Duration Of Interburst Interval Research Articles

Continuous electroencephalography (cEEG) in infants with congenital heart disease (CHD).

Neonates with congenital heart disease (CHD) undergoing cardiopulmonary bypass (CPB) surgery have increased risk of impaired neurodevelopmental outcomes secondary to brain injury. This study aims to characterize pre- and post-operative continuous EEG (cEEG) patterns to detect abnormal cerebral activity in infants with CHD and investigate whether an association exists between the degree of encephalopathy in pre- and post-operative cEEG. This retrospective cohort study conducted between 2010 and 2018 at a tertiary hospital in Cleveland, OH included infants with CHD with cEEG monitoring, who underwent CPB surgery within first6 months of life. Study included 77 patients, of which 61% weremales who were operated at median age 6 days. Pre-operatively, 69% and 87% had normal cEEG and sleep-wake cycles, respectively. Post-operatively, 80% had abnormal cEEG. Longer circulatory arrest time and CPB were associated with lack of continuity (p 0.011), excessive discontinuity (p 0.007) and prolonged inter-burst interval (IBI) duration (p value < 0.001). A significant association existed between severity of encephalopathy in immediate and 24-h post-operative period (p value < 0.001). More than 80% of neonates with CHD have abnormal post-operative EEG. Longer circulatory arrest time and CPB were associated with lack of continuity, excessive discontinuity, and prolonged IBI duration on post-operative EEG. This study shows that majority of neonates with congenital heart disease (CHD) have normal pre-operative EEG with a continuous background and normal sleep-wake cycles. Also, 80% of neonates had abnormal post-operative EEG. Longer duration of arrest time and bypass time was associated with lack of continuity, excessive discontinuity, and prolonged IBI duration during post-operative EEG monitoring. These findings will help clinicians when counseling parents in the intensive care unit, risk stratification, and long-term neurodevelopmental monitoring in these high-risk patients.

Assessment of neonatal EEG background and neurodevelopment in full-term small for their gestational age infants

BackgroundDelayed brain function development in small-gestational-age (SGA) infants has been reported. We aimed to quantify rates of immature neonatal EEG patterns and their association with neurodevelopment in SGA full-term neonates.MethodsUsing a cohort design, 50 SGA (birthweight <10th percentile) and 44 appropriate-gestational-age (AGA) term neonates underwent continuous video-EEG recordings lasting >3 h. Seventy-three of them were assessed at 2-years-old using Bayley-III-Scales. For EEG analysis, several segments of discontinuous/alternating EEG tracings were selected. Main outcomes measured: (1) Visual analysis (patterns of EEG maturity); (2) Power spectrum in δ, θ, α and β frequency bands; and (3) scores in motor, cognitive and language development.Results(1) SGA infants, compared to AGA, showed: (a) higher percentages of discontinuous EEG, both asynchrony and interhemispheric asymmetry, and bursts with delta-brushes, longer interburst-interval duration and more transients/hour; (b) lower relative power spectrum in δ and higher in α; and (c) lower scores on motor, language and cognitive neurodevelopment. (2) Asymmetry >5%, interburst-interval >5 s, discontinuity >11%, and bursts with delta-brushes >11% were associated with lower scores on Bayley-III.ConclusionsIn this prospective study, SGA full-term neonates showed high rates of immature EEG patterns. Low-birthweight and immaturity EEG were both correlated with low development scores.

The utility of EEG monitoring in neonates with hyperammonemia due to inborn errors of metabolism

BackgroundContinuous EEG studies demonstrate that neonates with seizures due to cerebral pathology, such as hypoxia ischemia, exhibit predominantly electrographic seizures (i.e. those only detected with EEG because they lack clinical features). Previous small case series demonstrate EEG changes and seizures during hyperammonemia associated with inborn errors of metabolism (IEM) but there are no reports utilizing continuous EEG in these conditions. ObjectiveTo characterize seizures and evaluate the utility of continuous EEG recording during hyperammonemia due to inborn errors of metabolism. MethodsWe retrospectively reviewed medical records and EEG tracings of neonates who presented with hyperammonemia due to inborn errors of metabolism who had continuous EEG and full medical records available for review, including follow up. ResultsEight neonates with hyperammonemia were studied, 7 had urea cycle defects: Argininosuccinate lyase deficiency [3], (ornithine transcarbamylase deficiency [3], carbomyl phosphate synthase deficiency [1] and one had an organic acidemia: Methylmalonic acidemia [1]. Most common presentations were lethargy and poor feeding at 12–72 h of life. The highest blood ammonia level was 874 μmol/L (median); range 823–1647 μmol/L (normal value <50 μmol/L in term neonates). Seven were treated with hemodialysis in addition to nitrogen scavengers. Seven neonates had seizures; six had only electrographic seizures. Seizures initially occurred within 24–36 h of clinical presentation, sometimes with normal ammonia and glutamine levels. Neonates with seizures all lacked state changes on EEG. Inter burst interval duration correlated with degree of hyperammonemia. Two cases with normal plasma ammonia but increasing interburst interval duration were proven to have stroke by MRI. ConclusionsSeizures occur frequently in neonates with hyperammonemia; most can be detected only with continuous EEG. Seizures may occur when ammonia and glutamine levels are normal. Interburst interval duration is associated with ammonia levels or cerebral dysfunction from other brain pathology. Continuous EEG can be a useful tool for managing infants with hyperammonemia and may be essential for seizure management especially for infants in deep metabolic coma.

Flat Out Unnecessary: Burst Characteristics, Not Duration of Interburst Intervals, Predict Successful Anesthetic Wean in Refractory Status Epilepticus.

Flat Out Unnecessary: Burst Characteristics, Not Duration of Interburst Intervals, Predict Successful Anesthetic Wean in Refractory Status Epilepticus.

Treatment Effects on Neonatal EEG.

Conventional EEG and amplitude-integrated electroencephalography are used in neonates to assess prognosis and significant changes in brain activity. Neuroactive medications and hypothermia can influence brain activity and therefore alter EEG interpretation. There are limited studies on the effect of these therapies on neonatal EEG background activity. Medication effects on the EEG or amplitude-integrated electroencephalography include increased interburst interval duration, voltage suppression, and sleep disruption. The effect is transient in term newborns but can be persistent in premature newborns. Although therapeutic hypothermia does not produce significant changes in EEG activity, it does change the time point at which EEG can accurately predict neurodevelopmental outcome. It is important to account for these effects on the EEG to avoid inaccurate interpretation that may affect prognostication.

PP14.2 – 2563: Early electrical brain activity in preterm neonates with very low birth weight with prolonged respiratory therapy without clinical and ultrasound features of acute brain damages

There is prevalence of neurodevelopmental impairment in children born extremely premature and in recent years it is observed and considers as a result of acute brains damage occurring during the first postnatal weeks. Development of methods that enable early identification of functional disorders and risk of acute brain injury in preterm infants is obvious necessary in NICU (neonatal intensive care unit). Aim To demonstrate the physiological features of brain activity in the early neonatal period in preterm infants receiving respiratory therapy (prolonger mechanical ventilation), with very low birth weights and gestational age up to 32 weeks, in acute neonatal period without clinical and brains images sings detecting by cranial ultrasound. Subjects: We studied 10 neurologically healthy preterm babies with prolonged mechanically ventilation, they gestation age was between 27–30 weeks (averages M=28.6±3.59 weeks), with averages weight birth (M) 1077±359 grams. Nobody obtained sedation therapy. Methods Scalp EEG was recorded with 8 electrodes on 3–5 days after birth, duration – 1 hour. Repeated cranial ultrasound investigations (cUS) were performed on days1, 3 and 7 and 4 weeks after birth. Results Structural brain changes has not been detected by cUS in all patients. Early EEG activity in all preterm patients consists of patterns discontinue: inter burst interval (IBI) and burst of electrical activity. Maximum duration of IBI was 8–25 sec, (M=15.8±10.45 sec), minimum duration – 4–12 sec (M=8, 2±6.28 s). Averages time of IBI in preterm infants with very low birth weight was 6–18.5 sec (M=11.4±8.97). Conclusion Study demonstrates that the electro-cortical background activity, in the early neonatal period in preterm infants with very low birth weight and receiving respiratory therapy (prolonger mechanical ventilation), without clinical and neuroimigine damage sings is presented by trace discontinue. The average durations of inter burst interval is 11.4±8.97 s.

Reference Curves Estimation Using Conditional Quantile and Radial Basis Function Network with Mass Constraint

This paper focuses on the improvement of reference curves building \(Y=q(X)\) using a fast algorithm, robust against outliers. Our method consists in plugging a radial basis function neural network in the local linear quantile regression estimation proposed by Yu and Jones (QYJ). This neural network (QRBFc) is designed with a constructive algorithm, introducing a constraint on its integral over the input space. After explaining the different models and algorithms, we compare the QYJ and QRBFc estimators with the quantile regression neural network (QRNN) implemented by A. J. Cannon through simulations with a known underlying model using the R software. We observe that the QRBFc estimator reduces the mean absolute deviation error obtained with other estimators by about 16 %, the introduction of the constraint allowing to lower the number of neurons and therefore the computation time. Finally, using a database of 416 electroencephalograms recorded on preterm infants, we compare the QYJ, QRBFc and QRNN models for the building of brain maturation curves which are based on the dependence of the mean duration of interburst intervals (called IBIs—periods of quiescence between periods of normal electrical activity) with the age. The pathological infants represent 12 % of the total population. Denoting by \(S_A\) the set of individuals whose coordinates (age, mean IBI length) are above the \(90~\%\)-quantile curve, the QRBFc network improves by \(16.5~\%\) the number of pathological infants in \(S_A\) compared to QYJ, when QRNN proved to be too unstable.

Changes of the electroencephalographic background in preterm infants before and after instillation of pulmonary surfactant in different ways

Objective To monitor the electroencephalographic background activities of preterm infants before and after using pulmonary surfactant(PS), so as to investigate an appropriate way to endotracheally instill PS through the changes of electroencephalographic background activities. Methods Thirty-five preterm infants who were hospita-lized in Neonatal Intensive Care Unit of Guangzhou Women and Children's Medical Center from Jun.2011 to Apr.2013 and treated with PS were involved.They were divided into the normal pressure group and the high pressure group, based on the peak inspiratory pressure when PS instilled.The electroencephalographic background activities of the preterm infants before using PS and 15 min, 30 min, 60 min and 120 min after using PS were monitored continuously by using cerebral function monitor.The changes of 2 groups were compared.Oxygen saturation and heart rate were recorded at the same time. Results 1.In normal pressure group, lower amplitude decreased and the duration of interburst interval(IBI) increased 15 min after instillation of PS compared with before using PS(t=-6.012, 5.202, all P 0.05). There were significant differences between the 2 groups(t=-4.832, 4.029, all P 0.05). Between the 2 groups, there were significant differences in lower amplitude(t=-2.828, P 0.05). Lower amplitude and IBI of the normal pressure group returned to the level before using PS at 60 min and 120 min after using PS(lower amplitude: t=0.557, 1.849, all P 0.05). Moreover, in the high pressure group, lower amplitude even increased at 60 min and 120 min after using PS(t=2.153, 3.112, all P<0.05).2.After using PS, desaturation happened in 8 preterm infants of the normal pressure group and 2 preterm infants of the high pressure group.There was significant difference between the 2 groups(P=0.025).3.Bradycardia accompanied with desaturation happened in 2 preterm infants of the normal pressure group, but none in the high pressure group. Conclusions Instillation of PS may cause embolism and obstruct the airway, which may induce hypoxia, and then lead to the depression of the elec-troencephalographic background.Therefore, when instilling PS, giving high pressure can shorten or avoid the hypoxia episode, and make PS reach alveoli as soon as possible to play a role in lung compliance. Key words: Pulmonary surfactant; Amplitude-integrated electroencephalogram; Background activity; Preterm infant

Video-EEG recordings in full-term neonates of diabetic mothers: observational study

ObjetiveTo determine whether full-term newborn infants of diabetic mothers (IDM) present immature/disorganised EEG patterns in the immediate neonatal period, and whether there was any relationship with maternal glycaemic control.Design and...

Maternal dexamethasone and EEG hyperactivity in preterm fetal sheep

Maternal treatment with synthetic corticosteroids such as dexamethasone (DEX)significantly reduces neonatal morbidity and mortality, but its effects on the fetal brain remain unclear. In this study we evaluated the effects of DEX on EEG activity in preterm fetal sheep. Ewes at 103 days gestation received two intramuscular injections of DEX (12 mg, n = 8) or saline vehicle (n = 7) 24 h apart. Fetal EEG activity was recorded from 6 h before until 120 h after the first injection (DEX-1). DEX-1 was associated with a marked transient rise in total EEG power, maximal at 12 h (P < 0.001), with a relative increase in delta and reduced theta, alpha and beta activity, resolving by 24 h. Continuous EEG records showed a shift to larger but less frequent transient waveforms (P < 0.001). Unexpectedly, evolving epileptiform activity, consistent with electrographic and clinical seizures, developed from 178 ± 44 min after DEX-1.Similar but smaller changes were seen after the second injection. Following the injections, total power returned to control values, but the proportion of alpha activity progressively increased vs. controls (P < 0.001), with reduced interburst interval duration and number (P < 0.001). No histological neural injury or microglial activation was seen. In summary, exposure to maternal dexamethasone was associated with dramatic, evolving low-frequency hyperactivity on fetal cortical EEG recordings, followed by sustained changes consistent with maturation of fetal sleep architecture. We postulate that these effects may contribute to improved neonatal outcomes.

Neuronal Firing Before and After Burst Discharges in the Monkey Basal Ganglia Is Predictably Patterned in the Normal State and Altered in Parkinsonism

It is known that burst discharges in basal ganglia neurons are more common in parkinsonism than under normal conditions, but changes in the structure of burst or peri-burst epochs have not been reported. In this study, the temporal structure of bursts and the timing of neuronal discharges that precede or follow them were examined in neuronal spike trains recorded in the subthalamic nucleus (STN) and the external and internal pallidal segment (GPe, GPi) in two awake Rhesus monkeys before and after they were rendered hemiparkinsonian by unilateral intracarotid infusion of the dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Bursts were detected by the "surprise" method. In the normal state, interspike intervals (ISIs) preceding or following bursts were frequently significantly longer than the average baseline ISI, and their duration was correlated with the burst length (i.e., the number of spikes/burst). Significant correlations were also found in all three structures between the burst length and the duration of interburst intervals. The incidence of burst discharges and the proportion of time spent in bursts increased in GPe, STN, and GPi after MPTP treatment. Burst lengths became more tightly related to preburst ISIs in the STN after MPTP treatment and to postburst ISI duration in all three structures. These results show that bursts in spontaneous GPe, STN, and GPi discharge are often preceded or followed by long ISIs, and that burst length, the length of pre- and postburst ISIs, and the length of interburst intervals are related to one another. Complex changes in these interactions may contribute to abnormal information processing in parkinsonism.

Phasing of Muscle Activity During Rapid Finger Oscillations

In rapid limb oscillations, bursts of muscle activity occur during certain phases of the movement. The authors examined phase stabilization in rapid oscillations of the index finger in a horizontal plane. Phase stabilization was rapid; therefore, a deviation from the mean phase was, on average, (almost) completely corrected in the subsequent movement cycle. Participants (N = 11) achieved rapid phase stabilization by using phase-dependent modulations of both the frequency of finger oscillation and the duration of interburst intervals. For example, with an early phase of a burst, oscillation frequency was increased immediately and the next burst of muscle activity was delayed. Whereas phase-stabilizing modulations of oscillation frequency are likely to be mechanically mediated, phase-stabilizing modulations of the timing of bursts of muscle activity must be neurally mediated. The present findings therefore strongly suggest that a central pattern generator does not generate rapid finger oscillations in an open-loop mode, but the pattern-generator network integrates, individually or in combination, afferent signals or predictive signals on the current or future states of the oscillating finger.

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.

L’échec du sommeil de l’enfant à prolonger l’état fœtal

We analyzed the relationship between normal neonatal EEG features and gestational age and conceptional age, and evaluated the normal aspects of EEG maturation in preterm babies compared to term babies. We report 46 newborns, divided into two groups. Group I consisted of 11 newborns with gestational age between 30 and 32 weeks, followed with weekly polysomnograms until they reach 42 weeks' conceptional age. Group II (control) consisted of 35 newborns with gestational ages of 34 weeks (n = 5), 36 weeks (n = 10), 38 weeks (n = 10) and 40 weeks (n = 10) evaluated with one polysomnogram in their first 24–48 h of life. In each examination one 5 min epoch in REM and NREM sleep was analyzed to quantify the number of delta brushes, the presence of frontal and temporal sharp transients, the presence of delta frontal rhythmic activity, the grade of concordance between EEG patterns and sleep stages, the percent of interhemispheric synchrony and the duration of interburst interval. The age dependent variability of the EEG patterns was evaluated during the subsequent weeks with group comparisons at weeks 34, 36, 38 and 40. Our results show that the number of delta brushes and the duration of the interburst interval decrease as gestational and conceptional age increase. The percent of interhemispheric synchrony increases with gestational and conceptional age. The presence of frontal sharp transients and delta frontal rhythmic activity suggest that the newborn is fullterm. The presence of temporal sharp transients suggest a preterm newborn. The degree of concordance between behavioral sleep patterns and EEG was more helpful in recognizing sleep stages than in estimating gestational or conceptional age. Although the EEG patterns were comparable between the groups at the same age, analyses of the behavioral patterns of concordance in NREM sleep showed that newborns in Group I had a more immature behavior than newborns in Group II. Our results also suggest that extrauterine life of preterm babies does not seem to accelerate EEG maturation but may influence the acquisition of behavioral patterns during NREM sleep.

Background electroencephalographic (EEG) activities of very preterm infants born at less than 27 weeks gestation: a study on the degree of continuity

AIMSTo clarify the features of the background electroencephalographic (EEG) activities in clinically well preterm infants born at less than 27 weeks gestation and to outline their chronological changes with increasing...

Excitatory Role of the Hyperpolarization-Activated Inward Current in Phasic and Tonic Firing of Rat Supraoptic Neurons

The properties and functional roles of the hyperpolarization-activated inward current (I(H)) in magnocellular neurosecretory cells (MNCs) were investigated during sharp microelectrode recordings from supraoptic neurons in superfused explants of rat hypothalamus. Under current clamp, voltage responses to hyperpolarizing current pulses featured depolarizing sags that were abolished by the I(H) blocker ZD 7288. Under voltage clamp, subtraction of current responses to hyperpolarizing steps recorded in the absence and presence of ZD 7288 was used to investigate the properties of I(H). Current-voltage analysis revealed that steady-state I(H) amplitude increases with hyperpolarization, with half-maximal activation of the underlying conductance occurring at -78 mV. The time course of activation of I(H) during hyperpolarizing steps was monoexponential with time constants (100-800 msec) decreasing with hyperpolarization. The effects of ZD 7288 on I(H) were slow (tau, approximately 15 min), irreversible, and half-maximal at 1.8 micrometer. When tested on continuously active MNCs, application of 30-60 micrometer ZD 7288 caused a significant reduction in firing rate. In phasically active MNCs, the drug decreased burst duration and intraburst firing frequency and caused an increase in the duration of interburst intervals. These effects were accompanied with a small hyperpolarization of the membrane potential. In contrast, ZD 7288 had no effect on spike duration, on the amplitude of calcium-dependent afterpotentials, or on the frequencies and amplitudes of spontaneous synaptic potentials. These results confirm the presence of I(H) in MNCs of the rat supraoptic nucleus and suggest that the presence of this conductance provides an excitatory drive that contributes to phasic and tonic firing.

Inhibition can disrupt hypersynchrony in model neuronal networks

1. 1. Model neuronal network simulations were performed using a reduced Traub neuronal network model. In the absence of inhibition the network produced synchronous population bursting. 2. 2. Bursting of individual neurons was dependent on 1 or more of the following: build-up of charge in the dendritic compartment, prolonged current flow through simulated NMDA associated channels, current flow through T channels. Interburst interval duration and consequent burst frequency was dependent on the density of slow afterhyperpolarizing potassium channels. 3. 3. Addition of an inhibitory interneuron population projecting to GABA A receptors resulted in rapid desynchronization of the population, generally after only 1–2 cycles. This effect was found to be due to reduced participation in the individual population burst and to the need for multi-synaptic activation of the individual neuron in the presence of inhibition. 4. 4. This desynchronizing effect could be offset by increasing the strength of interburst hyperpolarization either through increased density of I AHP, or through the addition of a separate inhibitory interneuron pool projected to GABA B receptors. 5. 5. These data suggest that the synchronizing effects of inhibition may vary depending on circumstances — with desynchronization being dominant in cases characterized by large population bursts such as those seen in epilepsy.

Polysomnographic quantification of bioelectrical maturation in preterm and fullterm newborns at matched conceptional ages

We analyzed the relationship between normal neonatal EEG features and gestational age and conceptional age, and evaluated the normal aspects of EEG maturation in preterm babies compared to term babies. We report 46 newborns, divided into two groups. Group I consisted of 11 newborns with gestational age between 30 and 32 weeks, followed with weekly polysomnograms until they reach 42 weeks' conceptional age. Group II (control) consisted of 35 newborns with gestational ages of 34 weeks (n = 5), 36 weeks (n = 10), 38 weeks (n = 10) and 40 weeks (n = 10) evaluated with one polysomnogram in their first 24–48 h of life. In each examination one 5 min epoch in REM and NREM sleep was analyzed to quantify the number of delta brushes, the presence of frontal and temporal sharp transients, the presence of delta frontal rhythmic activity, the grade of concordance between EEG patterns and sleep stages, the percent of interhemispheric synchrony and the duration of interburst interval. The age dependent variability of the EEG patterns was evaluated during the subsequent weeks with group comparisons at weeks 34, 36, 38 and 40. Our results show that the number of delta brushes and the duration of the interburst interval decrease as gestational and conceptional age increase. The percent of interhemispheric synchrony increases with gestational and conceptional age. The presence of frontal sharp transients and delta frontal rhythmic activity suggest that the newborn is fullterm. The presence of temporal sharp transients suggest a preterm newborn. The degree of concordance between behavioral sleep patterns and EEG was more helpful in recognizing sleep stages than in estimating gestational or conceptional age. Although the EEG patterns were comparable between the groups at the same age, analyses of the behavioral patterns of concordance in NREM sleep showed that newborns in Group I had a more immature behavior than newborns in Group II. Our results also suggest that extrauterine life of preterm babies does not seem to accelerate EEG maturation but may influence the acquisition of behavioral patterns during NREM sleep.