, advances over the past two decades have led to the development of specific brain oriented therapies directed at critical events contributing to tissue damage. The primary goal of these interventions is to prevent or attenuate neurologic and developmental sequelae of brain injury. Examples of current potential treatments include modest reductions in brain temperature, receptor antagonists of excitatory neurotransmitters, reductions in O2 free radicals, blockade of inflammatory mediators, and inhibition of apoptotic pathways. At present, some of these treatments have sufficient animal data that demonstrate benefit, to justify moving experiments from the laboratory to the clinical arena. Modest hypothermia represents the neuroprotective intervention that has been investigated in the most complete fashion for the newborn, and there are multiple ongoing clinical trials testing its efficacy. This review will address specific challenges that are pertinent to the evaluation of any neuroprotective therapy implemented shortly after birth. Specific issues to be covered include the therapeutic window, establishing a diagnosis of hypoxic-ischemic encephalopathy, patient selection, characteristics of an effective therapy, safety considerations, appropriate outcome variables, and sample size considerations. Since clinical trials of brain hypothermia are in progress, many of these issues will be addressed from the perspective of this specific intervention.

Cesarean section on demand

The safety of cesarean section has improved dramatically over the past 50 years. During the past 20 years a greater awareness of and discussion about the symptomatic morbidity that can result for women following vaginal delivery has occurred and women's expectations for the outcome of pregnancy for them and their babies has increased. A culture of choice has been promoted in recent years, but contrary to the anticipated demand for less obstetric intervention by those promoting choice, there has been an increase in demand for delivery by cesarean section rather than the reverse. With the balance in favor of benefit for the baby from delivery by cesarean section, it is now difficult to sustain the argument favoring vaginal delivery rather than planned cesarean section, using maternal morbidity and mortality statistics. A critical evaluation of the costs indicates that there are probably few grounds for denying women their request for cesarean section for economic reasons. It seems likely, therefore, that in the near future those advising women on the options for delivery will need to ensure that the risks of vaginal delivery are explained as well as those for planned cesarean section.

Intrapartum fever at term: serum and histologic markers of inflammation

OBJECTIVE

This study was undertaken to determine whether intrapartum fevers at term are associated with markers of acute inflammation in maternal, fetal, and placental compartments.

STUDY DESIGN

Term cases with intrapartum fever (temperature >/=100.4 degrees F) were recruited with gestational age-matched controls. Maternal serum and umbilical vein blood were collected and assayed for interleukin-6 (IL-6) levels. Placentas were examined for histologic chorioamnionitis. Demographic and clinical data were collected and compared between cases and controls.

RESULTS

Forty-seven case-control pairs were analyzed. Maternal IL-6 levels were higher in cases than in controls (median of 145 pg/mL vs 42 pg/mL, P <.0001). Umbilical vein IL-6 levels also were higher in cases than controls (median 9 pg/mL vs 3.5 pg/mL, P =.01), but more than half of levels in cases were below 11 pg/mL. Only 31.1% of febrile cases had moderate or severe histologic chorioamnionitis. Multivariable logistic regression identified maternal serum IL-6 levels, nulliparity, and number of vaginal examinations as the major predictors of intrapartum fever at term.

CONCLUSION

The maternal inflammatory response as measured by maternal serum IL-6 levels is a strong marker for term intrapartum fever. The much weaker association of fetal and placental inflammatory responses suggest a smaller than expected contribution of intra-amniotic inflammation to term intrapartum fevers.

Chorioamnionitis and brain injury

The limited available evidence supports a strong association of chorioamnionitis with neonatal encephalopathy and CP in the term infant. The association of chorioamnionitis with depressed Apgar scores or neonatal seizures and with CP is equivocal in the preterm infant. Different study results may be related to differences in study populations, perhaps specifically to differences in susceptibility by stages of neurologic development as well as differences in gene frequencies associated with inflammation and thrombophilia. We require further understanding of the normal roles of cytokines in brain development, pregnancy, and inflammatory homeostasis before clinical interventions directed at cytokines, their receptors, or the inflammatory process are considered.

The postnatal management of the asphyxiated term infant

Investigations in animal models of hypoxic-ischemic injury have not translated into clinical trials of success because of the complex pathology of hypoxic-ischemic brain injury in neonates, the difficulty in defining the onset and duration and severity of the injury, the underlying predisposing disorders of the mothers or the infant, the side effects of many of the investigational drugs precluded clinical use, and many of the investigational agents interfered with only one step of the cascade of events that lead to brain injury. It is possible that a combination of therapeutic agents, including those that affect different levels of the cascade to cell death, will have the greatest neuroprotective effects. Modest hypothermia postpones secondary energy failure and can prolong the window while pharmacotherapeutic agents can be used. It is possible that in the future, sequential administration of agents or strategies that are initiated in the intrapartum period and continued postnatally will be the optimum method for treating infants who are at highest risk for brain injury following acute hypoxic-ischemic asphyxia.

A confidential enquiry into cases of neonatal encephalopathy

OBJECTIVES

To assess the quality of care and timing of possible asphyxial events for infants with neonatal encephalopathy; to compare the quality of care findings with those relating to the deaths from the Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI); and to assess whether the confidential enquiry method is a useful clinical governance tool for investigating morbidity.

DESIGN

Independent, anonymised, multidisciplinary case reviews.

SETTING

Trent Health Region, UK.

PATIENTS

All cases of grade II and III neonatal encephalopathy born in 1997, excluding those due to congenital malformation, inborn error of metabolism, or infection. All CESDI deaths thought to have resulted from intrapartum asphyxia in 1996 and 1997.

MAIN MEASURES

Quality of care provided, timing of possible asphyxial episodes, and the source and timing of episodes of suboptimal care.

RESULTS

Significant or major episodes of suboptimal care were identified for 64% of the encephalopathy cases and 75% of the deaths. An average of 2.8 and 2.5 episodes of suboptimal care were identified for the deaths and encephalopathy cases respectively. Over 90% of episodes involved the care provided by health professionals. Results were fed directly back to the units concerned on request and changes in practice have been reported.

CONCLUSIONS

The findings were very similar for the encephalopathy cases and the deaths. We have demonstrated that with minor adaptations the CESDI process can be applied to serious cases of morbidity. However, explicit quality standards, control data, and a more formal mechanism for the implementation of findings would strengthen the confidential enquiry process as part of clinical governance.

Influence of maternal, obstetric and fetal risk factors on the prevalence of birth asphyxia at term in a Swedish urban population

BACKGROUND

The influence of maternal, obstetric and fetal risk factors on the prevalence of birth asphyxia at term in a Swedish urban population.

OBJECTIVE

To investigate risk factors for Apgar score-defined birth asphyxia, birth asphyxia with hypoxic-ischemic encephalopathy and birth asphyxia-related death/disability.

MATERIAL AND METHODS

Retrospective case-control study in term neonates with birth asphyxia defined as Apgar score < 7 at 5 min. Cases originating from nonasphyctic causes (e.g. infection, maternal sedation) were excluded. Hypoxic-ischemic encephalopathy was diagnosed according to criteria by Sarnat. Maternal, obstetric and fetal risk factors were registered in 225 cases of birth asphyxia diagnosed in 42 203 live births occurring in the urban Swedish population studied. A matched control group was used for statistical evaluation.

RESULTS

Asphyxia was associated with single civil status, OR = 7.1 (95%CI 2.0, 27.6); intrauterine meconium release, OR = 4.1 (95%CI 1.8, 9.8); operative delivery, OR = 8.7 (95%CI 3.4, 24.6); breech delivery, OR = 20.3 (95%CI 3.0, 416.5); oxytocin augmentation, OR = 2.9 (95%CI 1.4, 6.3); cord complication, OR = 15.8 (95%CI 2.1, 341.5); external compression to assist delivery OR = 6.2 (95%CI 1.3, 45.7); and cardiotocography score, OR = 0.5 (95%CI 0.4, 0.6). Normal fetal heart rate variability, OR = 0.4 (95%CI 0.2, 0.6), repeated late decelerations irrespective of amplitude or repeated variable decelerations, OR = 29.4 (95%CI 5.7, 540.8) or occasional late or variable decelerations, OR = 2.2 (95%CI 1.3, 3.8), and no accelerations, OR = 5.2 (95%CI 2.0, 16.4), were associated with asphyxia. Operative or instrumental delivery was more common in all three asphyxia groups compared with controls. Leanness was a risk factor for asphyxia and for hypoxic-ischemic encephalopathy. Maternal age, smoking and illnesses, time of delivery (day/night, seasonal) and previous caesarean section were not associated with birth asphyxia.

CONCLUSIONS

An association between neonatal asphyxia and cardiotocography parameters, intrauterine meconium release, operative delivery, breech delivery, single civil status, oxytocin augmentation, cord complication, external compression to assist delivery and neonatal leanness was found. Abnormal fetal heart rate variability, repeated late decelerations irrespective of amplitude or repeated variable decelerations, occasional late or variable decelerations and no accelerations were associated with asphyxia.

Is temperature important in delivery room resuscitation?

The possibility that temperature may affect the outcome of resuscitation from severe perinatal asphyxia has been a long-standing focus of research. Experimentally it is now well established that even small changes in temperature during severe hypoxia-ischemia critically modulate outcome. Clinical and experimental studies have now shown that hypoxic-ischemic injury continues to evolve after resuscitation. Experimentally, prolonged mild to moderate hypothermia can dramatically reduce this delayed injury, while mild hyperthermia over the same period worsens injury. Indeed there are data indicating that moderate post-ischemic hyperthermia can be deleterious as late as 24 h after reperfusion. Hypothermia has significant potential adverse effects, and at present its clinical use is restricted to large randomized controlled trials. The present paper reviews evidence suggesting that both primary prevention of maternal pyrexia during labour, and secondary prevention of hyperthermia after neonatal resuscitation, have the potential to significantly reduce the consequences of perinatal hypoxia-ischemia.

Developmental outcomes of newborn encephalopathy in the term infant

Newborn encephalopathy is a clinically defined condition of abnormal neurological behaviours in the newborn period. Though most cases have their origin in the preconceptional and antepartum period, newborn encephalopathy represents a crucial link between intrapartum events and permanent neurological problems in the child. The birth prevalence of newborn encephalopathy ranges from 1.8 to 7.7 per 1000 term live births according to the definition used and the population to which it is applied. Few studies have investigated the outcomes of newborn encephalopathy other than for cases solely attributed to intrapartum hypoxia. These adverse outcomes range from death to cerebral palsy, intellectual disability, and less severe neurological disabilities such as learning and behavioural problems. Outcomes following newborn encephalopathy may vary from country to country with 9.1% of affected babies dying in the newborn period in Western Australia and 10.1% manifesting cerebral palsy by the age of two. These compare to a case fatality of 30.5% in Kathmandu and a cerebral palsy rate of 14.5% by one year of age. The study by Robertson et al which followed children with hypoxic ischaemic encephalopathy found an incidence of impairment of 16% among survivors assessed at 8 years with 42% requiring school resource room help or special classes. This review emphasises the great need for comprehensive clinical and educational assessment as these infants approach school entry to enable appropriate educational provisions to be made.

Indications for caesarean section

Caesarean section rates are rising. Caesarean section confers an increase in maternal mortality and morbidity as well as having considerable financial implications. Caesarean section is usually justified by the assumed benefit for the fetus. These benefits are often unquantified and based on scanty evidence. The changing trends in the rates of caesarean section for various indications may be explained partly by improved anaesthetic and neonatal techniques. Cultural changes and expectations in the general population and obstetricians' fear of litigation may have made the changing rate and indications for caesarean section seem more acceptable. There is little research evidence in this area. The evidence that caesarean section is the optimal mode of delivery for various major indications is critically examined. The obstetrician is under an obligation to share the evidence that caesarean section is the optimum mode of delivery with the pregnant woman and her birth attendants to allow the woman to make wise decisions about her management.

Regional changes in kynurenic acid, quinolinic acid, and glial fibrillary acidic protein concentrations in the fetal sheep brain after experimentally induced placental insufficiency

OBJECTIVE

This study was undertaken to examine the effects of chronic embolization of the umbilical circulation during late gestation on regional concentrations of quinolinic acid and kynurenic acid (neuroactive products of tryptophan catabolism) and of the astrocyte-associated glial fibrillary acidic protein in the fetal brain.

STUDY DESIGN

Pregnant ewes bearing fetuses with long-term catheter placement were treated daily with injections of either saline solution (n = 4; control group) or mucopolysaccharide microspheres (n = 5; embolized group) into the umbilical circulation through a femoral artery catheter between 120 and 140 days' gestation. The fetuses in the embolized group received sufficient microspheres each day to reduce and maintain the femoral arterial PO2 at < or =12 mm Hg. Autopsies were performed at 140 days' gestation to obtain the fetal brain for chemical analysis.

RESULTS

Umbilical embolization resulted in nonacidemic hypoxia and hypoglycemia at 140 days' gestation. Quinolinic acid concentrations in the embolized group were significantly increased in the medulla, pons, midbrain, hypothalamus, and hippocampus, whereas kynurenic acid concentrations in the embolized group were reduced in the hippocampus and hypothalamus. There were significant reductions in glial fibrillary acidic protein contents in the occipitoparietal cortex, hippocampus, and pons in the embolized group.

CONCLUSION

Placental compromise during late pregnancy had effects on kynurenine metabolism and astrocyte function in some regions of the fetal sheep brain. We suggest that these changes increase the vulnerability of the brain to asphyxial injury during late gestation and the perinatal period.

Intrapartum fever and unexplained seizures in term infants

OBJECTIVE

Early-onset neonatal seizures are a strong predictor of later morbidity and mortality in term infants. Although an association of noninfectious intrapartum fever with neonatal seizures in term infants has been reported, it was based on only a small number of neonates with seizures. We therefore conducted a case control study to investigate this association further.

METHODS

All term infants with neonatal seizures born at Brigham and Women's Hospital between 1989 and 1996 were identified. For this study, cases consisted of all term neonates with a confirmed diagnosis of seizure born after a trial of labor for whom no proximal cause of seizure could be identified. Infants with sepsis or meningitis were excluded. Four controls matched by parity and date of birth were identified for each case. The rate of intrapartum maternal temperature >100.4 degrees F was compared for case infants and controls. Potential confounding was controlled in logistic regression analysis.

RESULTS

Cases comprised 38 term infants with unexplained seizures after a trial of labor. We identified 152 controls. Infants with seizures were more likely to be born to mothers who were febrile during labor (31.6% vs 9.2%). In almost all cases, the fever developed during labor (94.7% cases, 97.4% controls). At admission, mothers of infants with seizures were not significantly more likely to have factors associated with concern about infection such as a white blood cell count >15 000/mm(3) (28. 9% vs 19.1%) and premature rupture of the membranes (15.8% vs 17.8%). In a logistic regression analysis controlling for confounding factors, intrapartum fever was associated with a 3.4-fold increase in the risk of unexplained neonatal seizures (odds ratio = 3.4, 95% confidence interval = 1.03-10.9).

CONCLUSION

Our data indicate that intrapartum fever, even when unlikely to be caused by infection, is associated with a fourfold increase in the risk of unexplained, early-onset seizures in term infants.

Why is the placenta being ignored?

The relationship between the frequency of published recommended indications for placental pathological examination and the frequency of requests for such examination in a population-based study of term newborn encephalopathy was examined. Only 11.2% of placentas among 276 case infants and 0.7% of placentas among 564 term control infants were examined. Using the criteria set out in a consensus statement by the American College of Pathologists, all 276 cases fulfilled multiple maternal, fetal and placental indications for placental examination. Furthermore 43.3% of control infants fulfilled at least one criterion. Of the 25 case placentas that underwent pathological review, 16 were reported as having no diagnostic abnormality Six cases (24%) showed clinically important findings: four had evidence of infection, one had multiple chorangiomata and one had thrombosis and rupture of the umbilical vein. Of the three remaining placentas, one showed funisitis, one showed minor lymphohistiocytic villitis and one was from monochorionic twins. To our knowledge there are no agreed Australian guidelines for when a placenta should be submitted for pathological examination. We suggest that until guidelines based on properly designed studies are developed it may be appropriate to store all placentas for at least 72 hours. If the infant develops neurological symptoms or requires unexpected admission to a neonatal intensive care unit then placental examination may reveal important aetiological diagnostic and prognostic information.

Maternal thyroid disease: a risk factor for newborn encephalopathy in term infants

Two previously published studies of term newborn encephalopathy showed that maternal thyroid disease to be a risk factor. From these studies we identified 13 case and three control mothers with thyroid disease and investigated them further. The majority of affected case mothers had idiopathic or autoimmune hypothyroidism. Compared with control mothers, case mothers had fewer thyroid function tests in pregnancy, were more likely to remain on the same dose of medication throughout pregnancy and to have experienced other pregnancy complications. The association between maternal thyroid disease and encephalopathy may be the result of a series of different causal pathways, some of which are suggested by our data.

Risk factors for neonatal encephalopathy in Kathmandu, Nepal, a developing country: unmatched case-control study

OBJECTIVE

To determine the risk factors for neonatal encephalopathy among term infants in a developing country.

DESIGN

Unmatched case-control study.

SETTING

Principal maternity hospital of Kathmandu, Nepal.

SUBJECTS

All 131 infants with neonatal encephalopathy from a population of 21 609 infants born over an 18 month period, and 635 unmatched infants systematically recruited over 12 months.

MAIN OUTCOME MEASURES

Adjusted odds ratio estimates for antepartum and intrapartum risk factors.

RESULTS

The prevalence of neonatal encephalopathy was 6.1 per 1,000 live births of which 63% were infants with moderate or severe encephalopathy. The risk of death from neonatal encephalopathy was 31%. The risk of neonatal encephalopathy increased with increasing maternal age and decreasing maternal height. Antepartum risk factors included primiparity (odds ratio 2.0) and non-attendance for antenatal care (2.1). Multiple births were at greatly increased risk (22). Intrapartum risk factors included non-cephalic presentation (3.4), prolonged rupture of membranes (3.8), and various other complications. Particulate meconium was strongly associated with encephalopathy (18). Induction of labour with oxytocin was associated with encephalopathy in 12 of 41 deliveries (5.7). Overall, 78 affected infants (60%) compared with 36 controls (6%) either had evidence of intrapartum compromise or were born after an intrapartum difficulty likely to result in fetal compromise. A concentration of maternal haemoglobin of less than 8.0 g/dl in the puerperium was significantly associated with encephalopathy (2.5) as was a maternal thyroid stimulating hormone concentration greater than 5 mIU/l (2.1).

CONCLUSIONS

Intrapartum risk factors remain important for neonatal encephalopathy in developing countries. There is some evidence of a protective effect from antenatal care. The use of oxytocin in low income countries where intrapartum monitoring is suboptimal presents a major risk to the fetus. More work is required to explore the association between maternal deficiency states and neonatal encephalopathy.