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

Sudden Unexpected Postnatal Collapse: Review and Management

Sudden unexpected postnatal collapse (SUPC) of healthy newborns is a catastrophic event caused by cardiorespiratory collapse in a healthy newborn. The most common cause of SUPC is poor positioning of the newborn during skin-to-skin contact or breastfeeding when the newborn is not being observed by a health professional, attentive parent, or caretaker. Maternal/newborn health care professionals need to know about the essential information, definitions, incidence, risk factors, clinical presentation, outcomes, and prevention and management strategies to minimize the occurrence and impact of SUPC. A sample SUPC hospital policy is included in the manuscript.

Circadian patterns of heart rate variability in fetal sheep after hypoxia-ischaemia: A biomarker of evolving brain injury

Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and severe neurodevelopmental disability in survivors, including cerebral palsy, although there are no reliable biomarkers to detect at risk fetuses that may have suffered a transient period of severe HI. We investigated time and frequency domain measures of fetal heart rate variability (FHRV) for 3 weeks after HI in preterm fetal sheep at 0.7 gestation (equivalent to preterm humans) until 0.8 gestation (equivalent to term humans). We have previously shown that this is associated with delayed development of severe white and grey matter injury, including cystic white matter injury (WMI) resembling that observed in human preterm infants. HI was associated with suppression of time and frequency domain measures of FHRV and reduced their circadian rhythmicity during the first 3 days of recovery. By contrast, circadian rhythms of multiple measures of FHRV were exaggerated over the final 2 weeks of recovery, mediated by a greater reduction in FHRV during the morning nadir, but no change in the evening peak. These data suggest that the time of day at which FHRV measurements are taken affects their diagnostic utility. We further propose that circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury. KEY POINTS: Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and probably for disability in survivors, although there are no reliable biomarkers for antenatal brain injury. In preterm fetal sheep, acute HI that is known to lead to delayed development of severe white and grey matter injury over 3 weeks, was associated with early suppression of multiple time and frequency domain measures of fetal heart rate variability (FHRV) and loss of their circadian rhythms during the first 3 days after HI. Over the final 2 weeks of recovery after HI, exaggerated circadian rhythms of frequency domain FHRV measures were observed. The morning nadirs were lower with no change in the evening peak of FHRV. Circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury.

Born Too Early and Too Small: Higher Order Cognitive Function and Brain at Risk at Ages 8-16

Prematurity presents a risk for higher order cognitive functions. Some of these deficits manifest later in development, when these functions are expected to mature. However, the causes and consequences of prematurity are still unclear. We conducted a longitudinal study to first identify clinical predictors of ultrasound brain abnormalities in 196 children born very preterm (VP; gestational age ≤32 weeks) and with very low birth weight (VLBW; birth weight ≤1500 g). At ages 8-16, the subset of VP-VLBW children without neurological findings (124) were invited for a neuropsychological assessment and an MRI scan (41 accepted). Of these, 29 met a rigorous criterion for MRI quality and an age, and gender-matched control group (n = 14) was included in this study. The key findings in the VP-VLBW neonates were: (a) 37% of the VP-VLBW neonates had ultrasound brain abnormalities; (b) gestational age and birth weight collectively with hospital course (i.e., days in hospital, neonatal intensive care, mechanical ventilation and with oxygen therapy, surgeries, and retinopathy of prematurity) predicted ultrasound brain abnormalities. At ages 8-16, VP-VLBW children showed: a) lower intelligent quotient (IQ) and executive function; b) decreased gray and white matter (WM) integrity; (c) IQ correlated negatively with cortical thickness in higher order processing cortical areas. In conclusion, our data indicate that facets of executive function and IQ are the most affected in VP-VLBW children likely due to altered higher order cortical areas and underlying WM.

Evolving changes in fetal heart rate variability and brain injury after hypoxia-ischaemia in preterm fetal sheep

KEY POINTS

Fetal heart rate variability is a critical index of fetal wellbeing. Suppression of heart rate variability may provide prognostic information on the risk of hypoxic-ischaemic brain injury after birth. In the present study, we report the evolution of fetal heart rate variability after both mild and severe hypoxia-ischaemia. Both mild and severe hypoxia-ischaemia were associated with an initial, brief suppression of multiple measures of heart rate variability. This was followed by normal or increased levels of heart rate variability during the latent phase of injury. Severe hypoxia-ischaemia was subsequently associated with the prolonged suppression of measures of heart rate variability during the secondary phase of injury, which is the period of time when brain injury is no longer treatable. These findings suggest that a biphasic pattern of heart rate variability may be an early marker of brain injury when treatment or intervention is probably most effective.

ABSTRACT

Hypoxia-ischaemia (HI) is a major contributor to preterm brain injury, although there are currently no reliable biomarkers for identifying infants who are at risk. We tested the hypothesis that fetal heart rate (FHR) and FHR variability (FHRV) would identify evolving brain injury after HI. Fetal sheep at 0.7 of gestation were subjected to either 15 (n = 10) or 25 min (n = 17) of complete umbilical cord occlusion or sham occlusion (n = 12). FHR and four measures of FHRV [short-term variation, long-term variation, standard deviation of normal to normal R-R intervals (SDNN), root mean square of successive differences) were assessed until 72 h after HI. All measures of FHRV were suppressed for the first 3-4 h in the 15 min group and 1-2 h in the 25 min group. Measures of FHRV recovered to control levels by 4 h in the 15 min group, whereas the 25 min group showed tachycardia and an increase in short-term variation and SDNN from 4 to 6 h after occlusion. The measures of FHRV then progressively declined in the 25 min group and became profoundly suppressed from 18 to 48 h. A partial recovery of FHRV measures towards control levels was observed in the 25 min group from 49 to 72 h. These findings illustrate the complex regulation of FHRV after both mild and severe HI and suggest that the longitudinal analysis of FHR and FHRV after HI may be able to help determine the timing and severity of preterm HI.

Sex, drugs and rock and roll: tales from preterm fetal life

Premature fetuses and babies are at greater risk of mortality and morbidity than their term counterparts. The underlying causes are multifactorial, but include exposure to hypoxia. Immaturity of organs and their functional control may impair the physiological defence responses to hypoxia and the preterm fetal responses, or lack thereof, to moderate hypoxia appear to support this concept. However, as this review demonstrates, despite immaturity, the preterm fetus responds to asphyxia in a qualitatively similar manner to that seen at term. This highlights the importance in understanding metabolism versus homeostatic threat when assessing fetal responses to adverse challenges such as hypoxia. Data are presented to show that the preterm fetal adaptation to asphyxia is triphasic in nature. Phase one represents the rapid institution of maximal defences, designed to maintain blood pressure and central perfusion at the expense of peripheral organs. Phase two is one of adaptive compensation. Controlled reperfusion partially offsets peripheral tissue oxygen debt, while maintaining sufficient vasoconstriction to limit the fall in perfusion. Phase three is about decompensation. Strikingly, the preterm fetus generally performs better during phases two and three, and can survive for longer without injury. Paradoxically, however, the ability to survive can lead to longer exposure to hypotension and hypoperfusion and thus potentially greater injury. The effects of fetal sex, inflammation and drugs on the triphasic adaptations are reviewed. Finally, the review highlights the need for more comprehensive studies to understand the complexity of perinatal physiology if we are to develop effective strategies to improve preterm outcomes.

Electrocardiogram ST Analysis During Labor: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To compare the effectiveness of cardiotocography plus ST analysis with cardiotocography alone during labor.

DATA SOURCES

Randomized controlled trials were identified by searching electronic databases.

METHODS OF STUDY SELECTION

We included all randomized controlled trials comparing intrapartum fetal monitoring with cardiotocography plus ST analysis with cardiotocography alone. The primary outcome (ie, perinatal composite outcome) was a composite of intrapartum fetal death, neonatal death, Apgar score 3 or less at 5 minutes, neonatal seizure, metabolic acidosis (defined as umbilical arterial pH 7.05 or less, and extracellular fluid base deficit 12 mmol/L or greater), intubation for ventilation at delivery, or neonatal encephalopathy.

TABULATION, INTEGRATION, AND RESULTS

Six randomized controlled trials, which included 26,529 laboring singletons with cephalic presentation at term, were analyzed. Compared with women who were randomized to cardiotocography, those who were randomized to ST analysis and cardiotocography had a similar incidence of perinatal composite outcome (1.5% compared with 1.6%; relative risk [RR] 0.90, 95% confidence interval [CI] 0.74-1.10; five studies), neonatal metabolic acidosis (0.5% compared with 0.7%; RR 0.74, 95% CI 0.54-1.02; five studies), admission to the neonatal intensive care unit (5.4% compared with 5.5%; RR 0.99, 95% CI 0.90-1.10; six studies), perinatal death (0.1% compared with 0.1%; RR 1.71, 95% CI 0.67-4.33; six studies), neonatal encephalopathy (0.1% compared with 0.2%; RR 0.62, 95% CI 0.25-1.52; six studies), cesarean delivery (13.8% compared with 14.0%; RR 0.96, 95% CI 0.85-1.08; six studies), and operative delivery (either cesarean or operative vaginal delivery) (23.9% compared with 25.1%; RR 0.93, 95% CI 0.86-1.01; six studies).

CONCLUSION

The use of ST analysis during labor as an adjunct to the standard cardiotocography does not improve perinatal outcomes or decrease cesarean delivery.

Injury to the Cerebellum in Term Asphyxiated Newborns Treated with Hypothermia

BACKGROUND AND PURPOSE

Until now, most studies of brain injury related to term neonatal encephalopathy have focused on the cerebrum and ignored the cerebellum. We sought to evaluate whether cerebellar injury occurs in term asphyxiated neonates.

MATERIALS AND METHODS

Asphyxiated neonates treated with hypothermia were enrolled prospectively. Severity of brain injury in the cerebrum was scored on each MR imaging obtained during the first month of life; cerebellar injury was recorded when mentioned in the imaging or autopsy report. In addition, for some of the neonates, the ADC and fractional anisotropy were measured in 4 regions of interest in the cerebellum.

RESULTS

One hundred seventy-two asphyxiated neonates met the criteria for hypothermia. Cerebellar injury was visible only on conventional imaging of 4% of the neonates for whom brain imaging was available, but it was reported in the autopsy report of 72% of the neonates who died. In addition, 41 of the asphyxiated neonates had a total of 84 ADC and fractional anisotropy maps. Neonates with brain injury described only in the cerebrum demonstrated ADC and fractional anisotropy changes similar to those of the neonates with brain injury in the cerebrum and cerebellum--increased ADC around day 10 of life and decreased fractional anisotropy on day 2-3 of life, around day 10 of life, and around 1 month of age.

CONCLUSIONS

The cerebellum may be injured in term neonates after birth asphyxia. These cerebellar injuries are only rarely visible on conventional imaging, but advanced neuroimaging techniques may help to identify them.

Acute thymic involution in unexplained third trimester stillbirth: frequency, grade, and correlation with neuropathologic injury

Many 3rd-trimester stillbirths are unexplained, including the time course of the illness. Histologic acute thymic involution (ATI), when graded, correlates with duration of acute illness (grade 0, <12 hours; grade 4, >72 hours). Histologic brain injury is also common in stillbirth. We investigated ATI in unexplained stillbirth and correlated it with neuropathologic injury by identifying 58 autopsies of unexplained, 3rd-trimester stillborns (preterm, n  =  24; term, n  =  34) that included brain examination and graded ATI from 0 (resting state) to 4 (pronounced lymphodepletion). Gray matter injury (GMI) and white matter injury (WMI) were classified as older, recent, or absent, and ATI was correlated with GMI, WMI, thymic weight, and clinical data. Nine cases (16%) had ATI grade 0-1; 19 (33%), grade 2; 24 (41%), grade 3; and 6 (10%), grade 4. Older GMI and WMI were present in 39 (67%) and 10 (17%) stillborns, respectively. Higher ATI grade correlated significantly with older GMI (P < 0.001) and WMI (P  =  0.014). The ATI grade was higher in the small-for-gestational stillborns compared with the appropriate- or large-for-gestational stillborns (P  =  0.017) but did not correlate significantly with gestational age or other clinical or demographic factors evaluated. The ATI grades 2-4 were found in 84% of the stillborns, consistent with onset of acute illness between 24 and >72 hours before demise. Higher ATI grade correlated significantly with older brain injury, suggesting similar time of onset and shared underlying pathophysiologic events, the specific nature of which remains unclear.

The neuropathology of stillbirth - correlation with apolipoprotein genotype in a Scottish population based study

BACKGROUND

The neuropathology of stillbirths has been widely studied but rarely on a population basis. Whether foetal apolipoprotein E (APOE) genotype exerts any influence has been little investigated, despite well known effects in adult brains.

AIMS

To establish the neuropathology of a population cohort of stillbirths and compare with the APOE genotype.

STUDY DESIGN AND SUBJECTS

The brains of 191 stillbirths (≥24weeks of gestation) were recruited from a Scottish population cohort and grouped by clinical history. APOE genotype was available for 97%.

RESULTS AND CONCLUSIONS

One or more neuropathological features, most appearing relatively recent, were found in 54% of 157 antepartum singletons, 44% of 9 abruption-associated stillbirths, 85% of 13 in multiple pregnancies but in only 19% of 12 intrapartum stillbirths. White matter injury (WMI) occurred in 36% of preterm and 21% mature stillbirths. Fresh petechial haemorrhages were common in all groups (29%) but germinal matrix haemorrhage (GMH) (7%) and periventricular leucomalacia (1%) were confined to preterm. GMH was significantly associated with WMI (p=0.003). Placental inflammation was common in intrapartum stillbirths (50%), compared with antepartum (15%), multiple pregnancy (23%) and abruption (0%). β-Amyloid precursor protein (βAPP) positive axons (36% stillbirths overall) correlated closely with WMI (p<0.0001), justifying future routine inclusion in foetal neuropathological investigation. This study highlights the paucity of brain damage in intrapartum stillbirths. While APOE2 was significantly overrepresented in stillbirths, there was no correlation between APOE genotype and neuropathological findings. We conclude that APOE does not influence neuropathological outcomes in stillbirths.

Antenatal brain injury in third trimester neonates with severe congenital anomalies: an autopsy study

OBJECTIVE

With advances in therapy, more neonates with severe congenital anomalies are surviving, albeit some with neurologic disorders, possibly related to antenatal low brain blood flow. This autopsy series reports antenatal brain injury in neonates expiring due to severe anomalies, and provides correlation with umbilical cord blood gas and acid-base analysis.

METHODS

We identified autopsies of third trimester neonates expiring shortly following delivery due to severe anomalies or malformations. Brain injury classified as "older" included periventricular leukomalacia, gliosis and karyorrhectic neurons, and "recent" included red neurons and reactive glial changes.

RESULTS

We identified 22 cases (nine term, 13 preterm). 16 (73%) had brain injury, including 11 with older injury. Cord arterial blood was analyzed in 17, and six had pH <7 or base deficit >12 mmol/L. Four out of 5 (80%) neonates with neuronal necrosis compared to two out of 12 (17%) without had a pH <7 or base deficit >12 mmol/L (p = 0.03). Five out of nine (56%) neonates with white matter injury compared to one out of 8 (13%) without had pH <7 or base deficit >12 mmol/L (p = NS).

CONCLUSIONS

Antenatal brain injury is frequent in neonates with severe congenital anomalies. Severely abnormal cord blood analysis results correlate significantly with neuronal necrosis and show a trend toward white matter injury; however, the absence of these abnormal results does not preclude the presence of brain injury.

Astrocytes and microglia in acute cerebral injury underlying cerebral palsy associated with preterm birth

Cerebral palsy is one of the most devastating consequences of brain injury around the time of birth, and nearly a third of cases are now associated with premature birth. Compared with term babies, preterm babies have an increased incidence of complications that may increase the risk of disability, such as intraventricular hemorrhage, periventricular leukomalacia, sepsis, and necrotizing enterocolitis. The response to injury is highly dependent on brain maturity, and although cellular vulnerability is well documented, there is now evidence that premyelinating axons are also particularly sensitive to ischemic injury. In this review, we will explore recent evidence highlighting a central role for glia in mediating increased risk of disability in premature infants, including excessive activation of microglia and opening of astrocytic gap junction hemichannels in spreading injury after brain ischemia, in part likely involving release of adenosine triphosphate (ATP) and overactivation of purinergic receptors, particularly in white matter. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious circle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing effective neuroprotective strategies for preterm infants requires a detailed understanding of glial responses.

Third trimester fetal demise occurring at time of delivery: correlation of autopsy findings and placental pathology with emphasis on antenatal central nervous system injury

OBJECTIVE

Third trimester fetal deaths occurring in the hospital at the time of delivery are unusual. We report an autopsy series of such cases with emphasis on neuropathological injury and other lesions predating delivery.

METHODS

We identified autopsies performed on third trimester fetuses documented to be alive shortly before delivery, but that expired during, or very close to, time of delivery, and we correlate autopsy and placental findings. Fetuses with major congenital anomalies were excluded.

RESULTS

Ten cases were identified (6 term, 4 preterm). All were delivered by cesarean section and had attempted resuscitation. Established or recent brain injury was identified in 9 of 10 cases, including 3 with established neuronal damage and 1 with periventricular leukomalacia. Additional autopsy findings included thymic involution in eight (five mild; three severe), myocardial infarcts in two; intrathoracic petechiae in five, and ascites or pleural or pericardial effusions in six. Severe thymic involution and myocardial infarcts correlated with established brain injury. Placental lesions adaptive to decreased oxygenation (increased nucleated red blood cells or villous hypervascularity) were seen in five cases and correlated with established brain injury. Acute chorioamnionitis with funisitis was present in one, and chronic inflammatory placental lesions were present in six.

CONCLUSIONS

These findings indicate brain injury predated the time period immediately before delivery in 9 of 10 fetuses, and in the fetuses with established brain injury the onset of acute illness was possibly >72 h before delivery.

Why the term neonatal encephalopathy should be preferred over neonatal hypoxic-ischemic encephalopathy

The unresponsiveness of the full-term newborn is sometimes attributed to asphyxia, even when no severe physiologic disturbance occurred during labor and delivery. The controversy about whether to use the name "hypoxic-ischemic encephalopathy" or "newborn encephalopathy" has recently flared in publications directed toward pediatricians and neurologists. In this clinic opinion piece, I discuss the importance to obstetricians of this decision and explain why "newborn encephalopathy" should be the default term.

Neonatal encephalopathy: an inadequate term for hypoxic-ischemic encephalopathy

This Point of View article addresses neonatal encephalopathy (NE) presumably caused by hypoxia-ischemia and the terminology currently in wide use for this disorder. The nonspecific term NE is commonly utilized for those infants with the clinical and imaging characteristics of neonatal hypoxic-ischemic encephalopathy (HIE). Multiple magnetic resonance imaging studies of term infants with the clinical setting of presumed hypoxia-ischemia near the time of delivery have delineated a topography of lesions highly correlated with that defined by human neuropathology and by animal models, including primate models, of hypoxia-ischemia. These imaging findings, coupled with clinical features consistent with perinatal hypoxic-ischemic insult(s), warrant the specific designation of neonatal HIE.

Fetal central nervous system injury in third trimester stillbirth: a clinicopathologic study of 63 cases

We report the neuropathologic findings and clinicopathologic associations in 63 3rd trimester singleton stillborn fetuses. All were ≥ 28 weeks estimated gestational age (EGA) with complete autopsies, including placental examination. Fetuses with chromosomal abnormalities, major congenital anomalies, and intrapartum demise were excluded. The cases were divided into those with abruption (n  =  12) and those with unexplained fetal demise (n  =  51). The latter group was then subdivided by gestational age with 3 subgroups (preterm 28 to < 32 weeks EGA (n  =  16), preterm 32 to <37 weeks EGA (n  =  13), and term 37-41 weeks EGA (n  =  22). Each group was further subdivided as appropriate-for-gestational age/large-for-gestational age (AGA/LGA) or small-for-gestational age (SGA). Placental lesions were also evaluated and correlated with brain lesions. Established or recent injury involving gray or white matter was seen in 88% of the fetuses with unexplained demise versus 42% with abruption (P  =  0.001). The most common form of brain injury was established gray matter damage, seen in 65% of the fetuses with unexplained demise versus 25% with abruption (P  =  0.021), the most common pattern being established pontosubicular neuronal necrosis plus established neuronal necrosis in other sites. There was no significant difference in the frequency of brain injury between the SGA fetuses and AGA/LGA fetuses or between the unexplained stillbirth preterm and term subgroups, and there was no unequivocal correlation between placental lesions and brain lesions. Brain injury, most frequently established gray matter damage, is seen in the majority of stillborn infants with unexplained demise, indicating that the brain injury predates the period immediately before death.

Gliosis in neonatal SUDI cases

AIM

To review sudden unexpected infant deaths (SUDI) in the first 28 days of life referred to a Coronial Perinatal Forensic Pathology Service over a 10-year period from 2000 to 2009.

METHODS

Cases were collected from mortuary records, and a retrospective review of autopsy reports and other available infant records was undertaken.

RESULTS

Twenty-four neonatal SUDI were reviewed. For eight infants, a diagnosis was made at autopsy. For the remaining 16 infants, 14 (87.5%) were bedsharing at the time of death. Maori infants and those living in deprived neighbourhoods were over-represented. Only two infants were preterm, and four were growth-restricted. At post-mortem, white matter gliosis was found in 10 of the 16 (62.5%) unexplained SUDI cases.

CONCLUSION

Sudden unexpected infant deaths occur in the first month of life in association with bedsharing. Gliosis may be an important associated risk factor, and its presence indicates a previous insult of prenatal onset.

[Cerebral palsy and perinatal asphyxia (II--Medicolegal implications and prevention)]

Obstetric litigation is a growing problem in developed countries and its escalating cost together with increasing medical insurance premiums is a major concern for maternity service providers, leading to obstetric practice cessation by many practitioners. Fifty-four to 74 % of claims are based on cardiotocographic (CTG) abnormalities and their interpretation followed by inappropriate or delayed reactions. A critical analysis is performed about the nine criteria identified by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics in their task force on Neonatal Encephalopathy and Cerebral Palsy: four essential criteria defining neonatal asphyxia and five other suggesting an acute intrapartum event sufficient to cause cerebral palsy in term newborns. The importance of placental histologic examination is emphasized in order to confirm sudden catastrophic events occurring before or during labor or to detect occult thrombotic processes affecting the fetal circulation, patterns of decreased placenta reserve and adaptative responses to chronic hypoxia. It may also exclude intrapartum hypoxia by revealing some histologic patterns typical of acute chorioamnionitis and fetal inflammatory response or compatible with metabolic diseases. Magnetic resonance imaging (MRI) of the infant's damaged brain is very contributive to elucidate the mechanism and timing of asphyxia in conjunction with the clinical picture, by locating cerebral injuries predominantly in white or grey matter. Intrapartum asphyxia is sometimes preventable by delivering weak fetuses by cesarean sections before birth, by avoiding some "sentinel" events, and essentially by responding appropriately to CTG anomalies and performing an efficient neonatal resuscitation. During litigation procedures, it is necessary to have access to a readable CTG, a well-documented partogram, a complete analysis of umbilical cord gases, a placental pathology and an extensive clinical work-up of the newborn infant including cerebral MRI. Malpractice litigation in obstetric care can be reduced by permanent CTG education, respect of national CTG guidelines, use of adjuncts such as fetal blood sampling for pH or lactates, regular review of adverse events in Clinical Risk Management (CRM) groups and periodic audits about low arterial cord pH in newborns, admission to neonatal unit, the need for assisted ventilation and the decision-to-delivery interval for emergency operative deliveries. Considering the fast occurrence of fetal cerebral hypoxic injuries, and thus despite an adequate management, many intrapartum asphyxias will not be preventable. Conversely, well-documented hypoxic-ischemic brain insults during the antenatal period do not automatically exclude intrapartum suboptimal obstetric care.

Benefits of introducing universal umbilical cord blood gas and lactate analysis into an obstetric unit

BACKGROUND

Current evidence suggests that umbilical arterial pH analysis provides the most sensitive reflection of birth asphyxia. However, there's debate whether umbilical cord blood gas analysis (UC-BGA) should be conducted on some or all deliveries.

AIM

The aim of this study was to evaluate the impact of introducing universal UC-BGA at delivery on perinatal outcome.

METHODS

An observational study of all deliveries > or =20 weeks' gestation at a tertiary obstetric unit between January 2003 and December 2006. Paired UC-BGA was performed on 97% of deliveries (n = 19,646). Univariate and adjusted analysis assessed inter-year UC-BGA differences and the likelihood of metabolic acidosis and nursery admission.

RESULTS

There was a progressive improvement in umbilical artery pH, pO(2), pCO(2), base excess and lactate values in univariate and adjusted analyses (P < 0.001). There was a significant reduction in the newborns with an arterial pH <7.10 (OR = 0.71; 95%CI 0.53-0.95) and lactate >6.1 mmol/L (OR = 0.37; 95%CI 0.30-0.46). Utilising population specific 5th and 95th percentiles, there was a reduction in newborns with arterial pH less than 5th percentile (pH 7.12; OR = 0.75; 95%CI 0.59-0.96) and lactate levels greater than 95th percentile (6.7 mmol/L; OR = 0.37; 95%CI 0.29-0.49). There was a reduction in term (OR = 0.65; 95%CI 0.54-0.78), and overall (OR = 0.75; 95%CI 0.64-0.87) nursery admissions. These improved perinatal outcomes were independent of intervention rates.

CONCLUSIONS

These data suggest that introduction of universal UC-BGA may result in improved perinatal outcomes, which were observed to be independent of obstetric intervention. We suggest that these improvements might be attributed to provision of biochemical data relating to fetal acid-base status at delivery influencing intrapartum care in subsequent cases.

Brain cooling for preterm infants

There is strong evidence that prolonged, moderate cerebral hypothermia initiated within a few hours after severe hypoxia-ischemia and continued until resolution of the acute phase of delayed cell death can reduce neuronal loss and improve behavioral recovery in term infants and adults after cardiac arrest. This review examines the evidence that mild to moderate hypothermia is protective after hypoxia-ischemia in models of preterm brain injury and evaluates the potential risks. Induced hypothermia likely has potential to significantly reduce disability. Cautious, systematic trials are essential before hypothermia can be used in these vulnerable infants.

Amniotic fluid S100B protein and erythropoietin in pregnancies at risk for fetal hypoxia

OBJECTIVE

S100B protein is a biochemical marker for brain injury, and high serum S100B levels have been observed in newborns with birth asphyxia. We hypothesized that the concentration of amniotic fluid erythropoietin, which increases in chronic fetal hypoxia, correlates with amniotic fluid S100B concentration.

STUDY DESIGN

Amniotic fluid samples in 35 pregnancies at high risk for chronic fetal hypoxia were obtained at cesarean section or by amniocentesis done within a median of 2 days before delivery. S100B and erythropoietin concentrations were measured by chemiluminescent immunoassays.

RESULTS

A positive correlation existed between the concentrations of S100B and erythropoietin in the amniotic fluid (r=0.57, p<0.0001). Amniotic fluid S100B concentration was higher (70 ng/l; 33-469, n=17) (median; range) in pregnancies with elevated amniotic fluid erythropoietin (>or= 50 IU/l) than in pregnancies with normal erythropoietin (34 ng/l; 20-340, n=18) (p<0.0001, Mann-Whitney U-test). S100B predicted an elevated amniotic fluid erythropoietin concentration in the study population with the sensitivity of 94% and specificity of 83%.

CONCLUSION

A strong positive correlation exists between amniotic fluid S100B and erythropoietin concentrations in pregnancies at high risk for chronic fetal hypoxia. This suggests that chronic fetal hypoxia increases the intrauterine release of S100B.

Low Apgar score without acidosis may indicate neuromuscular disorder

OBJECTIVE

We hypothesized that in term infants low Apgar score with normal umbilical artery pH (UApH) indicates prenatal damage to the neuromuscular system.

STUDY DESIGN

Retrospective database search of 42,117 liveborn infants born 1993-2005. Medical record analysis of 3104 term infants with cardiorespiratory maladaptation referred for special neonatal care. Focus on infants with UApH >7.00 and 5-min Apgar <6 (group A, n=74), UApH <7.00 and 5-min Apgar >5 (group B, n=49), and UApH <7.00 and 5-min Apgar <6 (group C, n=14).

RESULTS

Incidence of 5-min Apgar score <6 was 0.50% in term infants. Mean (SD) UApH was 7.262 (0.075, P=0.075); incidence of UApH <7.00 was 0.30% in term infants. Nucleated red blood cells were elevated without differences in all three groups. Parental consanguinity was present in 39 of the 137 maladapted infants. In groups A/B/C, 10/18/2 infants were small for gestational age (P=0.002 for A vs B) and in 16/1/0 neuromuscular anomalies were identified (P=0.004 for A vs B). Eight of the 17 anomalies had been suspected prenatally. Logistic regression proved neuromuscular disorder the only independent variable discriminating between groups A and B.

CONCLUSIONS

Neuromuscular problems are the cause rather than the result of maladaptation. For unexplained low Apgar score, especially without acidosis, meticulous examination of the infant including brain imaging and EEG is justified.

Fetal brain monitoring: future applications

Future application of fetal brain monitoring is explored by selecting and analysing articles for information on types of brain damage that can be monitored, where in the brain this can be done, how long after the risk exposure, and with what method of investigation. A limited number of--mainly--case histories reported that early (cell death and oedema) and late (gliosis) effects of brain damage can be demonstrated before birth with multiplanar ultrasound and magnetic resonance imaging, and that hypoxic ischaemic injury or infection can induce local or widespread brain injury, occurring as transient or longer-lasting changes in age-related predilection areas for which normal features are known. The antenatal role of risk factors inducing abnormal brain development can be studied longitudinally with ultrasound and magnetic resonance imaging. A multidisciplinary approach will facilitate the introduction of various techniques with adequate know-how of underlying processes, to evaluate the predictive value on neurological outcome and prevent premature introduction into clinical application.

Nitrotyrosine in brain tissue of neonates after perinatal asphyxia

HYPOTHESIS

Nitrotyrosine, a reaction product of peroxynitrite and proteins, could be demonstrated in the postmortem examination of brain tissue of full-term neonates who had severe perinatal asphyxia.

METHODS

The brain tissue of 22 full-term neonates who died after severe perinatal asphyxia was examined, including cerebral cortex, basal ganglia, thalamus, hippocampus, brain stem, olives and cerebellum. Median age at death was 52 h. Routine histopathological examination and additional immunohistological staining were carried out with anti-cysteine protease protein 32 antibodies to detect activated caspase 3, anti-nitrotyrosine antibodies to detect nitrotyrosine and anti-CD68 antibodies to detect activated microglia and macrophages, which might be associated with the production of nitric oxide. Staining was scored as none, weak (1-25% positive cells), moderate (26-75% positive cells) or severe (>75% positive cells).

RESULTS

14 patients showed global injury, 4 showed injury of the basal ganglia and thalamus, and 4 showed predominantly parasagittal brain injury. One neonate without perinatal asphyxia served as a control. Nitrotyrosine staining of neurones was shown in all neonates with asphyxia, mostly in the thalamus (70%) and inferior olives (68%). Total nitrotyrosine staining tended to be less in the base of the pons and inferior olives of neonates with parasagittal brain injury. Activated caspase 3 was found mostly in the thalamus (60%) and hippocampus (53%). Positive CD68 staining was mainly present in the thalamus (70% positive).

CONCLUSION

Nitrotyrosine was found in brain tissue of full-term neonates, suggesting that nitric oxide toxicity might have a role in hypoxic-ischaemic brain injury at term. This may be relevant for neuroprotective strategies in full-term neonates with perinatal asphyxia.

Neonatal loss of gamma-aminobutyric acid pathway expression after human perinatal brain injury

OBJECT

Perinatal brain injury leads to chronic neurological deficits in children. Damage to the premature brain produces white matter lesions (WMLs), but the impact on cortical development is less well defined. Gamma-aminobutyric acid(GABA)ergic neurons destined for the cerebral cortex migrate through the developing white matter and form the subplate during late gestation. The authors hypothesized that GABAergic neurons are vulnerable to perinatal systemic insults in premature infants, and that damage to these neurons contributes to impaired cortical development.

METHODS

An immunohistochemical analysis involving markers for oligodendrocytes, GABAergic neurons, axons, and apoptosis was performed on a consecutive series of 15 human neonatal telencephalon samples obtained postmortem from infants born at 25 to 32 weeks of gestation. The tissue samples were divided into two groups based on the presence or absence of WMLs by performing routine histological analyses. The expression of GABAergic neurons was compared between the two groups by using age-matched samples. Two-tailed t-tests were used for statistical analyses. Ten infants had WMLs and five did not. Significant losses of oligodendrocytes and axons and markedly increased apoptosis were appreciated in tissue samples from the infants with WMLs. Samples from infants with WMLs also showed significant losses of glutamic acid decarboxylase-67-positive cells and calretinin-positive cells, shorter neuropeptide Y-positive neurite lengths, and losses of cells expressing GABA(A)alpha1, GABA(B)R1, and N-acetylaspartate diethylamide NR1 receptors when these factors were compared with those in samples from infants without WMLs (all p < 0.02).

CONCLUSIONS

In addition to oligodendrocyte loss, axonal disruption, and excess apoptosis, a significant loss of telencephalon GABAergic neuron expression was found in neonatal brains with WMLs, compared with neonates' brains without WMLs. The loss of GABAergic subplate neurons in infants with WMLs may contribute to the pathogenesis of neurological deficits in children.

The Scottish Perinatal Neuropathology Study-clinicopathological correlation in stillbirths

OBJECTIVE

To examine the neuropathology of fetuses dying before birth, to determine the timing of any brain damage seen and to ascertain clinical associations of pre-existing brain damage.

DESIGN

Population-based observational study.

SETTING

All 22 delivery units within Scotland, 1995-1998.

SAMPLE

All stillborn fetuses > or =24 weeks of gestation excluding those with chromosomal abnormality or central nervous system/cardiothoracic malformation.

METHODS

Clinical detail was collected on all stillborn fetuses. Requests for postmortem included separate request for detailed neuropathological examination. Stillborn fetuses were classified as full term antepartum (normal growth/growth restricted), preterm antepartum (normal growth/growth restricted), intrapartum (full term/preterm), multiple births and stillborn fetuses following abruptions. Clinicopathological correlation attempted to define the timing of brain insult. Placentas were examined for each case where available.

MAIN OUTCOME MEASURES

Presence of established and/or recent brain damage. RESULTS Clinical details were available for 471 stillborn fetuses, and detailed neuropathology was possible in 191 cases. Of these 191, 13 were multiple births, 9 died following abruption, 12 were intrapartum deaths and 157 were antepartum stillborn fetuses (99 preterm and 58 full term). Recent or established brain damage was seen in 66% of the entire cohort. Thirty-five percent of all cases showed well-established hypoxic damage predating the last evidence of fetal life, and this was more common in preterm fetuses (P = 0.015), those fetuses with evidence of recent damage (P < 0.001), in pregnancies complicated by pregnancy-induced hypertension (P = 0.044) and those in whom the placenta was <10th centile (P = 0.002).

CONCLUSIONS

Brain damage is commonly seen in stillborn infants, and in around one-third of cases, damage predates the period immediately before death. Factors suggesting suboptimal placental function are associated with such damage. Early identification of placental impairment may lead to improved pregnancy outcome.

Systemic prenatal insults disrupt telencephalon development: implications for potential interventions

Infants born prematurely are prone to chronic neurologic deficits including cerebral palsy, epilepsy, cognitive delay, behavioral problems, and neurosensory impairments. In affected children, imaging and neuropathological findings demonstrate significant damage to white matter. The extent of cortical damage has been less obvious. Advances in the understanding of telencephalon development provide insights into how systemic intrauterine insults affect the developing white matter, subplate, and cortex, and lead to multiple neurologic impairments. In addition to white matter oligodendrocytes and axons, other elements at risk for perinatal brain injury include subplate neurons, GABAergic neurons migrating through white matter and subplate, and afferents of maturing neurotransmitter systems. Common insults including hypoxia-ischemia and infection often affect the developing brain differently than the mature brain, and insults precipitate a cascade of damage to multiple neural lineages. Insights from development can identify potential targets for therapies to repair the damaged neonatal brain before it has matured.

The distribution of apolipoprotein E alleles in Scottish perinatal deaths

BACKGROUND

The apolipoprotein E (ApoE) polymorphism has been well studied in the adult human population, in part because the e4 allele is a known risk factor for Alzheimer's disease. Little is known of the distribution of ApoE alleles in newborns, and their association with perinatal brain damage has not been investigated.

METHODS

ApoE genotyping was undertaken in a Scottish cohort of perinatal deaths (n = 261), some of whom had prenatal brain damage. The distribution of ApoE alleles in perinatal deaths was compared with that in healthy liveborn infants and in adults in Scotland.

RESULTS

ApoE e2 was over-represented in 251 perinatal deaths (13% v 8% in healthy newborns, odds ratio (OR) = 1.63, 95% confidence interval (CI) 1.13 to 2.36 and 13% v 8% in adults, OR = 1.67, 95% CI 1.16 to 2.41), both in liveborn and stillborn perinatal deaths. In contrast, the prevalence of ApoE e4 was raised in healthy liveborn infants (19%) compared with stillbirths (13%, OR = 1.59, 95% CI 1.11 to 2.26) and with adults (15%, OR = 1.35, 95% CI 1.04 to 1.76). However, no correlation was found between ApoE genotype and the presence or absence of perinatal brain damage.

CONCLUSIONS

This study shows a shift in ApoE allelic distribution in early life compared with adults. The raised prevalence of ApoE e2 associated with perinatal death suggests that this allele is detrimental to pregnancy outcome, whereas ApoE e4 may be less so. However, ApoE genotype did not appear to influence the vulnerability for perinatal hypoxic/ischaemic brain damage, in agreement with findings in adult brains and in animal models.

Neonatal death after hypoxic ischaemic encephalopathy: does a postmortem add to the final diagnoses?

BACKGROUND

Case review after fatal perinatal asphyxia may have medicolegal implications. Accurate diagnosis of cause of death is therefore essential.

OBJECTIVE

To determine consent rate and utility of autopsy after fatal grade III hypoxic ischaemic encephalopathy (HIE) presumed to be secondary to birth asphyxia.

DESIGN

A retrospective clinical review from January 1995 to December 2002.

SETTING

Regional tertiary referral neonatal unit, Wellington, New Zealand.

POPULATION

Inclusion criteria were gestation >/=37 weeks, resuscitation after delivery and clinical course of grade III HIE. Exclusions were a recognised major lethal malformation.

METHODS

Review of clinical records including the autopsy report.

MAIN OUTCOME MEASURES

Consent for autopsy, change in diagnosis after autopsy.

RESULTS

Twenty-three infants died during the time period with a major diagnosis of grade III HIE. Three did not meet inclusion criteria. Of the remaining 20, 11 were female. Median gestation at birth was 40 weeks (range 38-42 weeks) and median birth weight was 3568 g (range 2140-4475 g). In 8/17 of the infants for whom length and head measurements were available, the Ponderal Index suggested intrauterine growth retardation. The 16/20 infants had an autopsy. Four of these were Coroner's cases giving an autopsy rate of 80% with a rate by consent of 60%. In 10 (62.5%) infants, significant new information was added to the clinical diagnoses.

CONCLUSIONS

Neonatal HIE is a symptom rather than a final clinical diagnosis. A full autopsy is required to fully explore the reasons for fatal neonatal HIE and may provide information that is important medicolegally.

Placental diagnostic criteria and clinical correlation – a workshop report

Placental pathology is a valuable link explaining how underlying pregnancy risk factors result in adverse pregnancy outcome. This potentially useful information is currently underutilized due to a general lack of rigor in placental diagnosis. This lack of rigor is in large part due to a failure to appreciate the importance of the information provided and hence to demand accurate and clinically responsive reporting. This workshop reviewed the results of a recent initiative by the Perinatal Section of the Society for Pediatric Pathology to systematize and validate diagnostic schema for the description of lesions related to three important pathologic processes: amniotic fluid infection, maternal vascular underperfusion, and fetal vascular obstruction. This was followed by presentation of three studies correlating these pathologic processes with the following clinical outcomes: complications of prematurity, fetal growth restriction, and neurodisability following term delivery.

Brain damage and axonal injury in a Scottish cohort of neonatal deaths

Despite the clinical and medicolegal significance attached to perinatal asphyxia, the neuropathological basis of this condition remains obscure. There are very few studies in the literature which correlate the pathological findings in neonatal brains with detailed epidemiological data, and none which are population based. In a Scotland-wide study of neonatal deaths, 70 brains have been examined. On the basis of glial and macrophage reactions, we previously identified infants with putative antepartum brain damage in this cohort and have related these reactions to signs of birth asphyxia. The present study explores the extent of neuronal/axonal injury in these infants since this is likely to be the basis for neurological deficits in surviving infants. We have also investigated these brains for beta-amyloid precursor protein (betaAPP) positivity to determine whether this is a useful marker of neuronal injury in neonates. Neuronal eosinophilia and karyorrhexes were detected in 43% and 27% of the cohort, respectively; maximally in the subiculum and ventral pons, but often present elsewhere. White matter damage was detected in 24% of cases but without classic cystic lesions of periventricular leucomalacia. betaAPP positivity was present in neuronal soma in 52% of cases and, in axons, in 27% of cases, and was seen from as early as 25-weeks gestation. Axonal bulbs were clearly delineated by betaAPP positivity and were usually located in the cerebral white matter and internal capsule, and infrequently in the brain stem. Although white matter damage and betaAPP axonal positivity were often detected in the same cases (P = 0.034), these features also occurred independently of each other. Both neuronal karyorrhexes and white matter betaAPP positivity were significantly correlated with the features of birth asphyxia, particularly a history of seizures. Immunocytochemistry for both betaAPP and glial fibrillary acidic protein proved useful in detecting neuropathological features which escaped detection on routine examination, particularly in preterm infants. The presence together of recent and older damage in individual brains suggests that there is an ongoing neuronal response to cerebral insults. We find that betaAPP is a useful marker of white matter damage in the neonatal brain. Immunopositivity for betaAPP in these circumstances is not attributable to inflicted or accidental trauma. While birth-related trauma cannot be ruled out, hypoxia/ischaemia is a likely cause in these infants. However, the exact pathogenesis of neuronal/axonal injury in the neonatal brain remains unclear.