The early diagnosis of periventricular leukomalacia in premature infants with positive rolandic sharp waves on serial electroencephalography

Negative central activity in extremely preterm newborns: EEG characterization and relationship with brain injuries and neurodevelopmental outcome

OBJECTIVE

To characterize Negative Central Activity (NCA), an overlooked electroencephalographic activity of preterm newborns and investigate its relationship with brain injuries, dysfunction, and neurodevelopmental outcome.

METHODS

109 preterm infants (23-28 weeks) were retrospectively included. NCA were selected at the negative peak on EEG. Individual averaged NCA were automatically characterized. Brain structural data were collected from cranial ultrasounds (cUS). The neurodevelopmental outcome at two years of age was assessed by the Denver Developmental Screening Test-II.

RESULTS

Thirty-six (33%) children showed NCA: 6,721 NCA were selected, a median of 75 (interquartile range, 25/157.3) per EEG. NCA showed a triphasic morphology, with a mean amplitude and duration of the negative component of 24.6-40.0 µV and 222.7-257.3 ms. The presence of NCA on EEG was associated with higher intraventricular haemorrhage (IVH) grade on the first (P = 0.016) and worst neonatal cUS (P < 0.001) and poorer neurodevelopmental outcome (P < 0.001).

CONCLUSIONS

NCA is an abnormal EEG feature of extremely preterm newborns that may correspond to the functional neural impact of a vascular pathology.

SIGNIFICANCE

The NCA relationships with an adverse outcome and the presence/severity of IVH argue for considering NCA in the assessment of pathological processes in the developing brain network and for early outcome prediction.

Dysmaturation of sleep state and electroencephalographic activity after hypoxia-ischaemia in preterm fetal sheep

Antenatal hypoxia-ischaemia (HI) in preterm fetal sheep can trigger delayed evolution of severe, cystic white matter injury (WMI), in a similar timecourse to WMI in preterm infants. We therefore examined how severe hypoxia-ischaemia affects recovery of electroencephalographic (EEG) activity. Chronically instrumented preterm fetal sheep (0.7 gestation) received 25 min of complete umbilical cord occlusion (UCO, n = 9) or sham occlusion (controls, n = 9), and recovered for 21 days. HI was associated with a shift to lower frequency EEG activity for the first 5 days with persisting loss of EEG power in the delta and theta bands, and initial loss of power in the alpha and beta bands in the first 14 days of recovery. In the final 3 days of recovery, there was a marked rhythmic shift towards higher frequency EEG activity after UCO. The UCO group spent less time in high-voltage sleep, and in the early evening (7:02 pm ± 47 min) abruptly stopped cycling between sleep states, with a shift to a high frequency state for 2 h 48 min ± 40 min, with tonic electromyographic activity. These findings demonstrate persisting EEG and sleep state dysmaturation after severe hypoxia-ischaemia. Loss of fetal or neonatal sleep state cycling in the early evening may be a useful biomarker for evolving cystic WMI.

Acute Diffusion-Weighted Imaging Signaling Severe Periventricular Leukomalacia in Preterm Infants: Case Report and Review of Literature

Introduction: Periventricular leukomalacia occurs in up to 25% of very preterm infants resulting in adverse neurodevelopmental outcomes. In its acute phase, periventricular leukomalacia is clinically silent. Although ultrasonography is widely available, its sensitivity in the early detection of periventricular leukomalacia is low. Case Report and Published Literature: We identified a preterm infant with early diffusion-weighted imaging changes that later evolved to periventricular leukomalacia. Thirty-two cases of abnormal diffusion-weighted imaging reliably heralding severe periventricular leukomalacia in the preterm infant have been published in the literature. Notable features include the following: (1) infants were more mature preterm infants (29-36 weeks' gestation); (2) findings were often serendipitous with benign clinical courses; (3) diffusion-weighted imaging changes only were evident in the first weeks of life with later evolution to more classical abnormalities on conventional magnetic resonance imaging (MRI) or ultrasonography. Conclusion: Diffusion-weighted imaging in the first week of life may be a reliable early marker of severe periventricular leukomalacia injury in more mature preterm infants.

Predicting the Neurodevelopmental Outcome in Extremely Preterm Newborns Using a Multimodal Prognostic Model Including Brain Function Information

IMPORTANCE

Early assessment of the prognosis of preterm newborns is crucial for accurately informing parents and making treatment decisions. The currently available prognostic models rarely incorporate functional brain information from conventional electroencephalography (cEEG).

OBJECTIVE

To examine the performance of a multimodal model combining (1) brain function information with (2) brain structure information (cranial ultrasonography), and (3) perinatal and (4) postnatal risk factors for the prediction of death or neurodevelopmental impairment (NDI) in extremely preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

Preterm newborns (23-28 weeks' gestational age) admitted to the neonatal intensive care unit at Amiens-Picardie University Hospital were retrospectively included (January 1, 2013, to January 1, 2018). Risk factors from the 4 categories were collected during the first 2 weeks post delivery. Neurodevelopmental impairment was assessed at age 2 years with the Denver Developmental Screening Test II. No or moderate NDI was considered a favorable outcome. Death or severe NDI was considered an adverse outcome. Data analysis was performed from August 26, 2021, to March 31, 2022.

MAIN OUTCOMES AND MEASURES

After the selection of variables significantly associated with outcome, 4 unimodal prognostic models (considering each category of variable independently) and 1 multimodal model (considering all variables simultaneously) were developed. After a multivariate analysis for models built with several variables, decision-tree algorithms were run on each model. The areas under the curve for decision-tree classifications of adverse vs favorable outcomes were determined for each model, compared using bootstrap tests, and corrected for type I errors.

RESULTS

A total of 109 newborns (58 [53.2% male]) born at a mean (SD) gestational age of 26.3 (1.1) weeks were included. Among them, 52 (47.7%) had a favorable outcome at age 2 years. The multimodal model area under the curve (91.7%; 95% CI, 86.4%-97.0%) was significantly higher than those of the unimodal models (P < .003): perinatal model (80.6%; 95% CI, 72.5%-88.7%), postnatal model (81.0%; 95% CI, 72.6%-89.4%), brain structure model (cranial ultrasonography) (76.6%; 95% CI, 67.8%-85.3%), and brain function model (cEEG) (78.8%; 95% CI, 69.9%-87.7%).

CONCLUSIONS AND RELEVANCE

In this prognostic study of preterm newborns, the inclusion of brain information in a multimodal model was associated with significant improvement in the outcome prediction, which may have resulted from the complementarity of the risk factors and reflected the complexity of the mechanisms that interfered with brain maturation and led to death or NDI.

CARFS7: A guide and proforma for reading a preterm neonate's EEG

OBJECTIVES

The important role of the EEG in preterm and term babies in investigating brain function and seizures, predicting outcomes, evaluating therapeutic interventions and decision-making is being increasingly acknowledged. Development of the brain in the last trimester of pregnancy results in rapid changes in the EEG patterns in this period. Acquiring and interpreting the EEG of a preterm baby can be challenging. The aim of this study was to develop a proforma titled CARFS⁷ (Continuity, Amplitude, Reactivity, Frequency, Synchrony, Symmetry, Sleep, Sharps, Shapes, Size and Seizures) to enable neurologists to read EEGs of premature babies with greater confidence, ease and accuracy and produce a report more easily repeatable and homogenous among operators.

METHODS

The CARFS⁷proforma was developed based on a literature review and the personal experience of the authors. The parameters of the EEG evaluated and scored in the proforma are Continuity, Amplitude, Reactivity/Variability, Frequency, Synchrony, Symmetry, Sleep, Sharps, Shapes/Patterns, Size and Seizures. We also assessed the interrater reliability of the proposed scoring system incorporated in the proforma.

RESULTS

CARFS⁷ proforma incorporates a number of parameters that help evaluate the preterm EEG. The interrater reliability of the proposed scoring system in the CARFS⁷proforma was high.

CONCLUSIONS

CARFS⁷ is a user friendly proforma for reading EEGs in the preterm infant. Interrater reliability using Cohen's k shows high agreement between two child neurologists who independently rated the EEGs of 25 premature babies using this proforma. CARFS⁷ has the potential to provide, accurate, reproducible and valuable information on brain function in the preterm infant in clinical practice.

Dysmature patterns of newborn EEG recordings: Biological markers of transitory brain dysfunction or brain injury

Perinatal hypoxic-ischemic brain injury is a major cause of non-progressive neurological deficits in children. Dysmature patterns can be seen in newborns' electroencephalograms (EEGs) and may have prognostic value for long-term outcomes.

OBJECTIVE

To investigate the prognostic value of dysmature EEG patterns in term or near-term newborns.

METHODS

Neonates with dysmature patterns in their first neonatal EEG, assessed during a 6-year period from January 2010 to December 2015, were included in the study. Their outcomes at their follow-ups in June 2019 (at the age of 3 years or more) were assessed, and the presence of neurological deficits and/or epilepsy was noted.

RESULTS

We identified 347 neonates with video-EEG recordings during the observed period, in which 10 neonates had dysmature patterns in their first EEG. Eight were born at term and two were born late preterms, born at the 35 and 36-week gestational age. The reasons for admission were HIE grade I in 2 patients, grade II in 6 neonates, and heart problems in 2 patients. The second EEG was recorded at different time intervals, in 7 infants between 1 and 6 weeks; three infants had second EEG much later and were excluded from the study. Six of seven infants showed normal background activity (BA), and five had sharp waves over different regions, all six had normal developmental outcomes. One child with dysrhythmic pattern in the second EEG was diagnosed with genetic encephalopathy, developed spastic cerebral palsy and died due to severe pneumonia at the age of 6 years.

CONCLUSION

Dysmature patterns may reflect transitory brain dysfunctions. Neonatal EEG tests remain reliable and important diagnostic tool in the very first weeks of life, particularly due to the availability of sequential EEG recordings and interpretations.

Technical recommendations and interpretation guidelines for electroencephalography for premature and full-term newborns

Electroencephalography (EEG) of neonatal patients is amongst the most valuable diagnostic and prognostic tool. EEG recordings, acquired at the bedside of infants, evaluate brain function and the maturation of premature and extremely premature infants. Strict conditions of acquisition and interpretation must be respected to guarantee the quality of the EEG and ensure its safety for fragile children. This article provides guidance for EEG acquisition including: (1) the required equipment and devices, (2) the modalities of installation and asepsis precautions, and (3) the digital signal acquisition parameters to use during the recording. The fundamental role of a well-trained technician in supervising the EEG recording is emphasized. In parallel to the acquisition recommendations, we present a guideline for EEG interpretation and reporting. The successive steps of EEG interpretation, from reading the EEG to writing the report, are described. The complexity of the EEG signal in neonates makes artefact detection difficult. Thus, we provide an overview of certain characteristic artefacts and detail the methods for eliminating them.

Impact of prematurity on neurodevelopment

The consequences of prematurity on brain functional development are numerous and diverse, and impact all brain functions at different levels. Prematurity occurs between 22 and 36 weeks of gestation. This period is marked by extreme dynamics in the physiologic maturation, structural, and functional processes. These different processes appear sequentially or simultaneously. They are dependent on genetic and/or environmental factors. Disturbance of these processes or of the fine-tuning between them, when caring for premature children, is likely to induce disturbances in the structural and functional development of the immature neural networks. These will appear as impairments in learning skills progress and are likely to have a lasting impact on the development of children born prematurely. The level of severity depends on the initial alteration, whether structural or functional. In this chapter, after having briefly reviewed the neurodevelopmental, structural, and functional processes, we describe, in a nonexhaustive manner, the impact of prematurity on the different brain, motor, sensory, and cognitive functions.

New means to assess neonatal inflammatory brain injury

Preterm infants are especially vulnerable to infection-induced white matter injury, associated with cerebral palsy, cognitive and psychomotor impairment, and other adverse neurological outcomes. The etiology of such lesions is complex and multifactorial. Furthermore, timing and length of exposure to infection also influence neurodevelopmental outcomes. Different mechanisms have been posited to mediate the observed brain injury including microglial activation followed by subsequent release of pro-inflammatory species, glutamate-induced excitotoxicity, and vulnerability of developing oligodendrocytes to cerebral insults. The prevalence of such neurological impairments requires an urgent need for early detection and effective neuroprotective strategies. Accordingly, noninvasive methods of monitoring disease progression and therapy effectiveness are essential. While diagnostic tools using biomarkers from bodily fluids may provide useful information regarding potential risks of developing neurological diseases, the use of magnetic resonance imaging/spectroscopy has emerged as a promising candidate for such purpose. Various pharmacological agents have demonstrated protective effects in the immature brain in animal models; however, few studies have progressed to clinical trials with promising results.

The whole spectrum of cystic periventricular leukomalacia of the preterm infant: results from a large consecutive case series

PURPOSE

The purpose of this study is to describe features of cystic periventricular leukomalacia (PVL) in a large consecutive cohort study including long-term neurodevelopmental follow-up.

METHODS

We performed a retrospective single-centre cohort study including all preterm infants ≤35 weeks of gestational age with PVL diagnosed by ultrasound scans (US) from a tertiary care university hospital between 1988 and 2012.

RESULTS

The majority of 160 consecutively diagnosed cases had a gestational age between 28 and 32 weeks (60.6%), and male sex was predominant (60.6%). The most common associated clinical findings included respiratory distress syndrome, preterm premature rupture of the membranes, and chorioamnionitis (57.5, 49.4, and 39.4%, respectively). Infants presented with apnoeas in 66.3 and neonatal seizures in 23.1%. Any kind of respiratory support was present in 75.0%. Associated low-grade intraventricular haemorrhage was evident in 33.1, high-grade haemorrhage in 9.4%. Cysts were located on both hemispheres in 75% and PVL grades 3 and 4 were predominant (75.6%). Neurodevelopmental follow-up of 146 cases at a median age of 72 months revealed normal development in 11.0, mental retardation in 50.0, and cerebral palsy in 83.6%. Visual impairment was diagnosed in 21.9% and hearing impairment in one case. A quarter of cases (27.4%) developed seizure disorders. Outcome data were significantly better in unilateral compared to bilateral PVL.

CONCLUSIONS

Long-term neurodevelopmental outcome of bilateral PVL always was adverse and different from unilateral PVL. The latter might be negatively influenced by associated intra- and periventricular haemorrhages.

Stem cell therapy for neonatal hypoxic-ischemic encephalopathy

Treatments for neonatal hypoxic-ischemic encephalopathy (HIE) have been limited. The aim of this paper is to offer translational research guidance on stem cell therapy for neonatal HIE by examining clinically relevant animal models, practical stem cell sources, safety and efficacy of endpoint assays, as well as a general understanding of modes of action of this cellular therapy. In order to do so, we discuss the clinical manifestations of HIE, highlighting its overlapping pathologies with stroke and providing insights on the potential of cell therapy currently investigated in stroke, for HIE. To this end, we draw guidance from recommendations outlined in stem cell therapeutics as an emerging paradigm for stroke or STEPS, which have been recently modified to Baby STEPS to cater for the “neonatal” symptoms of HIE. These guidelines recognized that neonatal HIE exhibit distinct disease symptoms from adult stroke in need of an innovative translational approach that facilitates the entry of cell therapy in the clinic. Finally, new information about recent clinical trials and insights into combination therapy are provided with the vision that stem cell therapy may benefit from available treatments, such as hypothermia, already being tested in children diagnosed with HIE.

ADVANCES IN THE CELL-BASED TREATMENT OF NEONATAL HYPOXIC-ISCHEMIC BRAIN INJURY

Stem cell therapy for adult stroke has reached limited clinical trials. Here, we provide translational research guidance on stem cell therapy for neonatal hypoxic-ischemic brain injury requiring a careful consideration of clinically relevant animal models, feasible stem cell sources, and validated safety and efficacy endpoint assays, as well as a general understanding of modes of action of this cellular therapy. To this end, we refer to existing translational guidelines, in particular the recommendations outlined in the consortium of academicians, industry partners and regulators called Stem cell Therapeutics as an Emerging Paradigm for Stroke or STEPS. Although the STEPS guidelines are directed at enhancing the successful outcome of cell therapy in adult stroke, we highlight overlapping pathologies between adult stroke and neonatal hypoxic-ischemic brain injury. We are, however, cognizant that the neonatal hypoxic-ischemic brain injury displays disease symptoms distinct from adult stroke in need of an innovative translational approach that facilitates the entry of cell therapy in the clinic. Finally, insights into combination therapy are provided with the vision that stem cell therapy may benefit from available treatments, such as hypothermia, already being tested in children diagnosed with hypoxic-ischemic brain injury.

EEG for predicting early neurodevelopment in preterm infants: an observational cohort study

OBJECTIVE

To clarify the prognostic value of conventional EEG for the identification of preterm infants at risk for subsequent adverse neurodevelopment in the current perinatal care and medicine setting.

METHODS

We studied 780 EEG records of 333 preterm infants born <34 weeks' gestation between 2002 and 2008. Serial EEG recordings were conducted during 3 time periods; at least once each within days 6 (first period), during days 7 to 19 (second period), and days 20 to 36 (third period). The presence and the grade of EEG background abnormalities were assessed according to an established classification system. Neurodevelopmental outcomes were assessed at a corrected age of 12 to 18 months.

RESULTS

Of the 333 infants, 33 (10%) had developmental delay and 34 (10%) had cerebral palsy. The presence of EEG abnormalities was significantly predictive of developmental delay and cerebral palsy at all 3 time periods: the first period (n = 265; odds ratio [OR], 4.5; 95% confidence interval [CI], 2.2-9.4), the second period (n = 278; OR, 7.6; 95% CI, 3.6-16), and the third period (n = 237; OR, 5.9; 95% CI, 2.8-13). The grade of EEG abnormalities correlated with the incidence of developmental delay or cerebral palsy in all periods (P < .001). After controlling for other clinical variables, including severe brain injury, EEG abnormality in the second period was an independent predictor of developmental delay (OR, 3.2; 95% CI, 1.1-9.7) and cerebral palsy (OR, 6.8; 95% CI 2.0-23).

CONCLUSIONS

EEG abnormalities within the first month of life significantly predict adverse neurodevelopment at a corrected age of 12 to 18 months in the current preterm survivor.

Electroencephalography in premature and full-term infants. Developmental features and glossary

Following the pioneering work of C. Dreyfus-Brisac and N. Monod, research into neonatal electroencephalography (EEG) has developed tremendously in France. French neurophysiologists who had been trained in Paris (France) collaborated on a joint project on the introduction, development, and currently available neonatal EEG recording techniques. They assessed the analytical criteria for the different maturational stages and standardized neonatal EEG terminology on the basis of the large amount of data available in the French and the English literature. The results of their work were presented in 1999. Since the first edition, technology has moved towards the widespread use of digitized recordings. Although the data obtained with analog recordings can be applied to digitized EEG tracings, the present edition, including new published data, is illustrated with digitized recordings. Herein, the reader can find a comprehensive description of EEG features and neonatal behavioural states at different gestational ages, and also a definition of the main aspects and patterns of both pathological and normal EEGs, presented in glossary form. In both sections, numerous illustrations have been provided. This precise neonatal EEG terminology should improve homogeneity in the analysis of neonatal EEG recordings, and facilitate the setting up of multicentric studies on certain aspects of normal EEG recordings and various pathological patterns.

Chronologic changes in neonatal EEG findings in periventricular leukomalacia

OBJECTIVE

This study sought to clarify chronologic changes in neonatal electroencephalographic (EEG) findings in periventricular leukomalacia (PVL).

METHODS

We obtained serial EEG findings for all premature infants who were admitted to our hospital at gestational age of < or =33 weeks between 1997 and 2006. EEG recordings were obtained on days 1 to 4, 5 to 14, 15 to 28, 29 to 56, and 57 to 84. Abnormal EEG findings were classified as acute-stage abnormalities (ASAs) or chronic-stage abnormalities (CSAs) and were subclassified as mild, moderate, or severe. PVL was classified as noncystic, localized cystic, or extensive cystic. The final diagnosis of PVL was made through neurologic assessment and MRI findings at 24 months.

RESULTS

Fifty-five infants were diagnosed as having PVL, including 23 with noncystic PVL, 9 with localized cystic PVL, and 23 with extensive cystic PVL. ASAs were observed most frequently on days 1 to 4 and were observed rarely thereafter in all groups. CSAs were observed most frequently on days 5 to 14, were most severe on days 5 to 14, and then resolved within 1 to 2 months in all groups. CSAs in patients with extensive cystic PVL were more severe and persisted longer, compared with other groups. ASA and CSA severity was correlated with PVL severity.

CONCLUSIONS

EEG findings in PVL differed according to the severity of PVL and the time of recording. To detect PVL, > or =2 EEG recordings are recommended, 1 within 48 hours after birth, to detect ASAs, and 1 in the second week of life, to detect CSAs.

Cerebrovascular injury in premature infants: current understanding and challenges for future prevention

Cerebrovascular insults are a leading cause of brain injury in premature infants, contributing to the high prevalence of motor, cognitive, and behavioral deficits. Understanding the complex pathways linking circulatory immaturity to brain injury in premature infants remains incomplete. These mechanisms are significantly different from those causing injury in the mature brain. The gaps in knowledge of normal and disturbed cerebral vasoregulation need to be addressed. This article reviews current understanding of cerebral perfusion, in the sick premature infant in particular, and discusses challenges that lie ahead.

[Pathological patterns in neonatal EEG before 30 weeks of gestational age]

Pathological features on very premature EEG concern background abnormalities and abnormal patterns. Positive rolandic sharp waves keep an important place regarding diagnosis and prognosis. Background abnormalities give essential complementary informations. Unusual patterns (abnormal localisation or morphological aspect, high amplitude) remain early markers of cerebral lesions. Analysis of these pathological features must always take into account treatment given to the baby, which can by itself modify the EEG.

Quantitative electroencephalographic patterns in normal preterm infants over the first week after birth

BACKGROUND

Currently available tools to assist clinicians with prediction of neurodevelopmental outcome of preterm infants are inadequate. Modified cotside electroencephalography (EEG) has the ability to produce quantitative electrophysiologic measures. These measures may be useful in future prediction of outcome.

AIM

To determine patterns of change in quantitative EEG measures in preterm infants during their first week after birth.

DESIGN

Observational.

SUBJECTS

Preterm infants born at less than 32 weeks completed gestation surviving to discharge with unremarkable serial ultrasound scans.

OUTCOME MEASURES

Changes in continuity, amplitude and spectral edge frequency measures of EEGs obtained over the first week after birth.

RESULTS

Results of EEGs performed using a novel EEG device on 63 infants are reported here. Their median (range) gestation was 29 (24-31) weeks and birthweight was 1,235 (540-1,980) g. Quantitative measures of EEG continuity increased over the first week after birth from 72 (25-99)% to 92 (54-100)% at the 25 microV threshold, and from 39 (10-87)% to 64 (34-75)% at the 50 microV threshold, both p<0.0001. There was a related 32% increase in median amplitude from 5.8 (2.6-10.6) microV on day 1 to 7.6 (4.3-9.4) microV on day 4, p=0.005. There was a trend for average spectral edge frequency to fall from 10.7 (9.3-12.9) Hz on day 1 to 9.9 (8.1-12.3) Hz on day 3, p=0.06. Each gestational tertile showed similar patterns.

CONCLUSIONS

There are consistent changes in quantitative neurophysiologic measures over the first week after birth, and particularly measures of continuity over the first 4 days, in normal preterm infants.

[Interest of EEG in full-term newborns with isolated unilateral ischemic stroke]

In full-term newborns, unilateral and recurrent clonic seizures which occur during the first 48 hours of life suggest an isolated unilateral ischemic stroke. These focal seizures are isolated, occuring during a short period, or make up a status epilepticus. Electroencephalogram (EEG) is a key tool for crisis and focal cerebral process diagnosis. It also allows to assess antiepileptic drugs effectiveness. But cerebral imaging is necessary to confirm vascular origin of the cerebral impairment. Hematologic data are also needful to look for a family thromphilia. Some particular unilateral EEG abnormalities could be associated with controlateral motor sequelae or long term behavioral problems. These findings may be used for prospective studies aimed at specifying possible links between EEG abnormalities and long term outcome.

Electroencephalography and brain damage in preterm infants

Electroencephalography (EEG) is a sensitive method for detection of brain injury in preterm infants. Although the acute and chronic EEG changes are mainly non-specific regarding type of damage, they correlate with later neurological and cognitive function. In infants developing brain white matter damage, acute EEG findings include depression of background activity and presence of epileptic seizure activity. The chronic EEG changes associated with white matter injury and abnormal neurological development include delayed maturation, and presence of abundant Rolandic sharp waves. Cognitive limitations in preterm infants have been associated with changes in various sleep measures in EEG's recorded at full term. Continuous EEG-monitoring during neonatal intensive care shows that cerebral electrical activity during this vulnerable period can be affected by several extracerebral factors, e.g. cerebral blood flow, acidosis and some commonly used medications. For diagnosis of brain damage in preterm infants with neurophysiological methods, a combination of early continuous EEG monitoring during the initial intensive care period and full EEG, performed at later stages, is probably optimal.

Fetal and neonatal inflammatory response and adverse outcome

This article will define the concept of fetal/neonatal inflammatory response, and examine the complex interaction between inflammation and neurotoxicity. There appear to be important interactions between infection/inflammation and hypoxia-ischaemia leading to cytokine release and subsequent brain injury. This article will also define adverse outcome and summarize the complexities inherent to neurodevelopmental assessment. Finally, this article will investigate the currently available evidence suggesting a link between inflammatory response and adverse neurodevelopmental outcome, and focus on those variables that need further study: timing and nature of the infectious/inflammatory process; established and new anti-insult strategies; morbidity in organs other than the brain; genetic influences; and environmental factors.

Positive temporal sharp waves in preterm infants with and without brain ultrasound lesions

OBJECTIVE

Clinical significance of neonatal positive temporal sharp waves (PTS) is controversial. The aim of this work is to study (1) PTS incidence in preterm infants with or without major ultrasound lesion (MUL) per gestational age (GA), and (2) the relationship between PTS in both sleep states and other electroencephalographic (EEG) findings with poor prognoses.

METHODS

97 preterm infants of <27-36 weeks GA, and 12 full-term healthy infants were presented. Prospective study included (1) neurodevelopmental assessment at 40-42 weeks conceptional age (CA), (2) serial neurosonography, and (3) EEG recording at postnatal week 1, 2, 4 and at 40-42 weeks CA.

RESULTS

In 50 neonates without MUL, peak PTS was at 31-32 weeks GA. In 47 neonates with MUL, PTS increased significantly from week 2 after birth, descending at the 4th. Neonates of <33 weeks GA with MUL showed significantly increased PTS at term. A significant relationship was found between PTS and other EEG abnormalities with poor neurologic prognoses. PTS incidence varied with sleep states, being predominant in indeterminate sleep in neonates with MUL.

CONCLUSIONS

PTS increased significantly in infants with MUL, mainly at week 2 of postnatal life, persisting high until term CA, and correlated with other abnormal EEG findings.

SIGNIFICANCE

PTS are highly sensitive to MUL.

Sharp waves in preterm infants with periventricular leukomalacia

We studied the incidence of positive and negative sharp waves in two pairs of twin infants with periventricular leukomalacia and compared it with that of normal cotwins by using remontage and refiltering functions of digital electroencephalography. Three electroencephalograms were serially performed in each infant. After the usual visual inspection with bipolar montage and low-cut filter of 0.5 Hz, the electroencephalogram montage was changed into monopolar derivation, and the low-cut filter into 5 Hz. The number of positive or negative sharp waves per minute, with an amplitude of more than 50 microV, was independently calculated. The number of negative sharp waves was large in the occipital and Pz areas in both infants with periventricular leukomalacia. The number of positive ones was large in the Cz area in both infants with periventricular leukomalacia. Disorganized patterns were observed in all electroencephalograms in the infants with periventricular leukomalacia on visual inspection. In conclusion, digital electroencephalography analysis using remontage and refiltering demonstrated an increased number of sharp transients in preterm infants with periventricular leukomalacia. The application of a higher low-cut filter will be useful for the assessment of sharp transients in neonatal electroencephalography.

Abnormal sharp transients on electroencephalograms in preterm infants with periventricular leukomalacia

OBJECTIVE

To determine the clinical significance of abnormal sharp transients other than positive rolandic sharp waves (PRS), electroencephalograms were used for the diagnosis of periventricular leukomalacia (PVL).

STUDY DESIGN

We evaluated 126 electroencephalograms from 93 preterm infants; 31 infants had PVL, and 62 were control infants. Frontal sharp waves (FS) were defined as sharp transients of positive polarity with an amplitude >100 microV. Occipital sharp waves (OS) were defined as those of negative polarity with an amplitude >150 microV. FS, OS, or PRS were considered to be present when there were >0.1 per minute.

RESULTS

The number of FS per minute was significantly higher in the PVL group than in the control group during days 0 to 4 and 5 to 7. The number of OS per minute was also significantly higher in the PVL group than in the control group during days 0 to 4, 5 to 7, and 8 to 14. The sensitivity of FS or OS was relatively high but that of PRS was low. The presence of two or more types of abnormal sharp transients was correlated with a poor outcome.

CONCLUSIONS

FS or OS may be useful for predicting which infant will have PVL.

[EEG and ischemic stroke in full-term newborns]

The aims of this study were to describe EEG anomalies in unilateral neonatal ischemic stroke without hypoxic-ischemic encephalopathy, and to determine possible links between these abnormalities and long-term outcome. In 6 full-term newborns without severe fetal distress ischemic stroke was confirmed by computed tomography and/or magnetic resonance imaging. Twenty EEGs were recorded during the neonatal period, 5 in acute stage and 15 later. The duration of the follow-up ranged from 3 to 9 years. All newborns developed unilateral clonic seizures, right-sided (5 cases) or left-sided (1 case); seizures began between 14 and 48 h of life. At follow-up, 3 children were normal at 2 and 6 years of age, while the 3 others had sequelae: epilepsy at 9 years of age in one, and unilateral mild cerebral palsy in the 2 others (3 and 4 years of age), with behavioral problems in one of them. Critical EEG discharges, rhythmic sharp waves and/or slow waves were recorded on the injured side. Abnormalities of interictal activity were excess of alpha or theta rhythms, transitory EEG discontinuity or low voltage. The 2 children with cerebral palsy had numerous unilateral post-ictal positive rolandic slow sharp waves (PRSSWs), which were similar to the positive rolandic sharp waves of premature infants; the child with behavioral problems had numerous positive left-sided temporal fast sharp waves. PRSSWs could be associated with contralateral motor sequelae, while positive left temporal fast sharp waves were associated with long term behavioral problems. These findings may be used for future prospective studies aimed at specifying the relation between EEG abnormalities and long-term outcome.

Lowered electroencephalographic spectral edge frequency predicts the presence of cerebral white matter injury in premature infants

OBJECTIVE

Current methods for early identification of cerebral white matter injury in the premature infant at the bedside are inadequate. This study investigated the utility of advanced spectral analysis of the neonatal electroencephalogram (EEG) in the early diagnosis of white matter injury in the premature infant. The critical measurement used, suggested largely by previous studies in animal models, was the spectral edge frequency (SEF), calculated here as the frequency below which 90% of the power in the EEG exists.

METHODS

Fifty-nine very low birth weight infants (87% of eligible infants) had electrodes placed over the central and parietal regions (C3, P3, C4, and P4 sites according to the 10-20 international system) for the collection of EEG amplitude, intensity, and SEF. All averaged signals were analyzed off-line using software (Chart Analyzer; BrainZ Instruments, Auckland, NZ). All infants had a magnetic resonance imaging scan at term to identify the presence and severity of white matter injury.

RESULTS

There was no significant difference between conventional EEG amplitude and intensity for infants with or without evidence of white matter injury. However, premature infants with increasingly severe white matter injury had progressively lower SEFs compared with infants who did not exhibit white matter injury.

CONCLUSIONS

These data suggest that SEF-based measures are useful for defining the presence and severity of white matter injury at the bedside.

[Early cerebral MRI in preterm infants: correlations with EEG and outcome]

AIM OF THE STUDY

Assess the potential benefits of performing an early cerebral MRI to evaluate the gravity of cerebral lesions among premature neonates at risk of neurologic sequels and establish correlations between EEG findings, abnormal neuroimaging findings and neurodevelopment.

METHODS

A MRI was performed in 34 premature newborn babies with abnormal neurological clinical signs, and/or with two abnormal EEG and/or with two abnormal cerebral ultrasound scans. The mean age and the adjusted age of our population were 5 weeks (range 1-11 weeks) and 35 weeks of adjusted age (range 29-40 weeks) respectively. The neuroimaging findings were correlated to the results of three EEGs (recorded before 15 days old, between 15 days and one month old, and after the first month of life) and to neurodevelopment.

RESULTS

Two statically significant correlations were found between: 1) the severity of brain injuries observed in MRI and the results of the latest EEG (sensitivity 100%, specificity 60%), 2) the severity of brain injuries observed in MRI and abnormal neurodevelopment (sensitivity 75%, specificity 80%). There was no correlation between the abnormal development and the results of EEG recordings.

CONCLUSION

Early cerebral MRI is justified in a selected premature population. It is useful for the diagnosis, the evaluation of the severity of brain injury and for the management of these children. The correlation with EEGs traces allows the detection of the majority of prematures babies that will develop sequels.

Normal EEG in very premature infants: reference criteria

OBJECTIVES

Objectives were to precise EEG criteria of normality in very premature infants.

METHODS

The neonatal electroencephalograms (EEGs) of 17 neurologically normal very premature infants recorded at a conceptional age (CA) of 26-28 weeks have been analyzed. The normality of the infants was defined as normal neonatal cranial ultrasound scans and normal neurological outcome at a minimum postnatal age of 2 years.

RESULTS

All tracings were discontinuous. The bursts (amplitude >/=30 microV) were interhemispherically synchronous and lasted up to 3 min. The interburst intervals lasted up to 46 s. EEG patterns consisted mainly of slow waves (</=3 Hz), with high amplitude (up to 300 microV), occipital predominance and superimposed alpha, beta and theta rhythms. High amplitude theta rhythms predominated on temporal areas, beta rhythms were mainly central, whereas alpha rhythms were central and occipital. Sleep state differentiation began as early as 26 weeks CA. On a given trace, the existence of more mature graphoelements than expected for the CA reflected a normal increasing maturation.

CONCLUSIONS

EEG has constant and reproductible patterns in normal very premature infants. This can constitute a basis for the determination of EEG criteria for neurological prognosis in infants of 26-28 weeks CA.

Occipital sawtooth: a physiological EEG pattern in very premature infants

OBJECTIVE

To evaluate EEG maturational features in preterm infants below 27 weeks postmenstrual age.

METHODS

EEGs recorded from 5 preterm infants (postmenstrual age 24-26 weeks) were examined and selected maturational features were scored and quantified. The five infants also had serial cranial ultrasound scans (US) and magnetic resonance images of the brain within the first weeks after birth.

RESULTS

Background activity was markedly discontinuous in all patients and very variable. Temporal sawtooths occurred but less frequently than in older preterm infants. All 5 infants also showed a particular novel feature, characterized by rhythmic, regularly shaped, medium-high amplitude 4-7 Hz activities, lasting 0.5-3 s and located in the occipital regions. This pattern was symmetrical but sometimes asynchronous.

CONCLUSIONS

Occipital sawtooth, so called because it shares shape and frequency with temporal sawtooth but has an occipital localisation, constitutes a physiological EEG pattern characteristic of premature infants between 24 and 26 weeks of postmenstrual age.

The relationships between antenatal management, the cause of delivery and neonatal outcome in a large cohort of very preterm singleton infants

OBJECTIVE

To determine whether the cause of very preterm delivery influences neonatal outcome.

DESIGN

A cohort study of 685 consecutive singletons born before 33 weeks of gestation.

METHODS

Causes of birth and perinatal outcome variables were correlated for statistical significance by uni- and multi-variate analyses.

RESULTS

Intrauterine growth retardation or pre-eclampsia were associated with a higher rate of respiratory distress syndrome compared with prolonged rupture of membranes, after controlling for gestational age, antenatal corticosteroid therapy, antenatal antibiotic administration, mode of delivery and origin (inborn or outborn) (adjusted OR 3.12; 95% CI 1.55-6.28). The prevalence of grade 3-4 intraventricular haemorrhage or cystic periventricular leukomalacia was 25% in newborn babies born after intrauterine infection or prolonged rupture of membranes. Among infants born after intrauterine growth retardation/pre-eclampsia, the rate of severe intraventricular haemorrhage was 3.2% and the rate of periventricular leukomalacia was 0.9%. Compared with intrauterine infection and after controlling for potential confounding covariates, intrauterine growth retardation/pre-eclampsia was associated with a lower rate of periventricular leukomalacia (adjusted OR 0.08; 95% CI 0.02-0.41). In the same multiple logistic regression model, antenatal corticosteroid administration was associated with a lower incidence of periventricular leukomalacia (adjusted OR 0.36; 95% CI 0.16-0.79).

CONCLUSIONS

The cause of very preterm delivery has an important influence on neonatal outcome.

Antenatal glucocorticoid treatment and cystic periventricular leukomalacia in very premature infants

BACKGROUND

Antenatal glucocorticoid therapy decreases the incidence of several complications among very premature infants. However, its effect on the occurrence of cystic periventricular leukomalacia, a major cause of cerebral palsy, remains unknown.

METHODS

We retrospectively analyzed a cohort of 883 live-born infants, with gestational ages ranging from 24 to 31 weeks, who were born between January 1993 and December 1996 at three perinatal centers in the Paris area. The mothers of 361 infants had received betamethasone before delivery, the mothers of 165 infants had received dexamethasone before delivery, and the mothers of 357 infants did not receive glucocorticoids. We compared the rates of cystic periventricular leukomalacia among the three groups of infants in bivariate and multivariate analyses after adjustment for confounding factors.

RESULTS

The rate of cystic periventricular leukomalacia was 4.4 percent among the infants whose mothers had received betamethasone, 11.0 percent among the infants whose mothers had received dexamethasone, and 8.4 percent among the infants whose mothers had not received a glucocorticoid. After adjustment for gestational age, the mode of delivery, and the presence or absence of chorioamnionitis, prolonged interval between the rupture of membranes and delivery (>24 hours), preeclampsia, and the use of tocolytic drugs, antenatal exposure to betamethasone was associated with a lower risk of cystic periventricular leukomalacia than was either the absence of glucocorticoid therapy (adjusted odds ratio, 0.5; 95 percent confidence interval, 0.2 to 0.9) or exposure to dexamethasone (adjusted odds ratio, 0.3; 95 percent confidence interval, 0.1 to 0.7). The adjusted odds ratio for the group of infants whose mothers had received dexamethasone as compared with the group of infants whose mothers had not received a glucocorticoid was 1.5 (95 percent confidence interval, 0.8 to 2.9).

CONCLUSIONS

Antenatal exposure to betamethasone but not dexamethasone is associated with a decreased risk of cystic periventricular leukomalacia among very premature infants.

Neonatal EEG: a powerful tool in the assessment of brain damage in preterm infants

Serial EEG recordings beginning immediately after birth are not only of great diagnostic and prognostic value but also useful to elucidate the timing and the mode of brain injuries in the preterm newborn. It is extremely useful to distinguish between acute stage and chronic stage EEG abnormalities. The former is characterized by findings of acute depression such as increased discontinuity, decreased faster frequency activities, and lowered amplitudes. The latter mainly includes dysmature patterns and disorganized patterns. The timing of brain insult can be assessed by considering EEG findings in relation to the time of birth. Different modes of brain injury are associated with different types of EEG abnormalities and different types of neurological outcome. Sudden strong brain insults are usually associated with findings of severe depression followed by disorganized pattern and later cerebral palsy, while persistent mild insults are usually associated with prolonged mild depression followed by dysmature pattern and later mental retardation. Routine serial EEG studies in preterm infants demonstrated that one fourth of cerebral palsies in these infants were of antenatal origin, two thirds of perinatal origin and postnatal injuries played the least role. Periventricular leucomalacia (PVL) manifesting itself on the ultrasound in the late neonatal period and suggesting postnatal origin was often found to be of antenatal origin with an EEG soon after birth. PVL without apparent causes was often associated with abnormal fetal heart rate patterns and early neonatal EEG abnormalities, and considered to have originated in the antepartum period.

Genetic features of Streptococcus agalactiae strains causing severe neonatal infections, as revealed by pulsed-field gel electrophoresis and hylB gene analysis

A collection of 114 independent Streptococcus agalactiae strains, including 54 strains isolated from the cerebrospinal fluid (CSF) samples of neonates and 60 strains from asymptomatic patients, was characterized by pulsed-field gel electrophoresis (PFGE) of DNA restricted with SmaI and by PCR analysis of the hylB gene. All strains were previously studied by multilocus enzyme electrophoresis (MLEE) (R. Quentin, H. Huet, F.-S. Wang, P. Geslin, A. Goudeau, and R. K. Selander, J. Clin. Microbiol. 33:2576-2581, 1995). Among these 114 strains, there were 92 PFGE patterns. Eleven genetic groups (A to K) were identified with 38% divergence. A more homogeneous group (PFGE group A) was defined, consisting of 73% of the strains previously identified as belonging to a particular MLEE phylogenetic group. A 162-kb fragment was identified as a marker of strains that invaded the central nervous system of neonates. It was detected in 69% of the PFGE patterns obtained with CSF isolates and in only 1.8% of the PFGE patterns obtained with carrier strains. The hylB gene encoding hyaluronate lyase was amplified for all strains in our collection. Ten of 15 isolates belonging to an MLEE subgroup, previously described as being likely to cause invasive infection, had an insertion in the hylB gene (IS1548).

[Electroencephalography of the premature and term newborn. Maturational aspects and glossary]

From the first publication of C. Dreyfus-Brisac and N. Monod, a strong tradition combined with tremendous development of neonatal EEG has taken place in France. After 3 years of collaborative work, 12 clinical neurophysiologists trained at the Port-Royal medical school in Paris detail in this paper the currently available neonatal EEG recording techniques. They have synthesized the criteria of maturational state analysis and have defined the normal and pathological neonatal EEG patterns, including descriptions already present in the French as well as the English literature. In this review one may find a complete description of neonatal EEG patterns according to the states of vigilance and to gestational age. Furthermore, definitions of all normal and pathological patterns are provided in a glossary. Both chapters are illustrated by numerous figures. This detailed terminology in neonatal EEG should allow a better homogeneity in EEG reports, and could lead to multicentric studies on normal, unusual or pathological patterns, according to etiology. Although based on analogic EEG data, this work can equally be applied to digitized EEG tracings.