Seizure Burden and Neurologic Outcomes After Neonatal Encephalopathy

Neuroprognostication in neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy

Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. Improved neuroprognostication also has the potential to foster more effective communication of findings to caregivers. In this review, we explore whether improved neuroprognostication is possible by assessing clinical, biochemical, electrographic, neurophysiological, and neuroimaging biomarkers and their role in neuroprognostication. IMPACT STATEMENT: Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. In this review article, we discuss general concepts and principles of neuroprognostication and the role of each prognostic marker.

Efficacy of phenobarbital is maintained after exposure to mild-to-moderate seizures in neonates

To study the relationship between the delay in treatment and the efficacy of phenobarbital in neonates, we re-analyzed data from the NEOLEV2 study. Continuous video EEG (cEEG) from patients treated with phenobarbital was reviewed by neurophysiologists who marked each seizure. The time from seizure onset to phenobarbital, total seizure burden pre-phenobarbital, and maximum seizure density (summed seizure burden per hour) pre-phenobarbital were calculated and correlated with phenobarbital efficacy at 20 mg/kg and at 40 mg/kg. The time between seizure onset and phenobarbital treatment did not predict refractoriness to phenobarbital. However, the maximum seizure density per hour and total seizure burden before phenobarbital treatment were strongly correlated with efficacy. ROC curve analysis showed cut-offs of maximum seizure density pre-phenobarbital of 10 ½ min/h and total seizure burden pre-phenobarbital of 36 ¼ min had excellent discriminatory ability in separating patients in whom phenobarbital would be effective from patients in whom it would not be effective (AUC 0.84, p = 0.0002 and AUC 0.85, p = 0.0051). These data suggest that whereas neonates with high seizure density must be treated as an emergency, mild-to-moderate seizures remain responsive to phenobarbital if treated within a time frame of several hours. PLAIN LANGUAGE SUMMARY: Phenobarbital is very effective at stopping seizures in newborns. But if phenobarbital is given after many hours of seizures, it becomes less effective. We do not know how quickly this happens. Our study found that it does not happen over the short term (<4 h). It is more difficult to stop seizures that cumulatively last more than 10 min/h.

Neonatal encephalopathy and hypoxic-ischemic encephalopathy: the state of the art

Neonatal Encephalopathy (NE) remains a major cause of death and long-term severe disabilities, including epilepsy and cerebral palsy in term and near-term infants. The single most common cause is hypoxic-ischemic encephalopathy (HIE). However, there are many other potential causes, including infection, intracranial hemorrhage, stroke, brain malformations, metabolic disorders, and genetic causes. The appropriate management depends on both the specific cause and the stage of evolution of injury. Key tools to expand our understanding of the timing and causes of NE include aEEG, or even better, video EEG monitoring, neuro-imaging including cranial ultrasound and MRI, placental investigations, metabolic, biomarker, and genetic studies. This information is critical to better understand the underlying causes of NE. Therapeutic hypothermia improves outcomes after HIE, but there is still considerable potential to do better. Careful clinical and pre-clinical studies are needed to develop novel therapeutics and to help provide the right treatment at the right time for this high-risk population. IMPACT: Neonatal encephalopathy is complex and multifactorial. This review seeks to expand understanding of the causes, timing, and evolution of encephalopathy in newborns. We highlight key unanswered questions about neonatal encephalopathy.

Incidence and Predictors of Later Epilepsy in Neonates with Encephalopathy: The Impact of Electrographic Seizures

OBJECTIVES

To determine the incidence of later epilepsy in full-term infants with neonatal encephalopathy (NE) who undergo continuous electroencephalography (cEEG) monitoring in the neonatal period and to identify potential predictors of later epilepsy both in infants with and without electrographic neonatal seizures (ENS).

METHODS

This was a retrospective observational study performed at Cork University Maternity Hospital, Cork, Ireland, between 2003 and 2019. All term infants with NE had a minimum of 2 h of cEEG monitoring in the neonatal period. ENS were identified via cEEG monitoring. Pediatric medical charts were reviewed to determine if epilepsy developed after the neonatal period and to determine potential predictors of epilepsy in infants both with and without ENS.

RESULTS

Two hundred and eighty infants were included. The overall incidence rate of epilepsy was 17.55 per 1000 person-years (95% CI: 10.91 to 28.23). In infants with ENS (n = 82), the incidence rate was 39.27 per 1000 person-years (95% CI: 22.30 to 69.16). In infants without ENS (n = 198), the incidence rate was 7.54 per 1000 person-years (95% CI: 3.14 to 18.12). The incidence rate was significantly higher in the ENS group compared to the non-ENS group (p-value = 0.002). Several potential predictors for the development of later epilepsy were identified including infants delivered vaginally, low Apgar scores at 1 and 5 min, severe HIE diagnosis, presence of ENS, a severely abnormal EEG background and an abnormal brain MRI.

SIGNIFICANCE

Following NE, term infants are at risk of epilepsy with a significantly higher incidence rate in infants who experience ENS compared to those who did not. Close follow-up is required in both groups well into the childhood period.

PLAIN LANGUAGE SUMMARY

This study aimed to determine the occurrence of epilepsy in children who were monitored for seizures in the newborn period. The occurrence of epilepsy was higher in infants who experienced seizures in the newborn period compared to those who did not. Several potential predictors of later epilepsy were identified in both groups of infants (those with and without seizures in the newborn period). Both groups of infants require close follow-up in childhood.

Effectiveness of sodium channel blockers in treating neonatal seizures due to arterial ischemic stroke

OBJECTIVE

Few studies have evaluated the efficacy of antiseizure medications (ASMs) according to the etiology of neonatal acute provoked seizures. We aimed to investigate the response to ASMs in term/near term neonates with acute arterial ischemic stroke (AIS), as well as the type of seizure at presentation and the monitoring approach.

METHODS

We retrospectively evaluated neonates from 15 European level IV neonatal intensive care units who presented with seizures due to AIS and were monitored by continuous electroencephalography (cEEG) and/or amplitude-integrated EEG (aEEG) in whom actual recordings, timing, doses, and response to ASMs were available for review.

RESULTS

One hundred seven neonates were referred, and 88 were included. Of those, 56 met the criteria for evaluating the treatment response. The mean time to treatment was 7.9 h (SD = 16.4), and the most frequently administered first-line ASM was phenobarbital (PB; 74/88, 84.1%). Seizures were controlled within 24 h from onset of symptoms in 64.3% (36/56) of neonates. Phenytoin (PHT) was effective in almost all neonates in whom it was trialed (24/25, 96.0%), whereas PB was effective in only 22.0% of patients (11/50). Infants treated with PB or PHT as first-line treatment (53/56, 94.6%) showed a higher response rate with PHT (6/6, 100.0%) than with PB (11/47, 23.4%). Monitoring approach and seizure types were evaluated in 88 infants. Forty-six of 88 (52.3%) were monitored with cEEG and 47.7% (42/88) with aEEG, with or without intermittent cEEG. The mean monitoring duration was 65.8 h (SD = 39.21). In 83 of 88 (94.3%) infants, the type of seizure suspected clinically prior to monitoring was confirmed afterward. Unilateral focal clonic seizures were seen in 71 of 88 infants (80.7%), whereas 11 of 88 (12.5%) presented with ictal apneas.

SIGNIFICANCE

Our findings provide evidence in a large, homogenous cohort that PHT is more effective than PB in treating neonatal acute symptomatic seizures due to AIS.

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.

Machine learning for forecasting initial seizure onset in neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

This study was undertaken to develop a machine learning (ML) model to forecast initial seizure onset in neonatal hypoxic-ischemic encephalopathy (HIE) utilizing clinical and quantitative electroencephalogram (QEEG) features.

METHODS

We developed a gradient boosting ML model (Neo-GB) that utilizes clinical features and QEEG to forecast time-dependent seizure risk. Clinical variables included cord blood gas values, Apgar scores, gestational age at birth, postmenstrual age (PMA), postnatal age, and birth weight. QEEG features included statistical moments, spectral power, and recurrence quantification analysis (RQA) features. We trained and evaluated Neo-GB on a University of California, San Francisco (UCSF) neonatal HIE dataset, augmenting training with publicly available neonatal electroencephalogram (EEG) datasets from Cork University and Helsinki University Hospitals. We assessed the performance of Neo-GB at providing dynamic and static forecasts with diagnostic performance metrics and incident/dynamic area under the receiver operating characteristic curve (iAUC) analyses. Model explanations were performed to assess contributions of QEEG features and channels to model predictions.

RESULTS

The UCSF dataset included 60 neonates with HIE (30 with seizures). In subject-level static forecasting at 30 min after EEG initiation, baseline Neo-GB without time-dependent features had an area under the receiver operating characteristic curve (AUROC) of .76 and Neo-GB with time-dependent features had an AUROC of .89. In time-dependent evaluation of the initial seizure onset within a 24-h seizure occurrence period, dynamic forecast with Neo-GB demonstrated median iAUC = .79 (interquartile range [IQR] .75-.82) and concordance index (C-index) = .82, whereas baseline static forecast at 30 min demonstrated median iAUC = .75 (IQR .72-.76) and C-index = .69. Model explanation analysis revealed that spectral power, PMA, RQA, and cord blood gas values made the strongest contributions in driving Neo-GB predictions. Within the most influential EEG channels, as the preictal period advanced toward eventual seizure, there was an upward trend in broadband spectral power.

SIGNIFICANCE

This study demonstrates an ML model that combines QEEG with clinical features to forecast time-dependent risk of initial seizure onset in neonatal HIE. Spectral power evolution is an early EEG marker of seizure risk in neonatal HIE.

Automated assessment of EEG background for neurodevelopmental prediction in neonatal encephalopathy

OBJECTIVE

Assess the capacity of brain state of the newborn (BSN) to predict neurodevelopment outcomes in neonatal encephalopathy.

METHODS

Trends of BSN, a deep learning-based measure translating EEG background to a continuous trend, were studied from a three-channel montage long-term EEG monitoring from a prospective cohort of 92 infants with neonatal encephalopathy and neurodevelopmental outcomes assessed by Bayley Scales of Infant Development, 3rd edition (Bayley-III) at 18 months. Outcome prediction used categories "Severe impairment" (Bayley-III composite score ≤70 or death) or "Any impairment" (score ≤85 or death).

RESULTS

"Severe impairment" was predicted best for motor outcomes (24 h area under the curve (AUC) = 0.97), followed by cognitive (36 h AUC = 0.90), overall (24 h AUC = 0.84), and language (24 h AUC = 0.82). "Any impairment" was best predicted for motor outcomes (12 h AUC = 0.95), followed by cognitive (24 h AUC = 0.85), overall (12 h AUC = 0.75), and language (12 and 24 h AUC = 0.68). Optimal BSN cutoffs for outcome predictions evolved with the postnatal age. Low BSN scores reached a 100% positive prediction of poor outcomes at 24 h of age.

INTERPRETATION

BSN is an excellent predictor of adverse neurodevelopmental outcomes in survivors of neonatal encephalopathy after therapeutic hypothermia, even at 24 h of life. The trend provides a fully automated, objective, quantified, and reliable interpretation of EEG background. The high temporal resolution supports continuous bedside brain assessment and early prognostication during the initial dynamic recovery phase.

Seizure Burden and Clinical Risk Factors in Glioma-Related Epilepsy: Insights From MRI Voxel-Based Lesion-Symptom Mapping

BACKGROUND

Epilepsy is the most common preoperative symptom in patients with supratentorial gliomas. Identifying tumor locations and clinical factors associated with preoperative epilepsy is important for understanding seizure risk.

PURPOSE

To investigate the key brain areas and risk factors associated with preoperative seizures in glioma patients.

STUDY TYPE

Retrospective.

POPULATION

A total of 735 patients with primary diffuse supratentorial gliomas (372 low grade; 363 high grade) with preoperative MRI and pathology data.

FIELD STRENGTH/SEQUENCE

Axial T2-weighted fast spin-echo sequence at 3.0 T.

ASSESSMENT

Seizure burden was defined as the number of preoperative seizures within 6 months. Tumor and high-signal edema areas on T2 images were considered involved regions. A voxel-based lesion-symptom mapping analysis was used to identify voxels associated with seizure burden. The involvement of peak voxels (those most associated with seizure burden) and clinical factors were assessed as risk factors for preoperative seizure.

STATISTICAL TESTS

Univariable and multivariable binary and ordinal logistic regression analyses and chi-square tests were performed, with results reported as odds ratios (ORs) and 95% confidence intervals. A P-value <0.05 was considered significant.

RESULTS

A total of 448 patients experienced preoperative seizures. Significant seizure burden-related voxels were located in the right hippocampus and left insular cortex (based on 1000 permutation tests), with significant differences observed in both low- and high-grade tumors. Tumor involvement in the peak voxel region was an independent risk factor for an increased burden of preoperative seizures (OR = 6.98). Additionally, multivariable binary logistic regression results indicated that 1p/19q codeletion (OR = 1.51), intermediate tumor volume (24.299-97.066 cm3), and involvement of the peak voxel (OR = 6.06) were independent risk factors for preoperative glioma-related epilepsy.

CONCLUSION

Voxel areas identified through voxel-based lesion-symptom mapping analysis, along with clinical factors, show associations with clinical seizure burden, offering insights for assessing seizure burden for glioma patients.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 1.

Temporal development of seizure threshold and spontaneous seizures after neonatal asphyxia and the effect of prophylactic treatment with midazolam in rats

Birth asphyxia (BA) and subsequent hypoxic-ischemic encephalopathy (HIE) is one of the most serious birth complications affecting full-term infants and can result in severe disabilities including mental retardation, cerebral palsy, and epilepsy. Animal models of BA and HIE are important to characterize the functional and behavioral correlates of injury, explore cellular and molecular mechanisms, and assess the potential of novel therapeutic strategies. Here we used a non-invasive, physiologically validated rat model of BA and acute neonatal seizures that mimics many features of BA and HIE in human infants to study (i) the temporal development of epilepsy with spontaneous recurrent seizures (SRS) in the weeks and months after the initial brain injury, (ii) alterations in seizure threshold and hippocampal EEG that may precede the onset of SRS, and (iii) the effect of prophylactic treatment with midazolam. For this purpose, a total of 89 rat pups underwent asphyxia or sham asphyxia at postnatal day 11 and were examined over 8-10.5 months. In vehicle-treated animals, the incidence of electroclinical SRS progressively increased from 0 % at 2.5 months to 50 % at 6.5 months, 75 % at 8.5 months, and > 80 % at 10.5 months after asphyxia. Unexpectedly, post-asphyxial rats did not differ from sham-exposed rats in seizure threshold or interictal epileptiform discharges in the EEG. Treatment with midazolam (1 mg/kg i.p.) after asphyxia, which suppressed acute symptomatic neonatal seizures in about 60 % of the rat pups, significantly reduced the incidence of SRS regardless of its effect on neonatal seizures. This antiepileptogenic effect of midazolam adds to the recently reported prophylactic effects of this drug on BA-induced neuroinflammation, brain damage, behavioral alterations, and cognitive impairment in the rat asphyxia model of HIE.

Electrographic monitoring for seizure detection in the neonatal unit: current status and future direction

Neonatal neurocritical intensive care is dedicated to safeguarding the newborn brain by prioritising clinical practices that promote early identification, diagnosis and treatment of brain injuries. The most common newborn neurological emergency is neonatal seizures, which may also be the initial clinical indication of neurological disease. A high seizure burden in the newborn period independently contributes to increased mortality and morbidity. The majority of seizures in newborns are subclinical (without clinical presentation), and hence identification may be difficult. Neuromonitoring techniques most frequently used to monitor brain wave activity include conventional electroencephalography (cEEG) or amplitude-integrated EEG (aEEG). cEEG with video is the gold standard for diagnosing and treating seizures. Many neonatal units do not have access to cEEG, and frequently those that do, have little access to real-time interpretation of monitoring. IMPACT: EEG monitoring is of no benefit to an infant without expert interpretation. Whilst EEG is a reliable cot-side tool and of diagnostic and prognostic use, both conventional EEG and amplitude-integrated EEG have strengths and limitations, including sensitivity to seizure activity and ease of interpretation. Automated seizure detection requires a sensitive and specific algorithm that can interpret EEG in real-time and identify seizures, including their intensity and duration.

Advances in Electroencephalographic Biomarkers of Neonatal Hypoxic Ischemic Encephalopathy

Electroencephalography (EEG) is a key objective biomarker of newborn brain function, delivering critical, cotside insights to aid the management of encephalopathy. Access to continuous EEG is limited, forcing reliance on subjective clinical assessments. In hypoxia ischaemia, the primary cause of encephalopathy, alterations in EEG patterns correlate with. injury severity and evolution. As HIE evolves, causing secondary neuronal death, EEG can track injury progression, informing neuroprotective strategies, seizure management and prognosis. Despite its value, challenges with interpretation and lack of on site expertise has limited its broader adoption. Technological advances, particularly in digital EEG and machine learning, are enhancing real-time analysis. This will allow EEG to expand its role in HIE diagnosis, management and outcome prediction.

Association Between Seizures and Neurodevelopmental Outcome at Two and Five Years in Asphyxiated Newborns With Therapeutic Hypothermia

OBJECTIVE

To investigate the association between the presence and severity of seizures in asphyxiated newborns and their neurodevelopmental outcome at ages two and five years.

METHODS

Retrospective data analysis from a prospectively collected multicenter cohort of 186 term-born asphyxiated newborns undergoing therapeutic hypothermia (TH) in 11 centers in the Netherlands and Belgium. Seizures were diagnosed by amplitude-integrated electroencephalography (EEG) and raw EEG signal reading up to 48 hours after rewarming. Neurodevelopmental outcome was assessed by standardized testing at age two and five years. Primary outcome was death or long-term neurodevelopmental impairment (NDI) including cerebral palsy. Associations were calculated using univariate and multivariate logistic regression analyses adjusting for Thompson score and a validated brain magnetic resonance imaging (MRI) score.

RESULTS

Seventy infants (38%) had seizures during TH or rewarming, and 44 (63%) of these needed two or more antiseizure medications (ASMs). Overall mortality was 21%. Follow-up data from 147 survivors were available for 137 infants (93%) at two and for 94 of 116 infants (81%) at five years. NDI was present in 26% at two and five years. Univariate analyses showed a significant association between seizures and death or NDI, but this was no longer significant after adjusting for Thompson and MRI score in the multivariate analysis; this was also true for severe seizures (need for two or more ASMs) or seizures starting during rewarming.

CONCLUSION

The presence or severity of seizures in newborns undergoing TH for hypoxic-ischemic encephalopathy was not independently associated with death or NDI up to age five years after adjusting for several confounders.

Epilepsy Incidence and Developmental Outcomes After Early Discontinuation of Antiseizure Medication in Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Neonatal seizures caused by hypoxic-ischemic encephalopathy (HIE) have significant morbidity and mortality. There is variability in clinical practice regarding treatment duration with antiseizure medication (ASM) after resolution of provoked neonatal seizures. We examined epilepsy incidence and developmental outcomes in post-HIE neonates discharged or not on ASM.

METHODS

We conducted a retrospective chart review of all HIE-admitted neonates to the University of Iowa Hospitals & Clinics neonatal intensive care unit between January 2008 and February 2021 who presented with encephalopathy, underwent therapeutic hypothermia, and developed seizures. Neonates were divided into two groups depending on whether ASM was continued or discontinued on discharge. We evaluated the incidence of epilepsy and developmental outcomes on follow-up in these two cohorts up to 12 months.

RESULTS

Sixty-nine neonates met the study criteria. ASM was continued on discharge in 41 neonates (59%) and discontinued before discharge in 28 (41%). At the 12-month follow-up, nine neonates (13%) had a diagnosis of epilepsy, out of which seven neonates had ASM continued on discharge (odds ratio [OR]: 2.84; 95% confidence interval [CI]: 0.48, 29.9)]. There was no statistical difference between the development of postneonatal epilepsy between the two groups (P value 0.29). There was no significant difference in developmental outcome between the two groups after adjusting for covariates like magnetic resonance imaging (MRI) brain abnormality and number of seizure days (OR: 0.68; 95% CI: 0.21, 2.22; P = 0.52).

CONCLUSION

We found no significant risk of seizure recurrence by age 12 months in infants who had discontinued ASM before discharge compared with those who had continued ASM. There was no difference in developmental outcomes at the 12-month follow-up between groups after adjusting for brain MRI abnormality and the number of seizure days during admission. Our results support early discontinuation of ASM after resolution of acute provoked seizures in neonates with HIE.

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.

Continuous versus Routine Electroencephalography in the Intensive Care Unit: A Review of Current Evidence

BACKGROUND

Electroencephalography (EEG) has long been used to detect seizures in patients with disorders of consciousness. In recent years, there has been a drastically increased adoption of continuous EEG (cEEG) in the intensive care units (ICUs). Given the resources necessary to record and interpret cEEG, this is still not available in every center and widespread recommendations to use continuous instead of routine EEG (typically lasting 20 min) are still a matter of some debate. Considering recent literature and personal experience, this review offers a rationale and practical advice to address this question.

SUMMARY

Despite the development of increasingly performant imaging techniques and several validated biomarkers, EEG remains central to clinicians in the intensive care unit and has been experiencing expanding popularity for at least 2 decades. Not only does EEG allow seizure or status epilepticus detection, which in the ICU often present without clinical movements, but it is also paramount for the prognostic evaluation of comatose patients, especially after cardiac arrest, and for detecting delayed ischemia after subarachnoid hemorrhage. At the end of the last Century, improvements of technical and digital aspects regarding recording and storage of EEG tracings have progressively led to the era of cEEG and automated quantitative analysis.

KEY MESSAGES

As compared to repeated rEEG, cEEG in comatose patients does not seem to improve clinical prognosis to a relevant extent, despite allowing a more performant of detection ictal events and consequent therapeutic modifications. The choice between cEEG and rEEG must therefore always be patient-tailored.

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.