Generalized Spike Wave Discharges Research Articles

Unilateral thalamic lesions and generalized or lateralized spike wave discharges

We report four adult patients who had thalamic lesions and lateralized or generalized spike wave discharges (SWDs). The first two patients also had cortical lesions. The role of the cortex and thalamus in the generation of SWDs is discussed. The third patient had a history of idiopathic generalized epilepsy (IGE) with intractable seizures. The last patient had partial seizures and absences. The coexistence of IGE with refractory focal epilepsy and the relation with thalamic lesions are discussed.

Bayesian multi-modal model comparison: A case study on the generators of the spike and the wave in generalized spike–wave complexes

We present a novel approach to assess the networks involved in the generation of spontaneous pathological brain activity based on multi-modal imaging data. We propose to use probabilistic fMRI-constrained EEG source reconstruction as a complement to EEG-correlated fMRI analysis to disambiguate between networks that co-occur at the fMRI time resolution. The method is based on Bayesian model comparison, where the different models correspond to different combinations of fMRI-activated (or deactivated) cortical clusters. By computing the model evidence (or marginal likelihood) of each and every candidate source space partition, we can infer the most probable set of fMRI regions that has generated a given EEG scalp data window. We illustrate the method using EEG-correlated fMRI data acquired in a patient with ictal generalized spike–wave (GSW) discharges, to examine whether different networks are involved in the generation of the spike and the wave components, respectively. To this effect, we compared a family of 128 EEG source models, based on the combinations of seven regions haemodynamically involved (deactivated) during a prolonged ictal GSW discharge, namely: bilateral precuneus, bilateral medial frontal gyrus, bilateral middle temporal gyrus, and right cuneus. Bayesian model comparison has revealed the most likely model associated with the spike component to consist of a prefrontal region and bilateral temporal–parietal regions and the most likely model associated with the wave component to comprise the same temporal–parietal regions only. The result supports the hypothesis of different neurophysiological mechanisms underlying the generation of the spike versus wave components of GSW discharges.

Changes in activity of striato–thalamo–cortical network precede generalized spike wave discharges

The pathophysiology of generalized spike wave discharges (GSW) is not completely understood. Thalamus, basal ganglia and neocortex have been implicated in the generation of GSW, yet the specific role of each structure remains to be clarified. In six children with idiopathic generalized epilepsy (IGE), we performed combined EEG–fMRI to identify GSW-related changes in blood oxygen level-dependent (BOLD) signal in the striato–thalamo–cortical network. In all patients, within-subject analysis demonstrated BOLD signal changes that preceded the GSW. An increase in BOLD signal in the medial thalamus started 6 s before the onset of the GSW. Decreases in cortical BOLD signal were mainly found in frontoparietal areas and precuneus starting 6 to 3 s before the GSW. All patients showed a decrease in BOLD signal in the head of the caudate nucleus with a variable onset. The temporospatial pattern of BOLD signal changes suggests that GSW on the cortical surface is preceded by a sequence of neuronal events in the thalamo–cortical–striatal network. Approximately 6 s before the GSW, the thalamus shows an increase in neuronal activity along with regional decreases in cortical activity. These changes in thalamo-cortical activity are followed by a deactivation of the caudate nucleus. These early changes in BOLD signal may reflect changes in neuronal activity that contribute to the generation of GSW and may contribute to the transition from a normal to a generalized hypersynchronous pattern of neuronal activity. Our preliminary findings warrant further studies on a larger number of patients to explore the influence of age, medication and type of epileptic syndrome.

Sleep Spindle Abnormalities with Generalized Spike-Wave Discharges

Sleep and sleep spindle parameters were examined in 15 children with primary generalized spike-and-wave discharges at University Hospitals, Leuven, Belgium.

Assessment of acute morbidity and mortality in nonconvulsive status epilepticus.

S: The natural history of nonconvulsive status epilepticus (NCSE) is not well defined, especially mortality and morbidity. The authors hypothesized that the mortality of NCSE is higher when NCSE is due to acute medical causes (systemic or neurologic) or associated with severe impairment of mental status or with acute complications, and lower when associated with generalized spike-wave (SW) discharges on EEG. The authors retrospectively identified 100 consecutive patients with NCSE from an EEG database. Data were collected from systematic review of medical records and actual EEG tracings. Specific etiologies were divided into three groups: acute medical, epilepsy, and cryptogenic. Of the 100 patients, 18 died. Fourteen of 52 patients in the acute medical group died, 1 of 31 in the epilepsy group died, and 3 of 17 in the cryptogenic group died. Mental status impairment was severe in 33, complications occurred in 39, and generalized SW discharges occurred in 36. Mortality rates were higher in patients 1) in the acute medical group (27%) vs the epilepsy (3%) and the cryptogenic (18%) groups (p < 0.02), 2) with severe mental status impairment (39%) compared to those with mild impairment (7%, p < 0.001), and 3) with acute complications (36%) when compared with those without complications (7%, p < 0.0002). The presence of generalized SW discharges on EEG did not correlate with mortality. Mental status impairment and etiology were independently associated with mortality (p < 0.001). NCSE is associated with substantial mortality. Mortality is associated with an acute medical cause as the underlying etiology, severe mental status impairment, and development of acute complications, but not the type of EEG discharge.

Ethosuximide, sodium valproate or lamotrigine for absence seizures in children and adolescents.

Absence seizures are brief epileptic seizures which present in childhood and adolescence. They are characterised by sudden loss of awareness and an electroencephalogram (EEG) typically shows generalised spike wave discharges at three cycles per second. Ethosuximide, valproate and lamotrigine are currently used to treat absence seizures. This review aims to determine the best choice of anticonvulsant for a child with typical absence seizures. To review the evidence for the effects of ethosuximide, valproate and lamotrigine as treatments for children and adolescents with absence seizures, when compared with placebo or each other. We searched the Cochrane Epilepsy Group trials register, the Cochrane Central Register of Controlled Trials (The Cochrane Library issue 1, 2003), MEDLINE (January 1966 to March 2003) and EMBASE (1988 to March 2003). We also contacted Sanofi Winthrop, Glaxo Wellcome (now GlaxoSmithKline) and Parke Davis (now Pfizer), manufacturers of sodium valproate, lamotrigine and ethosuximide respectively. Randomised parallel group monotherapy or add-on trials which include a comparison of any of the following in children or adolescents with absence seizures: ethosuximide; sodium valproate; lamotrigine or placebo. Outcome measures were: (i) proportion of individuals seizure free at 1, 6 and 18 months post randomisation; (ii) people with a 50% or greater reduction in seizure frequency; (iii) normalisation of EEG and/or negative hyperventilation test and (iv) adverse effects. Data were independently extracted by two reviewers. Results are presented as relative risks (RR) with 95% confidence intervals (95% CI). Four small trials were found, which were of poor methodological quality. One trial (29 participants) compared lamotrigine with placebo using a response conditional design. Individuals taking lamotrigine were significantly more likely to be seizure free than participants taking placebo during this short trial. Three studies compared ethosuximide, but because of diverse study designs and populations studied, we decided not to pool results in a meta-analysis. None of these studies found a difference between valproate and ethosuximide with respect to seizure control, but confidence intervals were wide and the existence of important differences could not be excluded. Although ethosuximide, lamotrigine and valproate are commonly used to treat people with absence seizures we have insufficient evidence to inform clinical practice, and the few trials included in this review were of poor methodological quality. More trials of better quality are needed.

M32 Topographic classification of Rolandic spikes by means of neural network

Generalised 3 Hz spike wave (SW) discharges with or without absences have been described in children with benign epilepsy with centrotemporal spikes (BECTS), leading to speculations about a continuum between childhood absence epilepsy (CAE) and BECTS. We thus decided to evaluate the prevalence of absence seizures (AS) and generalised 3 Hz SW in patients with BECTS. All patients with BECTS first referred since 1986 have been identified prospectively. Their medical and electroencephalograph (EEG) records were analysed retrospectively, in the search for AS and generalised SW discharges. Over a period of 11 years, we found typical rolandic spikes in 66 newly referred patients; 64 had seizures typical for the condition (18 female, 46 male), two were asymptomatic and were not further analysed. All had routine waking EEG recordings, and 49 children (76%) had at least one sleep EEG. AS or classical generalised 3 Hz SW were never recorded from history or EEG data, respectively. However, 17 patients had some diffuse SW discharges, lasting 1–5 s, which appeared as grossly symmetrical in only seven children, with a clearly asymmetrical aspect in the others. Among these seven patients, the discharges were only seen on awakening in one, both during waking and nREM sleep stage I or II in one and only during nREM sleep stage I or II in five. They were apparently subclinical in all. We thus found neither AS nor classical 3 Hz SW discharges among 64 consecutive patients with BECTS. Brief bursts of bilateral abnormalities occur in about 25% of the cases, mostly with sleepiness. Such findings do not substantiate the existence of a continuum between CAE and BECTS.

Generalized spike-waves, multiple loci, and clinical course in children with EEG features of benign epilepsy of childhood with centrotemporal spikes.

In 41 patients with EEG features of benign epilepsy of childhood with centrotemporal spikes (BECCT), we noted associated generalized spike-wave discharges (GSWD) in 14.6% and multiple independent sharp wave foci in 9.8%. The presence or absence of these EEG features was not predictive of the clinical course. The high incidence of GSWD in children with BECCT suggests a possible relation in the expression of these two EEG traits.

Some Genetic Aspects of Idiopathic and Symptomatic Absence Seizures: Waking and Sleep EEGs in Siblings

Epileptic activity was recorded in the waking and sleep EEG of 62.5% of 80 siblings of 38 patients with absence seizures. Epileptic discharges were noted in waking only in 8.7%, in waking as well as sleep in 28.8%, and in sleep only in 25%. Generalized, partly irregular, and slow spike-wave complexes were found, twice with lateral emphasis. Spike-wave complexes were recorded in 72% of 50 siblings of patients with idiopathic absence and in 46.7% of 30 siblings of patients with symptomatic absence. One epileptic discharge was observed every 108.6 s on the average, without striking differences between siblings of patients with idiopathic (99.7 s) and symptomatic absence (119.3 s). Without any differences between siblings of children with idiopathic and symptomatic absence, the most epileptic discharges were activated in sleep stages C and D, followed by stages A and B. The highest activation rate was observed in the 7-14-year-old group (73.5%) and to a somewhat lesser degree in the group between 15 and 20 years of age (66.7%); fewer epileptic discharges were recorded in younger (25%) and older patients (28.6%). The higher activation rates in the male sex were significant only in siblings of patients with idiopathic absence. Although only five patients (13.2%) were photosensitive, a photosensitivity was found in 24% of siblings of children with idiopathic absence and in 20% of siblings of patients with symptomatic absence. Three siblings of patients with idiopathic absence also had absence seizures; in one of them a febrile seizure occurred at an earlier age. All of them showed generalized spike wave discharges in waking as well as sleep. Occipital theta delta activity with generalization was observed more frequently in siblings of patients with idiopathic absence (82.2%) than in those of patients with symptomatic absence (63.6%). Our waking and sleep EEG recordings prove that concerning etiology-genetic factors play a striking role in idiopathic absence, but are also of considerable significance in the symptomatic types.

Clinical features of acute gastroenteritis associated with rotavirus, enteric adenoviruses, and bacteria.

In a prospective one year study, comprising children with acute gastroenteritis admitted to hospital or treated as outpatients, the clinical and laboratory features of rotavirus diarrhoea (168 cases) were compared with those of enteric adenovirus (32 cases), bacterial (42), mixed (16), and non-specific (135) infections. The rotavirus disease was remarkably consistent, with a sudden onset of vomiting, a high frequency of fever and dehydration, and a mean duration of diarrhoea of 5.9 days. Outpatients excreting rotavirus had a similar but milder illness, mainly on account of less pronounced vomiting. The predominant symptom of enteric adenoviruses was long lasting diarrhoea (mean 10.8 days). Abdominal pain, bloody stools, prolonged diarrhoea (mean 14.1 days), leucocytosis, and a raised erythrocyte sedimentation rate strongly suggested a bacterial aetiology. Mixed infections caused longer lasting diarrhoea (mean 8.0 days) than rotavirus alone, but the severity of the illness was not increased. The clinical features of infection with unidentified pathogens most resembled those of bacterial infections. Respiratory symptoms were not significantly associated with any particular pathogen. Hypernatraemia and complications were uncommon. This study showed that the clinical features of gastroenteritis with rotavirus, enteric adenoviruses, and bacteria each exhibited patterns that could guide the experienced clinician to a presumptive diagnosis.

Kopfschmerzen und generalisierte epileptische EEG-Aktivität unter starker Lichtexposition

The case of a 16 years old girl with bilateral headache attacks and simultaneous generalised paroxysmal activity in EEG triggered by light is reported. Headache intensity as well as the number of generalised spike wave discharges under photic stimulation depended on intensity of light whereas wavelength of used light had no influence. Paroxysmal activity was most intensive at a flash light frequency of 25 Hz.