Hemispheric predominance of abnormal findings in electroencephalogram (EEG)

Gatzonis, Stylianos; Roupakiotis, S. C.; Kambayianni, E.; Politi, Antonio; Triantafyllou, Nikolaos; Mantouvalos, V.; Chioni, A.; Zournas, C.; Siafakas, A.

doi:10.1053/seiz.2001.0642

Cited by 20 publications

(11 citation statements)

References 12 publications

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“…The peculiar left “dominance” found in the anterior cortical region of PS patients may also be attributable to the same distorted (genetic and developmental) mechanism that explains the differences between the anterior and posterior cortical areas. The greater propensity of the dominant hemisphere to generate hyperexcitability phenomena has been demonstrated in large populations of patients with focal epilepsies (Gatzonis et al., 2002; Aurlien et al., 2007), and we have found that patients with juvenile myoclonus epilepsy are more likely to generate jerk‐locked spikes in the dominant hemisphere (Panzica et al., 2001).…”

Section: Discussionmentioning

confidence: 57%

Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: A partial directed coherence study

Varotto

Visani²,

Canafoglia³

et al. 2011

Epilepsia

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SUMMARYPurpose: Photosensitive epilepsy (PSE) is the most common form of reflex epilepsy presenting with electroencephalography (EEG) paroxysms elicited by intermittent photic stimulation (IPS). To investigate whether the neuronal network undergoes dynamic changes before and during the transition to an EEG epileptic discharge, we estimated EEG connectivity patterns in photosensitive (PS) patients with idiopathic generalized epilepsy. Methods: EEG signals were evaluated under resting conditions and during 14 Hz IPS, a frequency that consistently induces photoparoxysmal responses (PPRs) in PS patients. Partial directed coherence (PDC), a linear measure of effective connectivity based on multivariate autoregressive models, was used in 10 PS patients and 10 controls. Anterior versus posterior (F3, F4, C3, C4, and P3, P4, O1, O2) and interhemispheric connectivity patterns (F4, C4, P4, O2, and F3, C3, P3, O1) were estimated with focus on beta and gamma band activity.Key Findings: PDC analysis revealed an enhanced connectivity pattern in terms of both the number and strength of outflow connections in the PS patient group. Under resting condition, the greater connectivity in the PS patients occurred in the beta band, whereas it mainly involved the gamma band during IPS (i.e., the frequencies ranging from 40-60 Hz that include the higher harmonics of the stimulus frequency). Both at rest and during IPS, the differences between the PS patients and controls were due primarily to clearly increased connectivity involving the anterior cortical regions. Significance: Our findings indicate that PS patients are characterised by abnormal EEG hyperconnectivity, primarily involving the anterior cortical regions under resting conditions and during IPS. This suggests that, even if the occipital cortical regions are the recipient zone of the stimulus and probably hyperexcitable, the anterior cortical areas are prominently involved in generating the hypersynchronization underlying the spike-and wave discharges elicited by IPS.

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Section: Discussionmentioning

confidence: 57%

Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: A partial directed coherence study

Varotto

Visani²,

Canafoglia³

et al. 2011

Epilepsia

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“…Dean et al studied the patients in two different laboratories with epileptiform discharge, it was found that spikes of 95 EEG indicating spikes arose from the left in 61 and from the right in 34[18]. Gatzonis et al reported that 128 of 162 epilepsy patients EEGs showed a strong left predominance (79%) while only 34 patients had a right predominance (23%) [1]. Similarly, left-sided brain tumors seemed much more likely than right-sided tumors to produce seizures.…”

Section: Discussionmentioning

confidence: 99%

“…It is widely accepted that the discrepancy between the EEG findings from the two hemispheres should be attributed to their inherent structural and functional organization which leads to the formation of more 'silent' or 'redundant' areas [1]. …”

Section: Discussionmentioning

confidence: 99%

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Left hemisphere predominance of pilocarpine-induced rat epileptiform discharges

Yang

Lai

Lei

et al. 2009

J NeuroEngineering Rehabil

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BackgroundThe left cerebral hemisphere predominance in human focal epilepsy has been observed in a few studies, however, there is no related systematic study in epileptic animal on hemisphere predominance. The main goal of this paper is to observe if the epileptiform discharges (EDs) of Pilocarpine-induced epileptic rats could present difference between left hemisphere and right hemisphere or not.MethodsThe electrocorticogram (ECoG) and electrohippocampogram (EHG) from Pilocarpine-induced epileptic rats were recorded and analyzed using Synchronization likelihood (SL) in order to determine the synchronization relation between different brain regions, then visual check and cross-correlation analysis were adopted to evaluate if the EDs were originated more frequently from the left hemisphere than the right hemisphere.ResultsThe data show that the synchronization between left-EHG and right-EHG, left-ECoG and left-EHG, right-ECoG and right-EHG, left-ECoG and right-ECoG, are significantly strengthened after the brain functional state transforms from non-epileptiform discharges to continuous-epileptiform discharges(p < 0.05). When the state transforms from continuous EDs to periodic EDs, the synchronization is significantly weakened between left-ECoG and left-EHG, left-EHG and right-EHG (p < 0.05). Visual check and the time delay (τ) based cross-correlation analysis finds that 10 out of 13 EDs have a left predominance (77%) and 3 out of 13 EDs are right predominance (23%).ConclusionThe results suggest that the left hemisphere may be more prone to EDs in the Pilocarpine-induced rat epilepsy model and implicate that the left hemisphere might play an important role in epilepsy states transition.

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“…From the results, we found the left hemisphere seemed to be more affected than the right hemisphere, consistent with a previous epilepsy model study which proved that the left hemisphere was easier to measure epileptiform discharges using the electrocorticogram and electrohippocampogram (13). EEG results of patients showed stronger left predominance than right predominance (14–16). Geschwind et al (17) found that the left hemisphere developed later than the right hemisphere, which was prone to affect to harmful factor.…”

Section: Discussionmentioning

confidence: 95%

Highlights in DD

Kiefer¹

2010

Developmental Dynamics

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, Dev Dyn 239:2014-2023) Tankyrase (Tnk) 1 and 2 are another of a seemingly ever-growing list of canonical Wnt pathway components. They are poly (ADP ribose) polymerases (PARPs) that destabilize Axin 1 and 2, components of the Wnt pathway destruction complex. Molecular biologists are drunk with excitement about their discovery because they are also targets of the small molecule antagonist IWR1, an inhibitor of canonical Wnt signaling. Here, Karner and colleagues test whether Tnks are general Wnt pathway components that operate during mouse development. Supporting this hypothesis, expression of Tnks1 and 2 mirrors sites of Wnt pathway activation, and application of IWR1 to organ cultures inhibits the b-catenin-dependent processes of lung and kidney branching morphogenesis. The authors also show that, when applied to kidney organ cultures, IWR1 specifically targets the Wnt pathway. IWR1 phenocopies IWP2, a small molecule antagonist that inhibits the essential Wnt pathway component porcupine, IWR1 also blocks expression of known Wnt pathway targets, and effects of IWR1 can be rescued by application of LiCl, a chemical that stabilizes b-catenin. Because porcupine operates in both canonical and noncanonical Wnt signaling, comparing IWR1 and IWP2 effects could aid in differentiating the two pathways. More than a tonic for developmental biologists, IWR1 may also prove to be a valuable reagent for studying b-catenin-related human diseases.

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Hemispheric predominance of abnormal findings in electroencephalogram (EEG)

Cited by 20 publications

References 12 publications

Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: A partial directed coherence study

Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: A partial directed coherence study

Left hemisphere predominance of pilocarpine-induced rat epileptiform discharges

Highlights in DD

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