Brief postnatal exposure to phenobarbital impairs passive avoidance learning and sensorimotor gating in rats

Non-pharmacologic and pharmacologic care of the neonate with opioid withdrawal syndrome

There has been a significant paradigm shift in the management of infants with NOWS to emphasizing the role of non-pharmacologic care centered on the mother-infant dyad. By promoting bonding through rooming-in, breast-feeding and skin-to skin contact in a low stimulation environment, short and long-term outcomes have dramatically improved, resulting in reduced length of stay and need for pharmacologic treatment of the newborn. This shift in care also empowers the mother and promotes bonding and attachment, providing a solid foundation for a safe discharge. When non-pharmacological treatments are not sufficient to control the infant's withdrawal symptoms then medications can be used as an adjunct, to the minimum extent necessary and should never be used in isolation of non-pharmacological interventions. Quality improvement efforts should focus on optimizing and standardizing both non-pharmacologic and pharmacologic care to best serve this population.

A quality improvement project on implementing a standardized pain assessment and opioid stewardship guidance at a level IV NICU

BackgroundBalancing between adequate analgesia and preventing the harmful side effects of opioids in the NICU is an important clinical conundrum. Lack of awareness among caregivers and guidance on pain management are the key limiting factors. By initiating this quality improvement (QI) project, we aimed to reduce the usage of opioids in a quaternary NICU care by 5% within 1 year.MethodsA multidisciplinary team developed standardized guidance focusing on regular pain assessment, appropriate initiation, and weaning of opioids for infants undergoing surgical procedures and those requiring mechanical ventilation. The Plan, Do, Study, Act (PDSA) methodology was used for improvement, beginning with a survey and Pareto analysis to identify key drivers. Data were collected for the baseline period and after implementing the QI interventions.ResultsWe demonstrated a significant decrease in the cumulative opioid use measured as morphine equivalent (mg/kg) from a mean of 2.7 to below 0.85 mg/kg, demonstrating a reduction of >50%. There was no worsening in pain or opioid withdrawal scores within three and 5 days after weaning of opioids, a surrogate measure for appropriate weaning.ConclusionImplementation of standardized guidelines for initiating and weaning of opioids can reduce the overall opioid use and thus minimize opioid withdrawal in critically ill neonates.

Padsevonil suppresses seizures without inducing cell death in neonatal rats

BACKGROUND

Padsevonil (PSL) is a rationally designed anti-seizure medication (ASM) which has overlapping mechanisms of action with the two most common ASMs used for neonatal seizures, phenobarbital (PB) and levetiracetam (LEV). Here we evaluated the anti-seizure properties of PSL across the neonatal and adolescent period in rats in the pentlyenetetrazole (PTZ) induced seizures model.

METHODS

Postnatal day (P)7, P14 and P21 Sprague-Dawley rat pups were pre-treated with PSL (1-30 mg/kg), and assessed for seizure latency and severity 30 min later following injection of PTZ. A separate cohort of P7 pups were treated with neonatal ASMs and euthanized 24 h later (on P8) to assess induction of cell death, a feature common to many ASMs when given to P7 rodents. This effect has been extensively reported with PB, but not with LEV. Cell death was assessed by PathoGreen staining.

RESULTS

PSL suppressed PTZ-evoked seizures across multiple age groups, particularly at higher doses, without producing increased cell death compared to vehicle. The effects of PSL were particularly notable at suppressing tonic-clonic seizure manifestations (82% of P7 and 100% of P14 and P21 animals were protected from tonic-clonic seizures with the 30 mg/kg dose).

CONCLUSIONS

PSL displayed dose-dependent anti-seizure effects in immature rodents in the PTZ model of seizures in immature rats. While many ASMs, including PB, induce cell death in neonatal rats, PSL does not. This suggests that PSL may offer therapeutic benefit and a favorable safety profile for the treatment of neonatal seizures.

A single exposure to brivaracetam or perampanel does not cause cell death in neonatal rats

Introduction

Exposure to a range of anti-seizure medications (ASMs) during early brain development adversely impacts neurodevelopmental outcomes in both animal models and in clinical studies. Many ASMs, including phenobarbital, phenytoin, valproate (VPA), and benzodiazepines, are associated with acute neurotoxicity (cell death), impaired synaptic development, and long-term behavioral changes following gestational or neonatal exposure in animals. This is mirrored in clinical studies which show lasting neurodevelopmental deficits following early-life or gestational exposure to these drugs. Brivaracetam (BRV) and perampanel (PER) are two newer generation anti-seizure medications and are of interest based on their mechanisms of action (SV2A modulator, AMPA antagonist, respectively), as other drugs with these mechanisms of action do not trigger acute neurotoxicity. Both BRV and PER show anti-seizure efficacy in developing animals, but potential neurotoxicity of these drugs is unexplored.

Methods

To address this gap, we treated postnatal day (P)7 Sprague-Dawley rats with BRV (20, 40, 80 mg/kg) and PER (0.1, 0.9, 2.7 mg/kg), and assessed the induction of cell death across a range of vulnerable brain regions 24 h after exposure. Cell death was assessed using pathogreen staining.

Results

In each of the regions examined (dorsal striatum, nucleus accumbens, motor cortex, cingulate cortex, lateral thalamus, septum, hippocampus), VPA, which served as a positive control, significantly increased cell death as measured by the numer of pathogreen positive cells. By contrast, neither BRV nor PER increased the number of pathogreen positive cells in any region examined.

Discussion

Our results suggest that BRV and PER may have a positive safety profile-at least with respect to acute induction of cell death - and therefore may offer a safer option for the treatment of early life seizures.

Early life phenobarbital exposure dysregulates the hippocampal transcriptome

Introduction: Phenobarbital (PB) and levetiracetam (LEV) are the first-line therapies for neonates with diagnosed seizures, however, a growing body of evidence shows that these drugs given during critical developmental windows trigger lasting molecular changes in the brain. While the targets and mechanism of action of these drugs are well understood-what is not known is how these drugs alter the transcriptomic landscape, and therefore molecular profile/gene expression during these critical windows of neurodevelopment. PB is associated with a range of neurotoxic effects in developing animals, from cell death to altered synaptic development to lasting behavioral impairment. LEV does not produce these effects. Methods: Here we evaluated the effects of PB and Lev on the hippocampal transcriptome by RNA sequencing. Neonatal rat pups were given a single dose of PB, Lev or vehicle and sacrificed 72 h later-at time at which drug is expected to be cleared. Results: We found PB induces broad changes in the transcriptomic profile (124 differentially expressed transcripts), as compared to relatively small changes in LEV-treated animals (15 transcripts). PB exposure decreased GABAergic and oligodendrocyte markers pvalb and opalin, and increased the marker of activated microglia, cd68 and the astrocyte- associated gene vegfa. These data are consistent with the existing literature showing developmental neurotoxicity associated with PB, but not LEV. Discussion: The widespread change in gene expression after PB, which affected transcripts reflective of multiple cell types, may provide a link between acute drug administration and lasting drug toxicity.

Anti-seizure medication-induced developmental cell death in neonatal rats is unaltered by history of hypoxia

BACKGROUND

Many anti-seizure medications (ASMs) trigger neuronal cell death when administered during a confined period of early life in rodents. Prototypical ASMs used to treat early-life seizures such as phenobarbital induce this effect, whereas levetiracetam does not. However, most prior studies have examined the effect of ASMs in naïve animals, and the degree to which underlying brain injury interacts with these drugs to modify cell death is poorly studied. Moreover, the degree to which drug-induced neuronal cell death differs as a function of sex is unknown.

METHODS

We treated postnatal day 7 Sprague Dawley rat pups with vehicle, phenobarbital (75 mg/kg) or levetiracetam (200 mg/kg). Separate groups of pups were pre-exposed to either normoxia or graded global hypoxia. Separate groups of males and females were used. Twenty-four hours after drug treatment, brains were collected and processed for markers of cell death.

RESULTS

Consistent with prior studies, phenobarbital, but not levetiracetam, increased cell death in cortical regions, basal ganglia, hippocampus, septum, and lateral thalamus. Hypoxia did not modify basal levels of cell death. Females - collapsed across treatment and hypoxia status, displayed a small but significant increase in cell death as compared to males in the cingulate cortex, somatosensory cortex, and the CA1 and CA3 hippocampus; these effects were not modulated by hypoxia or drug treatment.

CONCLUSION

We found that a history of graded global hypoxia does not alter the neurotoxic profile of phenobarbital. Levetiracetam, which does not induce cell death in normal developing animals, maintained a benign profile on the background of neonatal hypoxia. We found a sex-based difference, as female animals showed elevated levels of cell death across all treatment conditions. Together, these data address several long-standing gaps in our understanding of the neurotoxic profile of antiseizure medications during early postnatal development.

Current Insights Regarding Intestinal Failure-Associated Liver Disease (IFALD): A Narrative Review

Intestinal failure-associated liver disease (IFALD) is a spectrum of liver disease including cholestasis, biliary cirrhosis, steatohepatitis, and gallbladder disease in patients with intestinal failure (IF). The prevalence of IFALD varies considerably, with ranges of 40-60% in the pediatric population, up to 85% in neonates, and between 15-40% in the adult population. IFALD has a complex and multifactorial etiology; the risk factors can be parenteral nutrition-related or patient-related. Because of this, the approach to managing IFALD is multidisciplinary and tailored to each patient based on the etiology. This review summarizes the current knowledge on the etiology and pathophysiology of IFALD and examines the latest evidence regarding preventative measures, diagnostic approaches, and treatment strategies for IFALD and its associated complications.

The outcome of early life status epilepticus—lessons from laboratory animals

Status epilepticus (SE) is the most common neurologic emergency in children. Both clinical and laboratory studies have demonstrated that SE in early life can cause brain damage and permanent behavioral abnormalities, trigger epileptogenesis, and interfere with normal brain development. In experimental rodent models, the consequences of seizures are dependent upon age, the model used, and seizure duration. In studies involving neonatal and infantile animals, the model used, experimental design, conditions during the experiment, and manipulation of animals can significantly affect the course of the experiments as well as the results obtained. Standardization of laboratory approaches, harmonization of scientific methodology, and improvement in data collection can improve the comparability of data among laboratories.

Effects of Maternal Use of Antiseizure Medications on Child Development

Most children born to women with epilepsy (WWE) are normal, but have increased risks for malformations and poor neuropsychological outcomes. Antiseizure medications (ASMs) are among the most commonly prescribed teratogenic medications in women of childbearing age. However, WWE typically cannot avoid using ASMs during pregnancy. Teratogenic risks vary across ASMs. Valproate poses a special risk for anatomic and behavioral teratogenic risks compared with other ASMs. The risks for many ASMs remain uncertain. Women of childbearing potential taking ASMs should be taking folic acid. Breastfeeding while taking ASMs seems safe. WWE should receive informed consent outlining risks before conception.

Effect of Phenobarbital on Elevated Direct Bilirubin Concentrations in Neonates and Infants in the Neonatal Intensive Care Unit

OBJECTIVE

Few studies have evaluated the effect of phenobarbital (PB) on elevated direct bilirubin (DB) plasma concentrations in neonates and infants, and none have compared its effect with a control group with matched study baseline DB values. The purpose of this study was to quantify changes in elevated DB plasma concentrations (≥2 mg/dL) in neonates and infants between a PB-treated and control group.

METHODS

A retrospective, observational, matched, cohort study was performed comparing patients between a PB-treated group and a control group with similar study baseline plasma DB values ≥2 mg/dL over an 8-week period. The percent change in DB plasma concentrations from study baseline was compared for each week of the study period.

RESULTS

During the 8-year study period, 310 patients had DB plasma concentrations ≥2 mg/dL, of which 26 remained in each group after exclusions. The PB group had increased DB concentrations and the control group had decreased DB concentrations when compared with their study baseline DB concentrations each week of the study period. By study end, the mean DB concentration increased by 11.2% in the PB group and decreased by 48.5% in the control group (p = 0.02). In multiple regression analysis, only birth weight (standardized coefficient = 0.44, p = 0.02), and gastrointestinal obstruction (standardized coefficient = −0.4, p = 0.03) were associated with significant percent change in DB concentrations.

CONCLUSIONS

This study demonstrated PB does not improve cholestasis in neonates and infants.

Current strategies for managing intestinal failure-associated liver disease

Introduction: Intestinal failure-associated liver disease (IFALD) refers to hepatic dysfunction that results from prolonged parenteral nutrition (PN) use. IFALD is multifactorial in origin and remains a major cause of morbidity and mortality. Prior to 2004, IFALD was associated with mortality as high as 90% in infants who remained on PN greater than 1 year. The advent of new strategies for intravenous lipid emulsion (ILE) administration and improved catheter care now allow many patients to remain on PN and recover from this once fatal condition. Several additional treatment modalities are often used to further improve outcomes for IFALD patients and they are reviewed here.Areas covered: The etiology of IFALD is presented, as well as the rationale behind the use of ILEs that contain fish oil. Other management strategies are addressed, including the effects of several pharmacologic and nutritional interventions.Expert opinion: Like its etiology, the management of IFALD is multifactorial. Prompt recognition of patients at risk, avoiding macronutrient excess, and preventing central line associated bloodstream infections will improve outcomes. In patients who develop IFALD, the use of fish oil monotherapy seems to be efficacious. The most effective intervention, however, continues to be discontinuation of PN and achieving full enteral feedings.

Neonatal Opioid Withdrawal Syndrome

The opioid crisis has grown to affect pregnant women and infants across the United States, as evidenced by rising rates of opioid use disorder among pregnant women and neonatal opioid withdrawal syndrome among infants. Across the country, pregnant women lack access to evidence-based therapies, including medications for opioid use disorder, and infants with opioid exposure frequently receive variable care. In addition, public systems, such as child welfare and early intervention, are increasingly stretched by increasing numbers of children affected by the crisis. Systematic, enduring, coordinated, and holistic approaches are needed to improve care for the mother-infant dyad. In this statement, we provide an overview of the effect of the opioid crisis on the mother-infant dyad and provide recommendations for management of the infant with opioid exposure, including clinical presentation, assessment, treatment, and discharge.

Neonatal Seizures and Purinergic Signalling

Neonatal seizures are one of the most common comorbidities of neonatal encephalopathy, with seizures aggravating acute injury and clinical outcomes. Current treatment can control early life seizures; however, a high level of pharmacoresistance remains among infants, with increasing evidence suggesting current anti-seizure medication potentiating brain damage. This emphasises the need to develop safer therapeutic strategies with a different mechanism of action. The purinergic system, characterised by the use of adenosine triphosphate and its metabolites as signalling molecules, consists of the membrane-bound P1 and P2 purinoreceptors and proteins to modulate extracellular purine nucleotides and nucleoside levels. Targeting this system is proving successful at treating many disorders and diseases of the central nervous system, including epilepsy. Mounting evidence demonstrates that drugs targeting the purinergic system provide both convulsive and anticonvulsive effects. With components of the purinergic signalling system being widely expressed during brain development, emerging evidence suggests that purinergic signalling contributes to neonatal seizures. In this review, we first provide an overview on neonatal seizure pathology and purinergic signalling during brain development. We then describe in detail recent evidence demonstrating a role for purinergic signalling during neonatal seizures and discuss possible purine-based avenues for seizure suppression in neonates.

Status Epilepticus in the Neonate: Updates in Treatment Strategies

PURPOSE OF REVIEW

The purpose of this review is to report recent advances in treatment of neonatal seizures, with a specific focus on new literature since a 2013 systematic review performed by this author (Slaughter) and others. There is a paucity of data with regard to well-defined status epilepticus (SE) in neonates, so treatment of recurrent seizures was also included in this inquiry. We aimed to summarize the efficacy and safety profiles of current therapeutic options as well as describe trends in medication selection in the neonatal intensive care unit (NICU) setting.

RECENT FINDINGS

Phenobarbital remains first-line therapy in practice, though there is increasing evidence of its neurotoxicity and long-term sequelae. Bumetanide failed an open-label trial for efficacy, demonstrated an increased risk for hearing loss, and has since fallen out of favor for use in this population. New agents, such as levetiracetam and topiramate, still have very limited data but appear to be as efficacious as older medications, with more favorable side effect profiles. There are limited high-level evidence-based data to guide treatment of neonatal seizures. Emerging research focusing on drug mechanisms and safety profiles may provide additional information to guide decisions; however, further research is needed.

Impact of Traumatic Brain Injury on Neurogenesis

New neurons are generated in the hippocampal dentate gyrus from early development through adulthood. Progenitor cells and immature granule cells in the subgranular zone are responsive to changes in their environment; and indeed, a large body of research indicates that neuronal interactions and the dentate gyrus milieu regulates granule cell proliferation, maturation, and integration. Following traumatic brain injury (TBI), these interactions are dramatically altered. In addition to cell losses from injury and neurotransmitter dysfunction, patients often show electroencephalographic evidence of cortical spreading depolarizations and seizure activity after TBI. Furthermore, treatment for TBI often involves interventions that alter hippocampal function such as sedative medications, neuromodulating agents, and anti-epileptic drugs. Here, we review hippocampal changes after TBI and how they impact the coordinated process of granule cell adult neurogenesis. We also discuss clinical TBI treatments that have the potential to alter neurogenesis. A thorough understanding of the impact that TBI has on neurogenesis will ultimately be needed to begin to design novel therapeutics to promote recovery.

Outpatient Pharmacotherapy for Neonatal Abstinence Syndrome

OBJECTIVE

To determine differences in lengths of stay, length of therapy, emergency department (ED) utilization, and hospital readmissions between infants with neonatal abstinence syndrome (NAS) treated exclusively with inpatient pharmacotherapy compared with those discharged on outpatient pharmacotherapy.

STUDY DESIGN

This retrospective cohort study of infants enrolled in the Tennessee Medicaid program used administrative and vital records data from 2009 to 2011. Medical record review was used to confirm cases of NAS and classify treatment type. Negative binomial regression was used to compare length of therapy and ordinal regression was used to determine frequency of ED visits and hospital readmissions.

RESULTS

Among a cohort of 736 patients with confirmed NAS, 72.3% were treated with pharmacotherapy of which approximately one-half (45.5%) were discharged home on outpatient medications. For infants discharged on outpatient pharmacotherapy, initial hospital length of stay was shorter (11 vs 23 days; P < .001) and length of therapy was longer (60 vs 19 days; adjusted incidence rate ratio [aIRR] 2.84, 95%CI 2.31-3.52). After adjusting for potential confounders, infants discharged on outpatient pharmacotherapy had a greater number of ED visits within 6 months of discharge (adjusted odds ratio [aOR] 1.52, 95% CI 1.06-2.17) compared with those treated as inpatients alone.

CONCLUSIONS

Outpatient pharmacotherapy for NAS was associated with higher length of therapy and higher rates of ED utilization when compared with infants treated exclusively as inpatients. Future research should focus on improving the efficiency of NAS management while minimizing postdischarge complications.

Complex spectrum of phenobarbital effects in a mouse model of neonatal hypoxia-induced seizures

Seizures in neonates, mainly caused by hypoxic-ischemic encephalopathy, are thought to be harmful to the brain. Phenobarbital remains the first line drug therapy for the treatment of suspected neonatal seizures but concerns remain with efficacy and safety. Here we explored the short- and long-term outcomes of phenobarbital treatment in a mouse model of hypoxia-induced neonatal seizures. Seizures were induced in P7 mice by exposure to 5% O₂ for 15 minutes. Immediately after hypoxia, pups received a single dose of phenobarbital (25 mg.kg^-1) or saline. We observed that after administration of phenobarbital seizure burden and number of seizures were reduced compared to the hypoxic period; however, PhB did not suppress acute histopathology. Behavioural analysis of mice at 5 weeks of age previously subjected to hypoxia-seizures revealed an increase in anxiety-like behaviour and impaired memory function compared to control littermates, and these effects were not normalized by phenobarbital. In a seizure susceptibility test, pups previously exposed to hypoxia, with or without phenobarbital, developed longer and more severe seizures in response to kainic acid injection compared to control mice. Unexpectedly, mice treated with phenobarbital developed less hippocampal damage after kainic acid than untreated counterparts. The present study suggests phenobarbital treatment in immature mice does not improve the long lasting functional deficits induces by hypoxia-induced seizures but, unexpectedly, may reduce neuronal death caused by exposure to a second seizure event in later life.

Ursodeoxycholic acid versus phenobarbital for cholestasis in the Neonatal Intensive Care Unit

Background

Although neonates and young infants with cholestasis are commonly treated with either phenobarbital or ursodeoxycholic acid (ursodiol), there is no evidence that phenobarbital is effective for this indication. Our objective was to compare the effectiveness of ursodiol and phenobarbital for the treatment of cholestasis in a diverse NICU population.

Methods

This is a retrospective cohort study including infants with cholestasis who were admitted to a Level IV NICU between January 2010 and December 2015. Drug courses of phenobarbital and ursodiol were identified within the medical record, and medical, demographic, and drug information were extracted. The primary outcome was reduction in direct bilirubin.

Results

Sixty-eight infants provided a total of 112 courses of drug therapy for comparison. Diverse medical diagnoses were captured in the patient cohort. Ursodiol was significantly more effective in reducing direct bilirubin than was phenobarbital (− 1.89 vs + 0.76 mg/dL; − 33.33 vs + 13.0 umol/L, p-value 0.03), even after controlling for baseline cholestasis severity, intrauterine growth restriction status, and lipid lowering therapy (− 2.16 vs + 0.27 mg/dl; − 36.94 vs + 4.62 umol/L, p-value 0.03). There was no improvement in direct bilirubin in the majority of infants treated with phenobarbital.

Conclusions

Phenobarbital, as compared to ursodiol, has limited efficacy for the reduction of direct bilirubin in neonates and young infants with cholestasis. Given new data regarding the potential neurotoxicity of phenobarbital in the developing brain, providers may choose to avoid phenobarbital in the treatment of cholestasis in infants.

Evaluation of Acute and Chronic Effects of D-Galactose on Memory and Learning in Wistar Rats

Objective

D-galactose has been commonly used in rodent models to induce accelerated effects of aging, including those on learning, memory, and muscular tone and coordination. This is normally seen on chronic administration of D-galactose. However, there is minimal suggestive evidence on the short-term effects of the same. The aim of the study was to study the acute and chronic effects of D-galactose on learning and memory in Wistar rats.

Methods

Twenty four male Wistar rats were randomly assigned to the control, standard (rivastigmine), oral D-galactose (200 mg/kg/day) and subcutaneous D-galactose (200 mg/kg/day) for a total duration of 8 weeks. Effects on learning and memory were assessed at 2 weeks, 4 weeks and 8 weeks by Morris water maze model and passive avoidance testing.

Results

Both oral and subcutaneous D-galactose showed positive effects on learning and memory on acute dosing, whereas this beneficial effect was lost during chronic dosing.

Conclusion

Short-term administration of D-galactose showed positive effects, while long-term administration nullified these effects.

Neonatal phenobarbital exposure disrupts GABAergic synaptic maturation in rat CA1 neurons

OBJECTIVE

Phenobarbital is the most commonly utilized drug for the treatment of neonatal seizures. The use of phenobarbital continues despite growing evidence that it exerts suboptimal seizure control and is associated with long-term alterations in brain structure, function, and behavior. Alterations following neonatal phenobarbital exposure include acute induction of neuronal apoptosis, disruption of synaptic development in the striatum, and a host of behavioral deficits. These behavioral deficits include those in learning and memory mediated by the hippocampus. However, the synaptic changes caused by acute exposure to phenobarbital that lead to lasting effects on brain function and behavior remain understudied.

METHODS

Postnatal day (P)7 rat pups were treated with phenobarbital (75 mg/kg) or saline. On P13-14 or P29-37, acute slices were prepared and whole-cell patch-clamp recordings were made from CA1 pyramidal neurons.

RESULTS

At P14 we found an increase in miniature inhibitory postsynaptic current (mIPSC) frequency in the phenobarbital-exposed as compared to the saline-exposed group. In addition to this change in mIPSC frequency, the phenobarbital group displayed larger bicuculline-sensitive tonic currents, decreased capacitance and membrane time constant, and a surprising persistence of giant depolarizing potentials. At P29+, the frequency of mIPSCs in the saline-exposed group had increased significantly from the frequency at P14, typical of normal synaptic development; at this age the phenobarbital-exposed group displayed a lower mIPSC frequency than did the control group. Spontaneous inhibitory postsynaptic current (sIPSC) frequency was unaffected at either P14 or P29+.

SIGNIFICANCE

These neurophysiological alterations following phenobarbital exposure provide a potential mechanism by which acute phenobarbital exposure can have a long-lasting impact on brain development and behavior.

Variability in Preferred Management of Electrographic Seizures in Neonatal Hypoxic Ischemic Encephalopathy

BACKGROUND

Seizures may cause added harm in neonates with hypoxic-ischemic encephalopathy (HIE). Specific recommendations about seizure treatment in this context are lacking. We sought to determine the scope of practice regarding management of non-status epilepticus electrographic-only seizures in this setting.

METHODS

A case-based survey was distributed to members of the Child Neurology Society. Providers were asked about their preferred management strategy for sequential clinical scenarios.

RESULTS

A total of 177 child neurologists responded to the survey. Seventy-seven percent of providers would treat 20 seconds or less of electrographic seizure activity. In a neonate with mild HIE and an electrographic-only seizure, there was no agreement among providers regarding whether to start maintenance therapy in addition to a one-time anti-seizure drug load. In a neonate with moderate HIE on phenobarbital for early electro-clinical seizures, most providers would escalate treatment for ongoing electrographic-only seizures by increasing phenobarbital dosing. In a neonate with severe HIE complicated by status epilepticus on phenobarbital who subsequently develops recurrent electrographic-only seizures, providers varied substantially in their management preferences. For all three cases, 75% to 85% of providers would not change their management preferences based on the absence of a clinical correlate with the electrographic seizure.

CONCLUSIONS

We found marked variability among providers regarding preferred management of non-status epilepticus electrographic-only seizures after HIE. Our results identified specific aspects of electrographic-only seizure management in neonatal HIE where there is limited consensus. These discrepancies may serve as opportunities for future investigation.

Two Novel KCNQ2 Mutations in 2 Families With Benign Familial Neonatal Convulsions

Benign familial neonatal convulsion is a rare autosomal dominant inherited epilepsy syndrome characterized by unprovoked seizures in the first few days of life, normal psychomotor development, and a positive intergenerational family history of neonatal seizures. Over 90% of the affected individuals have inherited causal mutations in KCNQ2, which encodes for the potassium voltage-gated channel subfamily Q, member 2. Mutations in KCNQ2 are also associated with a severe neonatal encephalopathy phenotype associated with poor seizure control and neurodevelopmental deficits. The authors report the clinical presentations, response to medication, and intrafamilial phenotypic variability in 2 families with benign familial neonatal convulsions, carrying previously unreported heterozygous missense mutations, c.1066C>G (p.Leu356Val) and c.1721G<A (p.Gly574Asp), in KCNQ2. The cases reported herein suggest that inherited missense mutations in KCNQ2 can be associated with an intermediate phenotype and illustrate the challenges associated with prognosis and counselling for individuals with inherited missense mutations in KCNQ2.

Comparative neurotoxicity screening in human iPSC-derived neural stem cells, neurons and astrocytes

Induced pluripotent stem cells (iPSC) and their differentiated derivatives offer a unique source of human primary cells for toxicity screens. Here, we report on the comparative cytotoxicity of 80 compounds (neurotoxicants, developmental neurotoxicants, and environmental compounds) in iPSC as well as isogenic iPSC-derived neural stem cells (NSC), neurons, and astrocytes. All compounds were tested over a 24-h period at 10 and 100 μM, in duplicate, with cytotoxicity measured using the MTT assay. Of the 80 compounds tested, 50 induced significant cytotoxicity in at least one cell type; per cell type, 32, 38, 46, and 41 induced significant cytotoxicity in iPSC, NSC, neurons, and astrocytes, respectively. Four compounds (valinomycin, 3,3',5,5'-tetrabromobisphenol, deltamethrin, and triphenyl phosphate) were cytotoxic in all four cell types. Retesting these compounds at 1, 10, and 100 μM using the same exposure protocol yielded consistent results as compared with the primary screen. Using rotenone, we extended the testing to seven additional iPSC lines of both genders; no substantial difference in the extent of cytotoxicity was detected among the cell lines. Finally, the cytotoxicity assay was simplified by measuring luciferase activity using lineage-specific luciferase reporter iPSC lines which were generated from the parental iPSC line. This article is part of a Special Issue entitled SI: PSC and the brain.

Comparison of the long-term behavioral effects of neonatal exposure to retigabine or phenobarbital in rats

Anticonvulsant drugs, when given during vulnerable periods of brain development, can have long-lasting consequences on nervous system function. In rats, the second postnatal week approximately corresponds to the late third trimester of gestation/early infancy in humans. Exposure to phenobarbital during this period has been associated with deficits in learning and memory, anxiety-like behavior, and social behavior, among other domains. Phenobarbital is the most common anticonvulsant drug used in neonatology. Several other drugs, such as lamotrigine, phenytoin, and clonazepam, have also been reported to trigger behavioral changes. A new generation anticonvulsant drug, retigabine, has not previously been evaluated for long-term effects on behavior. Retigabine acts as an activator of KCNQ channels, a mechanism that is unique among anticonvulsants. Here, we examined the effects retigabine exposure from postnatal day (P)7 to P14 on behavior in adult rats. We compared these effects with those produced by phenobarbital (as a positive control) and saline (as a negative control). Motor behavior was assessed by using the open field and rotarod, anxiety-like behavior by the open field, elevated plus maze, and light-dark transition task, and learning/memory by the passive avoidance task; social interactions were assessed in same-treatment pairs, and nociceptive sensitivity was assessed via the tail-flick assay. Motor behavior was unaltered by exposure to either drug. We found that retigabine exposure and phenobarbital exposure both induced increased anxiety-like behavior in adult animals. Phenobarbital, but not retigabine, exposure impaired learning and memory. These drugs also differed in their effects on social behavior, with retigabine-exposed animals displaying greater social interaction than phenobarbital-exposed animals. These results indicate that neonatal retigabine induces a subset of behavioral alterations previously described for other anticonvulsant drugs and extend our knowledge of drug-induced behavioral teratogenesis to a new mechanism of anticonvulsant action.

Anticonvulsant drug-induced cell death in the developing white matter of the rodent brain

OBJECTIVE

During critical periods of brain development, both seizures and anticonvulsant medications can affect neurodevelopmental outcomes. In rodent models, many anticonvulsants trigger neuronal apoptosis. However, white matter apoptosis (WMA) has not been examined after anticonvulsant drug treatment. Herein, we sought to determine if anticonvulsant drugs induced apoptosis in the developing white matter (WM) in a rodent model.

METHODS

Postnatal day (P)7 rats were treated with phenobarbital (PB-75), MK-801 (dizocilpine, 0.5), lamotrigine (LTG-20), carbamazepine (CBZ-100), phenytoin (PHT-50), levetiracetam (LEV-250), or saline; all doses are mg/kg. Brain tissue collected 24 h after treatment was stained using the terminal deoxynucleotidyl transferase dUTP nick end labeling method. The number of degenerating cells within WM, that is, anterior commissure (AC), corpus callosum, cingulum, and hippocampus-associated WM tracts, was quantified.

RESULTS

Saline-treated rats showed low baseline level of apoptosis in developing WM on P8 in all the areas examined. PB, PHT, and MK-801 significantly increased apoptosis in all four brain areas examined. Exposure to CBZ, LTG, or LEV failed to increase apoptosis in all regions.

SIGNIFICANCE

Commonly used anticonvulsants (PB, PHT) cause apoptosis in the developing WM in a rat model; the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 has a similar effect. These results are consistent with reports of anesthesia-induced WMA during brain development. Consistent with the lack of neuronal apoptosis caused by LTG, LEV, and CBZ, these drugs did not cause WMA. Many infants treated with anticonvulsant drugs have underlying neurologic injury, including WM damage (e.g., following intraventricular hemorrhage [IVH] or hypoxic-ischemic encephalopathy [HIE]). The degree to which anticonvulsant drug treatment will alter outcomes in the presence of underlying injury remains to be examined, but avoiding drugs (when possible) that induce WMA may be beneficial.

Profile of retigabine-induced neuronal apoptosis in the developing rat brain

OBJECTIVE

Acute neonatal exposure to some, but not all, anticonvulsant drugs induces a profound increase in neuronal apoptosis in rats. Phenobarbital and phenytoin induce apoptosis at a therapeutically relevant dose range, lamotrigine and carbamazepine do so only at supratherapeutic doses or in polytherapy, and valproate does so even at subtherapeutic doses. Levetiracetam is devoid of pro-apoptotic effects. Retigabine, a new-generation drug, acts uniquely by enhancing the M-type potassium current. Because its safety profile in developing animals is unstudied, we sought to determine if retigabine would induce apoptosis.

METHODS

Postnatal day (P) 7 rat pups were treated with retigabine (5-30 mg/kg), vehicle (saline), or comparator drugs (phenobarbital, lamotrigine, levetiracetam, or carbamazepine). Cell death was assessed using amino-cupric-silver staining. A separate group of animals was treated repeatedly (three times over 24 h) with retigabine (15 mg/kg) or vehicle. To establish a pharmacokinetic profile for retigabine, we measured plasma and brain levels after drug treatment.

RESULTS

Consistent with prior studies from our group and others, we found phenobarbital-induced cell death throughout thalamus, nucleus accumbens, and several neocortical areas. By contrast, levetiracetam, lamotrigine, and carbamazepine were found to have no appreciable apoptotic effect on the aforementioned structures. Acute (single) exposure to retigabine, even at doses of 30 mg/kg, was also without effect on apoptosis. However, repeated (three times) exposure to retigabine triggered apoptosis in a subset of brain areas. The half-life of retigabine in plasma was 2.5 h, with appreciable concentrations reached in the brain within 1 h of administration.

SIGNIFICANCE

These data demonstrate that retigabine, like many other anticonvulsant drugs, is capable of triggering neuronal apoptosis in the developing rat brain. Unlike other drugs, repeated dosing of retigabine was necessary to induce this effect. This may be due to its shorter half-life as compared to other drugs, such as phenobarbital.

[Protective effect of succinic acid on cerebellar Purkinje cells of neonatal rats with convulsion]

OBJECTIVE

To investigate the protective effect of succinic acid (SA) on the cerebellar Purkinje cells (PCs) of neonatal rats with convulsion.

METHODS

A total of 120 healthy neonatal Sprague-Dawley rats aged 7 days were randomly divided into a neonatal period group and a developmental period group. Each of the two groups were further divided into 6 sub-groups: normal control, convulsion model, low-dose phenobarbital (PB) (30 mg/kg), high-dose PB (120 mg/kg), low-dose SA (30 mg/kg), and high-dose SA (120 mg/kg). Intraperitoneal injection of pentylenetetrazole was performed to establish the convulsion model. The normal control group was treated with normal saline instead. The rats in the neonatal group were sacrificed at 30 minutes after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Those in the developmental group were sacrificed 30 days after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Whole cell patch clamp technique was used to record the action potential (AP) of PCs in the cerebellar slices of neonatal rats; the parallel fibers (PF) were stimulated at a low frequency to induce excitatory postsynaptic current (EPSC). The effect of SA on long-term depression (LTD) of PCs was observed.

RESULTS

Compared with the normal control groups, the neonatal and developmental rats with convulsion had a significantly higher AP frequency of PCs (P<0.05), and the developmental rats with convulsion had a significantly decreased threshold stimulus (P<0.01) and a significantly greater inhibition of the amplitude of EPSC in PCs (P<0.05). Compared with the normal control groups, the neonatal and developmental rats with convulsion in the high-dose PB groups had a significantly decreased threshold stimulus (P<0.01), a significantly higher AP frequency of PCs (P<0.05), and a significantly greater inhibition of EPSC in PCs (P<0.05). Compared with the neonatal and developmental rats in the convulsion model groups, those in the high-dose SA groups had a significantly decreased AP frequency of PCs (P<0.05). The developmental rats in the low- and high-dose SA groups had a significantly higher AP threshold than those in the convulsion model group (P<0.05).

CONCLUSIONS

The high excitability of PCs and the abnormal PF-PC synaptic plasticity caused by convulsion in neonatal rats may last to the developmental period, which can be aggravated by PB, while SA can reduce the excitability of PCs in neonatal rats with convulsion and repair the short- and long-term abnormalities of LTD of PCs caused by convulsion.

[Protective effect of succinic acid on cerebellar Purkinje cells of neonatal rats with convulsion]

OBJECTIVE

To investigate the protective effect of succinic acid (SA) on the cerebellar Purkinje cells (PCs) of neonatal rats with convulsion.

METHODS

A total of 120 healthy neonatal Sprague-Dawley rats aged 7 days were randomly divided into a neonatal period group and a developmental period group. Each of the two groups were further divided into 6 sub-groups: normal control, convulsion model, low-dose phenobarbital (PB) (30 mg/kg), high-dose PB (120 mg/kg), low-dose SA (30 mg/kg), and high-dose SA (120 mg/kg). Intraperitoneal injection of pentylenetetrazole was performed to establish the convulsion model. The normal control group was treated with normal saline instead. The rats in the neonatal group were sacrificed at 30 minutes after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Those in the developmental group were sacrificed 30 days after the injection of PB, SA, or normal saline, and the cerebellum was obtained. Whole cell patch clamp technique was used to record the action potential (AP) of PCs in the cerebellar slices of neonatal rats; the parallel fibers (PF) were stimulated at a low frequency to induce excitatory postsynaptic current (EPSC). The effect of SA on long-term depression (LTD) of PCs was observed.

RESULTS

Compared with the normal control groups, the neonatal and developmental rats with convulsion had a significantly higher AP frequency of PCs (P<0.05), and the developmental rats with convulsion had a significantly decreased threshold stimulus (P<0.01) and a significantly greater inhibition of the amplitude of EPSC in PCs (P<0.05). Compared with the normal control groups, the neonatal and developmental rats with convulsion in the high-dose PB groups had a significantly decreased threshold stimulus (P<0.01), a significantly higher AP frequency of PCs (P<0.05), and a significantly greater inhibition of EPSC in PCs (P<0.05). Compared with the neonatal and developmental rats in the convulsion model groups, those in the high-dose SA groups had a significantly decreased AP frequency of PCs (P<0.05). The developmental rats in the low- and high-dose SA groups had a significantly higher AP threshold than those in the convulsion model group (P<0.05).

CONCLUSIONS

The high excitability of PCs and the abnormal PF-PC synaptic plasticity caused by convulsion in neonatal rats may last to the developmental period, which can be aggravated by PB, while SA can reduce the excitability of PCs in neonatal rats with convulsion and repair the short- and long-term abnormalities of LTD of PCs caused by convulsion.