Neonatal seizures: the Dublin Collaborative Study

Risk factors for seizures in the vigorous term neonate: A population-based register study of singleton births in Sweden

Background

Neonatal seizures have been associated with increased mortality and impaired neurodevelopment and, knowledge about risk factors may be useful for prevention. Clear associations have been established between labor-related risk factors and seizures in asphyxiated neonates. However, there is limited information about why some vigorous term-born infants experience seizures.

Objectives

Our aim was to assess antepartum and intrapartum risk factors for seizures in vigorous term-born neonates.

Methods

This was a national cohort study of singleton infants born at term in Sweden from 2009–2015. Vigorous was defined as an Apgar score of at least 7 at 5 and 10 minutes. Data on the mothers and infants were obtained from the Swedish Medical Birth Register and the Swedish Neonatal Quality Register. A diagnosis of neonatal seizures was the main outcome measure and the exposures were pregnancy and labor variables. Logistic regression analysis was used and the results are expressed as adjusted odds ratios (aOR) with 95% confidence intervals (CI).

Results

The incidence of neonatal seizures was 0.81/1,000 for 656 088 births. Seizures were strongly associated with obstetric emergencies (aOR 4.0, 95% CI 2.2–7.4), intrapartum fever and/or chorioamnionitis (aOR 3.4, 95% CI 2.1–5.3), and intrapartum fetal distress (aOR 3.0, 95% CI 2.4–3.7). Other associated intrapartum factors were: labor dystocia, occiput posterior position, operative vaginal delivery, and Cesarean delivery. Some maternal factors more than doubled the risk: a body mass of more than 40 (aOR 2.6, 95% CI 1.4–4.8), hypertensive disorders (aOR 2.3, 95% CI 1.7–3.1) and diabetes mellitus (aOR 2.6, 95% CI 1.7–4.1).

Conclusion

A number of intrapartum factors were associated with an increased risk of seizures in vigorous term-born neonates. Obstetric emergencies, intrapartum fever and/or chorioamnionitis and fetal distress were the strongest associated risks. The presence of such factors, despite a reassuring Apgar score could prompt close surveillance.

Perinatal asphyxia from the obstetric standpoint

Perinatal asphyxia remains one of the major causes of morbidity and mortality for term newborns. Though access to health care and birth attendants have decreased the rate, Neonatal encephalopathy (NE) has not been eliminated. Worldwide, women at socioeconomic disadvantage have the highest risk of delivering a neonate with NE. Neonates that will experience perinatal asphyxia cannot be easily identified prospectively and the intrapartum testing available is not specific enough to clearly indicate the best course of action in most cases. Despite this, training programs that aim to decrease morbidity and mortality from all causes appear to be associated with fewer cases of perinatal asphyxia. The current best approach is to support education and communication for all people involved in the care of birthing women. Ideally, new technology will address identification of the fetus likely to be affected or the fetus who is beginning to experience injury in advance of delivery.

Seizures and Antiseizure Medications are Important to Parents of Newborns With Seizures

BACKGROUND

Neonatal seizures and antiseizure medications both have potentially serious consequences on the developing brain. As such, optimal treatment of neonatal seizures remains unclear. Moreover, little is known about parental experiences, concerns, or unanswered questions. We conducted an online survey to assess parental perspectives regarding neonatal seizures and their management, along with their suggestions for specific high priority research topics.

METHODS

Parents whose children had neonatal seizures were recruited through social media support groups to complete an online survey. Respondents progressed through a tiered series of questions about their experiences with neonatal seizures and antiseizure medications.

RESULTS

There were 126 eligible respondents. On a Likert scale, parents reported that neonatal seizures had a major effect on their families (median 10 of 10; interquartile range 3; n = 85). They also reported that antiseizure medications had a significant impact on their families (median 7 of 10; interquartile range 5.5; n = 75). The emotional impact of the uncertainty regarding seizures and medications was highlighted. Effects on neurodevelopment, continued seizures, and adverse effects of medications were some of the most commonly reported parental concerns and their highest priority research topics.

CONCLUSIONS

Both neonatal seizures and the medications used to treat them contribute to parental worries and have major impact on families. Patient-centered outcomes research should focus on the risk-benefit ratio of neonatal seizures and antiseizure medication. The emotional impact on parents related to the uncertainty regarding both immediate and long-term neonatal seizure management is important to address in the clinical setting.

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.

Postterm pregnancy: should all women have labour induced? A review of the literature

All pregnancies are at some risk of adverse fetal and neonatal outcome. The risk increases, however, if the pregnancy ends too soon (preterm), or if it ends too late (postterm).

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.

Does the onset of neonatal seizures correlate with the timing of fetal neurologic injury?

The onset of seizures after birth has been considered evidence of an intrapartum asphyxial event. The present study was undertaken to determine whether the timing of neonatal seizures after birth correlated with the timing of a fetal asphyxial event. Thus, singleton term infants diagnosed with hypoxic ischemic encephalopathy and permanent brain injury had a mean birth to seizure onset interval of 9.8 +/- 17.7 (range 1-90) hours. When these infants were categorized according to their fetal heart rate (FHR) patterns, the acute group (normal FHR followed by a sudden prolonged FHR deceleration that continued until delivery) tended to have earlier seizures than infants did within the tachycardia group (normal FHR followed by tachycardia, repetitive decelerations, and diminished variability) and the preadmission group (persistent nonreactive FHR pattern intrapartum). These seizure intervals were as follows: acute, 6.6 +/- 18.0 (range 1-90) hours; tachycardia, 11.1 +/- 17.1 (range 1-61) hours; and preadmission, 11.8 +/- 17.9 (range 1-79) hours (p < 0.05). But the range varied widely and no group was categorically distinct. In conclusion, the onset of neonatal seizures after birth does not, in and of itself, appear to be a reliable indicator of the timing of fetal neurologic injury.

The syndrome of acute near-total intrauterine asphyxia in the term infant

Eleven term infants sustained an acute, near-total intrauterine asphyxia at the end of labor. Imaging studies documented a consistent pattern of injury in subcortical brain nuclei, including thalamus, basal ganglia, and brainstem; in contrast the cerebral cortex and white matter were completely or relatively spared. This pattern of injury correlated with the acute and long-term neurologic syndromes in these patients. Four patients had a severe neonatal encephalopathy that included prominent signs of brainstem dysfunction. The other seven patients had a moderate neonatal encephalopathy. Three of these patients had dystonia consistent with basal ganglia injury; all seven remained normocephalic and had good cognitive outcomes consistent with sparing of cerebral cortex and white matter. Finally, in all 11 patients, injury to organs other than the brain was usually subtle. The distribution of injury in these patients reflects the hierarchy of metabolic needs that are unmet after a severe, sudden disruption of substrate supply as occurs in an acute, severe asphyxia. Thus, the higher metabolic rate of the brain compared with other organs explains the significant neonatal encephalopathy with relative sparing of nonbrain organs. Similarly, the higher metabolic rate of subcortical nuclei compared with cerebral hemispheres explains the preponderance of subcortical damage. This clinical and imaging syndrome is in contrast with that seen in more prolonged but less severe intrauterine asphyxia, in which shunting of blood flow from nonbrain organs to the brain and from cerebral hemispheres to the thalamus and brainstem renders nonbrain organs and cerebral hemispheres most vulnerable.

Neonatal seizures: a clinician's overview

Seizures are the most frequent neurological event in newborns (NBs), provoked often by noxae not apt to cause them in later life. This is because receptor families of excitatory amino acids (EAA) are overexpressed at this stage of brain ontogenesis, which is also why most neonatal seizures rapidly abate, even when neurological deficits persist. The brain's immaturities dictate distinct seizure phenotypes. A classification proposed in the late 1960s has been criticized, and a new one has been advocated, based on correlations between EEGs and behaviors, leading to a classification of seizures into 'epileptic' and 'non-epileptic'. The taxonomic pitfalls of these classifications are discussed, and the notion advanced that many seizures fail to fulfil the criteria to label them as epileptic. While etiological factors have changed in time, the striking dichotomy in outcome has persisted. Many etiologies, often multifactorial, are unique in NBs, and they are discussed with reference to diagnosis and therapies. Four syndromes of NB seizures, accepted into the International Classification of the Epilepsies, are critically analyzed, some appearing to rest on fragile grounds. Controversies persist whether seizures per se are injurious to the immature brain. Clinical studies suggest that neither duration in days or length of seizure phenotypes correlates with outcomes, the most valid prognostic indices being offered by etiologies and by patterns of EEG polygraphy. However, because most seizures are symptomatic, it may be difficult to distinguish morbidity due to underlying pathology from that possibly added by seizures. Animal experiments suggested that they are injurious. The theory of energy failure, postulated to cause a cascade of events leading to inhibitions of DNA, proteins, lipids and disrupted neuronal proliferation, synaptogenesis, myelination, has largely been disproved. Brains of immature animals have been shown to have the oxidative machinery needed to fulfill energy demands, even during status convulsivus. They are also capable of using anaerobic metabolism and require less ATP when aerobic energy production ceases. Recent explanations for the injurious consequences of hypoxic ischemia and of prolonged convulsions postulate that neuronal damage occurs from excessive release of EAA which, by binding to their ligand-gated ionic receptors, cause a large influx of Ca2+, resulting in cell death. Because of the overabundance of EAA receptors in early ontogenesis, the excitotoxic hypothesis would appear attractive, but some observations militate against it. Among these is the dissociation found between the focal neurotoxicities induced by EAA injected into the brain and their absence following the concomitant convulsions. The latter are not blocked by pretreatment with EAA antagonists, while these prevent injuries caused by the injected EAA. There is no convincing evidence that excessive release of EAA occurs during NBs' seizures. Even if it does occur, it has been shown that immature neurons have a better capacity to self-protect from increased Ca2+ influx, and also that direct application of glutamate to immature neurons leads to significantly lower Ca2+ influx. These data raise doubts about the postulated excitotoxicity caused by NBs' seizures, being consistent with the fact that no one, so far, has observed neuronal damage from drug-induced convulsive states in NBs. Lack of overt neuronal injuries does not preclude that long-term subtle changes might be induced by noxae apt to provoke transient ictal events. Thus models developed in our laboratories demonstrate that long-term epileptogenicity results following postnatal O2 deprivation without evidence of neuronal injuries or of long-term behavioral or electrophysiological alteration. However, both age at which hypoxia occurs and specific proconvulsant methods used strictly determine whether increased epileptogenicity will occur.

Evolution of neonatal seizures

The evolution of the diagnosis, etiology, management, and prognosis of neonatal seizures over the past two decades is reviewed. Seizures in the neonate are unique and require special classification. They result from acquired or congenital abnormalities of the central nervous system. Clustering of prognostic parameters, including seizure characteristics, perinatal factors, neurologic signs, cause, and neuroimaging and electroencephalographic abnormalities, allows neonatal seizures to be viewed as clinical syndromes with predictable outcomes.

Phenobarbital in newborns with neonatal seizures. A study of plasma levels after intravenous administration

Phenobarbital plasma levels were studied in a group of 25 newborn infants. Phenobarbital was administered i.v. in all cases throughout the study period. The mean loading dose was 19.4 mg/kg, ranging from 16.4 to 20.5, and the mean maintenance dose was 4.0 mg/kg/day, varying from 2.6 to 5.0. We obtained mean plasma levels of 22.9 micrograms/ml, 24 h after administering the loading dose. Mean plasma levels at 4, 7, 14 and 21 days were in the therapeutic range (15-40 micrograms/ml), with only a few cases falling outside of it. There was no difference in plasma phenobarbital levels between term and pre-term infants. Side effects were not seen in infants without a severe neurological impairment prior to drug administration.

Does oxytocin augmentation increase perinatal risk in primigravid labor?

To assess the influence of high-dose oxytocin augmentation of spontaneous labor, a consecutive series of 30,874 primigravid term deliveries were analyzed for adverse perinatal outcome. In spite of a longer mean duration of labor, the frequencies of asphyxial perinatal death, neonatal seizures, and abnormal neonatal neurologic behavior were not significantly increased in 14,119 (45%) oxytocin-treated patients. There was no case of uterine rupture in any primigravid labor during the study. These results from 13 years of clinical practice provide reassurance about maternal and fetal safety if oxytocin is used as part of a protocol of active management to correct dystocia when spontaneous primigravid labor with vertex presentation fails to progress.

Seizure recurrence in infants with neonatal convulsions. A follow-up study

Twenty three infants with neonatal seizures were followed prospectively to a mean age of 11 months. Only 2 were pre-term and birth weight ranged from 1700 to 4230 grams, with 17 male and 6 female infants. Hypoxic-ischemic encephalopathy was the most common etiology (82.6%). Focal clonic convulsions were the predominant seizure type, present in 7/16 infants in which the seizure type could be identified. All infants had a neurological examination and EEG, and 18 had a cranial ultrasonography performed at the follow-up. Anticonvulsant medication was discontinued, if follow-up EEG and neurological examination were normal. At the follow-up, seizure recurrence was observed in 7/23 (30%) infants. Abnormal EEG, neurological examination and cranial ultrasonography were statistically correlated with seizure recurrence. We conclude that infants with neonatal seizures can remain free of anticonvulsant medication provided they have normal neurological examination, EEG and cranial ultrasonography.

Global and depth resolved phosphorus magnetic resonance spectroscopy to predict outcome after birth asphyxia

Twelve normal and 32 asphyxiated neonates were studied using global and depth resolved phosphorus magnetic resonance spectroscopy (31PMRS). Eight of the asphyxiated group died or survived with major neurodevelopmental abnormalities. A global phosphocreatinine/inorganic phosphate (PCr/Pi) ratio below the range of values from normal infants predicted adverse outcome after asphyxia with a positive predictive value of 64%, sensitivity 88%, and specificity 83%. Corresponding values for global inorganic orthophosphate/adenosine triphosphate (Pi/ATP) ratios were positive predictive value 88%, sensitivity 96%, and specificity 88%. Spatially localised MRS data, obtained using phase modulated rotating frame imaging, showed cerebral energy metabolism to be more abnormal in deep than superficial regions after birth asphyxia. However, in this population of full term infants none of the regional metabolite concentrations were superior to global data for prediction of outcome.

Postnatal epilepsy after EEG-confirmed neonatal seizures

We examined infants whose neonatal seizures were confirmed by randomly recorded ictal EEG tracings to determine the types and frequency of postnatal epilepsy (PNE)--unprovoked, recurring postnatal seizures. Perinatal and postnatal clinical and EEG variables were also examined for their relevance to PNE. Forty infants with EEG-documented neonatal seizures of diverse etiologies were studied. The 27 survivors were followed for a mean of 31 months. PNE developed in 56% (15 of 27) of the cohort. The first seizure appeared at a mean-corrected age of 12.7 months and occurred despite ongoing antiepileptic medication in 60% (9 of 15) of the group. Seizures were classified as infantile spasms or minor motor (7 patients), complex partial (4 patients), or generalized tonic-clonic (4 patients). Perinatal variables that significantly correlated with PNE included the presence of coma but not the age at seizure onset, the estimated gestational age, or Apgar scores. PNE occurred in 68% (13 of 19) of patients with moderately or markedly abnormal EEG backgrounds but in only 25% (2 of 8) without (p = 0.035). There was a strong trend for PNE to develop in patients with greater than 10 electrographic seizures per hour but in only 45% (9 of 20) of infants with fewer seizures (p = 0.058). Several postnatal variables were significantly related to PNE--the presence of cerebral palsy (CP), mental retardation (MR), CP with MR, and follow-up EEGs. PNE occurred in only 27% (3 of 11) of patients without spikes or sharp waves on postnatal EEGs performed at age 3 months but in 100% (3 of 3) of patients with spikes or sharp waves (p = 0.022).(ABSTRACT TRUNCATED AT 250 WORDS)