Ictal electroencephalographic findings of neonatal seizures in preterm infants

The aim of this study is to clarify the characteristics of ictal EEG findings of neonatal seizures in preterm infants. Seizures associated with ictal EEG changes were recognized in nine infants with gestational age of less than 37 weeks. Propagation, migration, shifting, changes in morphology of ictal EEG discharges were evaluated. Seizure manifestation was divided into the following categories; motor seizure, apneic seizure, automatic seizure and seizure without clinical symptoms. The types of the seizures were motor seizures in five infants, apneic in two, automatic in one and those without clinical symptoms in five. All seizures were of focal onset. The foci of seizures were temporal in six infants, occipital in two, central in one, and frontal in one. The morphology of ictal discharges was low voltage spikes or sharp waves in six infants, spikes in two, theta waves in one and high-voltage spiky theta in one. The propagation of ictal discharges was focal in five infants and regional in five. The migration of ictal discharges was observed in two infants and a shift in two. There was no clear relation between seizure manifestation and ictal EEG foci, duration of seizures and morphology or propagation of ictal discharges.     

Epileptic seizures induced by dexmedetomidine in a neonate

Background: Dexmedetomidine hydrochloride, a highly selective 2-adrenoceptoragonist, is used in combination with local anesthetics for sedation and analgesia. It is known to be efficacious in adult patients and is enthusiastically expected to be successful for sedation in neonates. Patient: The present case report details a term infant who was sedated by dexmedetomidine during artificial ventilation. He underwent electroencephalograms that confirmed epileptic seizures and non-epileptic abnormal movements. Twelve hours after the discontinuation of dexmedetomidine, both symptoms gradually disappeared without the use of any antiepileptic medication. After then, he had achieved normal development, with no obvious neurological abnormalities. Conclusion: Dexmedetomidine acts throughout the central nervous system and leads to a reduction in the anticonvulsant activity of the locus coeruleus. This case suggests potential adverse effects of dexmedetomidine in terms of inducing both epileptic seizures and non-epileptic movements in neonates.     

Criteria for discontinuing neonatal seizure therapy: a long-term appraisal

In order to evaluate the criteria for discontinuing neonatal anticonvulsant treatment, 55 newborns with seizures have been studied. Clinical and EEG serial examinations were performed: soon after the first seizure, throughout the hospital course, and during the follow-up every 3 months until a year, and every 6 months later on. Anticonvulsant treatment with phenobarbital was discontinued (at 4 days-19 months; mean 104 days) on the basis of the following variables: type and number of seizures, time taken for their control, type and persistence of EEG abnormalities, initial neurological features, and seizure etiology. At the follow-up (12 months-8 years; mean 36 months) only 4 children had relapsed, 3 of them with a single short seizure without EEG abnormalities. The results obtained by means of the correlation between the length of anticonvulsant treatment and the clinical and EEG variables provide evidence of the value of the criteria employed. Of these, the duration of persistence of EEG abnormalities was the most important for planning the maintenance of anticonvulsant treatment and its discontinuation.     

Maturational changes of neonatal electroencephalogram: A comparison between intra uterine and extra uterine development

ObjectivesTo evaluate electroencephalogram (EEG) patterns in very low birth weight premature newborns when reaching term-to-term neonates, thereby comparing extra uterine to intra uterine development.MethodsEEG recordings were obtained between 2 and 14 days of life in 47 preterm (<37 weeks) very low birth weight (⩽1500 g) newborns and repeated when reaching term age (38–42 weeks) in a subsample (n = 22). EEG recordings were also obtained in term newborns. Clinical evaluation was performed at birth and at 6 and 12 months.ResultsRelative to the first EEG, preterm newborns showed a reduction in delta brushes and interburst intervals and increased interhemispheric synchrony, suggesting an improvement in EEG maturation. Further organization in sleep patterns, like a reduction in total sleep time and phase shifts, were also observed. However, when reaching term, preterm newborns still had less mature EEG patterns, phase shifts and transitional sleep than matched controls. Background abnormalities and dysmaturity in preterm newborns during the first EEG predicted adverse neurological outcome later on.ConclusionsEEG patterns in preterm very low birth weight newborns might be influenced by extra uterine development. Specific EEG abnormalities are related to increased risk of neurological disorders.SignificanceExtra uterine development of very low birth weight delays the acquisition of maturational EEG patterns.     

Myoclonic seizures combined with partial seizures and probable pathophysiology of secondary bilateral synchrony.

OBJECTIVE: We report on a patient who showed an unusual transition from complex partial seizures to a combination of myoclonic seizures and partial seizures, and then to isolated myoclonic seizures. The pathophysiological mechanism of the myoclonic seizures in this uncommon condition was studied. METHODS: The interhemispheric small time differences were estimated in the ictal EEG discharges of myoclonic seizures for differentiation between primary and secondary bilateral synchrony. The estimation was performed by coherence and phase analysis based on the two-dimensional autoregressive model. RESULTS: The estimated interhemispheric time differences were at most 27.4 ms. The ictal activity of the myoclonic seizures was suggested to originate from a cortical focus in the right hemisphere, which was also the origin of the partial seizures. CONCLUSION: The patient was considered to have an unusual type of myoclonic seizures with a probable pathophysiological mechanism of secondary bilateral synchrony.     

Acute neonatal encephalopathy and seizures recurrence: A combined aEEG/EEG study

PurposeTo evaluate amplitude-integrated EEG (aEEG) in comparison with conventional (cEEG) for the identification of electrographic seizures in neonates with acute neonatal encephalopathies.MethodsThirty-one conventional cEEG/aEEG long-term recordings from twenty-eight newborns were reviewed in order to assess the electrographic seizure detection rate and recurrence in newborns. Two paediatric neurologists and one neonatologist, blinded to the raw full array cEEG, were asked to mark any events suspected to be an electrographic seizures on aEEG. They were asked to decide if the displayed aEEG trace showed the pattern of a single seizure (SS), repetitive seizures (RS) or status epilepticus (SE). Their ability to recognize electrographic seizures on aEEG was compared to seizures identified on full array cEEG.Results25 of the 31 long-term cEEGs recordings showed electrographic seizures. The two paediatric neurologists and the neonatologist identified SE in 100% of the reviewed traces using aEEG alone while they identified 49.4% and 37.5% of electrographic seizures using aEEG alone. Overall, the correct identification ranged from 23.5% to 30.7% for SS and 66% for RS. The inter-observer agreement (k) for the identification of SE for the two paediatric neurologists and the neonatologist was 1.0. Overall the inter-observer agreement (k) for the detection of SS, RS and SE of the two paediatric neurologists was 0.91.ConclusionsIn our study the observers identified SE in 100% of the reviewed traces using raw aEEG alone, thus aEEG might represent a useful tool to detect SE in the setting of NICU. SS may not be reliably identified using aEEG alone. Simultaneous recording of the raw cEEG/aEEG provides a good level of sensitivity for the detection of neonatal electrographic seizures.     

Automated detection of videotaped neonatal seizures of epileptic origin

PURPOSE: This study aimed at the development of a seizure-detection system by training neural networks with quantitative motion information extracted from short video segments of neonatal seizures of the myoclonic and focal clonic types and random infant movements. METHODS: The motion of the infants' body parts was quantified by temporal motion-strength signals extracted from video segments by motion-segmentation methods based on optical flow computation. The area of each frame occupied by the infants' moving body parts was segmented by clustering the motion parameters obtained by fitting an affine model to the pixel velocities. The motion of the infants' body parts also was quantified by temporal motion-trajectory signals extracted from video recordings by robust motion trackers based on block-motion models. These motion trackers were developed to adjust autonomously to illumination and contrast changes that may occur during the video-frame sequence. Video segments were represented by quantitative features obtained by analyzing motion-strength and motion-trajectory signals in both the time and frequency domains. Seizure recognition was performed by conventional feed-forward neural networks, quantum neural networks, and cosine radial basis function neural networks, which were trained to detect neonatal seizures of the myoclonic and focal clonic types and to distinguish them from random infant movements. RESULTS: The computational tools and procedures developed for automated seizure detection were evaluated on a set of 240 video segments of 54 patients exhibiting myoclonic seizures (80 segments), focal clonic seizures (80 segments), and random infant movements (80 segments). Regardless of the decision scheme used for interpreting the responses of the trained neural networks, all the neural network models exhibited sensitivity and specificity>90%. For one of the decision schemes proposed for interpreting the responses of the trained neural networks, the majority of the trained neural-network models exhibited sensitivity>90% and specificity>95%. In particular, cosine radial basis function neural networks achieved the performance targets of this phase of the project (i.e., sensitivity>95% and specificity>95%). CONCLUSIONS: The best among the motion segmentation and tracking methods developed in this study produced quantitative features that constitute a reliable basis for detecting neonatal seizures. The performance targets of this phase of the project were achieved by combining the quantitative features obtained by analyzing motion-strength signals with those produced by analyzing motion-trajectory signals. The computational procedures and tools developed in this study to perform off-line analysis of short video segments will be used in the next phase of this project, which involves the integration of these procedures and tools into a system that can process and analyze long video recordings of infants monitored for seizures in real time.     

Computerized motion analysis of videotaped neonatal seizures of epileptic origin

PURPOSE: The main objective of this research is the development of automated video processing and analysis procedures aimed at the recognition and characterization of the types of neonatal seizures. The long-term goal of this research is the integration of these computational procedures into the development of a stand-alone automated system that could be used as a supplement in the neonatal intensive care unit (NICU) to provide 24-h per day noninvasive monitoring of infants at risk for seizures. METHODS: We developed and evaluated a variety of computational tools and procedures that may be used to carry out the three essential tasks involved in the development of a seizure recognition and characterization system: the extraction of quantitative motion information from video recordings of neonatal seizures in the form of motion-strength and motor-activity signals, the selection of quantitative features that convey some unique behavioral characteristics of neonatal seizures, and the training of artificial neural networks to distinguish neonatal seizures from random infant behaviors and to differentiate between myoclonic and focal clonic seizures. RESULTS: The methods were tested on a set of 240 video recordings of 43 patients exhibiting myoclonic seizures (80 cases), focal clonic seizures (80 cases), and random infant movements (80 cases). The outcome of the experiments verified that optical- flow methods are promising computational tools for quantifying neonatal seizures from video recordings in the form of motion-strength signals. The experimental results also verified that the robust motion trackers developed in this study outperformed considerably the motion trackers based on predictive block matching in terms of both reliability and accuracy. The quantitative features selected from motion-strength and motor-activity signals constitute a satisfactory representation of neonatal seizures and random infant movements and seem to be complementary. Such features lead to trained neural networks that exhibit performance levels exceeding the initial goals of this study, the sensitivity goal being >or=80% and the specificity goal being >or=90%. CONCLUSIONS: The outcome of this experimental study provides strong evidence that it is feasible to develop an automated system for the recognition and characterization of the types of neonatal seizures based on video recordings. This will be accomplished by enhancing the accuracy and improving the reliability of the computational tools and methods developed during the course of the study outlined here.     

卒中后继发癫痫患者常规与动态脑电图检查的比较分析

目的研究卒中后继发癫痫患者常规脑电图(electroencephalography,EEG)与动态脑电图(ambulatory electroencephalography,AEEG)的特点。方法观察40例急性卒中后继发癫痫患者的病灶分布、范围、癫痫发作形式及频数,所有病例作EEG及AEEG检查,将检查结果分为正常、轻度异常、中度异常及重度异常进行统计分析。结果40例研究对象的病灶分布主要在颞叶、额叶及丘脑,癫痫发作类型主要为全面性强直阵挛发作。EEG检查异常的比率为47.5%,其中轻度异常占异常总数的52.6%,中度和重度异常占47.4%;AEEG检查异常的比率为80%,其中轻度异常占异常总数的12.5%,中度和重度异常占87.5%,AEEG较EEG检查的异常比率明显增高,具有统计学差异。结论AEEG可显著提高卒中后癫痫发作患者的脑电异常检出率,其检查结果对指导临床治疗具有一定的价值。     

Noninvasive dynamic imaging of seizures in epileptic patients

Epileptic seizures are due to abnormal synchronized neuronal discharges. Techniques measuring electrical changes are commonly used to analyze seizures. Neuronal activity can be also defined by concomitant hemodynamic and metabolic changes. Simultaneous electroencephalogram (EEG)‐functional MRI (fMRI) measures noninvasively with a high‐spatial resolution BOLD changes during seizures in the whole brain. Until now, only a static image representing the whole seizure was provided. We report in 10 focal epilepsy patients a new approach to dynamic imaging of seizures including the BOLD time course of seizures and the identification of brain structures involved in seizure onset and discharge propagation. The first activation was observed in agreement with the expected location of the focus based on clinical and EEG data (three intracranial recordings), thus providing validity to this approach. The BOLD signal preceded ictal EEG changes in two cases. EEG‐fMRI may detect changes in smaller and deeper structures than scalp EEG, which can only record activity form superficial cortical areas. This method allowed us to demonstrate that seizure onset zone was limited to one structure, thus supporting the concept of epileptic focus, but that a complex neuronal network was involved during propagation. Deactivations were also found during seizures, usually appearing after the first activation in areas close or distant to the activated regions. Deactivations may correspond to actively inhibited regions or to functional disconnection from normally active regions. This new noninvasive approach should open the study of seizure generation and propagation mechanisms in the whole brain to groups of patients with focal epilepsies. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Associated factors in neonatal hypoglycemic brain injury

Although associated factors are important for the occurrence of neural damage in neonatal hypoglycemia, they are not fully understood. Sixty patients with neonatal hypoglycemia were studied through a review of their medical records in Tottori University Hospital. The patients were classified into two main groups: Group I were patients who had mental retardation, developmental delay, cerebral palsy or epilepsy while Group II were those who were normal in their follow-up. Group I consisted of 12 patients while Group II consisted of 48 patients. The median gestational age was 38 weeks in Group I and 36.7 weeks in Group II. The frequencies of small for gestational age were similar in both groups. Blood glucose levels less than 15 mg/dl were more frequent in Group 1 (50.0%) than in Group 2 (14.6%) (P = 0.015). Duration of hypoglycemia was longer in Group I (median, 14 h) than in Group II (median, 1.75 h) (p < 0.001). The following factors were more frequent in Group I than in Group II: toxemia (33.3% and 8.3%, p = 0.043), fetal distress (58.3% and 14.5%, p = 0.004), an Apgar score of less than 5 at 1 min (33.3% and 6.4%, p = 0.025), neonatal seizure (53.8% and 4.3%, p < 0.001) and pathological jaundice (41.7% and 6.4%, p = 0.006). Cranial CT or MRI revealed cerebral lesions in 8 of the 9 Group I patients in follow-up examinations. This study indicates that severe and prolonged neonatal hypoglycemia can cause cerebral lesions and other perinatal risk factors, such as hypoxia, neonatal seizure and pathological jaundice, would exacerbate hypoglycemic brain injuries.     

Mapping hemodynamic correlates of seizures using fMRI: A review

Functional magnetic resonance imaging (fMRI) is able to detect changes in blood oxygenation level associated with neuronal activity throughout the brain. For more than a decade, fMRI alone or in combination with simultaneous EEG recording (EEG‐fMRI) has been used to investigate the hemodynamic changes associated with interictal and ictal epileptic discharges. This is the first literature review to focus on the various fMRI acquisition and data analysis methods applied to map epileptic seizure‐related hemodynamic changes from the first report of an fMRI scan of a seizure to the present day. Two types of data analysis approaches, based on temporal correlation and data driven, are explained and contrasted. The spatial and temporal relationship between the observed hemodynamic changes using fMRI and other non‐invasive and invasive electrophysiological and imaging data is considered. We then describe the role of fMRI in localizing and exploring the networks involved in spontaneous and triggered seizure onset and propagation. We also discuss that fMRI alone and combined with EEG hold great promise in the investigation of seizure‐related hemodynamic changes non‐invasively in humans. We think that this will lead to significant improvements in our understanding of seizures with important consequences for the treatment of epilepsy. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.     

Olanzapine‐related repetitive focal seizures with lingual dystonia

Olanzapine‐related seizures have rarely been reported despite associated proconvulsant risk factors described in the literature: myoclonic status, increased frequency of seizures, tonic‐clonic seizures, as well as fatal status epilepticus. We present a psychiatric patient who developed repetitive focal motor seizures and lingual dystonia when olanzapine was added for psychomotor agitation and aggressiveness. Olanzapine was immediately suspended and the seizures progressively disappeared. A control EEG showed no paroxysmal discharges. Olanzapine shares some pharmacological similarities with clozapine, a neuroleptic with a high risk of dose‐dependent seizures. This adverse effect should be taken into account, and olanzapine should be used with caution if concomitant circumstances decrease the seizure threshold. [Published with video sequence online]     

Brief rhythmic discharges in neonates: a marker for seizures

Brief rhythmic discharges (BRDs) are paroxysms of rhythmic electrographic activity with an amplitude of >2 μV and a duration of <10 seconds. Although BRDs are reported in neonates, this electrographic activity contrasts the accepted definition of neonatal seizures (duration of >10 seconds). BRDs are associated with background EEG abnormalities as well as increased morbidity and mortality (Oliveira et al., 2000, Nagarajan et al., 2011), and appear to be more closely related to formal neonatal seizures than post‐neonatal epilepsy (Nagarajan et al., 2011). Most neonatal units are restricted to one‐hour recordings, and if BRDs are observed without any accompanying electrographic seizures, then the neonate should be regarded as being at high risk of seizures and repeat recordings should be considered.