Morphological Patterns of Seizures Recorded Intracranially

Spencer, Susan S.; Guimarães, Pedro; Katz, Amiram; Kim, Jung; Spencer, Dennis D.

doi:10.1111/j.1528-1157.1992.tb01706.x

Cited by 209 publications

(124 citation statements)

References 10 publications

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“…Ictal-like activity was not recorded from the dentate gyrus, CA3 region or entorhinal cortex although multi-unit activity in these areas was increased by the convulsants. Ictal-like field potentials were similar to intracranial EEG records of mesial temporal lobe seizures in humans 17,18 and animals 19 . In slices from 20 individuals they consisted of recurrent rhythmic bursts of frequency 3.7±0.1 Hz (95% CI: [3.6-3.7]).…”

Section: Induction Of Ictal-like Events In the Epileptic Subiculummentioning

confidence: 55%

Glutamatergic pre-ictal discharges emerge at the transition to seizure in human epilepsy

et al. 2011

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Mechanisms involved in the transition to an epileptic seizure remain unclear. We studied this question in tissue slices from human subjects with mesial temporal lobe epilepsies. Ictal-like discharges were induced in the subiculum by increasing excitability together with an alkalinization or low Mg 2+ . During the transition, distinct pre-ictal discharges emerged concurrently with interictal events. Intracranial recordings from the mesial temporal cortex of epileptic subjects revealed similar discharges before seizures were restricted to seizure onset sites. In vitro, pre-ictal events spread faster, have a larger amplitude and a distinct initiation site than interictal discharges. They depend on glutamatergic mechanisms and are preceded by pyramidal cell firing, while interneuron firing precedes interictal events which depend on both glutamatergic and depolarizing GABAergic transmission. Once established, recurrence of these pre-ictal discharges triggers seizures. Thus the subiculum supports seizure generation and the transition to seizure involves a novel, emergent glutamatergic population activity.3

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Section: Induction Of Ictal-like Events In the Epileptic Subiculummentioning

confidence: 55%

Glutamatergic pre-ictal discharges emerge at the transition to seizure in human epilepsy

et al. 2011

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“…On average 32.1 channels (SD 10.1) were marked per patient, 4.8 (SD 3.7) of them being considered the SOZ. Seizure onset morphology could be divided into low-voltage fast activity in 22 patients and hypersynchronous high-amplitude EEG spikes (Spencer et al, 1992) in three.…”

Section: Resultsmentioning

confidence: 99%

Ictal and interictal high frequency oscillations in patients with focal epilepsy

Zijlmans¹,

Jacobs²,

Kahn³

et al. 2011

Clinical Neurophysiology

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Objective-High frequency oscillations (HFOs) can be recorded with depth electrodes in focal epilepsy patients. They occur during seizures and interictally and seem important in seizure genesis. We investigated whether interictal and ictal HFOs occur in the same regions and how they relate to epileptiform spikes.Methods-In 25 patients, spikes, ripples (80-250 Hz) and fast ripples (FR: 250-500 Hz) and their co-occurrences were marked during interictal slow wave sleep (5-10 min), during 10 preictal seconds and 5 s following seizure onset. We compared occurrence and spatial distribution between these periods.Results-HFOs and spikes increased from interictal to ictal periods: the percentage of time occupied by ripples increased from 2.3% to 6.5%, FR from 0.2% to 0.8%, spikes from 1.1% to 4.8%. HFOs increased from interictal to preictal periods in contrast to spikes. Spikes were in different channels in the interictal, preictal and ictal periods whereas HFOs largely remained in the same channels.Conclusions-HFOs remain confined to the same, possibly epileptogenic, area, during interictal and ictal periods, while spikes are more widespread during seizures than interictally.Significance-Ictal and interictal HFOs represent the same (epileptogenic) area and are probably similar phenomena.

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“…(Figure 1). 'Seizure onset zones' were defined as a single or multiple brain areas initially showing a sustained rhythmic change in the ECoG accompanied by subsequent clinically typical seizure activity, not explained by level of arousal, and clearly distinguished from background ECoG and interictal activity (Spencer et al, 1992;Asano et al, 2003). 'Non-onset areas' were defined as all brain regions not classified as 'seizure-onset zone'.…”

Section: Visual Analysis Of Ecog Datamentioning

confidence: 99%

Effect of sleep on interictal spikes and distribution of sleep spindles on electrocorticography in children with focal epilepsy

Asano

Mihaylova

Juhász

et al. 2007

Clinical Neurophysiology

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OBJECTIVE-To determine how sleep with central spindles alters the spatial distribution of interictal spike frequency in children with intractable focal seizures, and whether such children have spindles arising from the medial temporal region in addition to the frontal-central region.METHODS-Seventeen children (age: 7 months -17 years) were studied using extraoperative electrocorticography (ECoG).RESULTS-Overall spike frequency across the subdural electrodes was greater during sleep with central spindles compared to wakefulness. In 13 children showing at least 1 spike/min in an electrode, the spatial distribution of spike frequency was similar during wakefulness and sleep; in addition, the spike frequency was greater in the seizure onset zones compared to the non-onset areas, regardless of wakefulness or sleep. Spindles were identified in the medial temporal region during sleep with central spindles in all 17 children.CONCLUSION-Overall spike frequency may be increased by sleep with spindles, but the spatial distribution of spike frequency appears similar during wakefulness and sleep in children with intractable focal seizures. SIGNIFICANCE-Both awake and sleep ECoG may be useful to predict seizure onset zones in children with intractable focal epilepsy. Medial temporal spindles are present in some children with focal epilepsy.

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Morphological Patterns of Seizures Recorded Intracranially

Cited by 209 publications

References 10 publications

Glutamatergic pre-ictal discharges emerge at the transition to seizure in human epilepsy

Glutamatergic pre-ictal discharges emerge at the transition to seizure in human epilepsy

Ictal and interictal high frequency oscillations in patients with focal epilepsy

Effect of sleep on interictal spikes and distribution of sleep spindles on electrocorticography in children with focal epilepsy

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