The electroencephalogram of idiopathic generalized epilepsy

Abstract

SUMMARYIdiopathic generalized epilepsy (IGE) is classified into several subsyndromes based on clinical and electroencephalography (EEG) features. The EEG signature of IGE is bisynchronous, symmetric, and generalized spikewave complex; although focal, irregular, and so called ''fragments'' of discharges are not uncommon. Other characteristic EEG features include polyspikes, polyspike-wave discharges, occipital intermittent rhythmic delta activity, and photoparoxysmal response. Both human and animal data suggest involvement of the thalamus and the cortex in the generation of spike-wave discharges in IGE. Circadian variations of generalized epileptiform discharges are well described, and these can be useful in diagnostic confirmation. Those discharges tend to occur more often after awakening and during cyclic alternating pattern phase-A of nonrapid eye movement sleep. Activation procedures such as hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are useful techniques to increase the yield of both interictal and ictal EEG abnormalities. Although not in routine use, specific triggers such as pattern stimulation and cognitive tasks may also be of value in eliciting rare reflex seizure-related EEG abnormalities. Variations of EEG abnormalities are evident between different electroclinical syndromes. EEG is also affected by certain external as well as internal factors, which should be borne in mind when interpreting EEG studies in IGE.

Utility of Magnetic Resonance Imaging (MRI) and It’s Comparison with Electroencephalogram (EEG) in First Onset Seizures in Children

“…15,17,18 This study showed abnormal EEG recordings in 6 (35%) out of 17 patients who presented with complex partial seizures and 30 (36%) out of 83 patients who presented with generalized tonic clonic seizures.…”

The applicability of ambulatory electroencephalography (AEEG) in healthy horses and horses with abnormal behaviour or clinical signs of epilepsy

“…We found EEG signals suggestive of IEDs, or discharges suggesting an intracranial space-occupying mass or brain abnormality (Lacombe et al 2001;Stern 2005;Moeller et al 2011;Seneviratne et al 2012). In a cohort of over 13,000 normal humans, IEDs were found in 0.5% of the cases (Noachtar & R emi 2009) and the chance that healthy persons with IED would develop epilepsy was 2%-3% (Noachtar & R emi 2009;Brigo 2011).…”

“…The ambulatory system makes it more convenient to register EEG recordings since horses can walk around in their stable or can be hand-walked. Theoretically, this will increase the likelihood of recording abnormalities (Binnie & Stefan 1999;Moeller et al 2011;Seneviratne et al 2012). Since in humans many pathological events occur during certain phases of sleep (Binnie & Stefan 1999;Overvliet et al 2010), it seems advantageous that the horses showed a surprisingly frequent-occurring sleep pattern during the day, which might be beneficial for capturing abnormal recordings.…”

“…In horses, electroencephalography (EEG) has been applied for decades (Purohit et al 1981;Mysinger et al 1985) and is used to diagnose, locate and define possible intracranial abnormalities, for example, epilepsy (Lacombe et al 2001;Kaplan 2004;Noachtar & R emi 2009;Lacombe et al 2011;Moeller et al 2011;Seneviratne et al 2012). A differentiation between partial (focal) and generalised epileptic seizures can be made and the effect of treatment can be monitored (Stern 2005;Noachtar & R emi 2009).…”

Spatiotemporal mapping of interictal epileptiform discharges in human absence epilepsy: A MEG study

“…between 4 and 12 years (Loiseau et al, 2002), are still classified as generalized (Berg and Plioplys, 2012), although it is questioned whether there are fundamental differences between generalized and focal types of epilepsy (Lüders et al, 2009;Seneviratne et al, 2012;van Luijtelaar et al, 2014).…”