Prognostic value of electroencephalograms in asphyxiated newborns treated with hypothermia

Relationship between EEG spectral power and dysglycemia with neurodevelopmental outcomes after neonatal encephalopathy

OBJECTIVE

We investigated how electroencephalography (EEG) quantitative measures and dysglycemia relate to neurodevelopmental outcomes following neonatal encephalopathy (NE).

METHODS

This retrospective study included 90 neonates with encephalopathy who received therapeutic hypothermia. EEG absolute spectral power was calculated during post-rewarming and 2-month follow-up. Measures of dysglycemia (hypoglycemia, hyperglycemia, and glycemic lability) and glucose variability were computed for the first 48 h of life. We evaluated the ability of EEG and glucose measures to predict neurodevelopmental outcomes at ≥ 18 months, using logistic regressions (with area under the receiver operating characteristic [AUROC] curves).

RESULTS

The post-rewarming global delta power (average all electrodes), hyperglycemia and glycemic lability predicted moderate/severe neurodevelopmental outcome separately (AUROC = 0.8, 95%CI [0.7,0.9], p < .001) and even more so when combined (AUROC = 0.9, 95%CI [0.8,0.9], p < .001). After adjusting for NE severity and magnetic resonance imaging (MRI) brain injury, only global delta power remained significantly associated with moderate/severe neurodevelopmental outcome (odds ratio [OR] = 0.9, 95%CI [0.8,1.0], p = .04), gross motor delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), global developmental delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), and auditory deficits (OR = 0.9, 95%CI [0.8,1.0], p = .03).

CONCLUSIONS

In NE, global delta power post-rewarming was predictive of outcomes at ≥ 18 months.

SIGNIFICANCE

EEG markers post-rewarming can aid prediction of neurodevelopmental outcomes following NE.

Review of Noninvasive Neuromonitoring Modalities in Children II: EEG, qEEG

Critically ill children with acute neurologic dysfunction are at risk for a variety of complications that can be detected by noninvasive bedside neuromonitoring. Continuous electroencephalography (cEEG) is the most widely available and utilized form of neuromonitoring in the pediatric intensive care unit. In this article, we review the role of cEEG and the emerging role of quantitative EEG (qEEG) in this patient population. cEEG has long been established as the gold standard for detecting seizures in critically ill children and assessing treatment response, and its role in background assessment and neuroprognostication after brain injury is also discussed. We explore the emerging utility of both cEEG and qEEG as biomarkers of degree of cerebral dysfunction after specific injuries and their ability to detect both neurologic deterioration and improvement.

Prognostic Value of Various Diagnostic Methods for Long-Term Outcome of Newborns After Hypoxic-Ischemic Encephalopathy Treated With Hypothermia

INTRODUCTION

Prediction of outcome in newborns with hypoxic-ischemic encephalopathy (HIE) has been modulated by hypothermia treatment (HT). We assessed the predictive value of diagnostic methods commonly used in neonates with HIE for short-term neurodevelopmental outcome and long-term neurological outcome.

MATERIALS AND METHODS

This longitudinal cohort study followed up 50 term newborns who underwent HT after HIE between July 2006 and August 2015, until preschool age. We estimated sensitivity and specificity for short-term neurodevelopmental outcome at 18 months and long-term neurological outcome at five years based on Amiel-Tison Neurological Assessment (ATNA), electroencephalography (EEG), and magnetic resonance imaging (MRI) performed in the neonatal period.

RESULTS

The accuracy of all neonatal methods tested was higher for long-term neurological outcome compared to the predictive accuracy for short-term neurodevelopmental outcome at 18-24 months. Sensitivity and specificity in predicting unfavorable long-term neurological outcome were: MRI (sensitivity 1.0 [95%CI 0.96-1.0]; specificity 0.91 [95%CI 0.86-1.0]), EEG (sensitivity 0.94 [95%CI 0.71-1.0]; specificity 1.0 [95% CI 0.89-1.0]), and ATNA (sensitivity 0.94 [95%CI 0.71-1.0]; specificity 0.91 [95%CI 0.76-0.98]).

CONCLUSION

MRI is a powerful predictor of long-term neurological outcome when performed in the first week after HIE in HT treated infants, as are EEG and ATNA performed in the second or third week postnatally.

Clinical, Neuroimaging, and Electrographic Predictors of Phenobarbital Failure in Newborns With Hypoxic Ischemic Encephalopathy and Seizures

BACKGROUND

Many neonates with hypoxic ischemic encephalopathy and seizures do not respond to the first line antiepileptic drug, phenobarbital. Little is known about what factors are associated with its failure.

OBJECTIVE

To examine factors associated with failure of phenobarbital therapy in neonates with hypoxic ischemic encephalopathy and seizures.

DESIGN/METHODS

A single-center retrospective review of 50 term (>35 weeks) neonates with hypoxic ischemic encephalopathy and seizures treated with phenobarbital as the first-line antiepileptic. Neonates were classified into either responders (n = 30) or nonresponders (n = 20). Nonresponse was defined as continued seizures after maximum dosing of phenobarbital or an additional antiepileptic. Subjects with acceptable magnetic resonance imaging (MRI) scans obtained within 2 weeks of birth were included in the study and rated using an MRI injury scoring system. Charts were reviewed for demographic, clinical, and laboratory variables. Resuscitation and seizure scores were also calculated. Electroencephalographic (EEG) background activity was reviewed in 2 different time epochs (12-24 hours and 24-36 hours of life) and graded as per ACNS guidelines.

RESULTS

There were no significant group differences in demographic, clinical, and laboratory variables except nonresponders, who had higher mean seizure score (P = .01) and significantly more injury on MRI scan for white matter (P = .004), parenchymal cortex (P = .027), and watershed (P = .009) regions. Neonates with moderately abnormal or severely abnormal background EEG responded poorly to phenobarbital.

CONCLUSION

In the presence of above factors, one can anticipate that additional antiepileptic medication may be needed. These data also support that larger studies should be done to look prospectively at using alternative agents first line in patients with severe injury.

Association of cerebral activity with MRI scans in infants with neonatal encephalopathy undergoing therapeutic hypothermia

We aimed to correlate amplitude-integrated EEG (aEEG) in neonatal hypoxic ischemic encephalopathy (HIE) with early magnetic resonance imaging (MRI). In this retrospective study, 32 neonates over 35 weeks' gestation with moderate/severe HIE who were treated with hypothermia were included. Early MRI scans and daily aEEG background were categorized to mild/normal, moderate, and severely abnormal. Time to sleep cycling was noted on aEEG. Mantel-Haenszel test for trends was used to explore associations between aEEG and MRI and outcome. LOESS regression was used for exploring the association of cycling with MRI scores. MRI was normal/mildly abnormal in 20 (63%) infants; in 9 (28%), moderately abnormal; and in 3 (9%), severely abnormal. Twenty-seven (84%) infants s urvived. MRI severity score was significantly associated with aEEG background score on the third and fourth days of life (p < 0.01). An increase in the MRI severity score was noted if sleep cycling appeared after the fifth day of life.Conclusions: Depressed aEEG at the third and fourth days of life and appearance of cycling beyond the fifth day of life are associated with cerebral MRI abnormalities and may be associated with increased risk of abnormal outcome. What is known: • Since therapeutic hypothermia has been shown to change long-term outcome, amplitude-integrated EEG in infants with hypoxic ischemic neonatal encephalopathy soon after birth have a limited predictive power for long-term outcome in treated infants. • Brain MRI after therapeutic hypothermia in the above infants has a significant predictive value for long-term outcome What is new: • Background amplitude-integrated EEG activity depression at the age of 3 and 4 days and delay of appearance of cycling activity are associated with worse MRI scores and may be predictive of worse long-term outcome.

Interrater and Intrarater Agreement in Neonatal Electroencephalogram Background Scoring

PURPOSE

Many neonates undergo electroencephalogram (EEG) monitoring to identify and manage acute symptomatic seizures. Information about brain function contained in the EEG background data may also help predict neurobehavioral outcomes. For EEG background features to be useful as prognostic indicators, the interpretation of these features must be standardized across electroencephalographers. We aimed at determining the interrater and intrarater agreement among electroencephalographers interpreting neonatal EEG background patterns.

METHODS

Five neonatal electroencephalographers reviewed 5-to-7.5-minute epochs of EEG from full-term neonates who underwent continuous conventional EEG monitoring. The EEG assessment tool used to classify background patterns was based on the American Clinical Neurophysiology Society's guideline for neonatal EEG terminology. Interrater and intrarater agreement were measured using Kappa coefficients.

RESULTS

Interrater agreement was consistently highest for voltage (binary: substantial, kappa = 0.783; categorical: moderate, kappa = 0.562), seizure presence (fair-substantial; kappa = 0.375-0.697), continuity (moderate; kappa = 0.481), burst voltage (moderate; kappa = 0.574), suppressed background presence (moderate-substantial; kappa = 0.493-0.643), delta activity presence (fair-moderate; kappa = 0.369-0.432), theta activity presence (fair-moderate; kappa = 0.347-0.600), presence of graphoelements (fair; kappa = 0.381), and overall impression (binary: moderate, kappa = 0.495; categorical: fair-moderate, kappa = 0.347, 0.465). Agreement was poor or inconsistent for all other patterns. Intrarater agreement was variable, with highest average agreement for voltage (binary: substantial, kappa = 0.75; categorical: substantial, kappa = 0.714) and highest consistent agreement for continuity (moderate-substantial; kappa = 0.43-0.67) and overall impression (moderate-substantial; kappa = 0.42-0.68).

CONCLUSIONS

This study demonstrates substantial variability in neonatal EEG background interpretation across electroencephalographers, indicating a need for educational and technological strategies aimed at improving performance.

Prognostic Value of Electroencephalography in Hypothermia-Treated Neonates With Hypoxic-Ischemic Encephalopathy: A Meta-Analysis

BACKGROUND

Electroencephalography (EEG) background activity is associated with neurological outcome in neonates with hypoxic-ischemic encephalopathy. There is uncertainty about the prognostic value of EEG background activity after hypothermia was introduced.

METHODS

Searches were made on Pubmed, Embase, and the Cochrane Library, from inception to March 1, 2018. Pooled sensitivities and specificities were calculated to assess the diagnostic power of burst suppression, low voltage, and flat trace background activities in the prediction of an adverse neurological outcome in the follow-up period in hypothermia-treated neonates with hypoxic-ischemic encephalopathy. I² was used to assess heterogeneity, and meta-regression was done to explore the source of heterogeneity.

RESULTS

Eighteen studies with 940 neonates were included. Pooled sensitivities and specificities in predicting the combination of death and neurodevelopmental impairment were burst suppression (sensitivity 0.87 [95% confidence interval (CI) 0.79 to 0.93], specificity 0.60 [95% CI 0.44 to 0.74]), low voltage (sensitivity 0.84 [0.75 to 0.90], specificity 0.80 [0.58 to 0.92]), and flat trace (sensitivity 0.85 [0.75 to 0.92], specificity 0.94 [0.77 to 0.99]). Subgroup analysis revealed the sensitivities of background patterns obtained after 24 hours of life were higher than those within age 24 hours, whereas the specificities were just the reverse. Flat trace performed best on sensitivity 0.93 (0.60 to 0.99) and specificity 0.90 (0.64 to 0.98) in predicting death. Burst suppression demonstrated the highest sensitivity 0.87 (0.58 to 0.97) and flat trace performed best on specificity 0.85 (0.60 to 0.96) in predicting neurodevelopmental impairment.

CONCLUSIONS

EEG background activity is predictive of long-term neurological outcome in hypothermia-treated neonates with hypoxic-ischemic encephalopathy. Burst suppression, low voltage, and flat trace are potential predictors of death or neurodevelopmental impairment.

Automated EEG background analysis to identify neonates with hypoxic-ischemic encephalopathy treated with hypothermia at risk for adverse outcome: A pilot study

BACKGROUND

To improve the objective assessment of continuous video-EEG (cEEG) monitoring of neonatal brain function, the aim was to relate automated derived amplitude and duration parameters of the suppressed periods in the EEG background (dynamic Interburst Interval= dIBIs) after neonatal hypoxic-ischemic encephalopathy (HIE) to favourable or adverse neurodevelopmental outcome.

METHODS

Nineteen neonates (gestational age 36-41 weeks) with HIE underwent therapeutic hypothermia and had cEEG-monitoring. EEGs were retrospectively analyzed with a previously developed algorithm to detect the dynamic Interburst Intervals. Median duration and amplitude of the dIBIs were calculated at 1 h-intervals. Sensitivity and specificity of automated EEG background grading for favorable and adverse outcomes were assessed at 6 h-intervals.

RESULTS

Dynamic IBI values reached the best prognostic value between 18 and 24 h (AUC of 0.93). EEGs with dIBI amplitude ≥15 μV and duration <10 s had a specificity of 100% at 6-12 h for favorable outcome but decreased subsequently to 67% at 25-42 h. Suppressed EEGs with dIBI amplitude <15 μV and duration >10 s were specific for adverse outcome (89-100%) at 18-24 h (n = 10). Extremely low voltage and invariant EEG patterns were indicative of adverse outcome at all time points.

CONCLUSIONS

Automated analysis of the suppressed periods in EEG of neonates with HIE undergoing TH provides objective and early prognostic information. This objective tool can be used in a multimodal strategy for outcome assessment. Implementation of this method can facilitate clinical practice, improve risk stratification and aid therapeutic decision-making. A multicenter trial with a quantifiable outcome measure is warranted to confirm the predictive value of this method in a more heterogeneous dataset.

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.

Strong Relation Between an EEG Functional Connectivity Measure and Postmenstrual Age: A New Potential Tool for Measuring Neonatal Brain Maturation

Fetal and neonatal brain connectivity development is highly complex. Studies have shown that functional networks change dramatically during development. The purpose of the current study was to determine how the mean phase lag index (mPLI), a measure of functional connectivity (FC), assessed with electroencephalography (EEG), changes with postmenstrual age (PMA) during the early stages of brain development after birth. Neonates (N = 131) with PMA 27.6-45.3 weeks who underwent an EEG for a medical reason were retrospectively studied. For each recording, global FC was assessed by obtaining a whole-head average of all local PLI values (pairwise between sensor space EEG signals). Global FC results were consequently correlated with PMA values in seven frequency bands. Local results were obtained for the frequency band with the strongest global association. There was a strong negative correlation between mPLI and PMA in most frequency bands. The strongest association was found in the delta frequency band (R = -0.616, p < 0.001) which was therefore topographically explored; the strongest correlations were between pairs of electrodes with at least one electrode covering the central sulcus. Even in this heterogeneous group of neonates, global FC strongly reflects PMA. The decrease in PLI may reflect the process of segregation of specific brain regions with increasing PMA. This was mainly found in the central brain regions, in parallel with myelination of these areas during early development. In the future, there may be a role for PLI in detecting atypical FC maturation. Moreover, PLI could be used to develop biomarkers for brain maturation and expose segregation processes in the neonatal brain.

Visual and Quantitative Electroencephalographic Analysis in Healthy Term Neonates Within the First Six Hours and the Third Day of Life

BACKGROUND

What constitutes a "normal" background electroencephalography (EEG) rhythm immediately after birth is not well understood. We performed video-electroencephalography recordings in the first six hours (first measure) and the third day of life (second measure) for evidence of transient changes in brain function.

METHODS

We performed a cohort study of an incidental sample of healthy term neonates in a single-center nursery. Main outcome measures were as follows: (1) EEG visual analysis, which included sleep-wake cycles, proportions of discontinuity and bursts with delta brushes, and number per hour of alpha/theta rolandic activity, encoches frontales, and transients; and (2) the electroencephalographic spectral analysis, which included power spectrum in the following frequency bands: delta, 0.5 to 4 Hz; theta, 4 to 8 Hz; alpha, 8 to 13 Hz; and beta, 13 to 30 Hz. Theta/delta and alpha/delta ratios were also calculated.

RESULTS

Twenty-two babies were enrolled. Significant findings (P < 0.05) in the first six hours with respect to 48 to 72 hours of life were (1) increased discontinuity, indeterminate sleep, and bursts with delta brushes; (2) higher number of transients, and lower number of alpha/theta rolandic activity and encoches frontales. Minimal changes were found in power spectrum data. However, using receiver operating characteristic curve analysis, theta/delta ratio ≤0.484 was the best cutoff to discriminate between the two measures (positive predictive value, 100.0; 95% confidence interval 71.0 to 100).

CONCLUSIONS

In healthy term neonates, immature electroencephalographic patterns, lack of clearly defined sleep-wake cycles, and frequent transients can be considered normal electroencephalographic findings in the first six hours of life. Normative power spectrum data are provided. These findings suggest that neonatal adaptation immediately after birth leads to transient changes in brain function.

Optimal Duration of Continuous Video-Electroencephalography in Term Infants With Hypoxic-Ischemic Encephalopathy and Therapeutic Hypothermia

Continuous video-electroencephalography (EEG) is an important diagnostic and prognostic tool in newborns with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia. The optimal duration of continuous video-EEG during whole-body hypothermia is not known. We conducted a retrospective study of 35 neonates with hypoxic-ischemic encephalopathy undergoing whole-body hypothermia with continuous video-EEG. EEG ictal changes were detected in 9/35 infants (26%). Of these 9 infants, the seizures were initially observed within 30 minutes of EEG monitoring in 6 (67%), within 24 hours in 2 (22%), and during rewarming in 1 infant (11%). No new seizures were detected between 24-72 hours of therapeutic hypothermia. Background suppression was detected in 14 infants (40%) by 24 hours. In neonates with hypoxic-ischemic encephalopathy undergoing therapeutic hypothermia, continuous video-EEG has the highest diagnostic yield within the first 24 hours and during the rewarming phase. In the absence of prior seizures or antiepileptic therapy, limiting continuous video-EEG to these periods in resource-limited settings may reduce cost during therapeutic hypothermia.

Characterization of Death in Neonatal Encephalopathy in the Hypothermia Era

This study aimed to characterize the circumstances of death in encephalopathic neonates treated with therapeutic hypothermia. Patients who died after or during treatment with therapeutic hypothermia between 2007-2014 were identified. Patient circumstance of death was characterized using an established paradigm. Thirty-one of 229 patients died (14%) at a median of 3 days of life. Most who died were severely encephalopathic on examination (90%) and had severely abnormal electroencephalographic (EEG) findings (87%). All those who had magnetic resonance images (n = 13) had evidence of moderate-severe brain injury; 6 had near-total brain injury. Cooling was discontinued prematurely in 61% of patients. Most patients (90%) were physiologically stable at the time of death; 81% died following elective extubation for quality of life considerations. Three patients (10%) died following withholding or removal of artificial hydration and nutrition. Characterization of death in additional cohorts is needed to identify differences in decision making practices over time and between centers.

Levetiracetam for the Treatment of Seizures in Neonatal Hypoxic Ischemic Encephalopathy

The objective of this study was to determine the efficacy and safety of levetiracetam in treatment of neonatal seizures due to hypoxic ischemic encephalopathy. Seizures often persist in neonates with hypoxic ischemic encephalopathy despite phenobarbital. A retrospective single-center study was conducted in neonates ≥36 weeks gestation with hypoxic ischemic encephalopathy. A total of 127 neonates were identified born 2008-2015. Clinical seizures occurred in 83 infants. Fifty-one neonates (61%) had cessation of seizures with only phenobarbital. Thirty-two neonates received levetiracetam after phenobarbital, and the seizures stopped in 27 of these neonates. The mean total loading dose of levetiracetam was 63 mg/kg. Mean maintenance dose of levetiracetam was 65 mg/kg/d. We found no negative side effects in neonates following levetiracetam use. Our study finds that levetiracetam is an efficacious medication in treatment of seizures in the setting of neonatal hypoxic ischemic encephalopathy. Future prospective studies should explore its use as a first-line medication.

Value of electroencephalographic monitoring in newborns with hypoxic-ischemic encephalopathy treated with hypothermia

BACKGROUND

The values of electroencephalography (EEG) in neonatal hypoxic-ischemic encephalopathy (HIE) during therapeutic hypothermia (TH) are still uncertain.

AIMS

The aim of this study is to detect EEG background, the prevalence of seizures during cooling, and to determine different EEG patterns that can predict brain injury in magnetic resonance imaging (MRI).

PATIENTS AND METHODS

Thirty-nine newborns with HIE were subjected to TH. Continuous monitoring by video-EEG was carried out throughout cooling and during rewarming. MRI was done for all newborns after rewarming. The predictive value of EEG background for MRI brain injury was evaluated at 6-h intervals during cooling and rewarming.

RESULTS

At all-time intervals, normal EEG was associated with no or mild MRI brain injury. At the beginning of cooling, normal background was more predictive of a favorable MRI outcome than at later time points. After 24 h of monitoring, diffuse burst suppression and depressed patterns had the greatest prognostic value. In most patients, a discontinuous pattern was not associated with poor prognosis. Thirty-one percent developed electrical seizures, and 8% developed status epilepticus. Seizures were subclinical in 42%. There is a significant association between duration of seizure patterns detected on the EEG and severity of brain injury on MRI.

CONCLUSIONS

Continuous EEG monitoring in newborns with HIE under cooling has a prognostic value about early MRI brain injury and identifies electrographic seizures, approximately 50% of which are subclinical. Treatment of clinical and subclinical seizure results in a reduction of the total duration of seizure pattern supports the hypothesis that subclinical seizures should be treated.

Neonatal EEG and neurodevelopmental outcome in preterm infants born before 32 weeks

OBJECTIVE

To assess the value of neonatal EEG for predicting non-optimal neurodevelopmental outcomes in very preterm infants, using a multimodal strategy of evaluation comprising brain imaging and clinical assessment.

DESIGN AND SETTING

Between 2003 and 2009, we performed an observational, population-based study. Out of 2040 eligible preterm infants born before 32 weeks, 1954 were enrolled in the French regional Loire Infant Follow-Up Team (LIFT) cohort. 1744 (89%) of these completed the follow-up. Neonatal EEGs were recorded prospectively as two EEGs during the first 2 weeks of life and then one every 2 weeks up to 33 weeks.

MAIN OUTCOME MEASURES

The neurodevelopmental outcome was assessed by physical examination, the Brunet-Lézine Test and/or the Age and Stages Questionnaire at 2 years of corrected age.

RESULTS

Of the 1744 infants assessed at 2 years, 422 had a non-optimal outcome. A total of 4804 EEGs were performed, and 1345 infants had at least one EEG. EEG abnormalities were predictive of non-optimal outcomes after controlling for confounding factors such as severe intracranial lesions detected by brain imaging. Transient moderate and severe abnormalities were independent predictors of non-optimal outcomes with an OR and 95% CI of 1.49 (1.08 to 2.04) and 2.38 (1.49 to 3.81), respectively. In the validation group, the predictive risk stratification tree identified severe abnormalities as a factor contributing to the prognosis of two subgroups: infants with severe cranial lesions and infants with a normal examination at discharge and without severe cranial lesions.

Seizures and hypothermia: importance of electroencephalographic monitoring and considerations for treatment

Hypoxic-ischemic encephalopathy is a common cause of seizures in neonates. Despite the introduction of therapeutic hypothermia, seizure rates are similar to those reported in the pre-therapeutic hypothermia era. However, the seizure profile has been altered resulting in a lower overall seizure burden, shorter individual seizure durations, and seizures that are harder to detect. Electroencephalographic (EEG) monitoring is the gold standard for detecting all seizures in neonates and this is even more critical in neonates who are cooled, as they are often sedated, making seizures more difficult to detect. Several studies have shown that the majority of seizures in neonates undergoing therapeutic hypothermia remain subclinical, thus requiring EEG monitoring for diagnosis. Amplitude-integrated EEG monitoring is useful but shorter duration seizures are more likely to be missed. Evidence is emerging about the pharmacokinetic profile of routinely used antiepileptic drugs during therapeutic hypothermia and some modifications have been suggested, particularly for lidocaine use.

Prediction of outcome methods assessing short- and long-term outcome after therapeutic hypothermia

Therapeutic hypothermia has significantly changed outcomes for newborns suffering neonatal encephalopathy. Outcome predictors established in the pre-cooling era may not automatically be transferred to the cooling era. This article reviews how the reliability of routinely used outcome predictors has changed. We summarize current knowledge about why this may be the case and when to best obtain and analyze different clinical, biochemical, and imaging outcome markers to predict outcome in cooled asphyxiated newborns.

Electroencephalogram and magnetic resonance imaging comparison as a predicting factor for neurodevelopmental outcome in hypoxic ischemic encephalopathy infant treated with hypothermia

Hypoxic-ischemic encephalopathy (HIE) is an important cause of acute neurological damage in newborns at (or near) term. Several trials in recent years have shown that moderate hypothermia by total body cooling or selective head is an effective intervention to reduce mortality and major disability in infants survived a perinatal hypoxic-ischemic attack. Follow-up in these patients is very important to establish neurodevelopmental outcome, and specific markers can lead us to detect predicting sign for good or poor outcome. We reported a few cases of newborn with HIE treated with hypothermia, in whom the comparison between electroencephalogram (EEG) and magnetic resonance imaging (MRI) represents the first marker for neurodevelopment outcome prediction. The continuous EEG monitoring showed a depressed EEG activity with diffuse burst depression in 7 patients. No epileptic abnormalities were registered. In 10 out of 20 patients no abnormalities of the background activity and no epileptic abnormalities were observed. We found that a depressed EEG activity during the first 72 h of life and a diffused alteration of basal ganglia at MRI were correlated with a poor neurodevelopmental outcome at 18 months of follow-up.

Accuracy of amplitude-integrated electroencephalography in the prediction of neurodevelopmental outcome in asphyxiated infants receiving hypothermia treatment

AIM

Both hypothermia and central nervous system (CNS) drugs may alter the predictive accuracy of amplitude-integrated electroencephalography (aEEG) in hypoxic-ischaemic encephalopathy (HIE). The aim was to assess the predictive value of aEEG in hypothermia-treated HIE infants. Furthermore, we intended to investigate the association of cumulative doses of CNS drugs with aEEG recovery.

METHODS

Seventy term HIE infants treated with hypothermia for 72 h were continuously monitored by single-channel aEEG. Doses of administered morphine, phenobarbitone and midazolam were recorded. Poor outcome was defined as death or severe neurodevelopmental delay at 18-24 months (Bayley Scales of Infant Development II), good outcome as absence of these criteria.

RESULTS

Poor outcome n = 26, good outcome n = 44. Positive predictive values (PPV) of an abnormal background pattern to predict poor outcome were 0.5 at 6 h; 0.65 at 24 h; 0.82 at 48 h and 0.92 at 60 h. All infants who developed sleep-wake cycling (SWC) had a favourable outcome; the nondevelopment of SWC resulted in a PPV of 0.73 for a poor outcome. Cumulative doses of the investigated drugs did not differ between infants having an onset of a recovered background pattern before or after 24 h.

CONCLUSION

Amplitude-integrated electroencephalography provides reliable prediction of outcome from the 48th hour during hypothermia in HIE infants. Commonly used CNS drugs in HIE infants do not significantly delay aEEG recovery.

EEG findings in cooled asphyxiated newborns and correlation with site and severity of brain damage

OBJECTIVE

EEG and MRI are useful tools to evaluate the severity of brain damage and to provide prognostic indications in asphyxiated neonates. Aim of our study is to analyze the relationship between serial neonatal EEGs and severity and sites of brain lesions on MRI in neonates undergoing hypothermia, following a hypoxic-ischemic injury.

PATIENTS AND METHODS

Forty-eight term newborns underwent hypothermia. Serial videoEEG recordings were taken at 6, 24, 48 and 72 h and during 2nd week of life. Brain MRI was performed at the end of 2nd postnatal week and correlated with EEG.

RESULTS

EEGs improved during the first days. At the first recording 25 infants showed a severe or very low amplitude EEG pattern while at the 2nd week only 7 showed such patterns. As regards MRI, 21 infants showed a predominant Basal Ganglia and Thalami damage, 4 infants showed a predominant focal Thalami lesion and 23 showed normal imaging or just mild White Matter abnormalities. Severity of EEG pattern was associated with the odds of having MRI lesions at Basal Ganglia, Thalami, White Matter, Internal Capsule, but not at Cortex. Infants who showed only mild EEG abnormalities in the first 2 days had no Basal Ganglia and Thalami MRI lesion. The persistence of a discontinuous EEG at the 2nd week recording is always associated with Basal Ganglia and Thalami damage.

CONCLUSION

The severity of EEG background is associated with severity and site of MRI lesion pattern in neonates treated with hypothermia because of hypoxic-ischemic encephalopathy.

Neurophysiological testing in neurocritical care

PURPOSE OF REVIEW

To summarize a consensus of European authorities about the applications of clinical neurophysiology in the ICU and, particularly, for a clinically useful management of individual patients.

RECENT FINDINGS

Clinical neurophysiology is useful for diagnosis (epilepsy, brain death, and neuromuscular disorders), prognosis (anoxic ischemic encephalopathy, head trauma, and neurological disturbances of metabolic and toxic origin), and follow-up. The prognostic significance of each test varies as a function of coma etiology. A distinction should be made between tests whose abnormalities are indicative of a poor prognosis (bilateral absence of N20 in anoxic coma, abnormalities suggesting pontine involvement in head trauma) and those whose relative normalcy constitutes an argument for a good prognosis (integrity of brainstem conductions in head trauma, presence of cognitive evoked potentials - mismatch negativity, P300 - irrespective of coma etiology).The highlights of the recent literature mainly concern continuous neuromonitoring for early detection of nonconvulsive seizures, both in adult and neonatal ICU, brain entry into the ischemic penumbra zone, and neuronal functional consequences of intracranial hypertension.

SUMMARY

The domain of clinical neurophysiology is similar to that of clinical examination and complementary to that of imaging techniques. It substantially improves the individual management of ICU patients.

Neurodiagnostic techniques in neonatal critical care

This article reviews recent advances in the neurodiagnostic tools available to clinicians practicing in neonatal critical care. The advent of induced mild hypothermia for acute neonatal hypoxic-ischemic encephalopathy in 2005 has been responsible for renewed urgency in the development of precise and reliable neonatal neurodiagnostic techniques. Traditional evaluations of bedside head ultrasounds, head computed tomography scans, and routine electroencephalograms (EEGs) have been upgraded in most tertiary pediatric centers to incorporate protocols for MRI, continuous EEG monitoring with remote bedside access, amplitude-integrated EEG, and near-infrared spectroscopy. Meanwhile, recent studies supporting the association between placental pathology and neonatal brain injury highlight the need for closer examination of the placenta in the neurodiagnostic evaluation of the acutely ill newborn. As the pursuit of more effective neuroprotection moves into the "hypothermia plus" era, the identification, evaluation, and treatment of the neurologically affected newborn in the neonatal intensive care unit has increasing significance.

Use of amplitude-integrated electroencephalography (aEEG) and near infrared spectroscopy findings in neonates with asphyxia during selective head cooling

BACKGROUND

Amplitude-integrated electroencephalogram (aEEG) at <6 h is the best single outcome predictor in term infants with perinatal asphyxia at normothermia. Hypothermia treatment has changed the cutoff values for outcome prediction by using time at onset of normal trace and SWC. Cerebral hemodynamics and oxygenation changes detected by near infrared spectroscopy (NIRS) during hypothermia treatment in aphyxiated neonates are not a well known issue.

AIM

The aim of this study was to investigate the correlations between brain monitoring (amplitude integrated EEG and NIRS) and outcome in asphyxiated full-term infants with moderate/severe hypoxic-ischemic encephalopathy before, during and after hypothermia treatment.

METHOD

Ten neonates were recruited for hypothermia treatment by using the cool cap entry criteria. aEEG and NIRS were applied in 10 and 8 patients, respectively with moderate and severe hypoxic-ischemic encephalopathy before, just after brain cooling and rewarming periods. Patterns and voltages of aEEG backgrounds sleep-wake cycles (SWC) and NIRS values (TOI% and FTOE) were recorded. During the follow up their outcomes were assessed by using the Bayley Scales of Infant Development II.

CONCLUSION

Hypothermia changes the predictive value of early aEEG. Normalization of a baby's aEEG and the appearance of SWCs while being cooled occurs later. In our study one patient had normal aEEG background pattern at 80 and imminent SWC at 90 h after birth and still had normal Bayley scores at 24 months. Time to normal aEEG and SWC appearance should be carefully evaluated during the cooling period. NIRS values were different due to the clinical presentations of the patients.

[Neuroprotection with hypothermia in the newborn with hypoxic-ischaemic encephalopathy. Standard guidelines for its clinical application]

Standardisation of hypothermia as a treatment for perinatal hypoxic-ischaemic encephalopathy is supported by current scientific evidence. The following document was prepared by the authors on request of the Spanish Society of Neonatology and is intended to be a guide for the proper implementation of this therapy. We discuss the difficulties that may arise when moving from the strict framework of clinical trials to clinical daily care: early recognition of clinical encephalopathy, inclusion and exclusion criteria, hypothermia during transport, type of hypothermia (selective head or systemic cooling) and side effects of therapy. The availability of hypothermia therapy has changed the prognosis of children with hypoxic-ischaemic encephalopathy and our choices of therapeutic support. In this sense, it is especially important to be aware of the changes in the predictive value of the neurological examination and the electroencephalographic recording in cooled infants. In order to improve neuroprotection with hypothermia we need earlier recognition of to recognise earlier the infants that may benefit from cooling. Biomarkers of brain injury could help us in the selection of these patients. Every single infant treated with hypothermia must be included in a follow up program in order to assess neurodevelopmental outcome.

Delayed onset of sleep-wake cycling with favorable outcome in hypothermic-treated neonates with encephalopathy

OBJECTIVE

To determine whether hypothermia modulates acquisition of sleep-wake cycling in term neonates with moderate to severe hypoxic-ischemic encephalopathy (HIE) and the relationship to outcome.

STUDY DESIGN

Twenty-nine term infants with moderate to severe HIE treated with selective head cooling were evaluated. All were monitored with amplitude-integrated electroencephalography during and video electroencephalography immediately after hypothermia for ≥72 hours. Electroencephalograpic data were analyzed for background and sleep-wake cycling. Abnormal outcome included death or severe global neurodevelopmental disability ≥18 months.

RESULTS

Acquisition of sleep-wake cycling was noted in nine infants by 72 hours, in 13 by 96 hours, 19 by 120 hours, and 22 by 144 hours. Presence of sleep-wake cycling was associated with normal outcome, that is, 14 of 22 (64%), versus abnormal outcome, that is, none of seven without sleep-wake cycling (P = .006). The presence of sleep-wake cycling by 120 hours had a positive predictive value of 68% and negative predictive value of 90%. Magnetic resonance imaging abnormalities were related to onset of sleep-wake cycling.

CONCLUSIONS

Although onset of sleep-wake cycling is markedly delayed in term neonates with moderate to severe HIE treated with hypothermia, approximately 65% with acquisition of cycling have a normal outcome. Sleep-wake cycling is an important additional tool for assessing recovery in term infants with moderate to severe HIE treated with hypothermia.

Predictive value of an early amplitude integrated electroencephalogram and neurologic examination

OBJECTIVE

To examine the predictive validity of the amplitude integrated electroencephalogram (aEEG) and stage of encephalopathy among infants with hypoxic-ischemic encephalopathy (HIE) eligible for therapeutic whole-body hypothermia.

DESIGN

Neonates were eligible for this prospective study if moderate or severe HIE occurred at <6 hours and an aEEG was obtained at <9 hours of age. The primary outcome was death or moderate/severe disability at 18 months.

RESULTS

There were 108 infants (71 with moderate HIE and 37 with severe HIE) enrolled in the study. aEEG findings were categorized as normal, with continuous normal voltage (n=12) or discontinuous normal voltage (n=12), or abnormal, with burst suppression (n=22), continuous low voltage (n=26), or flat tracing (n=36). At 18 months, 53 infants (49%) experienced death or disability. Severe HIE and an abnormal aEEG were related to the primary outcome with univariate analysis, whereas severe HIE alone was predictive of outcome with multivariate analysis. Addition of aEEG pattern to HIE stage did not add to the predictive value of the model; the area under the curve changed from 0.72 to 0.75 (P=.19).

CONCLUSIONS

The aEEG background pattern did not significantly enhance the value of the stage of encephalopathy at study entry in predicting death and disability among infants with HIE.

The use of conventional EEG for the assessment of hypoxic ischaemic encephalopathy in the newborn: a review

Neonatal hypoxic ischaemic encephalopathy continues to be one of the leading causes of morbidity and mortality among neonates around the globe. With the advent of therapeutic hypothermia, the need to accurately classify the severity of injury in the early neonatal period is of great importance. As clinical measures cannot always accurately estimate the severity early enough for treatment to be initiated, clinicians have become more dependent on conventional and amplitude integrated EEG. Despite this, there is currently no single agreed classification scheme for the neonatal EEG in hypoxic ischaemic encephalopathy. In this review we discuss classification schemes of neonatal background EEG, published over the past 35 years, highlighting the urgent need for a universal visual analysis scheme.

Video-EEG monitoring in newborns with hypoxic-ischemic encephalopathy treated with hypothermia

BACKGROUND

Therapeutic hypothermia (TH) is becoming standard of care in newborns with hypoxic-ischemic encephalopathy (HIE). The prognostic value of the EEG and the incidence of seizures during TH are uncertain.

OBJECTIVE

To describe evolution of EEG background and incidence of seizures during TH, and to identify EEG patterns predictive for MRI brain injury.

METHODS

A total of 41 newborns with HIE underwent TH. Continuous video-EEG was performed during hypothermia and rewarming. EEG background and seizures were reported in a standardized manner. Newborns underwent MRI after rewarming. Sensitivity and specificity of EEG background for moderate to severe MRI brain injury was assessed at 6-hour intervals during TH and rewarming.

RESULTS

EEG background improved in 49%, remained the same in 38%, and worsened in 13%. A normal EEG had a specificity of 100% upon initiation of monitoring and 93% at later time points. Burst suppression and extremely low voltage patterns held the greatest prognostic value only after 24 hours of monitoring, with a specificity of 81% at the beginning of cooling and 100% at later time points. A discontinuous pattern was not associated with adverse outcome in most patients (73%). Electrographic seizures occurred in 34% (14/41), and 10% (4/41) developed status epilepticus. Seizures had a clinical correlate in 57% (8/14) and were subclinical in 43% (6/14).

CONCLUSIONS

Continuous video-EEG monitoring in newborns with HIE undergoing TH provides prognostic information about early MRI outcome and accurately identifies electrographic seizures, nearly half of which are subclinical.

Influence of hypothermia on the prognostic value of early EEG in full-term neonates with hypoxic ischemic encephalopathy

OBJECTIVE

To determine the prognostic value of early electroencephalograms (EEG) in full-term neonates suffering from hypoxic ischemic encephalopathy (HIE) exposed to whole-body hypothermia (cooled group), compared to neonates treated conventionally (control group).

METHODS

The study included all term neonates born at Grenoble Hospital between 2000 and 2006 with symptoms of HIE. The first two EEGs were reviewed retrospectively and classified according to current electrophysiological criteria. In the cooled group, EEGs were recorded with a mean body temperature of 33°C. Neurological outcome was correlated with EEG pattern.

RESULTS

An EEG inactive or paroxysmal pattern was associated with death in 60% of the controls, while all survivors had neurological sequels. In the cooled group, this EEG pattern was only predictive of death in 40% while survivors had normal examination at 1 year of age. Mild abnormalities on the first EEG correlated with a good prognosis in both groups. The second EEG had a high predictive value, particularly in the cooled group. Persistence of inactivity at 3 days after birth was always associated with death.

CONCLUSIONS

After HIE, the first two EEGs are good prognostic indicators, also in the cooled group. Strong discontinuity in the EEG observed on the first hours after hypothermia induction can be associated with a good outcome.

SIGNIFICANCE

Early Stage 4 EEGs recorded during the hypothermia may not always indicate a poor prognosis in HIE.

Patient selection and prognostication with hypothermia treatment

For infants with perinatal hypoxia-ischaemia, the ability to give an accurate prognosis at different ages enables the clinician to make decisions on the continuation of management, and also assists in discussions regarding further treatment and prognosis with parents and families. This review suggests which outcome markers are still valid, which need new 'cut-off values' and which can no longer be used in cooled infants. The main focus is on convenient bedside technologies such as the amplitude-integrated electroencephalogram that can be easily applied in routine clinical practice.

Effect of hypothermia on amplitude-integrated electroencephalogram in infants with asphyxia

OBJECTIVES

Amplitude-integrated electroencephalogram (aEEG) at <6 hours is the best single outcome predictor in term infants with perinatal asphyxia at normothermia. Hypothermia has been used to treat those infants and proved to improve their outcome. The objectives of this study were to compare the predictive value of aEEG at <6 hours on outcomes in normothermia- and hypothermia-treated infants and to investigate the best outcome predictor (time to normal trace or sleep-wake cycling [SWC]) in normothermia- and hypothermia-treated infants.

METHODS

Seventy-four infants were recruited by using the CoolCap entry criteria, and their outcomes were assessed by using the Bayley Scales of Infant Development II at 18 months. The aEEG was recorded for 72 hours. Patterns and voltages of aEEG backgrounds were assessed.

RESULTS

The positive predictive value of an abnormal aEEG pattern at the age of 3 to 6 hours was 84% for normothermia and 59% for hypothermia. Moderate abnormal voltage background at 3 to 6 hours of age did not predict outcome. The recovery time to normal background pattern was the best predictor of poor outcome (96.2% in hypothermia, 90.9% in normothermia). Never developing SWC always predicted poor outcome. Time to SWC was a better outcome predictor for infants who were treated with hypothermia (88.5%) than with normothermia (63.6%).

CONCLUSIONS

Early aEEG patterns can be used to predict outcome for infants treated with normothermia but not hypothermia. Infants with good outcome had normalized background pattern by 24 hours when treated with normothermia and by 48 hours when treated with hypothermia.