The temporal characteristics of seizures in neonatal hypoxic ischemic encephalopathy treated with hypothermia

Defining neonatal status epilepticus: A scoping review from the ILAE neonatal task force

OBJECTIVE

To review the available literature concerning the definition of neonatal status epilepticus (SE) and/or seizure burden.

METHODS

The International League Against Epilepsy Neonatal Task Force performed a scoping review of the definitions of neonatal SE. Following a systematic literature review, articles were screened and data were abstracted regarding: (1) article characteristics (author identification, publication year, journal name, digital object identifier, title, objective, and study design); (2) cohort characteristics (sample size, gestational age, seizure etiology); (3) definition of SE and/or seizure burden; and (4) the method used to identify and classify SE, including routine EEG (EEG), continuous EEG monitoring (cEEG), amplitude-integrated EEG (aEEG), or clinical features.

RESULTS

The scoping review yielded 44 articles containing a definition of neonatal SE. Studies mainly included infants with hypoxic-ischemic encephalopathy or neonates considered at risk for seizures. SE identification and classification most often relied on cEEG. The majority of studies based the definition of SE on seizure duration, including summed duration of seizures comprising ≥50% of any 1-h epoch, recurrent seizures for >50% of the total recording time, or either electrographic seizures lasting >30 min and/or repeated electrographic seizures totaling >50% in any 1-h period. Seizure burden was reported in 20 studies, and the most commonly used approach assessed total seizure burden, defined as total duration of EEG seizures in minutes. Sixteen studies assessed the relationship between seizure burden and outcomes, and most identified a significant association between higher seizure burden and unfavorable outcomes.

SIGNIFICANCE

This scoping review demonstrates a substantial variation in neonatal SE definitions across the literature. The most common definitions were based around a 30-min seizure duration criterion, but evidence was insufficient to support that 30 min was a cutoff defining prolonged seizures or that seizures exceeding this burden were more likely to be pharmacoresistant or associated with worse outcomes. As a next step, the Neonatal Task Force intends to develop a standardized approach to assessing and describing neonatal seizure burden and defining neonatal SE.

PLAIN LANGUAGE SUMMARY

Prolonged seizures are a neurologic emergency, if untreated, can lead to permanent injury or death. In adults and children, seizures lasting longer than 30 min are believed to cause brain damage. However, it is not clear if this definition can be applied to neonates. The International League Against Epilepsy Neonatal Taskforce performed a scoping literature review which identified 44 articles containing a definition of neonatal status epilepticus. In this article, the authors reviewed the current used definitions for prolonged seizures in neonates to establish a relationship between seizure duration and neurological outcome. As a next step, the Neonatal Task Force intends to develop a standardized approach to assessing and describing neonatal seizure burden and defining neonatal SE.

The American Clinical Neurophysiology Society Guideline on Indications for Continuous Electroencephalography Monitoring in Neonates

PURPOSE

Continuous EEG (cEEG) monitoring is increasingly used in the management of neonates with seizures. There remains debate on what clinically relevant information can be gained from cEEG in neonates with suspected seizures, at high risk for seizures, or with definite seizures, as well as the use of cEEG for prognosis in a variety of conditions. In this guideline, we address these questions using American Clinical Neurophysiology Society structured methodology for clinical guideline development.

METHODS

A working group was formed from American Clinical Neurophysiology Society membership with expertise in neonatal cEEG and a set of priority questions developed. We performed literature searches in PubMed and EMBASE to identify relevant studies. Evidence tables were compiled from extracted data and quality assessments performed. A modification of the GRADE process was used to evaluate the body of evidence and draft recommendations.

RESULTS

Our working group identified six priority questions to evaluate the accuracy of cEEG for neonatal seizure diagnosis and the formulation of prognosis. An initial literature search yielded 18,167 results, which were distilled to a set of 217 articles. Overall, the quality of evidence for most priority questions was rated as very low and we provided conditional recommendations based on published literature and expert consensus. For each priority question, we also considered the benefits and harms of cEEG, with relative harms considered to be far less than the potential benefits across recommendations.

CONCLUSIONS

We present evidence-based clinical guidelines regarding indications for cEEG monitoring in neonates. Considering resource utilization and feasibility, when cEEG monitoring results have a likelihood of altering clinical decision making, the authors felt the resource investment was justifiable.

Regional variability in therapeutic hypothermia eligibility criteria for neonatal hypoxic-ischemic encephalopathy

Early induced therapeutic hypothermia represents the cornerstone treatment in neonates with probable hypoxic-ischemic encephalopathy. The selection of patients for treatment usually involves meeting criteria indicating evidence of perinatal hypoxia-ischemia and the presence of moderate or severe encephalopathy. In this review, we highlight the variability that exists between some of the different regional and national eligibility guidelines. Determining the potential presence of perinatal hypoxia-ischemia may require either one, two or three signs amongst history of acute perinatal event, prolonged resuscitation at delivery, abnormal blood gases and low Apgar score, with a range of cutoff values. Clinical neurological exams often define the severity of encephalopathy differently, with varying number of domains required for determining eligibility and blurred interpretation of findings assigned to different severity grades in different systems. The role of early electrophysiological assessment is weighted differently. A clinical implication is that infants may receive different care depending on the location in which they are born. This could also impact epidemiological data, as inference of rates of moderate-severe encephalopathy based on therapeutic hypothermia rates are misleading and influenced by different eligibility methods used. We would advocate that a universally endorsed single severity staging of encephalopathy is vital for standardizing management and neonatal outcome. IMPACT: Variability exists between regional and national therapeutic hypothermia eligibility guidelines for neonates with probable hypoxic-ischemic encephalopathy. Differences are common in both criteria indicating perinatal hypoxia-ischemia and criteria defining moderate or severe encephalopathy. The role of early electrophysiological assessment is also weighted unequally. This reflects in different individual care and impacts research data. A universally endorsed single severity staging of encephalopathy would be crucial for standardizing management.

Temporal evolution of electrographic seizures in newborn infants with hypoxic-ischaemic encephalopathy requiring therapeutic hypothermia: a secondary analysis of the ANSeR studies

BACKGROUND

Despite extensive research on neonatal hypoxic-ischaemic encephalopathy, detailed information about electrographic seizures during active cooling and rewarming of therapeutic hypothermia is sparse. We aimed to describe temporal evolution of seizures and determine whether there is a correlation of seizure evolution with 2-year outcome.

METHODS

This secondary analysis included newborn infants recruited from eight European tertiary neonatal intensive care units for two multicentre studies (a randomised controlled trial [NCT02431780] and an observational study [NCT02160171]). Infants were born at 36+0 weeks of gestation with moderate or severe hypoxic-ischaemic encephalopathy and underwent therapeutic hypothermia with prolonged conventional video-electroencephalography (EEG) monitoring for 10 h or longer from the start of rewarming. Seizure burden characteristics were calculated based on electrographic seizures annotations: hourly seizure burden (minutes of seizures within an hour) and total seizure burden (minutes of seizures within the entire recording). We categorised infants into those with electrographic seizures during active cooling only, those with electrographic seizures during cooling and rewarming, and those without seizures. Neurodevelopmental outcomes were determined using the Bayley's Scales of Infant and Toddler Development, Third Edition (BSID-III), the Griffiths Mental Development Scales (GMDS), or neurological assessment. An abnormal outcome was defined as death or neurodisability at 2 years. Neurodisability was defined as a composite score of 85 or less on any subscales for BSID-III, a total score of 87 or less for GMDS, or a diagnosis of cerebral palsy (dyskinetic cerebral palsy, spastic quadriplegia, or mixed motor impairment) or epilepsy.

FINDINGS

Of 263 infants recruited between Jan 1, 2011, and Feb 7, 2017, we included 129 infants: 65 had electrographic seizures (43 during active cooling only and 22 during and after active cooling) and 64 had no seizures. Compared with infants with seizures during active cooling only, those with seizures during and after active cooling had a longer seizure period (median 12 h [IQR 3-28] vs 68 h [35-86], p<0·0001), more seizures (median 12 [IQR 5-36] vs 94 [24-134], p<0·0001), and higher total seizure burden (median 69 min [IQR 22-104] vs 167 min [54-275], p=0·0033). Hourly seizure burden peaked at about 20-24 h in both groups, and infants with seizures during and after active cooling had a secondary peak at 85 h of age. When combined, worse EEG background (major abnormalities and inactive background) at 12 h and 24 h were associated with the seizure group: compared with infants with a better EEG background (normal, mild, or moderate abnormalities), infants with a worse EEG background were more likely to have seizures after cooling at 12 h (13 [54%] of 24 vs four [14%] of 28; odds ratio 7·09 [95% CI 1·88-26·77], p=0·0039) and 24 h (14 [56%] of 25 vs seven [18%] of 38; 5·64 [1·81-17·60], p=0·0029). There was a significant relationship between EEG grade at 12 h (four categories) and seizure group (p=0·020). High total seizure burden was associated with increased odds of an abnormal outcome at 2 years of age (odds ratio 1·007 [95% CI 1·000-1·014], p=0·046), with a medium negative correlation between total seizure burden and BSID-III cognitive score (rS=-0·477, p=0·014, n=26).

INTERPRETATION

Overall, half of infants with hypoxic-ischaemic encephalopathy had electrographic seizures and a third of those infants had seizures beyond active cooling, with worse outcomes. These results raise the importance of prolonged EEG monitoring of newborn infants with hypoxic-ischaemic encephalopathy not only during active cooling but throughout the rewarming phase and even longer when seizures are detected.

FUNDING

Wellcome Trust, Science Foundation Ireland, and the Irish Health Research Board.

Duration of birth depression and neurodevelopmental outcomes after whole-body hypothermia for hypoxic ischemic encephalopathy in India, Sri Lanka and Bangladesh - an exploratory analysis of the HELIX trial

Background

Effect of duration of birth depression on neurodevelopmental outcomes in low- and middle-income countries (LMICs) is not known. We examined the association of birth depression with brain injury, neurodevelopmental outcomes, and hypothermia after hypoxic ischemic encephalopathy (HIE) in south Asia.

Methods

We compared cerebral magnetic resonance (MR) at 2 weeks, and adverse outcomes (death or moderate or severe disability) at 18 months in 408 babies with moderate or severe HIE who had long birth depression (positive pressure ventilation (PPV) >10 min or Apgar score<6 at 10 min or cord pH < 7.0) and short birth depression (PPV for 5-10 min or Apgar score<6 at 5 min, but ≥6 at 10 min).

Findings

Long depression group (n = 201) had more severe HIE (32.8% versus 6.8%), mortality (47.5% versus 26.4%), death or disability at 18 months (62.2% versus 35.4%) (all p < 0.001), MR injury (Odds ratio; 95% CI) to basal ganglia (2.4 (1.3, 4.1); p = 0.003), posterior limb of internal capsule (2.3 (1.3, 4.3); p < 0.001) and white matter (1.7 (1.1, 2.7); p = 0.021), and lower thalamic N-acetylaspartate levels (7.69 ± 1.84 versus 8.29 ± 1.60); p = 0.031) than short depression group (n = 207). Three babies had no heartbeat at 5 min, of which 1 died and 2 survived with severe disability. No significant interaction between the duration of birth depression and whole-body hypothermia was seen for any of the MR biomarker or clinical outcomes.

Interpretation

Long birth depression was associated with more brain injury and adverse outcomes than short depression. Effect of hypothermia was not modified by duration of birth depression.

Funding

National Institute for Health Research.

Treatment of seizures in the neonate: Guidelines and consensus-based recommendations-Special report from the ILAE Task Force on Neonatal Seizures

Seizures are common in neonates, but there is substantial management variability. The Neonatal Task Force of the International League Against Epilepsy (ILAE) developed evidence-based recommendations about antiseizure medication (ASM) management in neonates in accordance with ILAE standards. Six priority questions were formulated, a systematic literature review and meta-analysis were performed, and results were reported following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 standards. Bias was evaluated using the Cochrane tool and risk of Bias in non-randomised studies - of interventions (ROBINS-I), and quality of evidence was evaluated using grading of recommendations, assessment, development and evaluation (GRADE). If insufficient evidence was available, then expert opinion was sought using Delphi consensus methodology. The strength of recommendations was defined according to the ILAE Clinical Practice Guidelines development tool. There were six main recommendations. First, phenobarbital should be the first-line ASM (evidence-based recommendation) regardless of etiology (expert agreement), unless channelopathy is likely the cause for seizures (e.g., due to family history), in which case phenytoin or carbamazepine should be used. Second, among neonates with seizures not responding to first-line ASM, phenytoin, levetiracetam, midazolam, or lidocaine may be used as a second-line ASM (expert agreement). In neonates with cardiac disorders, levetiracetam may be the preferred second-line ASM (expert agreement). Third, following cessation of acute provoked seizures without evidence for neonatal-onset epilepsy, ASMs should be discontinued before discharge home, regardless of magnetic resonance imaging or electroencephalographic findings (expert agreement). Fourth, therapeutic hypothermia may reduce seizure burden in neonates with hypoxic-ischemic encephalopathy (evidence-based recommendation). Fifth, treating neonatal seizures (including electrographic-only seizures) to achieve a lower seizure burden may be associated with improved outcome (expert agreement). Sixth, a trial of pyridoxine may be attempted in neonates presenting with clinical features of vitamin B6-dependent epilepsy and seizures unresponsive to second-line ASM (expert agreement). Additional considerations include a standardized pathway for the management of neonatal seizures in each neonatal unit and informing parents/guardians about the diagnosis of seizures and initial treatment options.

Risk of seizures in neonates with hypoxic-ischemic encephalopathy receiving hypothermia plus erythropoietin or placebo

BACKGROUND

An ancillary study of the High-Dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) trial for neonates with hypoxic-ischemic encephalopathy (HIE) and treated with therapeutic hypothermia examined the hypothesis that neonates randomized to receive erythropoietin (Epo) would have a lower seizure risk and burden compared with neonates who received placebo.

METHODS

Electroencephalograms (EEGs) from 7/17 HEAL trial centers were reviewed. Seizure presence was compared across treatment groups using a logistic regression model adjusting for treatment, HIE severity, center, and seizure burden prior to the first dose. Among neonates with seizures, differences across treatment groups in median maximal hourly seizure burden were assessed using adjusted quantile regression models.

RESULTS

Forty-six of 150 (31%) neonates had EEG seizures (31% in Epo vs 30% in placebo, p = 0.96). Maximal hourly seizure burden after the study drug was not significantly different between groups (median 11.4 for Epo, IQR: 5.6, 18.1 vs median 9.7, IQR: 4.9, 21.0 min/h for placebo).

CONCLUSION

In neonates with HIE treated with hypothermia who were randomized to Epo or placebo, we found no meaningful between-group difference in seizure risk or burden. These findings are consistent with overall trial results, which do not support Epo use for neonates with HIE undergoing therapeutic hypothermia.

IMPACT

In the HEAL trial of erythropoietin (Epo) vs placebo for neonates with encephalopathy presumed due to hypoxic-ischemic encephalopathy (HIE) who were also treated with therapeutic hypothermia, electrographic seizures were detected in 31%, which is lower than most prior studies. Epo did not reduce the proportion of neonates with acute provoked seizures (31% in Epo vs 30% in placebo) or maximal hourly seizure burden after the study drug (median 11.4, IQR 5.6, 18.1 for Epo vs median 9.7, IQR 4.9, 21.0 min/h for placebo). There was no anti- or pro-convulsant effect of Epo when combined with therapeutic hypothermia for HIE.

The prognostic value of neonatal conventional-EEG monitoring in hypoxic-ischemic encephalopathy during therapeutic hypothermia

AIM

To determine the prognostic value of conventional electroencephalography (EEG) monitoring in neonatal hypoxic-ischemic encephalopathy (HIE).

METHOD

In this multicentre retrospective study, 95 full-term neonates (mean of 39.3wks gestational age [SD  1.4], 36 [38%] females, 59 [62%] males) with HIE (2013-2016) undergoing therapeutic hypothermia were divided between favourable or adverse outcomes. Background EEG activity (French classification scale: 0-1-2-3-4-5) and epileptic seizure burden (epileptic seizure scale: 0-1-2) were graded for seven 6-hour periods. Conventional EEG monitoring was investigated by principal component analysis (PCA), with clustering methods to extract prognostic biomarkers of development at 2 years and infant death.

RESULTS

Eighty-one per cent of infants with an adverse outcome had a French classification scale equal to or greater than 3 after H48 (100% at H6-12). The H6-12 epileptic seizure scale was equal to or greater than 1 for 39%, increased to 52% at H30-36 and then remained equal to or greater than 1 for 39% after H48. Forty-five per cent of infants with a favourable outcome had a H6-12 French classification scale equal to or greater than 3, which dropped to 5% after H48; 13% had a H6-12 epileptic seizure scale equal to or greater than 1 but no seizures after H48. Clustering methods based on PCA showed the high efficiency (96%) of conventional EEG monitoring for outcome prediction and allowed the definition of three prognostic EEG biomarkers: H6-78 French classification scale mean, H6-78 French classification scale slope, and H30-78 epileptic seizure scale mean.

INTERPRETATION

Early lability and recovery of physiological features is prognostic of a favourable outcome. Seizure onset from the second day should also be considered to accurately predict neurodevelopment in HIE and support the importance of conventional EEG monitoring in HIE in infants cooled with therapeutic hypothermia.

WHAT THIS PAPER ADDS

Comprehensive analysis showed the high prognostic efficiency (96%) of conventional electroencephalography (EEG) monitoring. Prognostic EEG biomarkers consist of the grade of background EEG activity, its evolution, and the mean seizure burden. Persistent seizures (H48) without an improvement in background EEG activity were consistently associated with an adverse outcome.

Neuromonitoring in neonatal critical care part I: neonatal encephalopathy and neonates with possible seizures

The blooming of neonatal neurocritical care over the last decade reflects substantial advances in neuromonitoring and neuroprotection. The most commonly used brain monitoring tools in the neonatal intensive care unit (NICU) are amplitude integrated EEG (aEEG), full multichannel continuous EEG (cEEG), and near-infrared spectroscopy (NIRS). While some published guidelines address individual tools, there is no consensus on consistent, efficient, and beneficial use of these modalities in common NICU scenarios. This work reviews current evidence to assist decision making for best utilization of neuromonitoring modalities in neonates with encephalopathy or with possible seizures. Neuromonitoring approaches in extremely premature and critically ill neonates are discussed separately in the companion paper. IMPACT: Neuromonitoring techniques hold promise for improving neonatal care. For neonatal encephalopathy, aEEG can assist in screening for eligibility for therapeutic hypothermia, though should not be used to exclude otherwise eligible neonates. Continuous cEEG, aEEG and NIRS through rewarming can assist in prognostication. For neonates with possible seizures, cEEG is the gold standard for detection and diagnosis. If not available, aEEG as a screening tool is superior to clinical assessment alone. The use of seizure detection algorithms can help with timely seizures detection at the bedside.

EEG in neonatal seizures: where to look and what to see

INTRODUCTION

Neonatal seizures are frequent and carry a detrimental prognostic outlook. Diagnosis is based on EEG confirmation. Classification has recently changed.

AREAS COVERED

We consulted original papers, book chapters, atlases, and reviews to provide a narrative overview on EEG characteristics of neonatal seizures. We searched PubMed, without time restrictions (last visited: 31 May 2022). Additional papers were extracted from the references list of selected papers. We describe the typical neonatal ictal EEG discharges morphology, location, and propagation, together with age-dependent features. Etiology-dependent electroclinical features, when identifiable, are presented for both acute symptomatic neonatal seizures and neonatal-onset epilepsies and developmental/epileptic encephalopathies. The few ictal variables known to predict long-term outcome have been discussed.

EXPERT OPINION

Multimodal neuromonitoring in critically ill newborns, high-density EEG, and functional neuroimaging might increase our insight into the neurophysiological bases of seizures in newborns. Increasing availability of long-term monitoring with conventional video-EEG and automated detection methods will allow clinicians and researchers to gather an ever expanding bulk of clinical and neurophysiological data to enhance accuracy with deep phenotyping. The latest classification proposal represents an input for critically revising our diagnostic abilities with respect to seizure definition, duration, and semiology, possibly further promoting clinical research.

Cerebral Oxygenation and Metabolism After Hypoxia-Ischemia

Perinatal hypoxia-ischemia (HI) is still a significant contributor to mortality and adverse neurodevelopmental outcomes in term and preterm infants. HI brain injury evolves over hours to days, and involves complex interactions between the endogenous protective and pathological processes. Understanding the timing of evolution of injury is vital to guide treatment. Post-HI recovery is associated with a typical neurophysiological profile, with stereotypic changes in cerebral perfusion and oxygenation. After the initial recovery, there is a delayed, prolonged reduction in cerebral perfusion related to metabolic suppression, followed by secondary deterioration with hyperperfusion and increased cerebral oxygenation, associated with altered neurovascular coupling and impaired cerebral autoregulation. These changes in cerebral perfusion are associated with the stages of evolution of injury and injury severity. Further, iatrogenic factors can also affect cerebral oxygenation during the early period of deranged metabolism, and improving clinical management may improve neuroprotection. We will review recent evidence that changes in cerebral oxygenation and metabolism after HI may be useful biomarkers of prognosis.

Diagnosis and Management of Seizures in the Preterm Infant

The risk of seizure is increased in premature neonates compared to full term infants, with a distinct profile of etiologies, timing and character. Despite improvements in neonatal care, preterm infants with seizure continue to have higher risk of abnormal neurodevelopmental outcomes when compared to preterm infants without seizures, or to full term infants with seizures. Very limited evidence guides the care of this challenging population, therefore, management of the preterm neonate with seizure is largely extrapolated from the care of full-term neonates. A critical need exists for well-designed clinical trials investigating and validating the safety, efficacy, and outcomes of seizure management in this vulnerable population.

Association of network connectivity via resting state functional MRI with consciousness, mortality, and outcomes in neonatal acute brain injury

BACKGROUND

An accurate and comprehensive test of integrated brain network function is needed for neonates during the acute brain injury period to inform on morbidity. This retrospective cohort study assessed whether integrated brain network function acquired by resting state functional MRI during the acute period in neonates with brain injury, is associated with acute exam, neonatal mortality, and 6-month outcomes.

METHODS

Study subjects included 40 consecutive neonates with resting state functional MRI acquired within 31 days after suspected brain insult from March 2018 to July 2019 at Phoenix Children's Hospital. Acute-period exam and test results were assigned ordinal scores based on severity as documented by respective treating specialists. Analyses (Fisher exact, Wilcoxon-rank sum test, ordinal/multinomial logistic regression) examined association of resting state networks with demographics, presentation, neurological exam, electroencephalogram, anatomical MRI, magnetic resonance spectroscopy, passive task functional MRI, and outcomes of discharge condition, outpatient development, motor tone, seizure, and mortality.

RESULTS

Subjects had a mean (standard deviation) gestational age of 37.8 (2.6) weeks, a majority were male (63%), with a diagnosis of hypoxic ischemic encephalopathy (68%). Findings at birth included mild distress (48%), moderately abnormal neurological exam (33%), and consciousness characterized as awake but irritable (40%). Significant associations after multiple testing corrections were detected for resting state networks: basal ganglia with outpatient developmental delay (odds ratio [OR], 14.5; 99.4% confidence interval [CI], 2.00-105; P < .001) and motor tone/weakness (OR, 9.98; 99.4% CI, 1.72-57.9; P < .001); language/frontoparietal network with discharge condition (OR, 5.13; 99.4% CI, 1.22-21.5; P = .002) and outpatient developmental delay (OR, 4.77; 99.4% CI, 1.21-18.7; P=.002); default mode network with discharge condition (OR, 3.72; 99.4% CI, 1.01-13.78; P=.006) and neurological exam (P = .002 (FE); OR, 11.8; 99.4% CI, 0.73-191; P = .01 (OLR)); and seizure onset zone with motor tone/weakness (OR, 3.31; 99.4% CI, 1.08-10.1; P=.003). Resting state networks were not detected in three neonates, who died prior to discharge.

CONCLUSIONS

This study provides level 3 evidence (OCEBM Levels of Evidence Working Group) demonstrating that in neonatal acute brain injury, the degree of abnormality of resting state networks is associated with acute exam and outcomes. Total lack of brain network detection was only found in patients who did not survive.

Neuromonitoring bei zerebralen Anfällen im Neugeborenenalter – Chancen und Herausforderungen

Angesichts der vielen Kinder mit neonatalen Risikofaktoren für erworbene ZNS-Läsionen und zerebrale Anfälle ist das EEG zunehmend relevant für eine optimierte Diagnostik und Therapieüberwachung 1 2. Folgender Artikel gibt einen Überblick über Besonderheiten des neonatalen EEG und über aktuelle Empfehlungen zum Stellenwert des Langzeit-EEG-Monitorings bei neonatalen Anfällen und epileptischen Enzephalopathien im Früh- und Neugeborenalter.

Management of seizures in neonates with neonatal encephalopathy treated with hypothermia

Neonatal encephalopathy (NE) is the most common etiology of acute neonatal seizures - about half of neonates treated with therapeutic hypothermia for NE have EEG-confirmed seizures. These seizures are best identified with continuous EEG monitoring, as clinical diagnosis leads to under-diagnosis of subclinical seizures and over-treatment of events that are not seizures. High seizure burden, especially status epilepticus, is thought to augment brain injury. Treatment, therefore, is aimed at minimizing seizure burden. Phenobarbital remains the mainstay of treatment, as it is more effective than levetiracetam and easier to administer than fosphenytoin. Emerging evidence suggests that, for many neonates, it is safe to discontinue the phenobarbital after acute seizures resolve and prior to hospital discharge.

Safety of Early Discontinuation of Antiseizure Medication After Acute Symptomatic Neonatal Seizures

Question

Is discontinuation of antiseizure medication (ASM) after resolution of acute symptomatic neonatal seizures and prior to discharge from the hospital associated with functional neurodevelopment or epilepsy at 24 months?

Findings

In this comparative effectiveness study of 303 children with neonatal seizures from 9 centers, 64% had ASM maintained at hospital discharge. No difference was found between ASM maintenance and discontinuation groups in functional neurodevelopment or epilepsy; 13% of children developed epilepsy, including more than one-third with infantile spasms.

Meaning

These results support discontinuing ASMs for most neonates with acute symptomatic seizures prior to discharge from the hospital, an approach that may represent an evidence-based change in practice for many clinicians.

Importance

Antiseizure medication (ASM) treatment duration for acute symptomatic neonatal seizures is variable. A randomized clinical trial of phenobarbital compared with placebo after resolution of acute symptomatic seizures closed early owing to low enrollment.

Objective

To assess whether ASM discontinuation after resolution of acute symptomatic neonatal seizures and before hospital discharge is associated with functional neurodevelopment or risk of epilepsy at age 24 months.

Design, Setting, and Participants

This comparative effectiveness study included 303 neonates with acute symptomatic seizures (282 with follow-up data and 270 with the primary outcome measure) from 9 US Neonatal Seizure Registry centers, born from July 2015 to March 2018. The centers all had level IV neonatal intensive care units and comprehensive pediatric epilepsy programs. Data were analyzed from June 2020 to February 2021.

Exposures

The primary exposure was duration of ASM treatment dichotomized as ASM discontinued vs ASM maintained at the time of discharge from the neonatal seizure admission. To enhance causal association, each outcome risk was adjusted for propensity to receive ASM at discharge. Propensity for ASM maintenance was defined by a logistic regression model including seizure cause, gestational age, therapeutic hypothermia, worst electroencephalogram background, days of electroencephalogram seizures, and discharge examination (all P ≤ .10 in a joint model except cause, which was included for face validity).

Main Outcomes and Measures

Functional neurodevelopment was assessed by the Warner Initial Developmental Evaluation of Adaptive and Functional Skills (WIDEA-FS) at 24 months powered for propensity-adjusted noninferiority of early ASM discontinuation. Postneonatal epilepsy, a prespecified secondary outcome, was defined per International League Against Epilepsy criteria, determined by parent interview, and corroborated by medical records.

Results

Most neonates (194 of 303 [64%]) had ASM maintained at the time of hospital discharge. Among 270 children evaluated at 24 months (mean [SD], 23.8 [0.7] months; 147 [54%] were male), the WIDEA-FS score was similar for the infants whose ASMs were discontinued (101 of 270 [37%]) compared with the infants with ASMs maintained (169 of 270 [63%]) at discharge (median score, 165 [interquartile range, 150-175] vs 161 [interquartile range, 129-174]; P = .09). The propensity-adjusted average difference was 4 points (90% CI, −3 to 11 points), which met the a priori noninferiority limit of −12 points. The epilepsy risk was similar (11% vs 14%; P = .49), with a propensity-adjusted odds ratio of 1.5 (95% CI, 0.7-3.4; P = .32).

Conclusions and Relevance

In this comparative effectiveness study, no difference was found in functional neurodevelopment or epilepsy at age 24 months among children whose ASM was discontinued vs maintained at hospital discharge after resolution of acute symptomatic neonatal seizures. These results support discontinuation of ASM prior to hospital discharge for most infants with acute symptomatic neonatal seizures.

Does the first hour of continuous electroencephalography predict neonatal seizures?

OBJECTIVE

Prolonged continuous video-electroencephalography (cEEG) is recommended for neonates at risk of seizures. The cost and expertise required to provide a real-time response to detected seizures often limits its utility. We hypothesised that the first hour of cEEG could predict subsequent seizures.

DESIGN AND SETTING

Retrospective multicentre diagnostic accuracy study.

PATIENTS

266 term neonates at risk of seizure or with suspected seizures.

INTERVENTION

The first hour of cEEG was graded by expert and novice interpreters as normal, mildly, moderately or severely abnormal; seizures were identified.

MAIN OUTCOME MEASURES

Association between abnormalities in the first hour of cEEG and the presence of seizures during total cEEG monitoring.

RESULTS

50/98 (51%) of neonates who developed seizures had their first seizure in the first hour of cEEG monitoring. The 'time-to-event' risk of seizure from 0 to 96 hours was 0.38 (95% CI 0.32 to 0.44) while the risk in the first hour was 0.19 (95% CI 0.15 to 0.24). cEEG background was normal in 48% of neonates, mildly abnormal in 30%, moderately abnormal in 13% and severely abnormal in 9%. Inter-rater agreement for determination of background was very good (weighted kappa=0.81, 95% CI 0.72 to 0.91). When neonates with seizures during the first hour were excluded, an abnormal background resulted in 2.4 times increased risk of seizures during the subsequent monitoring period (95% CI 1.3 to 4.4, p<0.003) while a severely abnormal background resulted in a sevenfold increased risk (95% CI 3.4 to 14.3, p<0.0001).

CONCLUSIONS

The first hour of cEEG in at-risk neonates is useful in identifying and predicting whether seizures occur during cEEG monitoring up to 96 hours. This finding enables identification of high-risk neonates who require closer observation.

Neuromonitoring in Neonatal-Onset Epileptic Encephalopathies

Considering the wide spectrum of etiologies of neonatal-onset epileptic encephalopathies (EE) and their unfavorable consequences for neurodevelopmental prognoses, neuromonitoring at-risk neonates is increasingly important. EEG is highly sensitive for early identification of electrographic seizures and abnormal background activity. Amplitude-integrated EEG (aEEG) is recommended as a useful bedside monitoring method but as a complementary tool because of methodical limitations. It is of special significance in monitoring neonates with acute symptomatic as well as structural, metabolic and genetic neonatal-onset EE, being at high risk of electrographic-only and prolonged seizures. EEG/aEEG monitoring is established as an adjunctive tool to confirm perinatal hypoxic-ischemic encephalopathy (HIE). In neonates with HIE undergoing therapeutic hypothermia, burst suppression pattern is associated with good outcomes in about 40% of the patients. The prognostic specificity of EEG/aEEG is lower compared to cMRI. As infants with HIE may develop seizures after cessation of hypothermia, recording for at least 24 h after the last seizure is recommended. Progress in the identification of genetic etiology of neonatal EE constantly increases. However, presently, no specific EEG changes indicative of a genetic variant have been characterized, except for individual variants associated with typical EEG patterns (e.g., KCNQ2, KCNT1). Long-term monitoring studies are necessary to define and classify electro-clinical patterns of neonatal-onset EE.

Quantitative approach to early neonatal EEG visual analysis in hypoxic-ischemic encephalopathy severity: Bridging the gap between eyes and machine

OBJECTIVES

To identify relevant quantitative parameters for early classification of neonatal hypoxic-ischemic encephalopathy (HIE) severity from conventional EEGs.

METHODS

Ninety EEGs, recorded in full-term infants within 6 h of life after perinatal hypoxia, were visually classified according to the French EEG classification into three groups of increasing HIE severity. Physiologically significant EEG features (signal amplitude, continuity and frequency content) were automatically quantified using different parameters. The EEG parameters selection was based on their ability to reproduce the visual EEG classification. Post hoc analysis based on clinical outcome was performed.

RESULTS

Six EEG parameters were selected, with overall EEG classification performances between 61% and 70%. All parameters differed significantly between group 3 (severe) and groups 1 (normal-mildly abnormal) and 2 (moderate) EEGs (p < 0.001). Amplitude and discontinuity parameters were different between the 3 groups (p < 0.01) and were also the best predictors of clinical outcome. Conversely, pH and lactate did not differ between groups.

DISCUSSION

This study provides quantitative EEG parameters that are complementary to visual analysis as early markers of neonatal HIE severity. These parameters could be combined in a multiparametric algorithm to improve their classification performance. The absence of relationship between pH lactate and HIE severity reinforces the central role of early neonatal EEG.

Effects of a potassium channel opener on brain injury and neurologic outcomes in an animal model of neonatal hypoxic-ischemic injury

BACKGROUND

Hypoxia-ischemia (HI) is the most common cause of brain injury in newborns and the survivors often develop cognitive and sensorimotor disabilities that undermine the quality of life. In the current study, we examined the effectiveness of flupirtine, a potassium channel opener, shown previously in an animal model to have strong anti-neonatal-seizure efficacy, to provide neuroprotection and alleviate later-life disabilities caused by neonatal hypoxic-ischemic injury.

METHODS

The rats were treated with a single dose of flupirtine for 4 days following HI induction in 7-day-old rats. The first dose of flupirtine was given after the induction of HI and during the reperfusion period. The effect of treatment was examined on acute and chronic brain injury, motor functions, and cognitive abilities.

RESULTS

Flupirtine treatment significantly reduced HI-induced hippocampal and cortical tissue loss at acute time point. Furthermore, at chronic time point, flupirtine reduced contralateral hippocampal volume loss and partially reversed learning and memory impairments but failed to improve motor deficits.

CONCLUSION

The flupirtine treatment regimen used in the current study significantly reduced brain injury at acute time point in an animal model of neonatal hypoxic-ischemic encephalopathy. However, these neuroprotective effects were not persistent and only modest improvement in functional outcomes were observed at chronic time points.

Early Electroencephalogram Background Could Guide Tailored Duration of Monitoring for Neonatal Encephalopathy Treated with Therapeutic Hypothermia

OBJECTIVE

To evaluate whether features of the early electroencephalographic (EEG) background could guide the optimal duration of continuous video EEG monitoring for seizure detection in newborn infants treated with therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

Retrospective cohort study of 114 consecutive infants treated with therapeutic hypothermia for moderate to severe HIE at a level IV neonatal intensive care unit (NICU) between 2012 and 2018. All infants were monitored with continuous video EEG through cooling and rewarming. Archived samples from the first 24 hours of these EEG traces were reviewed systematically and classified by background characteristics.

RESULTS

Electrographic seizures occurred in 56 of the 114 infants (49%). Seizure onset was within the first 24 hours after initiation of continuous video EEG in 49 if these 56 infants (88%), between 24 and 48 hours in 4 infants (7%), and >72 hours in 3 infants (5%). Infants with a normal or mildly abnormal EEG background either had seizure onset within the first 24 hours or never developed seizures. Four patients with seizure onset between 24 and 48 hours had markedly abnormal EEG backgrounds. The 3 patients with seizure onset beyond 72 hours had moderate or severely abnormal early continuous video EEG backgrounds.

CONCLUSIONS

The use of early continuous video EEG background categorization may be appropriate to guide the duration of continuous video EEG for infants with HIE treated with therapeutic hypothermia. Some infants may reasonably be monitored for 24 hours rather than throughout cooling and rewarming without a significant risk of missed seizures. This could have significant implications for continuous video EEG resource utilization.

EEG Monitoring of the Epileptic Newborn

PURPOSE OF REVIEW

Although differentiating neonatal-onset epilepsies from acute symptomatic neonatal seizures has been increasingly recognized as crucial, existing guidelines, and recommendations on EEG monitoring are mainly based on acute symptomatic seizures, especially secondary to hypoxic-ischemic encephalopathy. We aimed to narratively review current knowledge on neonatal-onset epilepsies of genetic, metabolic, and structural non-acquired origin, with special emphasis on EEG features and monitoring.

RECENT FINDINGS

A wide range of rare conditions are increasingly described, reducing undiagnosed cases. Although distinguishing features are identifiable in some, how to best monitor and detect less described etiologies is still an issue. A comprehensive approach considering onset, seizure evolution, ictal semiology, clinical, laboratory, EEG, and neuroimaging data is key to diagnosis. Phenotypic variability prevents precise recommendations, but a solid, consistent method moving from existing published guidelines helps in correctly assessing these newborns in order to provide better care, especially in view of expanding precision therapies.

Delay in Treatment of Neonatal Seizures: A Retrospective Cohort Study

INTRODUCTION

Neonatal seizures are common and caused by a variety of underlying disorders. There is increasing evidence that neonatal seizures result in further brain damage.

OBJECTIVE

To describe the time interval between diagnosis of amplitude-integrated electroencephalography (aEEG)-confirmed seizures and administration of anti-epileptic drugs (AEDs).

METHODS

Single-centre retrospective cohort study, with full-term infants (n = 106) admitted to a level III neonatal intensive care unit between 2012 and 2017 with seizures confirmed on 2-channel aEEG and corresponding raw electroencephalography traces, treated with AEDs. The time interval between the first seizure on the aEEG registration and AED administration was calculated. Factors associated with early treatment were analysed.

RESULTS

The median time interval of initiating treatment of aEEG-confirmed seizures was 01:50 h (interquartile range 00:43-4:30 h). Treatment of aEEG-confirmed seizures was initiated <1 h in 34/106 infants (32.1%), between 1 and 2 h in 21/106 infants (19.8%), 2-4 h in 23/106 infants (21.7%), 4-8 h in 14/106 infants (13.2%), and ≥8 h in 14/106 infants (13.2%). Seizures treated <1 h were significantly more often recognized by the seizure detection algorithm (SDA) compared to seizures treated >1 h (67 vs. 42%, p = 0.02) and showed more clinical signs (79.4 vs. 37.5%, p < 0.01). There was no difference for out-of-office hours (23.5 vs. 22.2%, p = 0.88).

CONCLUSION

With only 32.1% of the seizures being treated <1 h, there is room for improvement. Timely treatment occurred more often when seizures were clinical or recognised by the SDA. aEEG is a helpful tool for diagnosing seizures 24/7.

The probability of seizures during continuous EEG monitoring in high-risk neonates

OBJECTIVE

We evaluated the impact of monitoring indication, early electroencephalography (EEG), and clinical features on seizure risk in all neonates undergoing continuous EEG (cEEG) monitoring following a standardized monitoring protocol.

METHODS

All cEEGs from unique neonates 34-48 weeks postmenstrual age monitored from 1/2011-10/2017 (n = 291) were included. We evaluated the impact of cEEG monitoring indication (acute neonatal encephalopathy [ANE], suspicious clinical events [SCEs], or other high-risk conditions [OHRs]), age, medication status, and early EEG abnormalities (including the presence of epileptiform discharges and abnormal background continuity, amplitude, asymmetry, asynchrony, excessive sharp transients, and burst suppression) on time to first seizure and overall seizure risk using Kaplan-Meier survival curves and multivariable Cox proportional hazards models.

RESULTS

Seizures occurred in 28% of high-risk neonates. Discontinuation of monitoring after 24 hours of seizure-freedom would have missed 8.5% of neonates with seizures. Overall seizure risk was lower in neonates monitored for ANE compared to OHR (P = .004) and trended lower compared to SCE (P = .097). The time course of seizure presentation varied by group, where the probability of future seizure was less than 1% after 17 hours of seizure-free monitoring in the SCE group, but required 42 hours in the OHR group, and 73 hours in the ANE group. The presence of early epileptiform discharges increased seizure risk in each group (ANE: adjusted hazard ratio [aHR] 4.32, 95% confidence interval [CI] 1.23-15.13, P = .022; SCE: aHR 10.95, 95% CI 4.77-25.14, P < 1e-07; OHR: aHR 56.90, 95% CI 10.32-313.72, P < 1e-05).

SIGNIFICANCE

Neonates who undergo cEEG are at high risk for seizures, and risk varies by monitoring indication and early EEG findings. Seizures are captured in nearly all neonates undergoing monitoring for SCE within 24 hours of cEEG monitoring. Neonates monitored for OHR and ANE can present with delayed seizures and require longer durations of monitoring. Early epileptiform discharges are the best early EEG feature to predict seizure risk.

Neonatal Encephalopathy: Current Management and Future Trends

It is well-documented in the literature that infants who suffer from hypoxic ischemic encephalopathy are at high risk for neurologic sequelae or even death. With the addition of therapeutic hypothermia into the treatment regimen for neonatal hypoxic ischemic encephalopathy, newborns afflicted with hypoxic ischemic encephalopathy were given the opportunity for a better outcome. Questions linger as to the most optimal treatment strategy of therapeutic hypothermia for these newborns. The goal of this article is to discuss current management strategies, as well as future trends, for infants with hypoxic ischemic encephalopathy.

Practice variation in anti-epileptic drug use for neonatal hypoxic-ischemic encephalopathy among regional NICUs

Background

While intercenter variation (ICV) in anti-epileptic drug (AED) use in neonates with seizures has been previously reported, variation in AED practices across regional NICUs has not been specifically and systematically evaluated. This is important as these centers typically have multidisciplinary neonatal neurocritical care teams and protocolized approaches to treating conditions such as hypoxic ischemic encephalopathy (HIE), a population at high risk for neonatal seizures. To identify opportunities for quality improvement (QI), we evaluated ICV in AED utilization for neonates with HIE treated with therapeutic hypothermia (TH) across regional NICUs in the US.

Methods

Children’s Hospital Neonatal Database and Pediatric Health Information Systems data were linked for 1658 neonates ≥36 weeks’ gestation, > 1800 g birthweight, with HIE treated with TH, from 20 NICUs, between 2010 and 2016. ICV in AED use was evaluated using a mixed-effect regression model. Rates of AED exposure, duration, prescription at discharge and standardized AED costs per patient were calculated as different measures of utilization.

Results

Ninety-five percent (range: 83–100%) of patients with electrographic seizures, and 26% (0–81%) without electrographic seizures, received AEDs. Phenobarbital was most frequently used (97.6%), followed by levetiracetam (16.9%), phenytoin/fosphenytoin (15.6%) and others (2.4%; oxcarbazepine, topiramate and valproate). There was significant ICV in all measures of AED utilization. Median cost of AEDs per patient was $89.90 (IQR $24.52,$258.58).

Conclusions

Amongst Children’s Hospitals, there is marked ICV in AED utilization for neonatal HIE. Variation was particularly notable for HIE patients without electrographic seizures, indicating that this population may be an appropriate target for QI processes to harmonize neuromonitoring and AED practices across centers.

Levetiracetam optimal dose-finding as first-line treatment for neonatal seizures occurring in the context of hypoxic-ischaemic encephalopathy (LEVNEONAT-1): study protocol of a phase II trial

INTRODUCTION

Therapeutic schedules for treating neonatal seizures remain elusive. First-line treatment with phenobarbital is widely supported but without strong scientific evidence. Levetiracetam (LEV) is an emerging and promising antiepileptic drug (AED). The aim of this phase II trial is to determine the benefits of LEV by applying a strict methodology and to estimate the optimal dose of LEV as a first-line AED to treat seizures in newborns suffering from hypoxic-ischaemic encephalopathy.

METHODS AND ANALYSIS

LEVNEONAT-1 is an open and sequential LEV dose-finding study. The optimal dose is that which is estimated to be associated with a toxicity not exceeding 10% and an efficacy higher than 60%. Efficacy is defined by a seizure burden reduction of 80% after the loading dose. Four increasing dose regimens will be assessed including one loading dose of 30, 40, 50 or 60 mg/kg followed by eight maintenance doses (ie, a quarter of the loading dose) injected every 8 hours. A two-patient cohort will be necessary at each dose level to consider an upper dose level assignment. The maximal sample size expected is 50 participants with a minimum of 24 patients or fewer in the case of a high rate of toxicity. Patients will be recruited in five neonatal intensive care units beginning in October 2017 and continuing for 2 years. In parallel, the LEV pharmacokinetics will be measured five times (ie, 30 min; 4 and 7 hours after the loading dose; 1-3 hours and 12-18 hours after the last maintenance dose).

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the regional ethical committee (2016-R25) and the French Drug Safety Agency (160652A-31). The results will be published in a peer-reviewed journal. The results will also be presented at medical meetings.

TRIAL REGISTRATION NUMBER

NCT02229123; Pre-results.

Diagnosis of seizures and encephalopathy using conventional EEG and amplitude integrated EEG

Seizures are more common in the neonatal period than at any other time of life, partly due to the relative hyperexcitability of the neonatal brain. Brain monitoring of sick neonates in the NICU using either conventional electroencephalography or amplitude integrated EEG is essential to accurately detect seizures. Treatment of seizures is important, as evidence increasingly indicates that seizures damage the brain in addition to that caused by the underlying etiology. Prompt treatment has been shown to reduce seizure burden with the potential to ameliorate seizure-mediated damage. Neonatal encephalopathy most commonly caused by a hypoxia-ischemia results in an alteration of mental status and problems such as seizures, hypotonia, apnea, and feeding difficulties. Confirmation of encephalopathy with EEG monitoring can act as an important adjunct to other investigations and the clinical examination, particularly when considering treatment strategies such as therapeutic hypothermia. Brain monitoring also provides useful early prognostic indicators to clinicians. Recent use of machine learning in algorithms to continuously monitor the neonatal EEG, detect seizures, and grade encephalopathy offers the exciting prospect of real-time decision support in the NICU in the very near future.

Pharmaco-resistant Neonatal Seizures: Critical Mechanistic Insights from a Chemoconvulsant Model

Neonatal seizures are harmful to the developing brain and are associated with mortality and long-term neurological comorbidities. Hypoxic-ischemic encephalopathy (HIE) seizures represent a significant proportion of such seizures. Phenobarbital (PB) remains the first line anti-seizure drug (ASD) treatment but fails ~50% of the time. Translational models of neonatal seizures are crucial to investigating mechanisms underlying PB-resistance. A model of PB-resistant ischemic seizures in postnatal day 7 (P7) CD-1 mice reported K-Cl cotransporter 2 (KCC2) degradation that has been shown to be due to activation of the TrkB pathway. We investigated PB-efficacy in a pentylenetetrazole (PTZ) model of neonatal seizures in the same strain and age using identical treatment protocols to gain insights into mechanisms underlying PB-resistance. A single dose of PTZ (80 mg/kg; IP) consistently induced repetitive seizures that did not progress to status epilepticus (SE). PB (25 mg/kg; IP, single dose) significantly suppressed the PTZ-induced seizures. This was associated with significant KCC2 upregulation and stable Na-K-Cl cotransporter 1 (NKCC1) expression at 24h. The TrkB pathway was not activated. PTZ seizure burdens were significantly higher than those reported for ischemic seizures, indicating seizure severity did not dictate the differences in PB-efficacy. Bumetanide (BTN) (0.1-0.2 mg/kg; IP) did not work as an anti-seizure agent, similar to the ischemic model. When investigating mechanisms underlying the emergence of PB-resistance in translational models, the method by which seizures are induced may dictate mechanisms underlying emergence of PB-resistance.

Predictive value of early EEG for seizures in neonates with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia

OBJECTIVES

To assess the prognostic significance of an early normal/mildly abnormal conventional EEG (cEEG) on seizure risk in neonates undergoing therapeutic hypothermia.

METHODS

We reviewed the video-EEG recordings from a large cohort of neonates treated with therapeutic hypothermia for hypoxic-ischemic encephalopathy from 2008 to 2017 in a single tertiary center. Continuous video-EEG was started as soon as possible (median 8.2 h) and continued throughout hypothermia and rewarming. We studied those neonates with a normal/mildly abnormal EEG during the first 24 h of monitoring.

RESULTS

A total of 331 neonates were treated with hypothermia and 323 had cEEG recordings available for review; 99 were excluded because of a moderately/severely abnormal cEEG background and/or seizure during the first 24 h of recording, and an additional eight because of early rewarming. The remaining 216 had a normal/mildly abnormal cEEG in the first 24 h. None of these patients subsequently developed seizures.

CONCLUSION

A normal/mildly abnormal cEEG during the first 24 h indicates a very low risk of subsequent seizures. This suggests that cEEG monitoring can be safely discontinued after 24 h if it has remained normal or excessively discontinuous and no seizures are detected, limiting the need for this resource-intensive and expensive tool.

The fetus at the tipping point: modifying the outcome of fetal asphyxia

Brain injury around birth is associated with nearly half of all cases of cerebral palsy. Although brain injury is multifactorial, particularly after preterm birth, acute hypoxia-ischaemia is a major contributor to injury. It is now well established that the severity of injury after hypoxia-ischaemia is determined by a dynamic balance between injurious and protective processes. In addition, mothers who are at risk of premature delivery have high rates of diabetes and antepartum infection/inflammation and are almost universally given treatments such as antenatal glucocorticoids and magnesium sulphate to reduce the risk of death and complications after preterm birth. We review evidence that these common factors affect responses to fetal asphyxia, often in unexpected ways. For example, glucocorticoid exposure dramatically increases delayed cell loss after acute hypoxia-ischaemia, largely through secondary hyperglycaemia. This critical new information is important to understand the effects of clinical treatments of women whose fetuses are at risk of perinatal asphyxia.

Designing a trial for neonatal seizure treatment

Neonatal seizures are widely considered a neurological emergency with a need for prompt treatment, yet they are known to present a highly elusive target for bedside clinicians. Recent studies have suggested that the design of a neonatal seizure treatment trial will profoundly influence the sample size, which may readily increase to hundreds or even thousands as the achieved effect size diminishes to clinical irrelevance. The self-limiting and rapidly resolving nature of neonatal seizures diminishes the measurable treatment effect every hour after seizure onset and any effect may potentially be confused with spontaneous resolution, precluding the value of many observational studies. The large individual variability in seizure occurrence over time and between etiologies challenges group comparisons, while the absence of clinical signs mandates quantification of seizure occurrence with continuous multi-channel EEG monitoring. A biologically sound approach that views neonatal seizures as a functional cot-side biomarker rather than an object to treat can overcome these challenges.

The effects of adding prophylactic phenobarbital to therapeutic hypothermia in the term-equivalent hypoxic-ischemic rat

BackgroundHypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal morbidity and mortality. Therapeutic hypothermia (TH) is the only available intervention, but neuroprotection is incomplete and variable. Seizures are common in infants with HIE undergoing TH and may worsen outcome. Phenobarbital (PB) is sometimes added, although use of prophylactic PB is controversial in the neonate. We hypothesize that prophylactic PB will not reduce, and may enhance, the neuroprotective effects of TH on brain injury and motor outcomes in the postnatal day 10 (P10) hypoxic-ischemic (HI) rat.MethodsP10 rat pups were subjected to unilateral HI and 4 h recovery with: normothermia (N); hypothermia (TH); and hypothermia with phenobarbital (TH+PB). Brain damage was assessed longitudinally at 24 h and 2 weeks using brain magnetic resonance imaging and 12 weeks using histochemical analysis. Motor function was assessed with the beam walk and cylinder tests.ResultsTH and TH+PB induced neuroprotection, as measured by global brain damage score and improved motor function. Exploratory analyses suggest that TH+PB may confer enhanced protection, especially to the extent of damage.ConclusionProphylactic PB with TH is not deleterious and may provide additional long-term neuroprotection, including improvement of motor outcomes following HI in the term-equivalent, neonatal rat.

Electrographic Seizures during the Early Postnatal Period in Preterm Infants

OBJECTIVE

To investigate the frequency and characteristics of electrographic seizures in preterm infants in the early postnatal period.

STUDY DESIGN

Infants <32 weeks gestational age (GA) (n = 120) were enrolled for continuous multichannel electroencephalography (EEG) recording initiated as soon as possible after birth and continued for approximately up to 72 hours of age. Electrographic seizures were identified visually, annotated, and analyzed. Quantitative descriptors of the temporal evolution of seizures, including total seizure burden, seizure duration, and maximum seizure burden, were calculated.

RESULTS

Median GA was 28.9 weeks (IQR, 26.6-30.3 weeks) and median birth weight was 1125 g (IQR, 848-1440 g). Six infants (5%; 95% CI, 1.9-10.6%) had electrographic seizures. Median total seizure burden, seizure duration, and maximum seizure burden were 40.3 minutes (IQR, 5.0-117.5 minutes), 49.6 seconds (IQR, 43.4-76.6 seconds), and 10.8 minutes/hour (IQR, 1.6-20.2 minutes/hour), respectively. Seizure burden was highest in 2 infants with significant abnormalities on neuroimaging.

CONCLUSION

Electrographic seizures are infrequent within the first few days of birth in very preterm infants. Seizures in this population are difficult to detect accurately without continuous multichannel EEG monitoring.

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.

Periictal activity in cooled asphyxiated neonates with seizures

PURPOSE

Seizures are common in critically ill neonates. Both seizures and antiepileptic treatments may lead to short term complications and worsen the outcomes. Predicting the risks of seizure reoccurrence could enable individual treatment regimens and better outcomes. We aimed to identify EEG signatures of seizure reoccurrence by investigating periictal electrographic features and spectral power characteristics in hypothermic neonates with hypoxic-ischemic encephalopathy (HIE) with or without reoccurrence of seizures on rewarming.

METHODS

We recruited five consecutive HIE neonates, submitted to continuous EEG monitoring, with high seizure burden (>20% per hour) while undergoing therapeutic hypothermia. Two of them had reoccurrence of seizures on rewarming. We performed quantitative analysis of fifteen artifact-free consecutive seizures to appreciate spectral power changes between the interictal, preictal and ictal periods, separately for each patient. Visual analysis allowed description of electrographic features associated with ictal events.

RESULTS

Every patient demonstrated a significant increase in overall spectral power from the interictal to preictal and ictal periods (p<0.01). Alpha power increase was more pronounced in the two patients with reoccurrence of seizures on rewarming and significant when comparing both interictal-to-preictal and interictal-to-ictal periods. This alpha activity increase could be also appreciated using visual analysis and distinguished neonates with and without seizure reoccurrence.

CONCLUSION

This distinct alpha activity preceding ictal onset could represent a biomarker of propensity for seizure reoccurrence in neonates. Future studies should be performed to confirm whether quantitative periictal characteristics and electrographic features allow predicting the risks of seizure reoccurrence in HIE neonates and other critically ill patients.

Treatment Trials for Neonatal Seizures: The Effect of Design on Sample Size

Neonatal seizures are common in the neonatal intensive care unit. Clinicians treat these seizures with several anti-epileptic drugs (AEDs) to reduce seizures in a neonate. Current AEDs exhibit sub-optimal efficacy and several randomized control trials (RCT) of novel AEDs are planned. The aim of this study was to measure the influence of trial design on the required sample size of a RCT. We used seizure time courses from 41 term neonates with hypoxic ischaemic encephalopathy to build seizure treatment trial simulations. We used five outcome measures, three AED protocols, eight treatment delays from seizure onset (T_d) and four levels of trial AED efficacy to simulate different RCTs. We performed power calculations for each RCT design and analysed the resultant sample size. We also assessed the rate of false positives, or placebo effect, in typical uncontrolled studies. We found that the false positive rate ranged from 5 to 85% of patients depending on RCT design. For controlled trials, the choice of outcome measure had the largest effect on sample size with median differences of 30.7 fold (IQR: 13.7–40.0) across a range of AED protocols, T_d and trial AED efficacy (p<0.001). RCTs that compared the trial AED with positive controls required sample sizes with a median fold increase of 3.2 (IQR: 1.9–11.9; p<0.001). Delays in AED administration from seizure onset also increased the required sample size 2.1 fold (IQR: 1.7–2.9; p<0.001). Subgroup analysis showed that RCTs in neonates treated with hypothermia required a median fold increase in sample size of 2.6 (IQR: 2.4–3.0) compared to trials in normothermic neonates (p<0.001). These results show that RCT design has a profound influence on the required sample size. Trials that use a control group, appropriate outcome measure, and control for differences in T_d between groups in analysis will be valid and minimise sample size.

Implementation of a Neurocritical Care Program: Improved Seizure Detection and Decreased Antiseizure Medication at Discharge in Neonates With Hypoxic-Ischemic Encephalopathy

BACKGROUND

We report the impact of implementing continuous video electroencephalography monitoring for neonates with hypoxic-ischemic encephalopathy via a protocol in the context of neonatal neuro-critical care program.

METHODS

Neonates with hypoxic-ischemic encephalopathy were studied retrospectively two years before and after implementing continuous video electroencephalography for 72 hours as a care protocol. Before continuous video electroencephalography, a 60-minute routine electroencephalography was performed at the discretion of the provider.

PRIMARY OUTCOME

electrographic seizure detection; secondary outcome: use of maintenance antiseizure medications, discharge antiseizure medications, and cumulative burden for each antiseizure medication defined as total mg/kg during hospital stay.

RESULTS

A total of 157 patients with a median gestation of 40 weeks were analyzed; 103 (66%) underwent therapeutic hypothermia. Baseline and clinical characteristics including disease severity and cooling were similar. Before continuous video-electroencephalography (n = 86), 44 (51.2%) had clinical seizures, of those 35 had available routine electroencephalography; 12 of 35 (34%) had electrographic seizures. None of the infants without clinical seizures showed electrographic seizures. After continuous video-electroencephalography (n = 71), 34 (47.9%) had clinical seizures, of those 18 (53%) had electrographic seizures; five of 37 (14%) of infants with no clinical seizures had electrographic seizures. The introduction of continuous video-electroencephalography significantly increased electrographic seizure detection (P = 0.016). Although there was no significant difference in the initiation and maintenance use of antiseizure medications after continuous video-electroencephalography, fewer infants were discharged on any antiseizure medication (P = 0.008). Also, the mean phenobarbital burden reduced (P = 0.04), without increase in other antiseizure medications use or burden.

CONCLUSION

Use of continuous video-electroencephalography as part of the neonatal neuro-critical care program was associated with improved electrographic seizure detection, decreased phenobarbital burden, and antiseizure medication use at discharge.