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Cooling and seizure burden in term neonates: an observational study.

Objective To investigate any possible effect of cooling on seizure burden, the authors quantified the recorded electrographic seizure burden based on multichannel video-EEG recordings in term neonates with hypoxic-ischaemic encephalopathy (HIE) who received cooling and in those who did not. Study design Retrospective observational study. Patients Neonates >37 weeks gestation born between 2003 and 2010 in two hospitals. Methods Off-line analysis of prolonged continuous multichannel video-EEG recordings was performed independently by two experienced encephalographers. Comparison between the recorded electrographic seizure burden in non-cooled and cooled neonates was assessed. Data were treated as non-parametric and expressed as medians with interquartile ranges (IQR). Results One hundred and seven neonates with HIE underwent prolonged continuous multichannel EEG monitoring. Thirty-seven neonates had electrographic seizures, of whom 31 had EEG recordings that were suitable for the analysis (16 non-cooled and 15 cooled). Compared with non-cooled neonates, multichannel EEG monitoring commenced at an earlier postnatal age in cooled neonates (6 (3–9) vs 15 (5–20) h)and continued for longer (88 (75–101) vs 55 (41–60) h). Despite this increased opportunity to capture seizures in cooled neonates, the recorded electrographic seizure burden in the cooled group was significantly lower than in the non-cooled group (60 (39–224) vs 203 (141–406) min). Further exploratory analysis showed that the recorded electrographic seizure burden was only significantly reduced in cooled neonates with moderate HIE (49 (26–89) vs 162 (97–262) min). Conclusions A decreased seizure burden was seen in neonates with moderate HIE who received cooling. This finding may explain some of the therapeutic benefits of cooling seen in term neonates with moderate HIE.

Early postnatal EEG features of perinatal arterial ischaemic stroke with seizures.

Background Stroke is the second most common cause of seizures in term neonates and is associated with abnormal long-term neurodevelopmental outcome in some cases. Objective To aid diagnosis earlier in the postnatal period, our aim was to describe the characteristic EEG patterns in term neonates with perinatal arterial ischaemic stroke (PAIS) seizures. Design Retrospective observational study. Patients Neonates >37 weeks born between 2003 and 2011 in two hospitals. Method Continuous multichannel video-EEG was used to analyze the background patterns and characteristics of seizures. Each EEG was assessed for continuity, symmetry, characteristic features and sleep cycling; morphology of electrographic seizures was also examined. Each seizure was categorized as electrographic-only or electroclinical; the percentage of seizure events for each seizure type was also summarized. Results Nine neonates with PAIS seizures and EEG monitoring were identified. While EEG continuity was present in all cases, the background pattern showed suppression over the infarcted side; this was quite marked (>50% amplitude reduction) when the lesion was large. Characteristic unilateral bursts of theta activity with sharp or spike waves intermixed were seen in all cases. Sleep cycling was generally present but was more disturbed over the infarcted side. Seizures demonstrated a characteristic pattern; focal sharp waves/spike-polyspikes were seen at frequency of 1–2 Hz and phase reversal over the central region was common. Electrographic-only seizure events were more frequent compared to electroclinical seizure events (78 vs 22%). Conclusions Focal electrographic and electroclinical seizures with ipsilateral suppression of the background activity and focal sharp waves are strong indicators of PAIS. Approximately 80% of seizure events were the result of clinically unsuspected seizures in neonates with PAIS. Prolonged and continuous multichannel video-EEG monitoring is advocated for adequate seizure surveillance.

Validation of an automated seizure detection algorithm for term neonates.

Highlights • Seizure detection algorithm (SDA) validated on unseen, unedited EEG of 70 neonates.• Results at SDA sensitivity settings of 0.5–0.3 acceptable for clinical use.• Seizure detection rate of 52.6–75.0%, false detection rate 0.04–0.36 FD/h.

Early continuous video electroencephalography in neonatal stroke.

Perinatal stroke is the second most common cause of neonatal seizures, and can result in long‐term neurological impairment. Diagnosis is often delayed until after seizure onset, owing to the subtle nature of associated signs. We report the early electroencephalographic (EEG) findings in a female infant with a perinatal infarction, born at 41 weeks 2 days and weighing 3.42kg. Before the onset of seizures, the EEG from 3 hours after delivery demonstrated occasional focal sharp waves over the affected region. After electroclinical seizures, focal sharp waves became more frequent, complex, and of higher amplitude, particularly in ‘quiet sleep’. In ‘active sleep’, sharp waves often disappeared. Diffusion‐weighted imaging confirmed the infarct, demonstrating left frontal and parietal diffusion restriction. At 9 months, the infant has had no further seizures, and neurological examination is normal. To our knowledge, this report is the first to describe the EEG findings in perinatal stroke before seizures, and highlights the evolution of characteristic background EEG features.

In-depth performance analysis of an EEG based neonatal seizure detection algorithm

Highlights • A novel method for in-depth analysis of neonatal seizure detection algorithms is proposed.• The analysis estimated how seizure features are exploited by automated detectors.• This method led to significant improvement of the ANSeR algorithm.

Short-Term Effects of Phenobarbitone on Electrographic Seizures in Neonates

Background: Phenobarbitone is the most common first-line anti-seizure drug and is effective in approximately 50% of all neonatal seizures. Objective: To describe the response of electrographic seizures to the administration of intravenous phenobarbitone in neonates using seizure burden analysis techniques. Methods: Multi-channel conventional EEG, reviewed by experts, was used to determine the electrographic seizure burden in hourly epochs. The maximum seizure burden evaluated 1 h before each phenobarbitone dose (T-1) was compared to seizure burden in periods of increasing duration after each phenobarbitone dose had been administered (T+1, T+2 to seizure offset). Differences were analysed using linear mixed models and summarized as means and 95% CI. Results: Nineteen neonates had electrographic seizures and met the inclusion criteria for the study. Thirty-one doses were studied. The maximum seizure burden was significantly reduced 1 h after the administration of phenobarbitone (T+1) [-14.0 min/h (95% CI: -19.6, -8.5); p < 0.001]. The percentage reduction was 74% (IQR: 36-100). This reduction was temporary and not significant within 4 h of administrating phenobarbitone. Subgroup analysis showed that only phenobarbitone doses at 20 mg/kg resulted in a significant reduction in the maximum seizure burden from T-1 to T+1 (p = 0.002). Conclusions: Phenobarbitone significantly reduced seizures within 1 h of administration as assessed with continuous multi-channel EEG monitoring in neonates. The reduction was not permanent and seizures were likely to return within 4 h of treatment.

Phenobarbital reduces EEG amplitude and propagation of neonatal seizures but does not alter performance of automated seizure detection

Highlights • Phenobarbital reduces both amplitude and propagation of neonatal seizures.• These changes may help to explain electroclinical uncoupling.• The performance of our seizure detection algorithm was unaffected.

EEG suppression associated with apneic episodes in a neonate.

We describe the EEG findings from an ex-preterm neonate at term equivalent age who presented with intermittent but prolonged apneic episodes which were presumed to be seizures. A total of 8 apneic episodes were captured (duration 23–376 seconds) during EEG monitoring. The baseline EEG activity was appropriate for corrected gestational age and no electrographic seizure activity was recorded. The average baseline heart rate was 168 beats per minute (bpm) and the baseline oxygen saturation level was in the mid-nineties. Periods of complete EEG suppression lasting 68 and 179 seconds, respectively, were recorded during 2 of these 8 apneic episodes. Both episodes were accompanied by bradycardia less than 70 bpm and oxygen saturation levels of less than 20%. Short but severe episodes of apnea can cause complete EEG suppression in the neonate.

Monitoring cerebral oxygenation of preterm infants using a neonatal specific sensor

IntroductionCerebral oxygenation (rcSO2) monitoring in preterm infants may identify periods of cerebral hypoxia or hyperoxia. We hypothesised that there was a relationship between rcSO2 values and short term outcome in infants of GA < 32weeks.MethodsRcSO2 values were recorded for the first 48 h of life using an INVOS monitor with a neonatal sensor. The association between cranial ultrasound scan measured brain injury and rcSO2 was assessed.Results120 infants were included. Sixty-nine percent (83) of infants had a normal outcome (no IVH, no PVL, and survival at 1 month); less than one-quarter, 22% (26), had low grade IVH 1 or 2 (moderate outcome); and 9% (11) of infants had a severe outcome (IVH ≥ 3, PVL or died before 1 month age). rcSO2 values were lower for infants GA < 28weeks when compared with those GA 28–32, p < 0.001. There was no difference in absolute rcSO2 values between the three outcome groups but a greater degree of cerebral hypoxia was associated with preterm infants who had low grade 1 or 2 IVH.ConclusionInfants of GA < 28 weeks have lower cerebral oxygenation in the first 2 days of life. A greater degree of hypoxia was seen in infants with grade 1 or 2 haemorrhage. Normative ranges need to be gestation specific.

Clinical Validation of a Neonatal Seizure Detection Algorithm

Background and Aim: Since there is compelling evidence that seizures are harmful to the immature developing brain, accurate seizure detection at the cotside is imperative. Multichannel EEG is a reliable method for confirming neonatal seizures but interpretation requires expertise. We recently developed a neonatal seizure detection algorithm (NSDA) to aid EEG interpretation. We aimed to validate this algorithm using unseen data recorded in the neonatal intensive care unit (NICU).Methods: The NSDA was previously trained using an EEG dataset of 18 term neonates with seizures. The validation dataset contained lengthy and unprocessed multichannel EEG records from 41 term neonates with hypoxic-ischaemic encephalopathy. A total of 377 electrographic seizures were visually annotated by an experienced neurophysiologist in 7 of the 41 neonates. The performance of the NSDA was assessed using sensitivity and specificity via a receiver operating characteristic (ROC), the seizure detection rate and false alarm rate.Results: The NSDA identified 7/7 neonates with seizures and 33/34 neonates without seizures (AUROC= 0.954). The median error between the annotations of the neurophysiologist and the NSDA was 49 seconds/hour for neonates with seizures and 0 seconds/hour for neonates without seizures. The seizure detection rate was 60% with a false alarm rate of 0.1/hour. The seizure detection rate could be improved by increasing the false alarm rate.Conclusion: Our NSDA is approaching a level of accuracy that is sufficient for clinical implementation in the NICU. Further tests are ongoing to determine the common sources of false alarms which will help improve the NASDA performance.