Electroclinical features of absence seizures in sleep

doi:10.1016/j.eplepsyres.2010.12.009

Epilepsy Research

Volume 93, Issues 2–3, February 2011, Pages 216-220

https://doi.org/10.1016/j.eplepsyres.2010.12.009 Get rights and content

Summary

Purpose

To analyze electroclinical features of absence seizures during sleep.

Principal results

30 children with genetic generalized epilepsy had 52 paroxysms of GSW >2 s during sleep. 18/52 (35%) demonstrated a clinical sign. Ictal GSW lasted an average of 6.5 s.

Conclusion

Motor manifestations are seen during GSW > 2 s in sleep. 72% likely represent true ictal motor features while the rest may be serendipitous sleep phenomenon.

Introduction

Little is known about how absence seizures appear in sleep. The semiology of absence seizures have been explicated with the advent of video-EEG (Penry et al., 1975, Stefan et al., 1982, Holmes et al., 1987, Panayiotopoulos et al., 1989, Sadleir et al., 2006, Sadleir et al., 2008, Sadleir et al., 2009). The generic absence seizure is 9.4 s in duration with arrest of activity, loss of awareness, staring, eyelid movements and automatisms (Penry et al., 1975, Panayiotopoulos et al., 1989, Sadleir et al., 2006, Sadleir et al., 2008). Ictal EEG shows 2.5 Hz or faster generalized spike and wave (GSW) with one or more spikes (Panayiotopoulos et al., 1989, Sadleir et al., 2006, Sadleir et al., 2009). The specifics of the clinical and EEG features of absence seizures vary both between and within an individual child (Penry et al., 1975, Sadleir et al., 2006, Sadleir et al., 2008, Sadleir et al., 2009). This variation is determined by a complex interaction of many factors including the child's age, epilepsy syndrome, and the state (awake, drowsiness, or sleep) or provocation (hyperventilation or photic stimulation) that the seizure occurs in (Sadleir et al., 2006, Sadleir et al., 2008, Sadleir et al., 2009).

Several studies have described the effect of sleep on the inter-ictal EEG in children with idiopathic generalized epilepsy (Ross et al., 1966, Sato et al., 1973, Dhanuka et al., 2001). Sleep activates GSW producing shorter, more disorganized discharges, with increased number of spikes per wave (Ross et al., 1966, Sato et al., 1973, Dhanuka et al., 2001). There are no previous reports describing what, if any, the clinical features of absence seizures are during sleep. Here we describe in detail the clinical and EEG features of absence seizures during sleep.

Section snippets

Methods

The British Columbia's Children's Hospital (BCCH) EEG department is a primary facility with referrals from family physicians, pediatricians and pediatric neurologists. Video monitoring has been performed during all routine EEGs at BCCH since 1992. Demographic and electro-clinical information on patients is entered into an EEG database. The database of 14,452 EEGs was searched for patients less than 18 years of age who had at least one absence seizure during a routine video-EEG between January

Results

Seventy consecutive untreated children (35 females) who fit the inclusion and exclusion criteria were studied. These children had 509 seizures. Of the 56 children in whom sleep was captured, 30 children had 52 GSW discharges >2 s during sleep. A clinical sign was seen in 13 children during 18 seizures. Clinical features of these children are shown in Table 1.

The average duration of the GSW discharges during sleep was 7.44 ± 5.57 s (range 2.1–23.0 s). There was no clinically significant difference in

Discussion

Integral to absence seizures are the EEG signature of repetitive GSW and the clinical feature of altered awareness (Panayiotopoulos, 2008). Altered awareness may not be obvious and may require sophisticated testing if mild. Simple response testing however, demonstrates altered awareness in 95% of tested absence seizures (Sadleir et al., 2006). The other clinical features of absence seizures fall into two groups: (1) those directly related to the degree of altered awareness such as arrest of

Acknowledgements

We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. We are grateful to the Neurophysiology department at British Columbia's Children's Hospital and the patients for participating in this study.

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Citation Excerpt :
Absence seizures are classified as nonmotor generalized onset seizures in ILAE 2017; however, ILAE 2017 guidelines also state that automatisms and mild motor components commonly accompany typical absence seizures [10]. The semiology of absence seizures is described in detail in earlier video-EEG studies [20,22,35,41,42]. In this study, each absence seizure was classified primarily into two groups regarding motor/non-motor phenomenology according to the presence or absence of specific clinical semiologic features [10]: (1) Absence seizures without motor components (absence seizures with impairment of consciousness only): impairment of consciousness with loss of awareness, unresponsiveness, and behavioral arrest; (2) Absence seizures with motor components: staring associated with oral automatisms, mild clonic movements of the eyelids, or clear motor phenomena in the face, shoulders, or arms.
To analyze the ictal and interictal electroencephalographic (EEG) features in newly diagnosed childhood absence epilepsy (CAE) and determine the association between seizure onset topography, interictal focal spike-wave discharges (FSWDs) and accompanying clinical features of absence seizures.
The authors searched the EEG database for a definite diagnosis of CAE according to ILAE 2017 criteria. Video-EEGs of untreated pediatric patients during sleep and wakefulness were evaluated retrospectively.
The study included 47 patients (25 males, 22 females). Interictal FSWDs were observed in 49% of patients with CAE during wakefulness and in 85.1% during sleep (p = 0.001). Interictal FSWDs were most frequently observed in the frontal regions (awake: 34%; asleep: 74.5%), followed by the posterior temporoparietooccipital region (awake: 21.2%; asleep: 36.1%), and the centrotemporal region (awake: 6.4%; asleep: 8.5%). Eleven patients (23.4%) had polyspikes during sleep. Both bilateral symmetric and asymmetric seizure onset were noted in 32%, whereas focal seizure onset was observed in 14.9% of the patients. Absence seizures with and without motor components were seen in 72.3% and 61.7% of patients, respectively, and in 33% of patients both occurred. There were no associations between the existence of interictal FSWDs, focal/asymmetric seizure onset, and absence seizures with and/or without motor components.
Asymmetric and/or focal seizure onset, interictal FSWDs, and absence seizures with motor components are commonly observed in drug-naive CAE. This study found no association between seizure onset topography, interictal FSWDs, and semiological features of absence seizures.
Absence seizures during sleep in childhood absence epilepsy: A sign of drug resistance?
2022, Brain and Development
Citation Excerpt :
This could imply that absence seizure can not occur during sleep. In 2011, Sadleir et al. had described, for the first time, the clinical and EEG features of absence seizures during sleep in six patients with CAE [2]. All those seizures during sleep were similar to behaviors accompanying impairment of consciousness while awake (chin, eyelid, eyebrow jerks and eyes opening).
Childhood absence epilepsy (CAE) is a common pediatric epilepsy syndrome. It is characterized by typical absence seizures and a highly recognizable electroencephalography (EEG) pattern. But little is known about absence seizures during sleep.
A 7-year-old female presented with frequent typical absence seizures with 3 Hz generalized spike and wave discharges on EEG. Based on electro-clinical features she was diagnosed with CAE. When she was 8 years old, absence seizures occurred during sleep. She had refractory absence seizures even with valproic acid, lamotrigine, levetiracetam, and perampanel.
Absence seizures can occur during sleep in CAE. Absence seizures should be considered, especially when 3 Hz generalized spike and wave discharges last >2 s on EEG during sleep. It may be a sign of drug resistance and poor prognosis.
Temporally correlated fluctuations drive epileptiform dynamics
2017, NeuroImage
Macroscopic models of brain networks typically incorporate assumptions regarding the characteristics of afferent noise, which is used to represent input from distal brain regions or ongoing fluctuations in non-modelled parts of the brain. Such inputs are often modelled by Gaussian white noise which has a flat power spectrum. In contrast, macroscopic fluctuations in the brain typically follow a $1 / f^{b}$ spectrum. It is therefore important to understand the effect on brain dynamics of deviations from the assumption of white noise. In particular, we wish to understand the role that noise might play in eliciting aberrant rhythms in the epileptic brain.
To address this question we study the response of a neural mass model to driving by stochastic, temporally correlated input. We characterise the model in terms of whether it generates “healthy” or “epileptiform” dynamics and observe which of these dynamics predominate under different choices of temporal correlation and amplitude of an Ornstein-Uhlenbeck process. We find that certain temporal correlations are prone to eliciting epileptiform dynamics, and that these correlations produce noise with maximal power in the δ and θ bands. Crucially, these are rhythms that are found to be enhanced prior to seizures in humans and animal models of epilepsy. In order to understand why these rhythms can generate epileptiform dynamics, we analyse the response of the model to sinusoidal driving and explain how the bifurcation structure of the model gives rise to these findings. Our results provide insight into how ongoing fluctuations in brain dynamics can facilitate the onset and propagation of epileptiform rhythms in brain networks. Furthermore, we highlight the need to combine large-scale models with noise of a variety of different types in order to understand brain (dys-)function.
Current advances in childhood absence epilepsy
2014, Pediatric Neurology
Childhood absence epilepsy is an age-dependent, idiopathic, generalized epilepsy with a characteristic seizure appearance. The disorder is likely to be multifactorial, resulting from interactions between genetic and acquired factors, but the debate is still open. We review recent studies on different aspects of childhood absence epilepsy and also to describe new concepts.
Data for this review were identified using Medline and PubMed survey to locate studies dealing with childhood absence epilepsy. Searches included articles published between 1924 and 2013.
The diagnosis comprises predominant and associated seizure types associated with other clinical and electroencephalographic characteristics. Many studies have challenged the prevailing concepts, particularly with respect to the pathophysiological mechanisms underlying the electroencephalographic seizure discharges. Childhood absence epilepsy fits the definition of system epilepsy as a condition resulting from the persisting susceptibility of the thalamocortical system as a whole to generate seizures. This syndrome, if properly defined using strict diagnostic criteria, has a good prognosis. In some cases, it may affect multiple cognitive functions determining risk for academic and functional difficulties; the detection of children at risk allows tailored interventions. Childhood absence epilepsy is usually treated with ethosuximide, valproate, lamotrigine, or levetiracetam, but the most efficacious and tolerable initial empirical treatment has not been well defined.
We review recent studies and new concepts on the electroclinical features and pathophysiological findings of childhood absence epilepsy in order to highlight areas of consensus as well as areas of uncertainty that indicate directions for future research.
Dynamic characteristics of absence EEG recordings with multiscale permutation entropy analysis
2013, Epilepsy Research
Understanding the transition of brain activities towards an absence seizure, called pre-epileptic seizure, is a challenge. In this study, multiscale permutation entropy (MPE) is proposed to describe dynamical characteristics of electroencephalograph (EEG) recordings on different absence seizure states. The classification ability of the MPE measures using linear discriminant analysis is evaluated by a series of experiments. Compared to a traditional multiscale entropy method with 86.1% as its classification accuracy, the classification rate of MPE is 90.6%. Experimental results demonstrate there is a reduction of permutation entropy of EEG from the seizure-free state to the seizure state. Moreover, it is indicated that the dynamical characteristics of EEG data with MPE can identify the differences among seizure-free, pre-seizure and seizure states. This also supports the view that EEG has a detectable change prior to an absence seizure.
On-off intermittency of thalamo-cortical oscillations in the electroencephalogram of rats with genetic predisposition to absence epilepsy
2012, Brain Research
Spike-wave discharges (SWD) are electroencephalographic hallmarks of absence epilepsy. SWD are known to originate from thalamo-cortical neuronal network that normally produces sleep spindle oscillations. Although sleep spindles and SWD are considered as thalamo-cortical oscillations, functional relationship between them is not obvious. The present study describes temporal dynamics of SWD and sleep spindles as determined in 24 h EEG recorded in WAG/Rij rat model of absence epilepsy. SWD, sleep spindles (10–15 Hz) and 5–9 Hz oscillations were automatically detected in EEG using wavelet-based algorithm. It was found that non-linear dynamics of SWD fitted well to the law of ‘on–off intermittency’. Sleep spindles also demonstrated ‘on–off intermittency’, in contrast to 5–9 Hz oscillations, whose dynamics could not be classified as having any known type of non-linear behavior. Intermittency in sleep spindles and SWD implies that (1) temporal dynamics of these oscillations are deterministic in nature, and (2) it might be controlled by a system-level mechanism responsible for circadian modulation of neuronal network activity.

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Short communicationElectroclinical features of absence seizures in sleep

Summary

Purpose

Principal results

Conclusion

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgements

Seizure

Proposal for revised classification of epilepsies and epileptic syndromes

Epilepsia

Absence seizures in children: clinical and electrographic features

Ann. Neurol.

Differentiation of typical absence seizures in epileptic syndromes. A video EEG study of 224 seizures in 20 patients

Brain

Typical absence seizures and related epileptic syndromes: assessment of current state and directions for future research

Epilepsia

Simultaneous recording of absence seizures with video tape and electroencephalography. A study of 374 seizures in 48 patients

Brain

Short communication
Electroclinical features of absence seizures in sleep