The current etiologic profile and neurodevelopmental outcome of seizures in term newborn infants

Sevoflurane activates hippocampal CA3 kainate receptors (Gluk2) to induce hyperactivity during induction and recovery in a mouse model

BACKGROUND

In addition to general anaesthetic effects, sevoflurane can also induce hyperactive behaviours during induction and recovery, which may contribute to neurotoxicity; however, the mechanism of such effects is unclear. Volatile anaesthetics including isoflurane have been found to activate the kainate (GluK2) receptor. We developed a novel mouse model and further explored the involvement of kainate (GluK2) receptors in sevoflurane-induced hyperactivity.

METHODS

Maximal speed, mean speed, total movement distance and resting percentage of C57BL/6 mice were quantitatively measured using behavioural tracking software before and after sevoflurane anaesthesia. Age dependence of this model was also analysed and sevoflurane-induced hyperactivity was evaluated after intracerebral injection of the GluK2 receptor blocker NS-102. Neurones from the hippocampal CA3 region were used to undertake in vitro electrophysiological measurement of kainate currents and miniature excitatory postsynaptic potential (mEPSP).

RESULTS

Sevoflurane induced significant hyperactivities in mice under sevoflurane 1% anaesthesia and during the recovery period, characterized as increased movement speed and total distance. The hyperactivity was significantly increased in young mice compared with adults (P<0.01) and pre-injection of NS-102 significantly prevented this sevoflurane-induced hyperactivity. In electrophysiological experiments, sevoflurane significantly increased the frequency of mEPSP at low concentrations and evoked kainate currents at high concentrations.

CONCLUSIONS

We developed a behavioural model in mice that enabled characterization of sevoflurane-induced hyperactivity. The kainate (GluK2) receptor antagonist attenuated these sevoflurane-induced hyperactivities in vivo, suggesting that kainate receptors might be the underlying therapeutic targets for sevoflurane-induced hyperactivities in general anaesthesia.

Hypoglycaemia in the Newborn

AIM

Severe neonatal hypoglycaemia (HG) leads to neurologic damage, mental retardation, epilepsy, impaired cardiac performance and muscle weakness. The aim was to assess the frequency and severity of HG in a population of newborns.

PATIENTS AND METHODS

We investigated 739 patients with neonatal hypoglycaemia (HG) (M:F=370:369) born at the University Clinic for Gynaecology and Obstetritics in Skopje in the period 2014-2016 and treated at the neonatal intensive care unit (NICU). 1416 babies were treated in the same period in NICU, and HG was observed in 52.18%. The birth weight was dominated by children with low birth weight: very low birth weight (VLBW)(<1500g) 253 children, (34,23%), low birth weight (1500-2500g) 402 (54.39%), appropriate for gestational age (AGA) 78(10.55%), and high birth weight (>4000g) 6 babies (0.81%). The gestational age was also dominated by children with low gestational age: gestational week (GW) 20-25 four children (0.54%), 26-30 GW 133 babies (17.99%), 31-35 GW472 (63.87%), and 36-40 GW130 neonates (17.59 %). 241 mothers (32.61%) have had an infection during pregnancy, 82 preeclampsia or eclampsia (11.09%), 20 diabetes mellitus (2.70%), 78 placental situations (placenta previa, abruption) (10.55%). In this study 47 babies (6.35%) with HG and co-morbidities died. There was a significant positive correlation between HG birth weight (p<0.01), gestational age (p<0.05), and the lowest Apgar score (p<0.01). Neonatal deaths were significantly correlated with GA (р>0,01), co-morbidities of the mothers (р>0,05) but not with the birth weight (р>0,05). In contrast, a significant positive correlation was found between convulsions and body weight (р<0.05). The lowest Apgar score was positively correlated with the gestational age (0.01), but not with the birth weight (0.05).

CONCLUSION

Low birth weight, low gestational age, maternal risk factors, hypoxic-ischemic encephalopathy and neonatal infections are associated with HG and are a significant factor in overall neonatal mortality. Those results indicate that diminishing the frequency of the neonatal HG and the rates of neonatal mortality requires complex interaction of prenatal and postnatal interventions.

Connexin hemichannel blockade improves survival of striatal GABA-ergic neurons after global cerebral ischaemia in term-equivalent fetal sheep

Basal ganglia injury at term remains a major cause of disability, such as cerebral palsy. In this study we tested the hypotheses that blockade of astrocytic connexin hemichannels with a mimetic peptide would improve survival of striatal phenotypic neurons after global cerebral ischaemia in term-equivalent fetal sheep, and that neuronal survival would be associated with electrophysiological recovery. Fetal sheep (0.85 gestation) were randomly assigned to receive a short or long (1 or 25 h) intracerebroventricular infusion of a mimetic peptide or vehicle, starting 90 minutes after 30 minutes of cerebral ischaemia. Sheep were killed 7 days after ischaemia. Cerebral ischaemia was associated with reduced numbers of calbindin-28k, calretinin, parvalbumin and GAD positive striatal neurons (P < 0.05 ischaemia + vehicle, n = 6 vs. sham ischaemia, n = 6) but not ChAT or nNOS positive neurons. Short infusion of peptide (n = 6) did not significantly improve survival of any striatal phenotype. Long infusion of peptide (n = 6) was associated with increased survival of calbindin-28k, calretinin, parvalbumin and GAD positive neurons (P < 0.05 vs. ischaemia + vehicle). Neurophysiological recovery was associated with improved survival of calbindin-28k, calretinin and parvalbumin positive striatal neurons (P < 0.05 for all). In conclusion, connexin hemichannel blockade after cerebral ischaemia in term-equivalent fetal sheep improves survival of striatal GABA-ergic neurons.

Neuroinflammation in epileptogenesis: Insights and translational perspectives from new models of epilepsy

Animal models have provided a wealth of information on mechanisms of epileptogenesis and comorbidogenesis, and have significantly advanced our ability to investigate the potential of new therapies. Processes implicating brain inflammation have been increasingly observed in epilepsy research. Herein we discuss the progress on animal models of epilepsy and comorbidities that inform us on the potential role of inflammation in epileptogenesis and comorbidity pathogenesis in rodent models of West syndrome and the Theiler's murine encephalomyelitis virus (TMEV) mouse model of viral encephalitis-induced epilepsy. Rat models of infantile spasms were generated in rat pups after right intracerebral injections of proinflammatory compounds (lipopolysaccharides with or without doxorubicin, or cytokines) and were longitudinally monitored for epileptic spasms and neurodevelopmental and cognitive deficits. Anti-inflammatory treatments were tested after the onset of spasms. The TMEV mouse model was induced with intracerebral administration of TMEV and prospective monitoring for handling-induced seizures or seizure susceptibility, as well as long-term evaluations of behavioral comorbidities of epilepsy. Inflammatory processes are evident in both models and are implicated in the pathogenesis of the observed seizures and comorbidities. A common feature of these models, based on the data so far available, is their pharmacoresistant profile. The presented data support the role of inflammatory pathways in epileptogenesis and comorbidities in two distinct epilepsy models. Pharmacoresistance is a common feature of both inflammation-based models. Utilization of these models may facilitate the identification of age-specific, syndrome- or etiology-specific therapies for the epilepsies and attendant comorbidities, including the drug-resistant forms.

Anticonvulsant effect of flupirtine in an animal model of neonatal hypoxic-ischemic encephalopathy

Research studies suggest that neonatal seizures, which are most commonly associated with hypoxic-ischemic injury, may contribute to brain injury and adverse neurologic outcome. Unfortunately, neonatal seizures are often resistant to treatment with current anticonvulsants. In the present study, we evaluated the efficacy of flupirtine, administered at clinically relevant time-points, for the treatment of neonatal seizures in an animal model of hypoxic-ischemic injury that closely replicates features of the human syndrome. We also compared the efficacy of flupirtine to that of phenobarbital, the current first-line drug for neonatal seizures. Flupirtine is a KCNQ potassium channel opener. KCNQ channels play an important role in controlling brain excitability during early development. In this study, hypoxic-ischemic injury was induced in neonatal rats, and synchronized video-EEG records were acquired at various time-points during the experiment to identify seizures. The results revealed that flupirtine, administered either 5 min after the first electroclinical seizure, or following completion of 2 h of hypoxia, i.e., during the immediate reperfusion period, reduced the number of rats with electroclinical seizures, and also the frequency and total duration of electroclinical seizures. Further, daily dosing of flupirtine decreased the seizure burden over 3 days following HI-induction, and modified the natural evolution of acute seizures. Moreover, compared to a therapeutic dose of phenobarbital, which was modestly effective against electroclinical seizures, flupirtine showed greater efficacy. Our results indicate that flupirtine is an extremely effective treatment for neonatal seizures in rats and provide evidence for a trial of this medication in newborn humans.

Characterization of the motor performance of newborns in a neonatal unit of tertiary level

Objective:

To characterize the motor performance of newborns in a neonatal unit of tertiary level and compare the results to the values recommended by the Test of Infant Motor Performance (TIMP).

Method:

Newborns between 34 and 416/7 weeks of corrected gestational age, breathing spontaneously and presenting state of consciousness 4 or 5, according to Brazelton, were included. TIMP was used to evaluate the motor performance.

Results:

The age groups of 34-35 and 36-37 weeks showed on average TIMP scores similar to the reference values (p>0.05), while in the age groups of 38-39 weeks and 40-41 weeks TIMP scores were statistically lower than the reference values (p<0.001 and p=0.018, respectively). The 34-35 and 36-37 week groups were rated as average, while the 38-39 and 40-41 week groups were defined as low average. Classifications below average and very below average were not observed.

Conclusion:

The newborns showed average scores compared to the TIMP reference values; however, there were two groups whose performances were within the low average. There was no significant difference in motor performance of newborns in the age groups of 38-39 and 40-41 weeks. This behavior suggests that the sample studied has special features that possibly negatively influenced their motor performance. The results showed that the TIMP is a very useful tool and can be used safely in tertiary neonatal units.

AMPA GluA1-flip targeted oligonucleotide therapy reduces neonatal seizures and hyperexcitability

Glutamate-activated α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPA-Rs) mediate the majority of excitatory neurotransmission in brain and thus are major drug targets for diseases associated with hyperexcitability or neurotoxicity. Due to the critical nature of AMPA-Rs in normal brain function, typical AMPA-R antagonists have deleterious effects on cognition and motor function, highlighting the need for more precise modulators. A dramatic increase in the flip isoform of alternatively spliced AMPA-R GluA1 subunits occurs post-seizure in humans and animal models. GluA1-flip produces higher gain AMPA channels than GluA1-flop, increasing network excitability and seizure susceptibility. Splice modulating oligonucleotides (SMOs) bind to pre-mRNA to influence alternative splicing, a strategy that can be exploited to develop more selective drugs across therapeutic areas. We developed a novel SMO, GR1, which potently and specifically decreased GluA1-flip expression throughout the brain of neonatal mice lasting at least 60 days after single intracerebroventricular injection. GR1 treatment reduced AMPA-R mediated excitatory postsynaptic currents at hippocampal CA1 synapses, without affecting long-term potentiation or long-term depression, cellular models of memory, or impairing GluA1-dependent cognition or motor function in mice. Importantly, GR1 demonstrated anti-seizure properties and reduced post-seizure hyperexcitability in neonatal mice, highlighting its drug candidate potential for treating epilepsies and other neurological diseases involving network hyperexcitability.

Role of EEG background activity, seizure burden and MRI in predicting neurodevelopmental outcome in full-term infants with hypoxic-ischaemic encephalopathy in the era of therapeutic hypothermia

OBJECTIVE

To investigate the role of EEG background activity, electrographic seizure burden, and MRI in predicting neurodevelopmental outcome in infants with hypoxic-ischaemic encephalopathy (HIE) in the era of therapeutic hypothermia.

METHODS

Twenty-six full-term infants with HIE (September 2011-September 2012), who had video-EEG monitoring during the first 72 h, an MRI performed within the first two weeks and neurodevelopmental assessment at two years were evaluated. EEG background activity at age 24, 36 and 48 h, seizure burden, and severity of brain injury on MRI, were compared and related to neurodevelopmental outcome.

RESULTS

EEG background activity was significantly associated with neurodevelopmental outcome at 36 h (p = 0.009) and 48 h after birth (p = 0.029) and with severity of brain injury on MRI at 36 h (p = 0.002) and 48 h (p = 0.018). All infants with a high seizure burden and moderate-severe injury on MRI had an abnormal outcome. The positive predictive value (PPV) of EEG for abnormal outcome was 100% at 36 h and 48 h and the negative predictive value (NPV) was 75% at 36 h and 69% at 48 h. The PPV of MRI was 100% and the NPV 85%. The PPV of seizure burden was 78% and the NPV 71%.

CONCLUSION

Severely abnormal EEG background activity at 36 h and 48 h after birth was associated with severe injury on MRI and abnormal neurodevelopmental outcome. High seizure burden was only associated with abnormal outcome in combination with moderate-severe injury on MRI.

Selective head cooling during neonatal seizures prevents postictal cerebral vascular dysfunction without reducing epileptiform activity

Epileptic seizures in neonates cause cerebrovascular injury and impairment of cerebral blood flow (CBF) regulation. In the bicuculline model of seizures in newborn pigs, we tested the hypothesis that selective head cooling prevents deleterious effects of seizures on cerebral vascular functions. Preventive or therapeutic ictal head cooling was achieved by placing two head ice packs during the preictal and/or ictal states, respectively, for the ∼2-h period of seizures. Head cooling lowered the brain and core temperatures to 25.6 ± 0.3 and 33.5 ± 0.1°C, respectively. Head cooling had no anticonvulsant effects, as it did not affect the bicuculline-evoked electroencephalogram parameters, including amplitude, duration, spectral power, and spike frequency distribution. Acute and long-term cerebral vascular effects of seizures in the normothermic and head-cooled groups were tested during the immediate (2-4 h) and delayed (48 h) postictal periods. Seizure-induced cerebral vascular injury during the immediate postictal period was detected as terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive staining of cerebral arterioles and a surge of brain-derived circulating endothelial cells in peripheral blood in the normothermic group, but not in the head-cooled groups. During the delayed postictal period, endothelium-dependent cerebral vasodilator responses were greatly reduced in the normothermic group, indicating impaired CBF regulation. Preventive or therapeutic ictal head cooling mitigated the endothelial injury and greatly reduced loss of postictal cerebral vasodilator functions. Overall, head cooling during seizures is a clinically relevant approach to protecting the neonatal brain by preventing cerebrovascular injury and the loss of the endothelium-dependent control of CBF without reducing epileptiform activity.

Predictors of Mortality in Neonates with Seizures; a Prospective Cohort Study

OBJECTIVE

The aim of this study was to analyze prognostic indicators for mortality in neonates with seizures in a level III Neonatal Intensive Care Unit (NICU).

PATIENTS AND METHODS

A cohort of 100 neonates with clinically manifested seizures hospitalized in the NICU during 4 years period was prospectively monitored for the first year of life. The cohort consisted of 33 preterm and 67 full-term babies with 60 male and 40 female infants.

RESULTS

The mortality rate in the first year of life of infants with seizures in the neonatal period was 23%. The most common cause of seizures was birth asphyxia for full-term infants and intra-periventricular hemorrhage for preterm infants. Death was more common in pre-term than term infants (p <0,005). Simple regression demonstrated statistically significant associations between death in the first year of life and a cluster of highly associated variables: resuscitation (p<0, 01), mechanical ventilation (p<0,01) and asphyxia (p<0,05). This cluster of variables significantly correlates with: gestational age (p<0, 05), birth weight (p<0, 05) and intracranial hemorrhage (p<0, 05).

CONCLUSION

In this cohort of neonates with seizures asphyxia requiring neonatal resuscitation was the primary risk factor for death.

Does diffusion restriction changes in magnetic resonance imaging predict neurological outcome in neonatal seizures?

BACKGROUND

Neonatal seizures are a common manifestation of brain dysfunction. Neonatal magnetic resonance imaging (MRI) has rapidly become the study of choice for the evaluation of central nervous systems disorders in newborns. According to a study conducted in Wilhelmina Children's Hospital, University Medical Center Utrecht, diffusion Restriction (DR) changes in the MRI is a good indicator of cell dysfunction (reversible or irreversible) within one week of insult.

OBJECTIVES

The main aim of this study was to find the association of DR changes in MRI of brain for neonatal seizures with long term neurodevelopment outcome.

METHODS

This is a retrospective observational study conducted in Sri Ramachandra University. Retrospective data was collected for the time period of January 2010 to December 2011 from medical records department (MRD) for patient data, neonatal intensive care unit and reports from PACS for MRI images and the Karthikeyan child development unit for their developmental follow up reports.

RESULTS

Comparison of composite score for various domains with DR changes was done with a t-test and comparison of babies with developmental delay and DR changes with Chi-square test. MRI DR changes with developmental outcome in different domains namely cognition, language-receptive/expressive, fine and gross motor was studied. There is no statistical significance among those who have DR changes and with those who do not have DR changes.

CONCLUSION

Though diffusion restriction changes in MRI may not predict adverse long term neuro developmental outcome, they can be of use with regards to individual etiological profile as in stroke. Larger group study and long term follow up is required to substantiate these findings.

Pediatric epilepsy following neonatal seizures symptomatic of stroke

BACKGROUND

Neonatal seizures are a risk factor for later epilepsy and their etiology is known to be implicated in the outcome but, little is known about this issue in the subgroup of seizures symptomatic of perinatal arterial ischemic stroke. The aim of this study was to describe the long term risk of epilepsy after electroencephalographic confirmed neonatal seizures symptomatic of perinatal arterial ischemic stroke.

DESIGN/SUBJECT

Fifty-five patients with electroclinical ictal data, vascular territory confirmed by neuroimaging and a minimum follow up of 3.5 years were identified from a multi-centre prospective neonatal seizures registry. Primary outcome was occurrence of post-neonatal epilepsy. The association of outcome with family history of epilepsy, gender, location of the infarct, neonatal clinical and electroencephalogram data were also studied.

RESULTS

During a mean follow up of 8 years and 5 months, 16.4% of the patients developed post neonatal epilepsy. The mean age at first post neonatal seizure was 4 years and 2 months (range 1-10 years and 6 months). Location of the infarct was the only statistically significant risk factor (p=0.001); epilepsy was more represented in males but the difference was not statistically significant.

CONCLUSIONS

Neonatal seizures symptomatic of perinatal arterial ischemic stroke had lower risk and later onset of post-neonatal epilepsy, compared to seizures described in the setting of other perinatal brain insults. Our data have implications for counseling to the family at discharge from neonatal intensive care unit.

Treating EEG Seizures in Hypoxic Ischemic Encephalopathy: A Randomized Controlled Trial

BACKGROUND

The impact of treating electrographic seizures in hypoxic ischemic encephalopathy (HIE) is unknown.

METHODS

Neonates ≥36 weeks with moderate or severe HIE were randomly assigned to either treatment of electrographic seizures alone (ESG) or treatment of clinical seizures (CSG). Conventional EEG video was monitored in both groups for up to 96 hours. Cumulative electrographic seizure burden (SB) was calculated in seconds and converted to log units for analysis. MRI scans were scored for severity of brain injury. Infants underwent neurodevelopmental evaluation at 18 to 24 months. Statistical analyses were performed by using SAS 9.3 version (SAS Institute, Inc, Cary, NC).

RESULTS

Thirty-five of 69 neonates (51%) who were randomly assigned and included in the study developed seizures (15 in ESG and 20 in CSG). Excluding infants with status epilepticus, median SB (interquartile range) in seconds in ESG (n = 10) was lower than in CSG (n = 16) (449 [113-2070] vs 2226 [760-7654]; P = .02). ESG had fewer seizures with shorter time to treatment (P = .04). Twenty-four of 30 (80%) surviving infants with seizures underwent neurodevelopmental evaluation at 18 to 24 months. Increasing SB in the combined cohort was significantly associated with higher brain injury scores (P < .03) and lower performance scores across all 3 domains on BSID III (P = .03).

CONCLUSIONS

In neonates with HIE, EEG monitoring and treatment of electrographic seizures results in significant reduction in SB. SB is associated with more severe brain injury and significantly lower performance scores across all domains on BSID III.

Acute TrkB inhibition rescues phenobarbital-resistant seizures in a mouse model of neonatal ischemia

Neonatal seizures are commonly associated with hypoxic-ischemic encephalopathy. Phenobarbital (PB) resistance is common and poses a serious challenge in clinical management. Using a newly characterized neonatal mouse model of ischemic seizures, this study investigated a novel strategy for rescuing PB resistance. A small-molecule TrkB antagonist, ANA12, used to selectively and transiently block post-ischemic BDNF-TrkB signaling in vivo, determined whether rescuing TrkB-mediated post-ischemic degradation of the K(+)-Cl(-) co-transporter (KCC2) rescued PB-resistant seizures. The anti-seizure efficacy of ANA12 + PB was quantified by (i) electrographic seizure burden using acute continuous video-electroencephalograms and (ii) post-treatment expression levels of KCC2 and NKCC1 using Western blot analysis in postnatal day (P)7 and P10 CD1 pups with unilateral carotid ligation. ANA12 significantly rescued PB-resistant seizures at P7 and improved PB efficacy at P10. A single dose of ANA12 + PB prevented the post-ischemic degradation of KCC2 for up to 24 h. As anticipated, ANA12 by itself had no anti-seizure properties and was unable to prevent KCC2 degradation at 24 h without follow-on PB. This indicates that unsubdued seizures can independently lead to KCC2 degradation via non-TrkB-dependent pathways. This study, for the first time as a proof-of-concept, reports the potential therapeutic value of KCC2 modulation for the management of PB-resistant seizures in neonates. Future investigations are required to establish the mechanistic link between ANA12 and the prevention of KCC2 degradation.

Transient hypothyroidism associated with viral Human Parechovirus encephalitis in a newborn

Human Parechovirus type 3 (HPeV-3) is a neurotropic virus which can cause neonatal encephalitis, presenting as encephalopathy with seizures and diffuse white matter lesions on brain imaging. Neurodevelopmental outcome is linked to the extent of white matter abnormalities. We report on a neonate with clinical and biochemical findings of transient central hypothyroidism associated with HPeV-3 encephalitis. The co-occurrence of transient hypothyroidism and viral encephalitis has not been reported in newborns before. Transient suppression of the hypothalamo-pituitary-thyroidal axis is described in critically ill babies as the nonthyroidal-illness syndrome. Assessment of thyroid function in neonatal cases of HPeV-3 infection is required to conclude whether a transient hypothyroidism as in nonthyroidal-illness syndrome may be triggered by viral meningo-encephalitis and if treatment may influence neurodevelopmental outcome.

Association of Rotavirus With Seizures Accompanied by Cerebral White Matter Injury in Neonates

We aimed to identify whether rotavirus, human parechovirus, or enterovirus are causative or associated viral pathogens of seizures accompanied by diffuse cerebral white matter injury in neonates. Thirty neonates who presented with seizures and diffusion-restriction in the widespread bilateral cerebral white matter on diffusion-weighted magnetic resonance imaging (MRI) were included in this study. All patients were tested for rotavirus, human parechovirus, and enterovirus by using reverse transcription PCR. Stool, cerebrospinal fluid, and serum samples were examined in 30, 25, and 20 patients, respectively. Rotavirus was detected in stool samples from all 30 patients (100%). Stool samples from 5 patients (16.7%) were also positive for enterovirus. Rotavirus or human parechovirus were not detected in any cerebrospinal fluid samples from 25 patients, but 1 patient tested positive for enterovirus. No virus was detected in any of 20 patient sera. This study indicated an association between rotavirus and seizures accompanied by diffuse cerebral white matter lesions in neonates.

Increased excitability and excitatory synaptic transmission during in vitro ischemia in the neonatal mouse hippocampus

OBJECTIVE

The present study tested the hypothesis that exposure to in vitro hypoxia-ischemia alters membrane properties and excitability as well as excitatory synaptic transmission of CA1 pyramidal neurons in the neonatal mouse.

METHODS

Experiments were conducted in hippocampal slices in P7-P9 C57Bl/6 mice using whole-cell patch clamp in current- and voltage-clamp mode. Passive membrane potential (Vm), input resistance (Rin) and active (action potential (AP) threshold and amplitude) membrane properties of CA1 pyramidal neurons were assessed at baseline, during 10 min in vitro ischemia (oxygen-glucose deprivation (OGD)) and during reoxygenation. Spontaneous and miniature excitatory post-synaptic currents (s and mEPSCs) were studied under similar conditions.

RESULTS

OGD caused significant depolarization of CA1 pyramidal neurons as well as decrease in AP threshold and increase in AP amplitude. These changes were blocked by the application of tetrodotoxin (TTX), indicating Na(+) channels' involvement. Following 10 min of reoxygenation, significant membrane hyperpolarization was noted and it was associated with a decrease in Rin. AP threshold and amplitude returned to baseline during that stage. sEPSC and mEPSC frequency increased during both OGD and reoxygenation but their amplitude remained unchanged. Additionally, we found that OGD decreases Ih (hyperpolarization activated current) in CA1 neurons from neonatal mice and this effect persists during reoxygenation.

SIGNIFICANCE

These results indicate that in vitro ischemia leads to changes in membrane excitability mediated by sodium and potassium channels. Further, it results in enhanced neurotransmitter release from presynaptic terminals. These changes are likely to represent one of the mechanisms of hypoxia/ischemia-mediated seizures in the neonatal period.

Neonatal Neurocritical Care Service Is Associated With Decreased Administration of Seizure Medication

This cohort study examines medication use in term neonates with hypoxic-ischemic encephalopathy and seizures before and after implementation of a Neonatal Neurocritical Care Service (N = 108), which included increased seizure monitoring. Nearly all neonates received phenobarbital (96% pre- vs 95% post-Neonatal Neurocritical Care Service) and total loading dose did not vary among groups (33 [95% confidence interval 29-37] vs 30 [26-34] mg/kg). After adjustment for seizure burden, neonates managed during the Neonatal Neurocritical Care Service era, on average, received 30 mg/kg less cumulative phenobarbital (95% confidence interval 15-46 mg/kg) and were on maintenance 5 fewer days (95% confidence interval 3-8 days) than those who were treated prior to implementation of the service. In spite of the enhanced ability to detect seizures because of improved monitoring and increased vigilance by bedside practitioners, implementation of the Neonatal Neurocritical Care Service was associated with decreased use of potentially harmful phenobarbital treatment among neonates with hypoxic-ischemic encephalopathy.

Developmental factors in the pathogenesis of neonatal seizures

Neonatal seizures are inherently different from seizures in the child and the adult. The phenotype, often exhibiting electroclinical dissociation, is unique: neonatal seizures can be refractory to antiepileptic drugs otherwise effect for older patients. Recent experimental and human-based research reveals that the mechanism of neonatal seizures, as well as their long-term sequelae on later brain development, appears to involve a large number of age-specific factors. These observations help explain the resistance of neonatal seizures to conventional therapy as well as identify potential areas of risk for later neurocognitive development. Emerging targets from this research may suggest new therapies for this unique population of patients.

Levetiracetam in neonatal seizures: a review

Phenobarbital and phenytoin have been the mainstay treatment modalities for neonatal seizures. Studies have revealed these agents control seizures in less than half of neonates, can cause neuronal apoptosis in vitro, and have highly variable pharmacokinetics in neonates. In contrast, there have been no reports of levetiracetam causing these neurotoxic effects. Due to its favorable side effect and pharmacokinetic profiles and positive efficacy outcomes in neonatal studies to date, there is great interest in the use of levetiracetam for neonatal seizures. This article reviews the literature regarding the safety of levetiracetam in neonates and its efficacy in neonatal seizures.

Age- and sex-dependent susceptibility to phenobarbital-resistant neonatal seizures: role of chloride co-transporters

Ischemia in the immature brain is an important cause of neonatal seizures. Temporal evolution of acquired neonatal seizures and their response to anticonvulsants are of great interest, given the unreliability of the clinical correlates and poor efficacy of first-line anti-seizure drugs. The expression and function of the electroneutral chloride co-transporters KCC2 and NKCC1 influence the anti-seizure efficacy of GABAA-agonists. To investigate ischemia-induced seizure susceptibility and efficacy of the GABAA-agonist phenobarbital (PB), with NKCC1 antagonist bumetanide (BTN) as an adjunct treatment, we utilized permanent unilateral carotid-ligation to produce acute ischemic-seizures in post-natal day 7, 10, and 12 CD1 mice. Immediate post-ligation video-electroencephalograms (EEGs) quantitatively evaluated baseline and post-treatment seizure burdens. Brains were examined for stroke-injury and western blot analyses to evaluate the expression of KCC2 and NKCC1. Severity of acute ischemic seizures post-ligation was highest at P7. PB was an efficacious anti-seizure agent at P10 and P12, but not at P7. BTN failed as an adjunct, at all ages tested and significantly blunted PB-efficacy at P10. Significant acute post-ischemic downregulation of KCC2 was detected at all ages. At P7, males displayed higher age-dependent seizure susceptibility, associated with a significant developmental lag in their KCC2 expression. This study established a novel neonatal mouse model of PB-resistant seizures that demonstrates age/sex-dependent susceptibility. The age-dependent profile of KCC2 expression and its post-insult downregulation may underlie the PB-resistance reported in this model. Blocking NKCC1 with low-dose BTN following PB treatment failed to improve PB-efficacy.

Neonatal seizures in hypoxic-ischaemic encephalopathy--risks and benefits of anticonvulsant therapy

The risk of seizures is at its highest during the neonatal period, and the most common cause of neonatal seizures is hypoxic-ischaemic encephalopathy (HIE). This enhanced vulnerability is caused by an imbalance in the expression of receptors for excitatory and inhibitory neurotransmission, which is age dependent. There has been progress in detecting the electrophysiological abnormalities associated with seizures using amplitude-integrated electroencephalography (aEEG). Data from animal studies indicate a variety of risk factors for seizures, but there are limited clinical data looking at the long-term neurodevelopmental consequences of seizures alone. Neonatal seizures are also associated with increased risk of further epileptic seizures; however, it is less clear whether or not this results from an underlying pathology, and whether or not seizures confer additional risk. Phenobarbital and phenytoin are still the first-line antiepileptic drugs (AEDs) used to treat neonatal seizures, although they are effective in only one-third of affected infants. Furthermore, based on findings from animal studies, there are concerns regarding the risks associated with using these AEDs. Clinicians face a difficult challenge because, although seizures can be easily identified using aEEG, treatment options are limited, and there are uncertainties regarding treatment outcomes. There is a need to obtain long-term follow-up data, comparing groups of infants treated with or without current therapies. If these analyses indicate a definite benefit of treating neonatal seizures, then novel therapeutic approaches should be developed.

The aetiology of neonatal seizures and the diagnostic contribution of neonatal cerebral magnetic resonance imaging

AIM

The aim of this study was to delineate aetiologies and explore the diagnostic value of cerebral magnetic resonance imaging (MRI) in addition to cranial ultrasonography (cUS) in infants presenting with neonatal seizures.

METHOD

This retrospective cohort study comprised infants (gestational age 35.0-42.6wks) with seizures, confirmed by either continuous amplitude-integrated electroencephalography (aEEG) or standard EEG and admitted during a 14-year period to a level three neonatal intensive care unit (n=378; 216 males, 162 females; mean [SD] birthweight 3334g [594]). All infants underwent cUS and MRI (MRI on median of 5 days after birth, range 0-58d) within the first admission period.

RESULTS

An underlying aetiology was identified in 354 infants (93.7%). The most common aetiologies identified were hypoxic-ischaemic encephalopathy (46%), intracranial haemorrhage (12.2%), and perinatal arterial ischaemic stroke (10.6%). When comparing MRI with cUS in these 354 infants MRI showed new findings which did not become apparent on cUS, contributing to a diagnosis in 42 (11.9%) infants and providing additional information to cUS, contributing to a diagnosis in 141 (39.8%). cUS alone would have allowed a diagnosis in only 37.9% of infants (134/354).

INTERPRETATION

Cerebral MRI contributed to making a diagnosis in the majority of infants. In 11.9% of infants the diagnosis would have been missed if only cUS were used and cerebral MRI added significantly to the information obtained in 39.8% of infants. These data suggest that cerebral MRI should be performed in all newborn infants presenting with EEG- or aEEG-confirmed seizures.

Evaluation of clinical course and neurocognition in children with self-limited infantile epilepsy in a Turkish cohort study

The outcome of children with self-limited infantile epilepsy was reported to be normal psychosocial and cognitive development as a characteristic criterion. We aimed to investigate the clinical course and neurocognitive outcome in children with self-limited infantile epilepsy in a Turkish cohort. The clinical course, electroencephalographic (EEG) characteristics, neuroimaging, treatment, and outcome of children with self-limited infantile epilepsy were retrospectively analyzed. All infants were reevaluated with the Denver Developmental Screening Test in addition to neurologic examination. Of 44 patients, self-limited familial infantile epilepsy was diagnosed in 8 infants (18.2%) and self-limited nonfamilial infantile epilepsy in 28 (63.6%). Interictal EEGs and neurologic examinations were normal in all cases. Fine motor and gross motor skills, language, adaptive personal/social skills were near-normal in all patients with self-limited familial infantile epilepsy. Delay in language parameters was observed in 2 infants with self-limited nonfamilial infantile epilepsy. Language skills should be thoroughly evaluated with detailed neurocognitive screening tests in patients with self-limited infantile epilepsy.

Epilepsy after neonatal seizures: literature review

INTRODUCTION

Acute neonatal seizures are the most frequent neurological complication in the neonatal intensive care units and the seizing newborns have an increased risk of long-term morbidity. However, the relationship between neonatal seizures and the development of epilepsy later in life is still unclear.

METHODS

We performed a literature review using the search terms "neonatal seizures AND outcome", "neonatal seizures AND epilepsy", "neonatal seizures AND post-neonatal epilepsy", including secondary sources of data such as reference lists of articles reviewed. From the studies in which data were available, the incidence of epilepsy was calculated by dividing the number of all subjects who developed epilepsy in the different studies considered with the number of all newborns enrolled to the studies less the number of patients lost at follow-up.

RESULTS

We found 44 studies published between 1954 and 2013, of which 4 were population-based studies and the remaining were hospital-based case series. The overall population evaluated was 4538 newborns and 17.9% developed post-neonatal epilepsy, with an onset within the first year of life in 68.5% of the patients. In 80.7%, epilepsy was associated with other neurological impairments.

CONCLUSION

Estimates on epilepsy after neonatal seizures vary widely depending on selection criteria and length of the follow-up. However, it represents a common outcome of these newborns, especially in those with severe brain injury and additional neurodevelopmental disabilities.

Neonatal Seizures: Impact on Neurodevelopmental Outcomes

Neonatal period is the most vulnerable time for the occurrence of seizures, and neonatal seizures often pose a clinical challenge both for their acute management and frequency of associated long-term co-morbidities. Etiologies of neonatal seizures are known to play a primary role in the anti-epileptic drug responsiveness and the long-term sequelae. Recent studies have suggested that burden of acute recurrent seizures in neonates may also impact chronic outcomes independent of the etiology. However, not many studies, either clinical or pre-clinical, have addressed the long-term outcomes of neonatal seizures in an etiology-specific manner. In this review, we briefly review the available clinical and pre-clinical research for long-term outcomes following neonatal seizures. As the most frequent cause of acquired neonatal seizures, we focus on the studies evaluating long-term effects of HIE-seizures with the goal to evaluate (1) what parameters evaluated during acute stages of neonatal seizures can reliably be used to predict long-term outcomes? and (2) what available clinical and pre-clinical data are available help determine importance of etiology vs. seizure burdens in long-term sequelae.

Neonatal encephalopathy and the association to asphyxia in labor

OBJECTIVE

In cases with moderate and severe neonatal encephalopathy, we aimed to determine the proportion that was attributable to asphyxia during labor and to investigate the association between cardiotocographic (CTG) patterns and neonatal outcome.

STUDY DESIGN

In a study population of 71,189 births from 2 Swedish university hospitals, 80 cases of neonatal encephalopathy were identified. Cases were categorized by admission CTG patterns (normal or abnormal) and by the presence of asphyxia (cord pH, <7.00; base deficit, ≥12 mmol/L). Cases with normal admission CTG patterns and asphyxia at birth were considered to experience asphyxia related to labor. CTG patterns were assessed for the 2 hours preceding delivery.

RESULTS

Admission CTG patterns were normal in 51 cases (64%) and abnormal in 29 cases (36%). The rate of cases attributable to asphyxia (ie, hypoxic ischemic encephalopathy) was 48 of 80 cases (60%), most of which evolved during labor (43/80 cases; 54%). Both severe neonatal encephalopathy and neonatal death were more frequent with an abnormal, rather than with a normal, admission CTG pattern (13 [45%] vs 11 [22%]; P = .03), and 6 [21%] vs 3 [6%]; P = .04), respectively. Comparison of cases with an abnormal and a normal admission CTG pattern also revealed more frequently observed decreased variability (12 [60%] and 8 [22%], respectively) and more late decelerations (8 [40%] and 1 [3%], respectively).

CONCLUSION

Moderate and severe encephalopathy is attributable to asphyxia in 60% of cases, most of which evolve during labor. An abnormal admission CTG pattern indicates a poorer neonatal outcome and more often is associated with pathologic CTG patterns preceding delivery.

In vivo effects of bumetanide at brain concentrations incompatible with NKCC1 inhibition on newborn DGC structure and spontaneous EEG seizures following hypoxia-induced neonatal seizures

Neonatal seizures caused by perinatal asphyxia and hypoxic-ischemic encephalopathy can be refractory to conventional anticonvulsants. This may be due to the depolarizing effects of gamma-aminobutyric acid (GABA) achieved by the activity of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1). The aim of this study is to evaluate the long-term effects of bumetanide, a NKCC1 inhibitor, on hippocampal neurogenesis and seizure susceptibility in hypoxia-induced neonatal seizure model. Wistar rats were subjected to hypoxia-induced neonatal seizures at postnatal day 10 (P10). Following acute seizures, the rats were treated with intraperitoneal injection (i.p.) of bumetanide at a dose of 0.5mg/kg for 3 weeks. In later adulthood, hypoxia-induced seizures increased the number of newborn dentate gyrus cells (DGCs), promoted mossy fiber sprouting (MFS) and reduced the apical dendritic complexity of newborn DGCs 1 month after the insults. In addition, these seizures resulted in long-lasting consequences, such as spontaneous electroencephalography (EEG) seizures, though spatial learning impairments were not seen. Bumetanide treatments significantly enhanced cell proliferation and dendritic development of newborn DGCs after neonatal seizures, accompanied by the decreased seizure activity. However, systemic administration of bumetanide resulted in much lower brain concentrations, and was incompatible with NKCC1 inhibition in blood-brain barrier (BBB)-protected brain tissue. Our results suggested that bumetanide might have long-term effects in suppressing seizure activity, and altering the neurogenesis after neonatal seizures. These effects of bumetanide may be mediated by the targets outside the BBB-protected central nerve system (CNS) or CNS-located target(s) other than NKCC1.

Neonatal seizures: Predictors of adverse outcome

Context:

Early detection of predictors of adverse outcome will be helpful for neonatologists to plan management, follow up and rehabilitation in advance so that neurological disability can be minimised.

Aims:

The purpose of this study was to determine the factors affecting the adverse outcome of neonatal seizures.

Settings and Design:

This is a prospective study conducted in the neonatal unit of a tertiary care hospital. One hundred and eight newborns consecutively admitted with seizures were included in this study.

Materials and Methods:

Data was collected regarding perinatal history and seizure and evaluated for etiology. We conducted a retrospective analysis to identify the factors associated with adverse outcome after neonatal seizures.

Statistical Analysis Used:

Chi-square test with degree of freedom = 1 was used to find the variables significantly associated with adverse outcome (P < 0.05).

Results:

Gestational age, birth weight, Apgar score at 5 min, seizure onset <24 hrs, status epilepticus, radiological findings and EEG findings were significantly associated with outcome.

Conclusion:

Mortality and severe neurological impairment after neonatal seizure is associated with prematurity, LBW, low Apgar score at 5 min, etiologies like meningitis, sepsis, severe HIE, brain malformations, grade 3 or 4 IVH or intracranial haemorrhage, seizure onset <24 hours, presence of status epilepticus, severely abnormal radiological and EEG findings.

Recent advances in neonatal seizures

Neonatal seizures are the most important indicators of underlying brain injury. Seizures in a neonate are different from seizures in older children in many aspects including clinical presentation and etiology. The neonatal brain is immature and tends to have a decreased seizure threshold. Neonatal seizures are classified, based on their presentation as, clinical seizures, electroclinical seizures and electroencephalographic seizures; based on the pathophysiology as epileptic and nonepileptic seizures; and also on the basis of the etiology. Hypoxic ischemic encephalopathy is the leading cause of neonatal seizures, followed by intracranial hemorrhage, metabolic causes such as hypoglycemia and hypocalcemia, intracranial infections and strokes. Neonatal epilepsy syndromes are rare. Electroencephalography (EEG) is the gold standard for diagnosis. Amplitude integrated EEG (aEEG) is also used for continuous monitoring. The approach to management consists of initial stabilization of the neonate followed by treatment of potentially correctable injurious processes such as hypocalcemia, hypoglycemia and electrolyte disturbances, etiology specific therapies and antiepileptic drug (AED) therapy. Phenobarbital remains the first line AED therapy. Pharmacokinetic data on newer drugs is limited. Prognosis depends on the etiology, seizure type, neurological examination at discharge and EEG. Long term neurodevelopmental follow up is essential for babies with neonatal seizures.

Neonatal seizures: magnetic resonance imaging adds value in the diagnosis and prediction of neurodisability

AIM

To determine the aetiological associations, neurological sequelae and role of magnetic resonance imaging (MRI) in term newborn infants with seizures.

METHODS

Cohort study of infants ≥37 weeks' gestation delivered in a tertiary level centre, prospectively identified and followed longitudinally for 18-24 months.

RESULTS

An underlying aetiology was found in 95% of the 77 infants identified with seizures (3.0/1000 live births). The most common diagnosis was hypoxic-ischaemic encephalopathy (HIE) (65%), followed by neonatal stroke (12%). Nine infants died, 28 of the 68 survivors developed neurodevelopmental impairment (NDI), and 15 had recurrent seizures in the first 2 years, with both outcomes more likely in those with a diagnosis other than HIE. Abnormal MRI findings were found in 45 of the 70 infants imaged. The absence of major cerebral lesions was highly predictive of a normal neurological outcome.

CONCLUSION

We report the first cohort of term infants with seizures fully investigated by MRI. The universal use of MRI enabled a cause to be identified in 95% of cases. The probability of having NDI or recurrence of seizures was extremely low with absence of major cerebral lesions on MRI. This study demonstrates the added value of MRI for diagnosis of aetiology and the prediction of neurological outcome.

Advances in management of neonatal seizures

Seizures are more common in the neonatal period than any other time in the human lifespan. A high index of suspicion for seizures should be maintained for infants who present with encephalopathy soon after birth, have had a stroke, central nervous system (CNS) infection or intracranial hemorrhage or have a genetic or metabolic condition associated with CNS malformations. Complicating the matter, most neonatal seizures lack a clinical correlate with only subtle autonomic changes and often no clinical indication at all. Over the last three decades, several tools have been developed to enhance the detection and treatment of neonatal seizures. The use of electroencephalography (EEG) and the later development of amplitude-integrated EEG (aEEG), allows for Neurologists and non-Neurologists alike, to significantly increase the sensitivity of seizure detection. When applied to the appropriate clinical setting, time to diagnosis and start of therapy is greatly reduced. Phenobarbital maintains the status of first-line therapy in worldwide use. However, newer anti-epileptic agents such as, levetiracetam, bumetanide, and topiramate are increasingly being applied to the neonatal population, offering the potential for seizure treatment with a significantly better side-effect profile. Seizures in premature infants, continue to confound clinicians and researchers alike. Though the apparent seizure burden is significant and there is an association between seizures and adverse outcomes, the two are not cleanly correlated. Compounding the issue, GABA-ergic anti-epileptic drugs are not only less effective in this age group due to reversed neuronal ion gradients but may cause harm. Selecting an appropriate treatment group remains a challenge.

Sex-specific consequences of early life seizures

Seizures are very common in the early periods of life and are often associated with poor neurologic outcome in humans. Animal studies have provided evidence that early life seizures may disrupt neuronal differentiation and connectivity, signaling pathways, and the function of various neuronal networks. There is growing experimental evidence that many signaling pathways, like GABAA receptor signaling, the cellular physiology and differentiation, or the functional maturation of certain brain regions, including those involved in seizure control, mature differently in males and females. However, most experimental studies of early life seizures have not directly investigated the importance of sex on the consequences of early life seizures. The sexual dimorphism of the developing brain raises the question that early seizures could have distinct effects in immature females and males that are subjected to seizures. We will first discuss the evidence for sex-specific features of the developing brain that could be involved in modifying the susceptibility and consequences of early life seizures. We will then review how sex-related biological factors could modify the age-specific consequences of induced seizures in the immature animals. These include signaling pathways (e.g., GABAA receptors), steroid hormones, growth factors. Overall, there are very few studies that have specifically addressed seizure outcomes in developing animals as a function of sex. The available literature indicates that a variety of outcomes (histopathological, behavioral, molecular, epileptogenesis) may be affected in a sex-, age-, region-specific manner after seizures during development. Obtaining a better understanding for the gender-related mechanisms underlying epileptogenesis and seizure comorbidities will be necessary to develop better gender and age appropriate therapies.

Neonatal seizures: aetiology by means of a standardized work-up

Neonatal seizures are an alarming symptom and are frequent in neonates. It is important to find the cause of neonatal seizures to start a specific treatment and to give a meaningful prognosis. The aim of this study is to investigate the incidence of different aetiologies of neonatal seizures in our hospital by a specific work-up.

METHODS

All full-term born neonates from January 2002 till September 2009 with neonatal seizures, admitted to our neonatal intensive care unit were included (n = 221). Aetiology was investigated by means of a standardized aetiologic work-up.

RESULTS

The frequencies of aetiologies of neonatal seizures were: hypoxic-ischemic encephalopathy (HIE) (n = 119; 53.9%), metabolic or electrolyte disorders (n = 24; 10.9%), intracranial hemorrhage (n = 20; 9.0%), ischemic infarction (n = 16; 7.2%), intracranial infections (n = 14; 6.3%), congenital malformations of the central nervous system (n = 7; 3.2%), inborn errors of metabolism (n = 5; 2.3%), epileptic syndromes (n = 1; 0.5%), HIE + hypoglycemia (n = 4; 1.8%), HIE + intracranial hemorrhage (n = 3; 1.4%), HIE + ischemic infarction (n = 1; 0.5%), ischemic infarction + intracranial hemorrhage (n = 1; 0.5%), idiopathic (n = 4, 1.8%), intoxications (n = 1; 0.5%) and unknown (n = 1; 0.5%).

CONCLUSION

Our work-up is a practical tool to find the aetiology of neonatal seizures.

Impact of transient acute hypoxia on the developing mouse EEG

Hypoxemic events are common in sick preterm and term infants and represent the most common cause of seizures in the newborn period. Neonatal seizures often lack clinical correlates and are only recognized by electroencephalogram (EEG). The mechanisms leading from a hypoxic/ischemic insult to acute seizures in neonates remain poorly understood. Further, the effects of hypoxia on EEG at various developmental stages have not been fully characterized in neonatal animals, in part due to technical challenges. We evaluated the impact of hypoxia on neonatal mouse EEG to define periods of increased susceptibility to seizures during postnatal development. Hippocampal and cortical electrodes were implanted stereotaxically in C57BL/6 mice from postnatal age 3 (P3) to P15. Following recovery, EEG recordings were obtained during baseline, acute hypoxia (4% FiO2 for 4min) and reoxygenation. In baseline recordings, maturation of EEG was characterized by the appearance of a more continuous background pattern that replaced alternating high and low amplitude activity. Clinical seizures during hypoxia were observed more frequently in younger animals (100% P3-4, 87.5% P5-6, 93% P7-8, 83% P9-10, 33% P11-12, 17% P15, r(2)=0.81) and also occurred at higher FiO2 in younger animals (11.2±1.1% P3-P6 vs. 8.9±0.8% P7-12, p<0.05). Background attenuation followed the initial hypoxemic seizure; progressive return to baseline during reoxygenation was observed in survivors. Electrographic seizures without clinical manifestations were observed during reoxygenation, again more commonly in younger animals (83% P3-4, 86% P5-6, 75% P7-8, 71% P9-10, 20% P11-12, r(2)=0.82). All P15 animals died with this duration and degree of hypoxia. Post-ictal abnormalities included burst attenuation and post-anoxic myoclonus and were more commonly seen in older animals. In summary, neonatal mice exposed to brief and severe hypoxia followed by rapid reoxygenation reliably develop seizures and the response to hypoxia varies with postnatal age and maturation.

Risk factors and scoring system as a prognostic tool for epilepsy after neonatal seizures

BACKGROUND

Neonatal seizures may cause irreversible changes to the immature brain and. A scoring system for early prognostic information could be a useful clinical tool. The aim of the study was to analyze risk factors for epilepsy after neonatal seizures, to validate Garfinkle's scoring system, and to analyze whether a new scoring system is feasible.

METHODS

A retrospective study of 176 newborns (59.1% boys, 40.9% girls, 70.5% term, 29.5% preterm; mean birth weight 2820 g), admitted to the Department of Neonatology, Division of Pediatrics, University Medical Centre, Ljubljana, because of neonatal seizures (clinical and/or neurophysiological), was performed. Epilepsy rate between 2 and 12 years of follow-up was 18.1%. Five independent predictors from Garfinkle's study and other known predictors were entered into hierarchical binary logistic regression models and analyzed through four steps to identify independent predictors of epilepsy. We tested whether any of the predictors was an effect modifier.

RESULTS

Of five potential predictors from Garfinkle's score, electroencephalograph background findings and etiology were predictive. Etiologies, gestation, mode of delivery, duration of seizures, and other risk factors at birth were found to be independent predictors. Duration of seizures has a different effect on prognosis depending on the gestational age.

CONCLUSION

Gestational age determines the association between duration of seizures and epilepsy. Scoring systems to predict development of epilepsy after neonatal seizures need to limit interaction between important predictor variables.

The prognostic value of amplitude-integrated EEG in full-term neonates with seizures

Neonatal seizures pose a high risk for adverse outcome in survived infants. While the prognostic value of amplitude-integrated electroencephalogram (aEEG) is well established in neonates with encephalopathy and asphyxia, neonatal seizure studies focusing on the direct correlation between early aEEG measurement and subsequent neurologic outcome are scarce. In this study, the prognostic value of aEEG features was systematically analyzed in 143 full-term neonates to identify prognostic indicators of neurodevelopmental outcome. Neonatal aEEG features of background pattern, cyclicity, and seizure activity, as well as the etiology of neonatal seizures, were significantly associated with neurodevelopmental outcome at one year of age. aEEG background pattern was highly associated with neurologic outcomes (χ² = 116.9), followed by aEEG cyclicity (χ² = 87.2) and seizure etiology (χ² = 79.3). Multiple linear regression showed that the four predictors explained 71.2% of the variation in neurological outcome, with standardized β coefficients of 0.44, 0.24, 0.22, and 0.14 for the predictors of aEEG background pattern, cyclicity, etiology, and aEEG seizure activity, respectively. This clinically applicable scoring system based on etiology and three aEEG indices would allow pediatricians to assess the risk for neurodevelopmental impairment and facilitate an early intervention in newborns developing seizures.

AMPA receptor antagonist NBQX attenuates later-life epileptic seizures and autistic-like social deficits following neonatal seizures

PURPOSE

To determine whether AMPA receptor (AMPAR) antagonist NBQX can prevent early mammalian target of rapamycin (mTOR) pathway activation and long-term sequelae following neonatal seizures in rats, including later-life spontaneous recurrent seizures, CA3 mossy fiber sprouting, and autistic-like social deficits.

METHODS

Long-Evans rats experienced hypoxia-induced neonatal seizures (HS) at postnatal day (P)10. NBQX (20 mg/kg) was administered immediately following HS (every 12 h × 4 doses). Twelve hours post-HS, we assessed mTOR activation marker phosphorylated p70-S6 kinase (p-p70S6K) in hippocampus and cortex of vehicle (HS + V) or NBQX-treated post-HS rats (HS + N) versus littermate controls (C + V). Spontaneous seizure activity was compared between groups by epidural cortical electroencephalography (EEG) at P70-100. Aberrant mossy fiber sprouting was measured using Timm staining. Finally, we assessed behavior between P30 and P38.

KEY FINDINGS

Postseizure NBQX treatment significantly attenuated seizure-induced increases in p-p70S6K in the hippocampus (p < 0.01) and cortex (p < 0.001). Although spontaneous recurrent seizures increased in adulthood in HS + V rats compared to controls (3.22 ± 1 seizures/h; p = 0.03), NBQX significantly attenuated later-life seizures (0.14 ± 0.1 seizures/h; p = 0.046). HS + N rats showed less aberrant mossy fiber sprouting (115 ± 8.0%) than vehicle-treated post-HS rats (174 ± 10%, p = 0.004), compared to controls (normalized to 100%). Finally, NBQX treatment prevented alterations in later-life social behavior; post-HS rats showed significantly decreased preference for a novel over a familiar rat (71.0 ± 12 s) compared to controls (99.0 ± 15.6 s; p < 0.01), whereas HS + N rats showed social novelty preference similar to controls (114.3 ± 14.1 s).

SIGNIFICANCE

Brief NBQX administration during the 48 h postseizure in P10 Long-Evans rats suppresses transient mTOR pathway activation and attenuates spontaneous recurrent seizures, social preference deficits, and mossy fiber sprouting observed in vehicle-treated adult rats after early life seizures. These results suggest that acute AMPAR antagonist treatment during the latent period immediately following neonatal HS can modify seizure-induced activation of mTOR, reduce the frequency of later-life seizures, and protect against CA3 mossy fiber sprouting and autistic-like social deficits.

Neonatal seizures: soothing a burning topic

Neonatal seizures are a potentially life-threatening pediatric problem with a variety of causes, such as birth trauma, asphyxia, congenital anomalies, metabolic disturbances, infections, and drug withdrawal or intoxication. Thorough and timely evaluations of such patients are necessary to identify and treat the underlying etiology, therefore reducing potential morbidity and mortality. We review neonatal seizures and hypocalcemia and present the case of a 6-day-old male infant who presented to a tertiary pediatric emergency department with seizure-like episodes. He was found to have markedly low serum calcium, magnesium, and parathyroid hormone concentrations, as well as a significantly elevated serum phosphate concentration. The etiology of these abnormalities was found to be maternal ingestion of extremely high doses of calcium carbonate during the third trimester of her pregnancy, an occurrence that has been reported only once in the literature. Education pertaining to the dangers of excessive calcium carbonate intake during pregnancy may be an important piece of anticipatory guidance for pregnant mothers with symptoms of gastroesophageal reflux, and questioning the mother of a neonate presenting with seizures about such over-the-counter medications may help to elucidate the diagnosis.

Diagnosing neonatal seizures and status epilepticus

Continuous electroencephalographic (CEEG) monitoring is often applied in the Neonatal Intensive Care Unit to aid in the diagnosis and management of seizures. Neonatal seizures are particularly difficult to identify on the basis of clinical observation alone; diagnosis is greatly facilitated by CEEG monitoring. There is building evidence to suggest which neonates are at highest risk for seizures, and how CEEG can aid diagnosis. For the neurophysiologist, the unique features of neonatal seizures can distinguish them from nonictal patterns. These features include duration, location, morphology, and evolution. At the extreme, very frequent or prolonged neonatal seizures constitute status epilepticus. There is no consensus definition for neonatal status epilepticus, although the proposed criteria share some features. This article reviews available evidence to guide the application and interpretation of CEEG in the diagnosis of neonatal seizures and status epilepticus.