Prognostic value of continuous electroencephalographic recording in full term infants with hypoxic ischaemic encephalopathy

Neurological outcomes and mortality after neonatal seizures with electroencephalographical verification. A systematic review

AIM

To conduct a systematic review of post-neonatal neurological outcomes and mortality following neonatal seizures with electroencephalographical verification.

METHODS

The databases Medline, Embase and Web of Science were searched for eligible studies. All abstracts were screened in a blinded fashion between research team members and reports found eligible were obtained and screened in full text by two members each. From studies included, outcome results for post-neonatal epilepsy, cerebral palsy, intellectual disability, developmental delay, mortality during and after the neonatal period and composite outcomes were extracted. A quality assessment of each study was performed.

RESULTS

In total, 5518 records were screened and 260 read in full text. Subsequently, 31 studies were included, containing cohorts of either mixed or homogenous etiologies. Follow-up time and gestational ages varied between studies. No meta-analysis could be performed due to the low number of studies with comparable outcomes and effect measures. Reported cumulative incidences of outcomes varied greatly between studies. For post-neonatal epilepsy the reported incidence was 5-84%, for cerebral palsy 9-78%, for intellectual disability 24-67%, for developmental delay 10-67% and for mortality 1-62%. Subgroup analysis had more coherent results and in cohorts with status epilepticus a higher incidence of post-neonatal epilepsy from 46 to 84% was shown.

CONCLUSION

The large variation of reported incidences for neurological outcomes and mortality found even when restricting to cohorts with electroencephalographically verified neonatal seizures indicates selection bias as a significant confounder in existing studies. Population-based approaches are thus warranted to correctly predict outcomes in this group.

Efficacy and safety of ketamine for neonatal refractory status epilepticus: case report and systematic review

Background

Evidence-based data on treatment of neonatal status epilepticus (SE) are scarce. We aimed to collect data on the efficacy and safety of ketamine for the treatment of neonatal SE and to assess its possible role in the treatment of neonatal SE.

Methods

We described a novel case and conducted a systematic literature review on neonatal SE treated with ketamine. The search was carried out in Pubmed, Cochrane, Clinical Trial Gov, Scopus and Web of Science.

Results

Seven published cases of neonatal SE treated with ketamine were identified and analyzed together with our novel case. Seizures typically presented during the first 24 h of life (6/8). Seizures were resistant to a mean of five antiseizure medications. Ketamine, a NMDA receptor antagonist, appeared to be safe and effective in all neonates treated. Neurologic sequelae including hypotonia and spasticity were reported for 4/5 of the surviving children (5/8). 3/5 of them were seizure free at 1-17 months of life.

Discussion

Neonatal brain is more susceptible to seizures due to a shift towards increased excitation because of a paradoxical excitatory effect of GABA, a greater density of NMDA receptors and higher extracellular concentrations of glutamate. Status epilepticus and neonatal encephalopathy could further enhance these mechanisms, providing a rationale for the use of ketamine in this setting.

Conclusions

Ketamine in the treatment of neonatal SE showed a promising efficacy and safety profile. However, further in-depth studies and clinical trials on larger populations are needed.

The features of neonatal seizures as predictors of drug-resistant epilepsy in children

PURPOSE

The aim of this study was to evaluate the predictive value of the features of neonatal seizures for pharmacoresistant epilepsy in children.

METHOD

This is a retrospective study that involved all children diagnosed as having epilepsy who had neonatal seizures and who were hospitalized at the Neurology Department of the Mother and Child Healthcare Institute in Belgrade from January the 1st 2017 until December 31st 2017. The following parameters and their impact on the outcome were investigated: perinatal data, the characteristics of epileptic seizures in the neonatal period, and the response to anticonvulsant treatment. The presence of pharmacoresistance was observed as an outcome parameter. Univariate and multivariate logistic regression analyses were used to define predictors of drug-resistant epilepsy.

RESULTS

The study involved 55 children, 35 (63.6%) male and 20 (36.4%) female. The average age of the children at the end of the observation period was 5.17 years (min: 0.25, max: 17.75, iqr (interquartile range): 6.92). Pharmacoresistant epilepsy was found in 36 (65.5%) children. The most common type of epilepsy was focal, which affected 30 patients (54.5%), than generalized, which affected 15 patients (27.3%), and combined generalized and focal, which affected 8 patients (14.5%). At the end of the observation period, 28 patients (50.9%) had no seizures, while 14 (25.5%) had daily seizures. It was found that the pharmacoresistant neonatal seizures and metabolic-genetic disorders were predictive factors of the occurrence of pharmacoresistant epilepsy.

CONCLUSION

Patients prone to developing pharmacoresistant epilepsy might be identified as early as the neonatal and early infant period. High incidence of asphyxia cooccurring with established genetic-metabolic disease further emphasizes need for genetic testing in infants with neonatal seizures including in the presence of hypoxic-ischemic injury.

Combined vEEG and Cerebral Oximetry Results to Determine the Severity of Hypoxic–Ischemic Encephalopathy

The objectives of the study were to evaluate the prognostic utility of bedside monitoring tools for hypoxic–ischemic encephalopathy (HIE) outcome and develop a prognostic predictive model. This retrospective study reviewed neonatal HIE treated with hypothermia between 2013 and 2016. Continuous video electroencephalography (vEEG) recordings scored for background electrocerebral activity, seizure, and sleep–wake cycles, and rSO2 data were stratified by magnetic resonance imaging (MRI) severity. The vEEG and rSO2 were combined in a predictive model. The analysis included 38 patients. The rSO2 was significantly higher in the severe group. vEEG showed early and persistent maximal suppression in the severe group. The predictive correlation of the rSO2 improves when combined with the vEEG.

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.

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.

What is new: Talk about status epilepticus in the neonatal period

Nowadays, no general consensus was achieved regarding neonatal status epilepticus and its definition. Indeed, different criteria (mainly based on seizure duration) were used. Whereas a recent proposal has been developed to define status epilepticus in older ages, it seems that the peculiar characteristics of neonatal seizures and of the immature brain make difficult to find a tailored definition for this period of life. Achieving a consensus on this entity would mean to make the first step toward a targeted therapeutic strategy of intervention.

Automated electroencephalographic discontinuity in cooled newborns predicts cerebral MRI and neurodevelopmental outcome

BACKGROUND AND HYPOTHESIS

Prolonged electroencephalographic (EEG) discontinuity has been associated with poor neurodevelopmental outcomes after perinatal asphyxia but its predictive value in the era of therapeutic hypothermia (TH) is unknown. In infants undergoing TH for hypoxic-ischaemic encephalopathy (HIE) prolonged EEG discontinuity is associated with cerebral tissue injury on MRI and adverse neurodevelopmental outcome.

METHOD

Retrospective study of term neonates from three UK centres who received TH for perinatal asphyxia, had continuous two channel amplitude-integrated EEG with EEG for a minimum of 48 h, brain MRI within 6 weeks of birth and neurodevelopmental outcome data at a median age of 24 months. Mean discontinuity was calculated using a novel automated algorithm designed for analysis of the raw EEG signal.

RESULTS

Of 49 eligible infants, 17 (35%) had MR images predictive of death or severe neurodisability (unfavourable outcome) and 29 (59%) infants had electrographic seizures. In multivariable logistic regression, mean discontinuity at 24 h and 48 h (both p=0.01), and high seizure burden (p=0.05) were associated with severe cerebral tissue injury on MRI. A mean discontinuity >30 s/min-long epoch, had a specificity and positive predictive value of 100%, sensitivity of 71% and a negative predictive value of 88% for unfavourable neurodevelopmental outcome at a 10 µV threshold.

CONCLUSIONS

In addition to seizure burden, excessive EEG discontinuity is associated with increased cerebral tissue injury on MRI and is predictive of abnormal neurodevelopmental outcome in infants treated with TH. The high positive predictive value of EEG discontinuity at 24 h may be valuable in selecting newborns with HIE for adjunctive treatments.

Hemodynamic response to burst-suppressed and discontinuous electroencephalography activity in infants with hypoxic ischemic encephalopathy

Burst suppression (BS) is an electroencephalographic state associated with a profound inactivation of the brain. BS and pathological discontinuous electroencephalography (EEG) are often observed in term-age infants with neurological injury and can be indicative of a poor outcome and lifelong disability. Little is known about the neurophysiological mechanisms of BS or how the condition relates to the functional state of the neonatal brain. We used simultaneous EEG and diffuse optical tomography (DOT) to investigate whether bursts of EEG activity in infants with hypoxic ischemic encephalopathy are associated with an observable cerebral hemodynamic response. We were able to identify significant changes in concentration of both oxy and deoxyhemoglobin that are temporally correlated with EEG bursts and present a relatively consistent morphology across six infants. Furthermore, DOT reveals patient-specific spatial distributions of this hemodynamic response that may be indicative of a complex pattern of cortical activation underlying discontinuous EEG activity that is not readily apparent in scalp EEG.

Neonatal status epilepticus: differences between preterm and term newborns

BACKGROUND

Despite the many studies on neonatal seizures, neonatal status epilepticus (NSE) remains a controversial entity, with no general consensus about its definition. We report the characteristics of newborns with NSE in order to assess whether they showed homogeneous features or displayed clinical and/or instrumental differences depending on gestational age (GA). Preterm and term neonates were compared and risk factors for adverse outcome evaluated.

METHODS

From 154 newborns with video-EEG confirmed neonatal seizures admitted to the NICU of Parma University Hospital between January 1999 and December 2012, we collected a cohort of 47 newborns (19 preterm, 28 full-term) with NSE. NSE was defined as continuous seizure activity for at least 30 min or recurrent seizures lasting a total of 30 min without definite return to the baseline neurologic condition between seizures. Outcome was assessed at least at one year. We applied the χ(2) test to compare nominal data, and multivariate logistic regression analysis to determine independent risk factors for adverse outcome.

RESULTS

Only Apgar scores and neurologic examination (p ≤ .02) were different between the groups. None of the preterm newborns had a favourable outcome compared to 25% of the full-term ones (p = .032). Moreover, 52.6% of preterm neonates died compared to 17.8% of the full-term newborns (p = .01; OR = 5.11). The only variable related to outcome was Apgar score at 5 min (p = .02).

CONCLUSION

Newborns with NSE represented a quite homogeneous group regardless of the GA. Outcome was unfavourable in most of the subjects; however adverse outcome and death were more represented in preterm 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.

EEG, evoked potentials and pulsed Doppler in asphyxiated term infants

OBJECTIVE

To evaluate electroencephalograms (EEG), evoked potentials (EPs) and Doppler findings in the cerebral arteries as predictors of a 1-year outcome in asphyxiated newborn infants.

METHODS

EEG and EPs (brain stem auditory (BAEP), somatosensory (SEP), visual (VEP) evoked potentials) were assessed in 30 asphyxiated and 30 healthy term infants during the first days (range 1-8). Cerebral blood flow velocities (CBFV) were measured from the cerebral arteries using pulsed Doppler at ∼24h of age. EEG, EPs, Doppler findings, symptoms of hypoxic ischemic encephalopathy (HIE) and their combination were evaluated in predicting a 1-year outcome.

RESULTS

An abnormal EEG background predicted poor outcome in the asphyxia group with a sensitivity of 67% and 81% specificity, and an abnormal SEP with 75% and 79%, respectively. Combining increased systolic CBFV (mean+3SD) with abnormal EEG or SEP improved the specificity, but not the sensitivity. The predictive values of abnormal BAEP and VEP were poor. Normal EEG and SEP predicted good outcome in the asphyxia group with sensitivities from 79% to 81%. The combination of normal EEG, normal SEP and systolic CBFV<3SD predicted good outcome with a sensitivity of 74% and 100% specificity.

CONCLUSIONS

Combining abnormal EEG or EPs findings with increased systolic CBFV did not improve prediction of a poor 1-year outcome of asphyxiated infants. Normal EEG and normal SEP combined with systolic CBFV<3SD at about 24 h can be valuable in the prediction of normal 1-year outcome.

SIGNIFICANCE

Combining systolic CBFV at 24 h with EEG and SEP examinations can be of use in the prediction of normal 1-year outcome among asphyxiated infants.

Cord blood proteins and multichannel-electroencephalography in hypoxic-ischemic encephalopathy

OBJECTIVE

To explore the association between multiple umbilical cord blood proteins and severity of hypoxic-ischemic encephalopathy as defined by continuous multichannel electroencephalography.

DESIGN

A prospective case-control cohort study, which was divided into separate exploratory and validation cohorts.

SETTING

A single tertiary neonatal intensive care facility.

PATIENTS

The study recruited full-term infants with perinatal asphyxia and controls. Identical procedures were used to recruit a representative exploratory sample (n = 30) and a subsequent validation cohort (n = 100).

INTERVENTION

All had umbilical cord blood drawn and biobanked at delivery, continuous multichannel electroencephalography commenced in the first 24 hours, and a modified Sarnat score assigned. Analysis of 37 potential cord blood protein markers of hypoxic-ischemic encephalopathy was performed using Luminex multiplex assays.

MEASUREMENTS AND RESULTS

Cord blood from 130 infants was analyzed. Interleukin-16 and interleukin-6 significantly differentiated between a moderate-severely abnormal and normal-mildly abnormal electroencephalography background in both exploratory (p = 0.005 and p = 0.016, respectively) and validation cohorts (p = 0.039 and p = 0.024, respectively). To develop a predictive model for a moderate-severely abnormal electroencephalography, stepwise regression analysis was used to combine these analytes with current standard clinical markers of asphyxia (pH, base deficit, and 10-min Apgar). Only Apgar score and interleukin-16 remained in the model, which was highly predictive of an abnormal electroencephalography (area under the curve [AUC] = 0.956, p < 0.001, positive predictive value = 89%, and negative predictive value = 94%).

CONCLUSIONS

Cord blood interleukin-6 and interleukin-16 were associated with electrographic grade of hypoxic-ischemic encephalopathy. To predict an abnormal electroencephalography, interleukin-16 and 10-minute Apgar used in combination performed better than current markers.

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.

Neonatal status epilepticus controlled with levetiracetam at Sturge Weber syndrome

Sturge-Weber syndrome is a rare, sporadic, congenital neurocutaneous syndrome characterized by facial cutaneous vascular malformation, leptomeningeal angioma and eye abnormalities. Seizures develop during the first year of life, may become refractory to multiple anticonvulsants and status epilepticus may develop. A rare subtype of Sturge-Weber syndrome with bilateral facial vascular malformation, unilateral cerebral involvement and neonatal status epilepticus is reported here. Neonatal status epilepticus was successfully controlled with intravenous levetiracetam infusion.

Therapeutic hypothermia in term infants after perinatal encephalopathy: the last 5 years in Switzerland

BACKGROUND

Therapeutic hypothermia (TH) following perinatal asphyxial encephalopathy in term infants improves mortality and neurodevelopmental outcome. In Europe, most neonatal units perform active cooling whereas in Switzerland passive cooling is predominantly used.

AIMS

(i) To determine how many infants were cooled within the last 5years in Switzerland, (ii) to assess the cooling methods, (iii) to evaluate the variation of temperature of different cooling methods, and (iv) to evaluate the use of neuromonitoring.

STUDY DESIGN

Retrospective cohort study.

PATIENTS

Notes of all cooled term infants between March 2005 and December 2010 in 9 perinatal and two paediatric intensive care centres were retrospectively reviewed. Active cooling was compared to passive cooling alone and to passive cooling in combination with gel packs.

RESULTS

150 infants were cooled. Twenty-seven (18.2%) were cooled actively, 34 (23%) passively and 87 (58.8%) passively in combination with gel packs. Variation of temperature was significantly different between the three methods. Passive cooling had a significant higher variation of temperature (SD of 0.89) than both passive cooling in combination with gel packs (SD of 0.79) and active cooling (SD of 0.76). aEEG before TH was obtained in 35.8% of the infants and 86.5% had full EEG. One cUS was performed in 95.3% and MRI in 62.2% of the infants.

CONCLUSION

Target temperature can be achieved with all three cooling methods. Passive cooling has the highest variation of temperature. Neuromonitoring should be improved in Swiss neonatal and paediatric intensive care units. Our results stress the importance of national registries.

An observational study exploring amplitude-integrated electroencephalogram and spectral edge frequency during paediatric anaesthesia

Processed electroencephalography is used in adults to guide anaesthesia, but the algorithms used may not apply to infants. Knowledge of infants' electroencephalogram (EEG) responses to anaesthetics is fragmentary. An earlier pilot study suggested amplitude-integrated EEG (aEEG) may be a useful measure of anaesthetic effect. The aim of this study was to determine how aEEG changes between awake and anaesthetised children of varying ages and to compare the response to that seen with Spectral Edge Frequency 90% (SEF90). A prospective observational study of children receiving a general anaesthetic was conducted. Anaesthetic regimen remained at the discretion of the treating anaesthetist. EEG data were collected using the BrainZ ReBrim(TM) monitor using forehead and biparietal montages. SEF90 and aEEG were compared across age groups, EEG montage and between awake and anaesthetised states. A total of 178 children (aged 24 days to 14 years) were recruited. All aEEGs were greater during anaesthesia compared to when awake and this difference varied with age. Only children older than two years showed lower SEF90 while anaesthetised compared to when awake. SEF90 from children younger than six months was higher during anaesthesia compared to when awake. Analysis of parietal and forehead EEG montages revealed age-related differences. These findings suggest that SEF90 and aEEG can discriminate between awake and anaesthetised states in older children. In younger children aEEG changes are less pronounced and SEF90 either cannot discriminate between states or responds paradoxically. The aEEG may be marginally better than other EEG parameters in measuring anaesthetic depth in children.

Prognostic capacity of automated quantification of suppression time in the EEG of post-asphyctic full-term neonates

AIM

To evaluate the prognostic capacity of a new method for automatic quantification of the length of suppression time in the electroencephalogram (EEG) of a group of asphyxiated newborn infants.

METHODS

Twenty-one full-term newborn infants who had been resuscitated for severe birth asphyxia were studied. Eight channel continuous EEG was recorded for prolonged time periods during the first days of life. Artefact detection or rejection was not applied to the signals. The signals were fed through a pretrained classifier and then segmented into burst and suppression periods. Total suppression length per hour was calculated. All surviving patients were followed with structured neurodevelopmental assessments to at least 18 months of age.

RESULTS

The patients who developed neurodevelopmental disability or died had significant suppression periods in their EEG during the first days of life while the patients who had a normal follow-up had no or negligible amount of suppression.

CONCLUSIONS

This new method for automatic quantification of suppression periods in the raw, neonatal EEG discriminates infants with good from those with poor outcome.

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.

Early EEG findings in hypoxic-ischemic encephalopathy predict outcomes at 2 years

OBJECTIVE

We examined the evolution of electroencephalographic (EEG) changes after hypoxic injury.

METHODS

Continuous, multichannel, video-EEG was recorded for term infants with hypoxic-ischemic encephalopathy, from <6 hours to 72 hours after delivery. One-hour segments at 6, 12, 24, and 48 hours of age of the EEG were analyzed visually, and neurologic outcome was assessed at 24 months.

RESULTS

Forty-four infants completed neurodevelopmental follow-up. Of those, 20 (45%) had abnormal outcomes. The EEG grade assigned correlated significantly with outcome. EEG abnormalities improved with time, with the worst EEG grade seen on the earliest recording in all cases. The best predictive ability was seen at 6 hours of age (area under the receiver operator characteristic curve: 0.958 [95% confidence interval: 0.88-1.04]; P = .000). Normal/mildly abnormal EEG results at 6, 12, or 24 hours had 100% positive predictive values for normal outcomes and negative predictive values of 67% to 76%. By 48 hours, many of the EEG findings had improved significantly. This led to the positive predictive value of abnormal EEG results being greater at 48 hours (93%), with a concurrent negative predictive value of 71%. EEG features that were associated with abnormal outcomes were background amplitude of <30 microV, interburst interval of >30 seconds, electrographic seizures, and absence of sleep-wake cycling at 48 hours.

CONCLUSIONS

Early EEG is a reliable predictor of outcome in HIE. A normal or mildly abnormal EEG results within 6 hours after birth were associated with normal neurodevelopmental outcomes at 24 months.

Assessment of neonatal electroencephalography (EEG) background by conventional and two amplitude-integrated EEG classification systems

OBJECTIVE

To determine the agreement among conventional electroencephalography (CEEG) terminology background classification and a simple and an advanced amplitude-integrated EEG (aEEG) system, and to evaluate whether aEEG interpreter experience or electrographic seizures affect this agreement.

STUDY DESIGN

CEEG background was classified by traditional interpretive criteria for 144 neonatal recordings, from which a single channel was converted to aEEGs. These aEEGs were independently interpreted by neonatologists according to the simple and advanced classification systems.

RESULTS

Interreader agreement was better with the simple aEEG system compared with the advanced aEEG system (multirater kappa, 0.66 vs 0.44). Fair-to-moderate agreement was found between both of the aEEG classification systems and CEEG (simple: kappa, 0.34 to 0.45; advanced: kappa, 0.36 to 0.45). Agreement did not vary significantly based on the aEEG interpreter experience or the presence of seizures.

CONCLUSIONS

Neonatologists found better agreement using the simple aEEG system regardless of their expertise or the presence of seizures. This finding has implications for patient selection in future multicenter neonatal neuroprotection studies.

Continuous EEG monitoring in a paediatric intensive care unit

Monitoring with continuous EEG (cEEG) has become a valuable tool in the adult neurointensive care unit. The benefits of cEEG or amplitude-integrated EEG in neonatal intensive care have also been described. The aim of the present study was to describe and evaluate the use of cEEG in a paediatric intensive care unit. The study is a description of children and adolescents with acute neurological disorders monitored by cEEG in a paediatric intensive care unit for more than 12h. The indication for cEEG and the outcome are reported for 54 patients during a 4-year period. Twelve patients were monitored for high intracranial pressure, eight of whom died. Fourteen were monitored due to suspected, but not detected, epilepsy, their underlying diagnoses being variable. Refractory status epilepticus was the reason for cEEG in 24 cases. All of these patients survived the acute phase of status epilepticus. Four patients had seizure activity on cEEG due to global anoxia; these were not classified as status epilepticus. In conclusion, in the paediatric intensive care unit the most important indication for cEEG monitoring is in patients with suspected refractory status epilepticus where it adds to the diagnosis and choice of treatment. Continuous EEG should therefore be part of the paediatric intensive care unit technical support to select and monitor, among children with critical neurological disorders, those with refractory status epilepticus.

Variability of Cerebral Hemoglobin Concentration in Very Preterm Infants During the First 6 Hours of Life

Cerebral hemoglobin concentration (cHbc), a major determinant of oxygen transport capacity in the brain, shows a considerable variability due to physiological and methodological factors. In order to determine the (relative) contribution of these factors, the cHbc variability within the first 6 hours of life was studied in 28 very preterm infants using near infrared spectrophotometry (NIRS). Mean cHbc values were 46.4 +/- 14.1 micromol/l (2.75 +/- 0.84 ml/100 g). Is the variability in cHbc related to the methodology of cHbc measurements or to physiological variables? A statistical model of stepwise regression (backward selection) with 13 independent variables and with cHbc as a dependent variable showed that, from the total variability of +/- 14.1 micromol/l, only 3.7 micromol/l (26%) were of methodological origin, while the major portion, 9.3 micromol/l (66%) were related to four physiological variables: birth weight, gestational age, blood glucose and transcutaneous carbon dioxide tension. The remaining 1.1 micromol/l (7.8%) were unexplained. We conclude that NIRS, which allows continuous monitoring of cerebral oxygenation and metabolism even in the first hours of postnatal life, is a valid technique to measure cHbc in very preterm infants. The major portion of the large variability of early cHbc registrations can be attributed to physiological factors.

Cerebral function monitoring: a new scoring system for the evaluation of brain maturation in neonates

OBJECTIVE

Cerebral function monitoring (CFM), using compressed single-channel amplitude-integrated electroencephalogram recorded from 2 biparietal electrodes, has been shown previously to be a simple bedside tool for monitoring neonatal central nervous system (CNS) status. As the pattern of the CFM changes with gestational age, the technique can be used to assess brain maturation in premature infants. We have developed a new scoring system for the interpretation of neonatal CFM recordings. The objective of this study was to evaluate CFM tracings at increasing gestational and postnatal ages to develop a scoring system to quantify CFM pattern changes.

METHODS

Term and preterm neonates were studied with CFM at 12 to 24 hours of life, 48 to 72 hours of life, and then weekly or biweekly until hospital discharge. Each study comprised 8 to 24 hours of continuous CFM recording. CFM recordings were evaluated using the scoring system for record continuity, presence of cyclic changes in electrical activity, degree of voltage amplitude depression, and bandwidth. Each variable was scored for each recording. All variables were summed to yield a total score (minimum 0, maximum 13). Total scores were correlated with gestational and postconceptional ages.

RESULTS

Thirty infants were studied with gestational ages at birth that ranged from 24 to 39 weeks and birth weights that varied between 450 and 3850 g. A total of 146 CFM tracings were analyzed. With advancing gestational and postconceptional age, scores for each variable as well as total scores progressively increased with CNS maturation. The highest scores were attained at 35 to 36 weeks' postconceptional age, which corresponded to previously reported subjective observations performed by visual description of CFM patterns. Of the 4 component variables that we analyzed, the most sensitive indicators of CNS maturity were 1) the presence of a cycling pattern, 2) the continuity of the record pattern, and 3) the CFM recording bandwidth.

CONCLUSIONS

Our proposed scoring system may be a valuable tool to quantify changes during CFM more objectively, reflecting variations in CNS activity in newborn infants and allowing for better statistical comparisons between amplitude-integrated electroencephalogram tracings from different patients as well as from the same patient at different points of time.

Factors predictive of seizures and neurologic outcome in perinatal depression

To identify which early clinical variables are predictive of outcome in newborns with perinatal depression, we prospectively examined newborns with persistently abnormal neurologic examinations at 48 hours and (1) arterial pH </= 7.15, (2) 5-minute Apgar </= 5, (3) requirement for positive pressure ventilation in the delivery room, or (4) fetal heart rate monitoring abnormalities. Eighty-four such infants completed neurodevelopmental assessment at 1 year. Five-minute Apgar (P = 0.0064), arterial pH (P = 0.0065) and base excess (P = 0.0003), neonatal encephalopathy grade at 48 hours and 7 days (both P = 0.0001), EEG at 48 hours and 7 days (both P = 0.0001), cranial ultrasound (US) at 48 hours (P = 0.0013) and 7 days (P = 0.0002), and the occurrence of neonatal seizures (P = 0.0001) all correlated significantly with developmental outcome, whereas fetal heart rate monitoring, mode of delivery, and presence of the non-neurologic hypoxic-ischemic encephalopathy syndrome did not. In the multivariate analysis, a combination of the 48-hour EEG and 48-hour cranial ultrasound provided the best model to predict developmental outcome, and a point system to predict developmental outcome based on these two variables is proposed.

Seizure detection in the neonatal EEG with synchronization likelihood

OBJECTIVE

To investigate whether epileptic seizure activity can be distinguished from non-epileptic background activity in the neonatal electroenceplalogram (EEG), using synchronization likelihood as a measure of synchronization between EEG channels.

METHODS

Forty-two 21s EEG epochs and two complete EEGs from 21 different neonatal patients in a 12-channel bipolar recording were studied (AD-conversion 16bit; sample frequency 200Hz; filter setting 0.5-30Hz). For EEG of each patient, we selected one epoch with epileptic discharges and one without. Synchronization was calculated in all epochs. In two complete EEGs, synchronization was calculated and correlated with a visual scoring of the EEG.

RESULTS

Synchronization likelihood was higher in all the epochs with epileptic seizures as compared to the epochs without epileptic activity (P<0.01). When synchronization likelihood exceeded 0.11, the sensitivity for the presence of epileptic activity was 0.85 (95% confidence limits [CL(95)]=0.69-1) and the specificity was 0.75 (CL(95)=0.56-0.94).Analysis of EEG score and synchronization likelihood of two complete EEGs revealed a high correlation between the occurrence of epileptic seizures and elevated synchronization likelihood (Spearman r=0.707, P<0.001).

CONCLUSIONS

The results of this study demonstrate that synchronization likelihood is a potential tool in the automatic monitoring of high-risk infants for epileptic activity on neonatal wards.

Prognostic value of neonatal discontinuous EEG

The burst suppression pattern on the neonatal electroencephalogram (EEG) is associated with a poor outcome. However, this serious abnormality constitutes only a small proportion of discontinuous neonatal EEGs. We sought to establish whether any easily measurable parameters among the broad range of excessively discontinuous neonatal EEGs are predictive of outcome. We retrospectively reviewed the EEGs and medical records of 43 term infants with excessively discontinuous EEGs. We quantitated 10 parameters in the bursts and interburst intervals, among them the predominant interburst interval duration (defined as the duration of more than 50% of all interburst intervals of an EEG). Univariate and multivariate analyses were performed on the 10 EEG variables in relation to neurologic outcome and subsequent epilepsy. Based on multivariate analysis, a single easily measurable EEG parameter related significantly to outcome. A predominant interburst interval duration of more than 30 seconds correlated with the occurrence of both unfavorable neurologic outcome and subsequent epilepsy (P = 0.040 and P = 0.033, respectively). In conclusion, a infant whose EEG contains a predominant interburst interval duration of more than 30 seconds has a 100% probability of experiencing severe neurologic disabilities or death and an 86% chance of developing subsequent epilepsy. This easily quantitated EEG parameter could be valuable for the early estimation of neurologic prognosis.

Neurologic examination in infants with hypoxic-ischemic encephalopathy at age 9 to 14 months: use of optimality scores and correlation with magnetic resonance imaging findings

OBJECTIVES

To evaluate whether a structured and scorable neurologic examination (The Hammersmith Infant Neurological Examination) correlates with early magnetic resonance imaging findings in a group of infants with hypoxic-ischemic encephalopathy (HIE) and whether the scores of this assessment can predict the locomotor function in these children.

STUDY DESIGN

A total of 53 term infants fulfilling the criteria for HIE underwent scanning within 4 weeks from delivery with a 1 Tesla HPQ magnet. The scores from the neurologic examination performed between 9 to 14 months were correlated to the neonatal magnetic resonance imaging findings and to the maximal locomotor function defined at the ages of 2 and 4 years.

RESULTS

The scores were always optimal in the infants with normal or minor neonatal magnetic resonance imaging findings. The lowest scores were associated with severe basal ganglia and white matter lesions. All the infants who had a global score between 67 and 78 at 1 year were able to walk independently at 2 years and without restrictions at 4 years. Scores between 40 and 67 were associated with restricted mobility and scores <40 with severely limited self-mobility at 2 and 4 years.

CONCLUSIONS

The use of a standardized neurologic optimality scoring system gives additional prognostic information, easily available in the clinic, on the severity of the functional motor outcome in infants with HIE.

Combined use of electroencephalogram and magnetic resonance imaging in full-term neonates with acute encephalopathy

OBJECTIVE

The electroencephalogram (EEG) is widely used in full-term infants with acute neonatal encephalopathy, and its prognostic value has been confirmed by several studies. Magnetic resonance imaging (MRI) of the brain has also been applied in these patients, and increasing numbers of reports affirm its prognostic reliability. The aim of this study has been to investigate the correlation between an early EEG and MRI findings in infants with acute neonatal encephalopathy and to assess the prognostic value of a combination of EEG and MRI findings.

PARTICIPANTS AND METHODS

Twenty-five full-term infants had an EEG recorded within the first 72 hours after birth and a neonatal brain MRI scan after the end of the first week.

RESULTS

Both EEG and MRI were predictive of outcome. A normal MRI was always associated with normal EEG background activity and normal outcome and severe abnormalities on MRI with marked EEG abnormalities and an abnormal outcome. When the MRI showed moderate abnormalities, the EEG in all cases but one identified patients with normal and abnormal outcome.EEG, MRI, HIE, neurodevelopment.

Early serial EEG in hypoxic ischaemic encephalopathy

OBJECTIVES

To perform early serial EEGs in infants with hypoxic ischaemic encephalopathy (HIE) and compare the findings with neurodevelopmental outcome.

METHODS

Nine full-term neonates with HIE had simultaneous video-EEG polygraphic studies within 8 h of birth. The EEG was repeated at 12-24 h intervals. All surviving infants had a neurodevelopmental assessment at 1 year.

RESULTS

Two infants had a normal or mildly abnormal EEG within 8 h of birth and neurodevelopmental outcome was normal. Seven infants had severely depressed background activity in the first 8 h of life. In 3 infants the EEG activity recovered within 12-24 h showing continuous activity with no or only minor abnormalities. All these infants had a normal outcome. The remaining 4 infants, who also had an initially inactive recording, subsequently developed severe background abnormalities. At follow-up, two infants had died and the remainder developed major neurological sequelae.

CONCLUSIONS

Early EEG is an excellent prognostic indicator for a favourable outcome if normal within the first 8 h of life and for a poor outcome if the background activity continues to be inactive or grossly abnormal beyond 8-12 h of life. However, an inactive or very depressed EEG within the first 8 h of life can be associated with good outcome if the EEG activity recovers within 12 h.

Prognostic value of EEG in neonatal bacterial meningitis

The contribution of electroencephalogram (EEG) findings early in the course of neonatal bacterial meningitis to the prediction of severe adverse outcome was assessed in a retrospective cohort study. Infants had known outcomes to 1 year of age and an EEG performed during the first week of illness. EEGs were subclassified as follows: overall EEG description, background activity, presence of positive rolandic sharp waves, presence of seizure activity, and presence of focal abnormal activity. EEG patterns predictive of severe adverse outcome were identified by univariate and multivariate analyses. Of 101 infants admitted with bacterial meningitis, 37 had an EEG performed. Of the 37 infants, 21 had adverse outcomes; nine infants died, and 12 infants had moderate or severe disability. EEG background activity and overall EEG description were identified as predictors of adverse outcome; multivariate analysis indicated that the latter was a stronger predictor (sensitivity 88%, specificity 90%). Infants with normal or mildly abnormal EEGs had good outcomes whereas those with moderate to markedly abnormal EEGs died or survived with adverse outcome. The accuracy of predictions increased when EEGs were repeated. In a high-risk population of infants with bacterial meningitis, moderate-to-markedly abnormal EEG reliably predicts adverse outcome.

Electrocortical brain activity, cerebral haemodynamics and oxygenation during progressive hypotension in newborn piglets

OBJECTIVES

To investigate the relationships between systemic and cerebral haemodynamics and oxygenation, and electroencephalogram (EEG) amplitude and frequency analysis studied by the cerebral function analyzing monitor (CFAM) during progressive hypovolemic hypotension.

METHODS

Six piglets of 1 week of age, weighing 1.9-3.4 kg were mechanically ventilated under 1-1.5% halothane anaesthesia. After 1 h stabilization, blood was withdrawn in aliquots of 10 ml/kg over 15 min up to a total of 40-60 ml/kg. Arterial oxygenation was maintained at normal levels. Thereafter, the total blood volume previously withdrawn, was reinfused. Changes in near infrared spectroscopy (NIRS) parameters [cerebral oxidized cytochrome aa3 (Cytaa3), cerebral blood volume (CBV) or total haemoglobin (tHb: oxy- + deoxyhaemoglobin)], carotid blood flow (Q(car)), maximal EEG amplitude and EEG frequency percentages were analyzed continuously.

RESULTS

The EEG amplitude remained stable until the mean arterial blood pressure (MAP), Q(car) and tHb dropped below 30 mmHg (41% of baseline), 20 ml/min (33% of baseline) and 82% of baseline, respectively. Delta (delta) wave frequency percentage of the CFAM increased significantly at MAP below 30 mm Hg. EEG amplitude remained depressed after blood reinfusion and haemodynamic recovery. Cytaa3 changes were not statistically significant, reflecting sufficient neuronal oxygenation.

CONCLUSION

Our results show that electrocortical function is affected only by profound systemic hypotension. This occurred at a higher level of cerebral oxygen delivery than the level associated with neuronal hypoxia and secondary cell damage.

Outcome after intrapartum asphyxia in term infants

Investigatory techniques, particularly magnetic resonance (MR) imaging and spectroscopy, performed in the early neonatal period on infants suspected of intrapartum asphyxia i.e. abnormal fetal heart recording, poor cord gases, low Apgar scores and the need for resuscitation, or with neonatal encephalopathy or seizures, have allowed a much better understanding of the patterns of brain injury and the biochemical processes that follow these events. It is usually possible to distinguish these patterns from those seen in other, often confounding, diagnoses. This has allowed far more precision about the timing of insults and in the prediction of particularly motor, feeding and visual outcome and to some extent intellectual outcome. Long-term neurological and psychometric follow-up of infants in whom detailed perinatal clinical histories and examination, haematological and biochemical investigation and MR brain scans are obtained will allow even more accurate prediction of outcome in the future. Such studies also help to validate standardized neonatal and infant clinical neurological examinations, making them useful tools to predict outcome.

Selection of babies for intervention after birth asphyxia

Based on animal experiments, the therapeutic window for neonates with signs of perinatal hypoxia-ischaemia is probably less than 6 h, and early selection of patients is of utmost importance. In term neonates, fetal heart rate and blood flow patterns, the Apgar score, and other clinical scoring systems are insufficient to select patients for intervention, whereas umbilical artery pH<7.0 combined with umbilical arteriovenous differences in PCO(2), lactate/pyruvate ratios in cord blood, and CSF interleukin-1beta have a better predictive value. At present, neurophysiological methods such as (amplitude-integrated) EEG and evoked potentials have the best predictive value. In preterm neonates, lactate/pyruvate and uric acid measurements in cord blood, as well as neurophysiology appear to be helpful to predict brain injury, and might be used to select patients for intervention.

Assessment of neonatal encephalopathy by amplitude-integrated electroencephalography

OBJECTIVE

To define normal and abnormal patterns, test interobserver variability, and the prognostic accuracy of amplitude-integrated electroencephalography (aEEG) soon after the onset of neonatal encephalopathy.

METHODS

Consecutive cases of neonatal encephalopathy (n = 56; gestation median, 40; range, 35-42 weeks) and healthy infants (n = 14; gestation median, 40; range, 39-40 weeks) were studied. aEEG was recorded using a cerebral function monitor, at median, 0, range, 0-21 days of age. Of the infants, 24 of the 56 with encephalopathy and all of the normal infants were studied within 12 hours of birth (median, 5; range, 3-12 hours). Forty infants were suspected of having suffered birth asphyxia. Criteria for normal and abnormal patterns were defined and the interobserver variability of these classifications determined. Results were compared with neurodevelopmental outcome assessed at 18 to 24 months of age. aEEG also was compared with a standard EEG and with magnetic resonance imaging.

RESULTS

The median upper margin of the widest band of aEEG activity in the control infants was 37.5 microV (range, 30-48 microV), and median lower margin was 8 microV (range, 6.5-11 microV). We classified the aEEG background activity as normal amplitude, the upper margin of band of aEEG activity >10 microV and the lower margin >5 microV; moderately abnormal amplitude, the upper margin of band of aEEG activity >10 microV and the lower margin </=5 microV; and suppressed amplitude, the upper margin of the band of aEEG activity <10 microV and lower margin <5 microV. Recordings were analyzed further for the presence of seizures, defined as periods of sudden increase in voltage accompanied by a narrowing of the band of aEEG activity. Tests of interobserver variability showed excellent agreement both for assessment of amplitude (kappa statistic = 0.85) and for identification of seizures (kappa statistic = 0.76) There was a close relationship between the aEEG and subsequent outcome: 19 of 21 infants with a normal aEEG finding were normal on follow-up at 18 to 24 months of age, whereas 27 of 35 infants with a moderately abnormal or suppressed aEEG and/or seizures died or developed neurologic abnormalities. Thus, aEEG predicted outcome with a sensitivity of 0. 93, a specificity of 0.70, positive predictive value of 0.77, negative predictive value of 0.90, and the likelihood ratio of a positive result of 3.1 and a negative result of 0.06. For the 24 infants studied within 12 hours of birth, the corresponding results were sensitivity, 1.0; specificity, 0.82; positive predictive value, 0.85; negative predictive value, 1; likelihood ratio of a positive result, 5.5; and likelihood ratio of a negative result, 0.18.

CONCLUSION

The aEEG is a simple but accurate and reproducible clinical tool that could be useful in the assessment of infants with encephalopathy.

Prediction of neurological outcome after birth asphyxia from early continuous two-channel electroencephalography

OBJECTIVE

To determine whether two-channel continuous electroencephalography (EEG) applied within 12 h of birth can predict the severity of neurological complications and neurodevelopmental outcome following birth asphyxia.

METHODS

A continuous two-channel EEG was performed within 12 h of birth in 22 infants suspected of having suffered birth asphyxia and 11 healthy control infants (22 infants at a general and 11 at a specialist paediatric unit). Criteria to categorise normal and abnormal EEG records were defined and compared with the severity of hypoxic/ischaemic encephalopathy (HIE) and with neurodevelopmental outcome, assessed at or after 12 months of age.

RESULTS

EEG recordings were commenced at a median (range) of 2 h 50 min (1 h 45 min to 12 h) after birth. Technically satisfactory recordings were obtained in all but one infant. All control infants remained asymptomatic and had a normal EEG with discernible sleep/awake periods. 12 h after birth the EEG was normal in all 12 infants suspected of asphyxia who remained well or developed grade 1 HIE and was abnormal in six of nine infants with grade II or III HIE. Fifteen of 16 infants suspected of asphyxia with a normal neurodevelopmental outcome had a normal EEG at 12 h; transient abnormalities lasting not more than 8 h had been detected in three of these infants. All five infants who died or developed neurodevelopmental abnormalities had an abnormal EEG. At 12 h of age the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratio for predicting severe (grade II or III) HIE were: 67, 100, 100, 80% and infinity and for subsequent death or neurodevelopmental impairments: 100, 94, 83, 100 and 16%, respectively. Assessment of the EEG before 12 h of age altered prognostic accuracy: 4 h after birth the sensitivity, specificity, positive and negative predictive values and the likelihood ratio for poor neurodevelopmental outcome were 100, 71, 33%, 100 and 3.7%, respectively (16 infants).

CONCLUSION

Continuous two-channel EEG is an accurate tool for assessing the severity of neurological insult soon after birth asphyxia.

Automatic EEG analysis during long-term monitoring in the ICU

To assist in the reviewing of prolonged EEGs, we have developed an automatic EEG analysis method that can be used to compress the prolonged EEG into two pages. The proposed approach of Automatic Analysis of Segmented-EEG (AAS-EEG) consists of 4 basic steps: (1) segmentation; (2) feature extraction; (3) classification; and (4) presentation. The idea is to break down the EEG into stationary segments and extract features that can be used to classify the segments into groups of like patterns. The final step involves the presentation of the processed data in a compressed form. This is done by providing the EEGer with a representative sample from each group of EEG patterns and a compressed time profile of the complete EEG. To verify the above approach, 41 6 h EEG records were assessed for normality via the AAS-EEG and conventional EEG approaches. The difference between the overall assessment via compressed and conventional EEG was within one abnormality level 100% of the time, and within one-half level for 73.6% of the records. We demonstrated the feasibility and reliability of automatically segmenting and clustering the EEG, thus allowing the reduction of a 6 h tracing to a few representative segments and their time sequence. This should facilitate review of long recordings during monitoring in the ICU.

Ischaemic and haemorrhagic brain lesions in newborns with seizures and normal Apgar scores

Serial ultrasound scans and conventional and diffusion weighted magnetic resonance imaging (MRI) were performed on 16 neonates who presented with seizures. The Apgar scores were normal and subsequently no metabolic or infective cause could be found. The aim of the study was to evaluate the extent to which early sequential imaging can elucidate the cause of seizures in apparently neurologically normal infants. Fourteen of the infants had haemorrhagic or ischaemic lesions on MRI and these were detected by ultrasound scanning in 11. Early ultrasound scanning detected the haemorrhagic lesions but the ischaemic lesions were often not seen until the end of the first week of life. Early MRI, however, was able to detect all the ischaemic lesions. The evolution of the insult could be timed by using serial ultrasound scans and a combination of diffusion weighted and conventional MRI during the first week of life, confirming a perinatal insult even in the absence of fetal distress. Although the aetiology of these lesions remains obscure, serial ultrasound scans will detect the presence of cerebral lesions in neonates presenting with isolated seizures but additional MRI sequences will give better definition on type, site, and extent of the pathology.