Cerebral palsy and neonatal encephalopathy

Risk Factors and Outcomes for Cerebral Palsy With Hypoxic-Ischemic Brain Injury Patterns Without Documented Neonatal Encephalopathy

BACKGROUND AND OBJECTIVES

Perinatal hypoxic-ischemic brain injury is a leading cause of term-born cerebral palsy, the most common lifelong physical disability. Diagnosis is commonly made in the neonatal period by the combination of neonatal encephalopathy (NE) and typical neuroimaging findings. However, children without a history of neonatal encephalopathy may present later in childhood with motor disability and neuroimaging findings consistent with perinatal hypoxic-ischemic injury. We sought to determine the prevalence of such presentations using the retrospective viewpoint of a large multiregional cerebral palsy registry.

METHODS

Patient cases were extracted from the Canadian Cerebral Palsy Registry with gestational age >36 weeks, an MRI pattern consistent with hypoxic-ischemic injury (HII, acute total, partial prolonged, or combined), and an absence of postnatal cause for HII. Documentation of NE was noted. Maternal-fetal risk factors, labor and delivery, neonatal course, and clinical outcome were extracted. Comparisons were performed using χ2 tests and multivariable logistic regression with multiple imputation. Propensity scores were used to assess for bias.

RESULTS

Of the 170 children with MRI findings typical for HII, 140 (82.4%, 95% confidence interval [CI] 75.7%-87.7%) had documented NE and 29 (17.0%, 95% CI 11.7%-23.6%) did not. The group without NE had more abnormalities of amniotic fluid volume (odds ratio [OR] 15.8, 95% CI 1.2-835), had fetal growth restriction (OR 4.7, 95% CI 1.0-19.9), had less resuscitation (OR 0.03, 95% CI 0.007-0.08), had higher 5-minute Apgar scores (OR 2.2, 95% CI 1.6-3.0), were less likely to have neonatal seizures (OR 0.004, 95% CI 0.00009-0.03), and did not receive therapeutic hypothermia. MRI was performed at a median 1.1 months (interquartile range [IQR] 0.67-12.8 months) for those with NE and 12.2 months (IQR 6.6-25.9) for those without (p = 0.011). Patterns of injury on MRI were seen in similar proportions. Hemiplegia was more common in those without documented NE (OR 5.1, 95% CI 1.5-16.1); rates of preserved ambulatory function were similar.

DISCUSSION

Approximately one-sixth of term-born children with an eventual diagnosis of cerebral palsy and MRI findings consistent with perinatal hypoxic-ischemic brain injury do not have documented neonatal encephalopathy, which was associated with abnormalities of fetal growth and amniotic fluid volume, and a less complex neonatal course. Long-term outcomes seem comparable with their peers with encephalopathy. The absence of documented neonatal encephalopathy does not exclude perinatal hypoxic-ischemic injury, which may have occurred antenatally and must be carefully evaluated with MRI.

Early Biomarkers in the Prediction of Later Functional Impairment in Term Children with Cerebral Palsy

AIM

To identify possible early biomarkers that could predict later functional capabilities in children at risk for cerebral palsy (CP).

METHODS

Data from 869 term children with CP were extracted from the Canadian Cerebral Palsy Registry. Univariate analyses were conducted to measure the association between readily available objective early biomarkers (neonatal encephalopathy [NE], cord or first hour of life pH, magnetic resonance imaging [MRI]) and functional outcomes such as mobility and feeding status. Multivariable regressions were then modeled to study whether adding predictors would affect the strength of the observed association.

RESULTS

Patients with NE have higher odds of having an assigned Gross Motor Function Classification Score level of IV to V (prevalence ratio [PR], 2.87; 95% confidence interval [CI], 2.07 to 3.97) and are more likely to require dependent tube feeding (PR, 2.09; 95% CI, 1.12 to 3.88); this was similarly seen in patients with MRI findings of deep gray matter injury, watershed injury, near-total brain injury, and/or cortical malformation (mobility status [PR, 5.13; 95% CI, 3.73 to 7.11] and feeding status [PR, 4.87; 95% CI, 2.57 to 9.75]). Patients with cord or first hour of life pH <7 were also more likely to predict dependent mobility status (PR, 2.86; 95% CI, 1.76 to 4.69), however, not significantly more likely to predict eventual dependent feeding status (PR, 1.47; 95% CI, 0.58 to 3.32).

CONCLUSIONS

This retrospective cohort study demonstrates that NE, MRI findings and cord or first hour of life pH can reliably predict later CP related functioning. These associations can be used to inform and clarify early prognosis discussions between caregivers and health professionals.

Determinants of cerebral palsy in children: systematic review

Cerebral palsy (CP) is a group of disorders of movement and postural control caused by a nonprogressive defect or lesion of the developing brain. Several prepregnancy risk factors have been described including maternal age, parity and maternal diseases including epilepsy, diabetes and thyroid disease. There are few in-depth studies on the causes of CP. In the present systematic review, databases searched were Google Scholar and PubMed to identify data on determinants of CP in the world. Studies were included if they specifically mentioned CP as an outcome, the study objective is to identify factors associated with CP in children and all quantitative observational studies. JBI Critical Appraisal Tools were used to assess the methodological quality of a study. Papers that meet the inclusion criteria were rigorously appraised by two critical appraisers. 40 consistent determinants of CP in children from 95 research articles that meet inclusion criteria are included in the review. The majority of studies (24 articles) showed that premature babies and low weight were determinants of CP in children, whereas 15 studies showed that low Apgar scores were determinants of CP in children. The commonest determinants of CP in children are premature babies and low weight, low Apgar scores, intrauterine infection, congenital brain malformations, thyroid disease, premature rupture of membrane (PROM) and placental abruption. Preventing preterm delivery, low birth weight and intrauterine infection as well as immediate neonatal resuscitation for newborns with low Apgar scores may help to prevent CP in children.

Markers of perinatal hypoxia-ischaemia and neurological injury: assessing the impact of insult duration

Hypoxic-ischaemic insults occurring during or after birth can cause both acute and long-term neurological impairment. The duration of the insult is a critical factor, but most published reports of duration have important limitations. After the onset of a persistent bradycardia in 125 term born infants, abnormal outcomes occurred in two by 10 minutes, in 12 out of 47 (26%) delivered between 11 and 20 minutes, and in 55 out of 65 (85%) delivered after 20 minutes. Series with unspecified gestation or including infants born preterm give comparable results in over 500 additional cases. Before 20 minutes there was little correlation with severity, while after 20 minutes most were severely impaired. Limited neuroimaging data suggest that damage restricted to the basal ganglia and thalamus may begin to occur after 10 minutes, associated Rolandic damage after 15 minutes, and other cortical involvement after 20 minutes. Associated white matter damage can occur after any duration. There were little data for other patterns of damage. WHAT THIS PAPER ADDS: Some term born infants can withstand 20 minutes of fetal bradycardia without acute or chronic damage. Durations in humans are not the same as in animal models.

The Placenta in Neonatal Encephalopathy: A Case-Control Study

OBJECTIVE

We assessed whether specific histologic placental lesions were associated with risk for neonatal encephalopathy, a strong predictor of death or cerebral palsy.

STUDY DESIGN

Case-control study of singletons with gestational ages ≥35 weeks. Data were abstracted from a prospectively collected database of consecutive births at a hospital in which placental samples from specified sites are collected and stored for all inborn infants. Placentas of infants with neonatal encephalopathy were compared with randomly selected control infants (ratio of 1:3). Placental histologic slides were read by a single experienced perinatal pathologist unaware of case status, using internationally recommended definitions and terminology. Findings were grouped into inflammatory, maternal, or fetal vascular malperfusion (FVM) and other lesions.

RESULTS

Placental samples were available for 73 of 87 (84%) cases and 253 of 261 (97%) controls. Delivery complications and gross placental abnormalities were more common in cases, of whom 4 died. Inflammation and maternal vascular malperfusion did not differ, and findings consistent with global FVM were more frequent in case (20%) than control (7%) placentas (P = .001). There was a trend toward more segmental FVM and high-grade FVM (fetal thrombotic vasculopathy) among cases. Some type of FVM was observed in 24% of placentas with neonatal encephalopathy. In infants with both neonatal encephalopathy and placental FVM, more often than in infants with neonatal encephalopathy without FVM, electronic fetal monitoring tracings were considered possibly or definitely abnormal (P = .028).

CONCLUSIONS

Vascular malperfusion of subacute or chronic origin on the fetal side of the placenta was associated with increased risk of neonatal encephalopathy.

Cerebral palsy after neonatal encephalopathy: do neonates with suspected asphyxia have worse outcomes?

AIM

We sought to investigate how brain injury and severity, and neurological subtype of cerebral palsy (CP) differed in term-born children with CP after neonatal encephalopathy, between those with suspected birth asphyxia and those without.

METHOD

Using the Canadian CP Registry, which included 1001 children, those with CP born at ≥ 36 wks after moderate or severe neonatal encephalopathy, were dichotomized according to the presence or absence of suspected birth asphyxia. Gross Motor Function Classification System (GMFCS) scores, neurological subtypes, comorbidities, and magnetic resonance imaging findings were compared.

RESULTS

Of the 147 term-born children with CP (82 males, 65 females; median age 37 months, interquartile range [IQR] 26-52.5) who after moderate or severe neonatal encephalopathy had the required outcome data, 61 (41%) met criteria for suspected birth asphyxia. They had a higher frequency of non-ambulatory GMFCS status (odds ratio [OR] 3.4, 95% confidence interval [CI] 1.72-6.8), spastic quadriplegia (OR 2.8, 95% CI 1.4-5.6), non-verbal communication skills impairment (OR 4.2, 95% CI 2.0-8.6), isolated deep grey matter injury (OR 4.1, 95% CI 1.8-9.5), a lower frequency of spastic hemiplegia (OR 0.17, 95% CI 0.07-0.42), focal injury (OR 0.20; 95% CI 0.04-0.93), and more comorbidities (p=0.017) than those who did not meet criteria.

INTERPRETATION

Term-born children who develop CP after neonatal encephalopathy with suspected birth asphyxia have a greater burden of disability than those without suspected birth asphyxia.

Less severe cerebral palsy outcomes in infants treated with therapeutic hypothermia

AIM

To describe the incidence, type and severity of cerebral palsy at 24 months in a regional cohort of infants treated with whole-body therapeutic hypothermia for neonatal encephalopathy.

METHODS

Data were collected prospectively in a regional centre providing TH. Antenatal and perinatal clinical variables and severity of encephalopathy were collected. Infants were assessed at 18 months using the Bayley Scales of Infant and Toddler Development-III, and the presence and severity of CP was investigated at 24 months.

RESULTS

A total of 125 of 132 infants fulfilled entry criteria for TH trials and completed 72 h of TH. Sixteen (13%) of the 125 infants died, and eight (6%) were not available for follow-up. Eighteen infants (14%; 18% of those assessed) developed CP. Of these, 12 (67%) were classified using the Gross Motor Function Classification System, at level 1, six (33%) at level 5 and none at levels 2, 3 or 4.

CONCLUSION

Our regional clinical cohort had lower mortality and comparable rates of CP compared with historical outcomes in TH trials. In contrast to historical cohorts, only one-third of the 18 children with CP were severely affected and 12 were mildly affected, all of whom were independently ambulant by 24 months.

Cerebral Palsy after Neonatal Encephalopathy: How Much Is Preventable?

OBJECTIVES

To determine the expected proportion of term cerebral palsy (CP) after neonatal encephalopathy (NE) that could theoretically be prevented by hypothermia and elucidate the perinatal factors associated with CP after NE in those who do not meet currently used clinical criteria required to qualify for hypothermia ("cooling criteria").

STUDY DESIGN

Using the Canadian CP Registry, we categorized children born at ≥ 36 weeks with birth weight ≥ 1800 g with CP after moderate or severe NE according to the presence or absence of cooling criteria. Maternal, perinatal, postnatal, and placental factors were compared between the 2 groups. A number needed to treat of 8 (95% CI 6-17) to prevent one case of CP was used for calculations.

RESULTS

Among the 543 term-born children with CP, 155 (29%) had moderate or severe NE. Sixty-four of 155 (41%) met cooling criteria and 91 of 155 (59%) did not. Shoulder dystocia was more common in those who did not meet cooling criteria (OR 8.8; 95% CI 1.1-71.4). Low birth weights (20% of all singletons), small placentas (42%), and chorioamnionitis (13%) were common in both groups.

CONCLUSIONS

The majority of children with CP after NE did not meet cooling criteria. An estimated 5.1% (95% CI 2.4%-6.9%) of term CP after NE may be theoretically prevented with hypothermia. Considering shoulder dystocia as an additional criterion may help recognize more neonates who could potentially benefit from cooling. In all cases, a better understanding of the antenatal processes underlying NE is essential in reducing the burden of CP.

Consequences of meconium stained amniotic fluid: what does the evidence tell us?

BACKGROUND

Meconium stained amniotic fluid (MSAF) is common and associated with meconium aspiration syndrome (MAS). Other consequences of meconium passage before birth are less well understood.

METHODS

We reviewed the literature for original papers reporting on outcomes associated with MSAF.

FINDINGS

Among preterm infants MSAF is more prevalent than previously believed and is associated with higher neonatal morbidity. Intrauterine exposure to meconium is associated with inflammation of tissues of the lung, chorionic plate and umbilical vessels and through various mechanisms may contribute to neonatal morbidity, independent of MAS. No compelling evidence supported an association between MSAF and increased neurological impairment, including early seizure activity.

Antepartum and intrapartum factors preceding neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

To determine whether antepartum factors alone, intrapartum factors alone, or both in combination, are associated with term neonatal hypoxic-ischemic encephalopathy (HIE).

METHODS

A total of 405 infants ≥ 35 weeks' gestation with early encephalopathy, born between 1992 and 2007, were compared with 239 neurologically normal infants born between 1996 and 1997. All cases met criteria for perinatal asphyxia, had neuroimaging findings consistent with acute hypoxia-ischemia, and had no evidence for a non-hypoxic-ischemic cause of their encephalopathy.

RESULTS

Both antepartum and intrapartum factors were associated with the development of HIE on univariate analysis. Case infants were more often delivered by emergency cesarean delivery (CD; 50% vs 11%, P < .001) and none was delivered by elective CD (vs 10% of controls). On logistic regression analysis only 1 antepartum factor (gestation ≥ 41 weeks) and 7 intrapartum factors (prolonged membrane rupture, abnormal cardiotocography, thick meconium, sentinel event, shoulder dystocia, tight nuchal cord, failed vacuum) remained independently associated with HIE (area under the curve 0.88; confidence interval 0.85-0.91; P < .001). Overall, 6.7% of cases and 43.5% of controls had only antepartum factors; 20% of cases and 5.8% of controls had only intrapartum factors; 69.5% of cases and 31% of controls had antepartum and intrapartum factors; and 3.7% of cases and 19.7% of controls had no identifiable risk factors (P < .001).

CONCLUSIONS

Our results do not support the hypothesis that HIE is attributable to antepartum factors alone, but they strongly point to the intrapartum period as the necessary factor in the development of this condition.

Term neonatal encephalopathy antecedent cerebral palsy: a retrospective population-based study

OBJECTIVE

To compare the clinical profile of term-born cerebral palsy children with or without antecedent moderate to severe neonatal encephalopathy. We hypothesized that antecedent neonatal encephalopathy is associated with a spastic quadriparesis cerebral palsy clinical profile, a higher severity of functional motor impairment, and a greater number of associated comorbidities.

METHODS

Using the Quebec Cerebral Palsy Registry, neurologic subtype, Gross Motor Function Classification System stratification, and comorbidities were compared in children with cerebral palsy with and without antecedent neonatal encephalopathy. Differences between groups were evaluated using chi square analysis for categorical variables and student t test for continuous variables.

RESULTS

We identified 132 children with cerebral palsy born full term over a 4 year-interval (1999-2002 inclusive) within the Quebec Cerebral Palsy Registry, of which 44 (33%) had an antecedent neonatal encephalopathy. Spastic quadriplegia subtype of cerebral palsy and Gross Motor Function Classification System Level III-V (non-independent ambulation) were significantly associated with antecedent neonatal encephalopathy. The mean number of comorbidities experienced was not different in the two groups. Of five documented comorbidities, only severe communication difficulties were found to be associated (p < 0.05) with antecedent neonatal encephalopathy.

CONCLUSION

A pattern of increased neuromotor impairment, functional gross motor severity and possible communication difficulties was found in the 33% of children with cerebral palsy born at term and with a history of neonatal encephalopathy.

Induction of labor and cerebral palsy: a population-based study in Norway

OBJECTIVE

To investigate the association between labor induction and later development of cerebral palsy (CP).

DESIGN

Registry-based cohort study.

SETTING

Perinatal data on all children born in Norway 1996-1998 were obtained from the Medical Birth Registry of Norway (MBRN). Neurodevelopmental data were collected from the Norwegian Cerebral Palsy Registry (CPRN).

POPULATION

A total of 176,591 children surviving the neonatal period. Of 373 children with CP, detailed data were available on 241.

METHODS

Unadjusted and adjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated as estimates of the relative risk that a child with CP was born after labor induction.

MAIN OUTCOME MEASURES

Total CP and spastic CP subtypes.

RESULTS

Bilateral cerebral palsy was more frequently observed after induced labor (OR: 3.1; 95% CI 2.1-4.5). For children born at term the association between bilateral CP and labor induction was stronger (OR: 4.4; 95% CI 2.3-8.6). The association persisted after adjustment for maternal disease, gestational age, standard deviation score for birthweight (z-score) and prelabor rupture of membranes (PROM) (adjusted OR: 3.7; 95%CI 1.8-7.5). Among children with CP born at term, four-limb involvement (quadriplegia) was significantly more frequent after induced (45.5%) compared with non-induced labor (8.0%). There was no significant association between labor induction and unilateral CP subtype or CP in preterm born children.

CONCLUSIONS

In this study population, we found that labor induction at term was associated with excess risk of bilateral spastic CP and in particular CP with four-limb involvement.

[Cerebral palsy and perinatal asphyxia (I--diagnosis)]

Cerebral palsy (CP) is a group of disorders of the development of movement and posture, causing activity limitations, that are attributed to nonprogressing disturbances that occurred in the developing fetal or infant brain. The motor abnormalies are often accompanied by disturbances of sensation, perception, cognition, behavior and/or by a seizure disorder. The prevalence of CP has not decreased in developed countries over the past 30 years, despite the widespread use of electronic fetal heart rate monitoring and a 5- to 6-fold increase in the cesarean delivery rate. In the term newborn, CP may be attributed to perinatal asphyxia in case of metabolic acidosis in the cord blood (pH<7,00 and base deficit>12 mmol/L), followed by a moderate or severe neonatal encephalopathy within 24 hours and a further neurological impairement characterized by spastic quadriplegia and dyskinesia/dystonia. Dating the time of fetal asphyxia during delivery is possible when there are acute catastrophic complications during labor and unexpected acute or progressive fetal heart rate anomalies after a normal admission test, when there is a need for intensive neonatal resuscitation, a multi-organ failure within 72 hours of birth and visualization of acute non focal cerebral abnormalities, mainly by early magnetic resonance imaging (MRI). MRI sequences show either a brain-damaged pattern of the central basal ganglia, thalami and posterior limbs of internal capsules with relative cortical sparing, in acute, near-total asphyxial insults manifested by a continuous bradycardia or a pattern of cortical injury in the watershed zones and relative sparing of the central grey matter, in prolonged partial asphyxia, manifested by late or atypical variable decelerations with progressive fetal tachycardia, loss of reactivity and absent fluctuation. Prolongation of either type of asphyxial insult results in more global brain damage. In order to differentiate a CP occurring after perinatal asphyxia from other neurological sequelae in relation with infection, hemorrhage, stroke, malformations, genetic or metabolic diseases, it is essential that a definitive information from the brain by MRI and an extensive histological examination of the placenta are at disposal.

A randomized controlled trial of phenobarbital in neonates with hypoxic ischemic encephalopathy

BACKGROUND

Phenobarbital is one of the oldest, cheapest and most easily available cerebro-protective drugs for the hypoxic brain. It has multiple actions that could be of benefit to the asphyxiated brain. However, its potential has not been fully explored.

OBJECTIVE

To study the effect of phenobarbital given within six hours of life to term and near-term asphyxiated neonates, on mortality, neurological abnormality at discharge and seizures.

METHODS

This was a randomized controlled trial set in a tertiary care referral perinatal centre. Asphyxiated neonates (gestational age >or= 34 weeks) manifesting with hypoxic ischemic encephalopathy (HIE) in the first six hours of life were randomized to receive either injection of phenobarbital 20 mg/kg IV or to the control group. The primary outcome was death or abnormal neurological examination at discharge while seizures, need for ventilation and multi-organ dysfunction were secondary outcomes.

RESULTS

Twenty-five babies received phenobarbital and 20 were in the control group. The mortality (20% vs. 15%) and abnormal neurological outcome at discharge (30% vs. 53%, p = 0.15) were statistically not different between the two groups. In the phenobarbital group, 8% of neonates developed seizures while 40% of babies in the control group developed seizures (p = 0.01, relative risk (RR) = 0.20 (0.05-0.84)). Phenobarbital was well tolerated and did not increase the need for respiratory support.

CONCLUSIONS

Phenobarbital in the dose of 20 mg/kg IV given within six hours of life to term and near-term neonates with HIE, significantly decreased the incidence of neonatal seizures and was well tolerated. However, it did not alter the mortality and neurologic outcome at discharge.

Anatomic changes and imaging in assessing brain injury in the term infant

Encephalopathy from hypoxic-ischemic injury is a major cause of morbidity and mortality in term infants. MRI is the gold standard in evaluating the nature and extent of injury. Although imaging this population is challenging, important information can be obtained safely. Patterns of injury and the likely mechanisms that cause them are reviewed. Conventional images combined with additional techniques provide clues to cause, timing, and long-term prognosis. As altering acute neurologic damage with interventions in the acute period becomes a reality, MRI will play a crucial role in delineating which infants have the most to gain and act as a biomarker to gauge response.

Cerebral palsy in term infants: a clinicopathologic analysis of 158 medicolegal case reviews

Our understanding of cerebral palsy (CP) in term infants is hindered by its low incidence and sporadic presentation. Many of these CP cases enter litigation, and a focused review of medicolegal consultations provides an opportunity to better understand the pathogenesis of these cases. In this study complete clinical and pathologic data from 158 cases of CP complicating singleton pregnancies after 36 weeks of gestation were prospectively collected over a 10-year period extending from 1998 to 2008. A hierarchical system was used to separate cases into the following 5 groups: (1) clinical/sentinel events (20%), (2) severe large fetoplacental vascular lesions (34%), (3) placental lesions indicative of chronic placental dysfunction (23%), and (4) placental lesions indicative of subacute/chronic adaptation to hypoxia (15%). The remaining 8% (group 5) of cases were idiopathic. Common to all subgroups was clinical and/or pathologic evidence of umbilical cord obstruction, which was observed in 63% of cases. The following clinical features significantly differed among subgroups. Group 1 had less maternal obesity and more cases involving multicystic encephalopathy. Group 2 had increased oligohydramnios, cerebral edema, nucleated red blood cell counts greater than 10 000/mm(3), hypoglycemia, pulmonary hypertension, and cardiac dysfunction. Group 3 had more preeclampsia and, together with group 2, more infants with a low ponderal index. Group 5 had a higher prevalence of positive family history of neurodevelopmental disorders. In conclusion, infant cases subject to litigation related to CP following term birth can be separated into distinct clinicopathologic subgroups with only a small number lacking either clinical/sentinel events or placental evidence of subacute or chronic in utero stress.

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.

The relationship between intrapartum maternal fever and neonatal acidosis as risk factors for neonatal encephalopathy

OBJECTIVES

This study was undertaken to investigate the relationship among maternal intrapartum fever, neonatal acidosis, and the risk of neonatal encephalopathy.

STUDY DESIGN

Cohort study of pregnancies at term. Logistic regression was used to estimate the effect of maternal fever and acidosis on the risk of neonatal encephalopathy. The potential interaction between maternal fever and acidosis was included in the models.

RESULTS

Of 8299 women, 25 neonates (0.3%) had encephalopathy develop. These were more often born acidotic (adjusted odds ratio 11.5; 95% CI, 5.0-26.5) or after a maternal intrapartum fever (adjusted odds ratio 8.1; 95% CI, 3.5-18.6). Where both risk factors coexisted, the risk was 12.5% (adjusted odds ratio 93.9; 95% CI, 28.7-307.2). Although this effect is multiplicative, there was no evidence of statistical interaction (P = .93); the effect of maternal fever on the risk of encephalopathy was similar in infants with (adjusted odds ratio 8.7; 95% CI, 2.4-31.7) and without acidosis (adjusted odds ratio 7.4; 95% CI, 2.4-21.9).

CONCLUSION

The combination of a maternal fever with cord acidosis greatly increases the risk of neonatal encephalopathy, but there is evidence against interaction between them, suggesting that they represent 2 separate causal pathways.

Prevalence and pathogenesis of congenital anomalies in cerebral palsy

BACKGROUND

It has been hypothesised that cerebral palsy (CP) and other congenital anomalies are attributable to feto-fetal transfusion problems in a monochorionic multiple gestation. Thus more than one organ could be compromised leading to the coexistence of two or more anomalies in a fetus. Such anomalies in a singleton birth may be attributable to early demise of the co-conceptus as a vanishing twin.

AIM

To determine whether the coexistence of congenital anomalies and CP is greater than a chance finding by comparing the prevalence of congenital anomalies in children with CP with that in the general population of children.

METHODS

A population-based register of children with CP born in 1966-1991 in the counties of Merseyside and Cheshire, UK, comprised the index population. Coexisting congenital anomalies were recorded. For comparison the population prevalence of congenital anomalies was obtained from eight congenital malformation registers in the UK.

RESULTS

Children with CP were found to have highly significant increases in risk for microcephaly, isolated hydrocephaly, congenital anomalies of the eye, congenital cardiac anomalies, cleft lip and/or palate and congenital dislocation of the hips and talipes (p<0.001) and atresias of the oesophagus (p<0.001) and intestines (p<0.01). The relative risks ranged from 3.1 (95% CI 1.9 to 4.8; p<0.001) for congenital malformations of the cardiac septa to 116.09 (95% CI 84.0 to 162.3; p<0.001) for microcephaly.

CONCLUSIONS

Congenital anomalies in children with CP are found much more frequently than expected by chance. A common pathogenic mechanism may account for the coexistence of disparate congenital anomalies. A hypothesis is proposed for such a common pathogenic mechanism.

Brain and cognitive-behavioural development after asphyxia at term birth

Perinatal asphyxia occurs in approximately 1-6 per 1000 live full-term births. Different patterns of brain damage can result, though the relation of these patterns to long-term cognitive-behavioural outcome remains under investigation. The hippocampus is one brain region that can be damaged (typically not in isolation), and this site of damage has been implicated in two different long-term outcomes, cognitive memory impairment and the psychiatric disorder schizophrenia. Factors in addition to the acute episode of asphyxia likely contribute to these specific outcomes, making prediction difficult. Future studies that better document long-term cognitive-behavioural outcome, quantitatively identify patterns of brain injury over development and consider additional variables that may modulate the impact of asphyxia on cognitive and behavioural function will forward the goals of predicting long-term outcome and understanding the mechanisms by which it unfolds.

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.

Fetal hypoxic and ischemic injuries

PURPOSE OF REVIEW

The principles of neonatal neurological protection following intrapartum hypoxia are briefly reviewed. The physiological principles behind the use of cardiotocograph patterns in defining the timing and mechanism of fetal hypoxia and injury are then demonstrated.

RECENT FINDINGS

Fetal neurological injury may result from progressive hypoxemia, acidosis, diminished cardiac output and cerebral ischemia, manifested at birth as low Apgar scores, multisystem compromise, severe acidosis and encephalopathy. More commonly, however, intrapartum injury results from often intermittent, regional ischemia secondary to umbilical cord or head compression resulting in hemorrhage or infarction. Under these circumstances, the amount of umbilical acidosis and neonatal encephalopathy varies and the potential candidate for neuroprotection may escape recognition and timely treatment. Selecting infants likely to benefit from neuroprotection requires information on the timing, duration and mechanism of hypoxia. Neonatal parameters, including low Apgar scores, acidosis, even seizures, lack sensitivity and specificity. Cardiotocograph patterns are capable of determining the duration, mechanism and severity of hypoxia and occasionally, the timing of neurological injury.

SUMMARY

Protecting the newborn from the neurological consequences of intrapartum hypoxia requires critical definition of the mechanism and timing of this exposure. cardiotocograph tracings offer the opportunity to refine the selection of candidates for neonatal rescue.

Severe fetal placental vascular lesions in term infants with neurologic impairment

OBJECTIVE

This study tests the hypothesis that placental disease can identify antepartum processes that either progress into the intrapartum period or predispose to intrapartum brain injury.

STUDY DESIGN

Lesions that affect large fetal vessels were compared in the placentas of 125 neurologically impaired term infants who were the focus of clinical negligence litigation and 250 consecutive singleton deliveries of >/=36 weeks of gestation.

RESULTS

One or more of 4 severe placental fetal vascular lesions (fetal thrombotic vasculopathy, chronic villitis with obliterative fetal vasculopathy, chorioamnionitis with severe fetal vasculitis, and meconium-associated fetal vascular necrosis) were found in 51% of index cases versus 10% of the comparison group ( P <.0001). Prevalence of these lesions in the 64 infants with cerebral palsy was 52% ( P <.0001).

CONCLUSION

Severe fetal placental vascular lesions are correlated highly with neurologic impairment and cerebral palsy. Their nature, duration, and anatomic location make them strong candidates for the antepartum processes that place fetuses at risk for brain injury during the intrapartum period.

Term neonatal asphyxial seizures and peripartum deaths: lack of correlation with a rising cesarean delivery rate

OBJECTIVE

The purpose of this analysis was to study the relationship between an increasing cesarean delivery rate and term neonatal seizures and peripartum deaths.

STUDY DESIGN

This was a retrospective analysis of annually collated institutional data on cesarean delivery and perinatal outcome.

RESULTS

Of 77,350 women who delivered at 37 weeks' gestation or more through 12 years (1989 to 2000), the cesarean rate increased from 6.9% to 15.1%; perinatal mortality at term, average 3.1/1000, was unchanged. The cesarean rate for nulliparas doubled from 8.3% to 17.5%. The overall neonatal term seizure rate (overall 1.3/1000; and for nulliparas 2.5/1000) did not change. The overall peripartum death rate (0.8/1000) was unchanged, although the rate for nulliparas (1.5/1000) showed a significant decline. Overall seizure rate in nulliparas was 5-fold higher than in multiparas; presumed intrapartum asphyxia was associated with 84% of both seizures and neonatal deaths in nulliparas. Among 2547 prelabor cesarean deliveries, there were no peripartum deaths and one neonatal seizure, an incidence comparable with that in multiparas who labored.

CONCLUSION

Despite a greater than 2-fold rise in cesarean section rate, the seizure rate and overall peripartum death rate at term did not alter significantly. Neonatal seizures occurred 5 times more often following first deliveries.

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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.

The epidemiology and causes of cerebral palsy

Cerebral palsy is the commonest physical disability in childhood, occurring in 2.0 to 2.5 per 1000 live births. Although the total number of children with cerebral palsy has remained stable or increased slightly since 1970, there has been a consistent rise in the proportion of cerebral palsy associated with preterm and very preterm births. Known causes of cerebral palsy--whether prenatal, perinatal or postnatal--must be distinguished from risk factors or associations. Much is known about such risk factors which, alone or in combination, may indirectly result in cerebral palsy. Causes and risk factors implicated in cerebral palsy are discussed in detail, together with directions for future research.

Origin and timing of brain lesions in term infants with neonatal encephalopathy

BACKGROUND

The role of intrapartum asphyxia in neonatal encephalopathy and seizures in term infants is not clear, and antenatal factors are being implicated in the causal pathway for these disorders. However, there is no evidence that brain damage occurs before birth. We aimed to test the hypothesis that neonatal encephalopathy, early neonatal seizures, or both result from early antenatal insults.

METHODS

We used brain MRI or post-mortem examination in 351 fullterm infants with neonatal encephalopathy, early seizures, or both to distinguish between lesions acquired antenatally and those that developed in the intrapartum and early post-partum period. We excluded infants with major congenital malformations or obvious chromosomal disorders. Infants were divided into two groups: those with neonatal encephalopathy (with or without seizures), and evidence of perinatal asphyxia (group 1); and those without other evidence of encephalopathy, but who presented with seizures within 3 days of birth (group 2).

FINDINGS

Brain images showed evidence of an acute insult without established injury or atrophy in 197 (80%) of infants in group 1, MRI showed evidence of established injury in only 2 infants (<1%), although tiny foci of established white matter gliosis, in addition to acute injury, were seen in three of 21 on post-mortem examination. In group 2, acute focal damage was noted in 62 (69%) of infants. Two (3%) also had evidence of antenatal injury.

INTERPRETATION

Although our results cannot exclude the possibility that antenatal or genetic factors might predispose some infants to perinatal brain injury, our data strongly suggest that events in the immediate perinatal period are most important in neonatal brain injury.

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.

The relation between pre-eclampsia at term and neonatal encephalopathy

OBJECTIVES

To determine whether pre-eclampsia, hypothesised to be an inflammatory condition, is associated with fever in term labour, and confirm and examine the reported association of pre-eclampsia at term with neonatal encephalopathy.

DESIGN

Prospective cohort study.

SETTING

A Dublin teaching hospital.

PARTICIPANTS

6163 women in labour with singleton pregnancies at term at low risk for intrapartum hypoxia, recruited to a randomised trial examining the effect of admission cardiotocography on neonatal outcome.

RESULTS

Pre-eclampsia was associated with maternal fever > 37.5 degrees in labour (odds ratio (OR) 3.39, 95% confidence interval (CI) 2.1 to 5.4); this was independent of obstetric intervention (adjusted OR 2.07, 95% CI 1.24 to 3.47). Pre-eclampsia was associated with neonatal encephalopathy (OR 25.5, 95% CI 8.4 to 74.7); this too was independent of obstetric intervention (adjusted OR 18.5, 95% CI 5.9 to 58.1). Cord arterial pH values were significantly lower in pre-eclamptics (7.20 v 7.24), although severe cord acidaemia was not significantly more common (OR 2.91, 95% CI 0.7 to 9.9). The association of pre-eclampsia with encephalopathy was independent of maternal fever (adjusted OR 16.5, 95% CI 5.1 to 54) and cord acidaemia (adjusted OR 13.5, 95% CI 3.2 to 56.7).

CONCLUSIONS

The association of pre-eclampsia with maternal fever at term supports the hypothesis that pre-eclampsia is an inflammatory condition. The association of pre-eclampsia with neonatal encephalopathy is independent of obstetric intervention and cannot be explained by either acidaemia or maternal fever. A systemic inflammatory response in the fetus, perhaps secondary to oxidative stress, could explain the link between maternal pre-eclampsia and neonatal encephalopathy, and this may occur through cerebral vasoconstriction.

Placental lesions associated with cerebral palsy and neurologic impairment following term birth

OBJECTIVE

The aim of this study was to determine the association of placental findings with cerebral palsy and related forms of neurologic impairment (NI) following birth at > or =37 weeks gestation (term).

DESIGN

In a retrospective comparison, placentas from 40 term infants with NI ascertained on the basis of clinicopathologic review for medicolegal consultation were compared with placentas from 176 consecutive meconium-stained term infants at low risk for NI.

RESULTS

After stratification for severity, 9 lesions were significantly increased in placentas from infants with NI: 5 lesions generally considered to occur within days of the time of labor and delivery (meconium-associated vascular necrosis, severe fetal chorioamnionitis, chorionic vessel thrombi, increased nucleated red blood cells, and findings consistent with abruptio placenta) and 4 lesions generally believed to have their onset long before labor and delivery (diffuse chronic villitis, extensive avascular villi, diffuse chorioamnionic hemosiderosis, and perivillous fibrin). Findings independently associated with NI by logistic regression in this descriptive study were severe fetal chorioamnionitis (odds ratio [OR], 13.2; 95% confidence interval [CI], 1.2-144); extensive avascular villi (OR, 9.0; 95% CI, 1.6-51); and diffuse chorioamnionic hemosiderosis (OR, 74.8; 95% CI, 6.3-894). The risk of NI increased as a function of the number of lesions present (OR, 10.1; 95% CI, 5.1-20 for each additional lesion), particularly when lesions generally considered to occur near the time of labor and those believed to occur well before labor were found in the same placenta (OR, 94.2; 95% CI, 11.9-747).

CONCLUSIONS

These findings suggest that placental pathology can contribute to an understanding of the mechanisms that contribute to NI at term.

Outcome after intrapartum asphyxia in term infants

Investigatory techniques, particularly magnetic resonance (MR) imaging and spectroscopy, performed in the early neonatal period on infants suspected of intrapartum asphyxia i.e. abnormal fetal heart recording, poor cord gases, low Apgar scores and the need for resuscitation, or with neonatal encephalopathy or seizures, have allowed a much better understanding of the patterns of brain injury and the biochemical processes that follow these events. It is usually possible to distinguish these patterns from those seen in other, often confounding, diagnoses. This has allowed far more precision about the timing of insults and in the prediction of particularly motor, feeding and visual outcome and to some extent intellectual outcome. Long-term neurological and psychometric follow-up of infants in whom detailed perinatal clinical histories and examination, haematological and biochemical investigation and MR brain scans are obtained will allow even more accurate prediction of outcome in the future. Such studies also help to validate standardized neonatal and infant clinical neurological examinations, making them useful tools to predict outcome.

Antepartum risk factors for newborn encephalopathy: the Western Australian case-control study

OBJECTIVE

To ascertain antepartum predictors of newborn encephalopathy in term infants.

DESIGN

Population based, unmatched case-control study.

SETTING

Metropolitan area of Western Australia, June 1993 to September 1995.

SUBJECTS

All 164 term infants with moderate or severe newborn encephalopathy; 400 randomly selected controls.

MAIN OUTCOME MEASURES

Adjusted odds ratio estimates.

RESULTS

The birth prevalence of moderate or severe newborn encephalopathy was 3.8/1000 term live births. The neonatal fatality was 9.1%. The risk of newborn encephalopathy increased with increasing maternal age and decreased with increasing parity. There was an increased risk associated with having a mother who was unemployed (odds ratio 3.60), an unskilled manual worker (3.84), or a housewife (2.48). Other risk factors from before conception were not having private health insurance (3.46), a family history of seizures (2.55), a family history of neurological disease (2.73), and infertility treatment (4.43). Risk factors during pregnancy were maternal thyroid disease (9.7), severe pre-eclampsia (6.30), moderate or severe bleeding (3.57), a clinically diagnosed viral illness (2.97), not having drunk alcohol (2.91); and placenta described at delivery as abnormal (2.07). Factors related to the baby were birth weight adjusted for gestational age between the third and ninth centile (4.37) or below the third centile (38.23). The risk relation with gestational age was J shaped with 38 and 39 weeks having the lowest risk.

CONCLUSIONS

The causes of newborn encephalopathy are heterogeneous and many of the causal pathways start before birth.

A hypothesis for the aetiology of spastic cerebral palsy--the vanishing twin

The aetiology of spastic cerebral palsy (CP), in the majority of cases, is not known but the general consensus is that cerebral impairment occurs prepartum. In monochorionic twin pregnancies, death of one twin late in gestation is recognised as being an important risk factor for the surviving cotwin to have CP. It has been suggested that a significant proportion of singletons with spastic CP may be the result of death of a cotwin in the second half of gestation. In this paper it is hypothesised that spastic CP of unknown aetiology is the result of the death of a monochorionic cotwin and that the death of the cotwin may impair the neurological development of the survivor throughout gestation. If so, vanishing-twin syndrome, which is now a recognised phenomenon revealed by ultrasound examination in early pregnancy, is important in the aetiology of spastic CP.

The changing epidemiology of cerebral palsy

AIM

To determine the prevalence of cerebral palsy in a specific population.

METHODS

Multiple sources of ascertainment were used to create and maintain a register of all cases of cerebral palsy born to mothers resident in the counties of Merseyside and Cheshire in the years 1966 to 1989. Denominator data of infant births and deaths from 1966 to 1981 were obtained from statutory notifications made to health authorities and, for the period 1982-89, from statutory birth and death registrations. Over 1500 cases formed the database for the study.

RESULTS

The prevalence of cerebral palsy has increased among all the low birthweight groups with, most recently, an increase in infants weighing < 1000 g at birth. Low birthweight infants now comprise about 50% of all cases of cerebral palsy; in the early years of the study they comprised about 32% of all cases. The proportion of cerebral palsy by clinical type has changed among low birthweight babies, with relatively fewer cases with diplegia and a concomitant increase in the proportion with hemiplegia. An increase in the severity of functional disability, determined by the proportion of children with severe learning, manual, and ambulatory disabilities, was also found.

CONCLUSIONS

The change in the epidemiology of cerebral palsy has implications for the aetiology of the condition, and for health, educational, and social service provision.

Monitoring technology and the clinical perspective

Currently available technology requires a new look to reduce intervention as well as to improve the detection of the truly at-risk fetus. Iatrogenic causes of so-called fetal distress, in particular the administration of uterotonics without due attention to avoiding hyperstimulation, predominate as a reason for intervention. There needs to be a better definition of the starting point, i.e assessment of the fetal condition and identification of any risk factors, such as oligohydramnios and growth retardation, that might diminish fetal reserve. This will allow 'customization' of surveillance and management according to the needs of each individual fetus. There also needs to be better training and better agreement about the end-point of monitoring. For prospective surveillance, the aim is to avoid rather than to identify damage, and the definition of the appropriate point for intervention needs to come from better consensus on what is and what is not acceptable management based on current knowledge. New technology holds the promise that it can give trended information during labour, allow early recognition of problems and reduce unnecessary intervention. However, there is a need to ensure reliability and reproducibility of the readings before a new method is released. Co-operation with industry is essential, but the roles need to be well defined and the ultimate responsibility for establishing the role of a new technique has to come from the clinicians involved in intrapartum care.

Risk factors for cerebral palsy: a case-control study in Greece

The purpose of this study was to investigate the relation between a series of maternal, antenatal, perinatal, socioeconomic and environmental variables and the occurrence of cerebral palsy (CP) in a setting different from those in which previous analytic epidemiologic studies had been undertaken. The study was of case-control design and included 103 children with cerebral palsy born between 1984 and 1988 and residents of the Greater Athens area at any time during 1991 and 1992. Controls were chosen among the neighbors of the index case or were healthy siblings of children with neurological diseases other than CP seen by the same neurologists as the children with CP; a total of 254 control children were eventually included. Statistical analysis was done by modeling the data through unconditional logistic regression. Statistically significant (p < 0.05) risk factors of potential causal importance were: twin membership (OR = 10.2), gestational age (OR = 0.5 per 4 weeks), birth weight conditional on gestational age (OR = 0.9 per 100 g), congenital malformations (OR = 7.5), unhealthy placenta (OR = 6.6), placenta previa (6 cases, no controls), abnormal amniotic fluid (OR = 3.6), head circumference more than 36 cm (OR = 9.0), general anesthesia during labor (OR = 4.3), forceps delivery (OR = 6.8), and birth trauma (OR = 11.5). Among children with no identifiable prenatal risk factors there was no excess prevalence of one or more perinatal risk factors in CP cases compared to controls, which implies that the latter factors impart their effect through interactions with co-existing prenatal or other risk factors.

Talking to the parents of a baby who is likely to develop permanent neurological impairment following a brain insult in the perinatal period

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