Intracranial broadband EEG analysis and surgical outcome: Case report

Modur, Pradeep N.; Scherg, Michael

doi:10.1016/j.clinph.2009.03.022

Cited by 18 publications

(40 citation statements)

References 16 publications

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“…[910] Around the same time, using much larger, commercially-available clinical electrodes (4 mm 2 , ~4000 - 9400× larger than microelectrodes), other investigators described HFOs in human depth and subdural recordings obtained from both mesial temporal and neocortical structures. [111213141516] These investigators described both ictal and interictal HFOs in the 70-500 Hz range in chronic extraoperative intracranial recordings as well as intraoperative electrocorticography (ECoG). The effect of electrode size on the recorded frequency band was further explored by Worrell et al .…”

Section: Hfosmentioning

confidence: 99%

“…[111213141516] In the microelectrode studies, the recordings were confined to mesial temporal structures; the mean frequency of ripples was 96 Hz (±14 Hz) and that of FRs was 262 Hz (±59 Hz), with FRs being significantly shorter in duration than ripples. [6719] Compared with ripples, FRs were found to be generated locally, in <1 mm 3 of tissue.…”

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

“…However, subsequent studies using a large subdural grids convincingly demonstrated that the ictal HFOs occurred in a widespread manner in all brain regions. [1114272829]…”

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

“…Relying on time-frequency methods to carefully analyze the HFOs, some investigators have shown that the ictal HFOs with sufficiently high spectral power are usually< 300 Hz in frequency. [111314272829] An exception to this was noted in a study done with a sampling rate of 2000 Hz using macroelectrodes (0.8 mm 2 ), which showed the occurrence of ictal HFOs around 300-375 Hz at seizure onset followed by slower 120-190 Hz activity as the seizure evolved. [9] Although the lower frequency range for the ictal HFOs could be attributed to the larger electrode size, the possibility that the ictal front may synchronize the HFOs at a lower frequency at seizure onset than interictally needs to be entertained and further explored.…”

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

“…[11] Similar spatial and temporal features of ictal HFOs were also noted in adults with neocortical epilepsy. [1427] In a prospectively-defined surgical protocol, Modur et al . differentiated 2 types of ictal HFOs: HFO+ that appeared at seizure onset, and persisted as HFOs or transitioned into lower frequency activity with seizure evolution until the first clinical seizure symptom appeared; and HFO– that appeared at seizure onset but did not evolve.…”

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

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High frequency oscillations and infraslow activity in epilepsy

Modur

2014

Ann Indian Acad Neurol

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In pre-surgical evaluation of epilepsy, there has been an increased interest in the study of electroencephalogram (EEG) activity outside the 1-70 Hz band of conventional frequency activity (CFA). Research over the last couple of decades has shown that EEG activity in the 70-600 Hz range, termed high frequency oscillations (HFOs), can be recorded intracranially from all brain regions both interictally and at seizure onset. In patients with epilepsy, HFOs are now considered as pathologic regardless of their frequency band although it may be difficult to distinguish them from the physiologic HFOs, which occur in a similar frequency range. Interictal HFOs are likely to be confined mostly to the seizure onset zone, thus providing a new measure for localizing it. More importantly, several studies have linked HFOs to underlying epileptogenicity, suggesting that HFOs can serve as potential biomarkers for the illness. Along with HFOs, analysis of ictal baseline shifts (IBS; or direct current shifts) and infraslow activity (ISA) (ISA: <0.1 Hz) has also attracted attention. Studies have shown that: IBSs can be recorded using the routine AC amplifiers with long time constants; IBSs occur at the time of conventional EEG onset, but in a restricted spatial distribution compared with conventional frequencies; and inclusion of IBS contacts in the resection can be associated with favorable seizure outcome. Only a handful of studies have evaluated all the EEG frequencies together in the same patient group. The latter studies suggest that the seizure onset is best localized by the ictal HFOs, the IBSs tend to provide a broader localization and the conventional frequencies could be non-localizing. However, small number of patients included in these studies precludes definitive conclusions regarding post-operative seizure outcome based on selective or combined resection of HFO, IBS and CFA contacts. Large, preferably prospective, studies are needed to further evaluate the implications of different EEG frequencies in epilepsy.

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Section: Hfosmentioning

confidence: 99%

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

“…However, subsequent studies using a large subdural grids convincingly demonstrated that the ictal HFOs occurred in a widespread manner in all brain regions. [1114272829]…”

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

Section: Hfos: Clinical Implicationsmentioning

confidence: 99%

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High frequency oscillations and infraslow activity in epilepsy

Modur

2014

Ann Indian Acad Neurol

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Surgery for extratemporal nonlesional epilepsy in adults: an outcome meta-analysis

Ansari

Tubbs²,

Terry

et al. 2010

Acta Neurochir

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This meta-analysis confirms the findings of other centers: ETLE surgical outcomes are less desirable than those for temporal lobe epilepsy. None of the factors studied in adults showed significant association with outcome. Contrary to some reports, shortening the duration of epilepsy by pursuing surgery as early as possible also does not appear to improve outcomes. The creation of standard protocols among epilepsy centers is needed to allow for a detailed evaluation of outcomes across different centers and, ultimately, to better assess the factors associated with improved outcomes.

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Electroencephalographic evaluation of epileptogenicity: traditional versus novel biomarkers to guide surgery

Swarnalingam,

Jacobs

2025

Pediatric Epilepsy Surgery Techniques

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Intracranial broadband EEG analysis and surgical outcome: Case report

Cited by 18 publications

References 16 publications

High frequency oscillations and infraslow activity in epilepsy

High frequency oscillations and infraslow activity in epilepsy

Surgery for extratemporal nonlesional epilepsy in adults: an outcome meta-analysis

Electroencephalographic evaluation of epileptogenicity: traditional versus novel biomarkers to guide surgery

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