Focal ictal direct current shifts in human epilepsy as studied by subdural and scalp recording

Akio Ikeda, Waro Taki, Takeharu Kunieda, Kiyohito Terada, Nobuhiro Mikuni, Takashi Nagamine, Shogo Yazawa, Shinji Ohara, Tomokatsu Hori, Ryuji Kaji, Jun Kimura, Hiroshi Shibasaki

Research output: Contribution to journalArticle

Abstract

In order to clarify further the characteristics of ictal direct current (DC) shifts in human epilepsy, we investigated them by subdural and scalp recording in six and three patients, respectively, both having mainly neocortical lobe epilepsy (five with frontal lobe epilepsy, two with parietal lobe epilepsy and two with temporal lobe epilepsy). By using subdural electrodes made of platinum, ictal DC shifts were observed in 85% of all the recorded seizures (89 seizures) among the six patients, and they were localized to just one or two electrodes at which the conventional initial ictal EEG change was also observed. They were closely accompanied by the electrodecremental pattern in all patients except for one in whom 1 Hz rhythmic activity was superimposed on clear negative slow shifts. Seizure control after resection of the cortex, including the area showing DC shifts, was favourable irrespective of histological diagnosis. Scalp-recorded ictal slow shifts were observed in 23% of all the recorded seizures (60 seizures) among the three patients. They were, like the subdurally recorded ones, mainly surface-negative in polarity, closely related to the electrodecremental pattern and consistent in their location. It seems that scalp-recorded DC shifts were detected particularly when seizures were clinically intense, while no slow shifts were observed in small seizures. It is concluded that at least subdurally recorded ictal slow shifts are clinically useful before epilepsy surgery to delineate more specifically an epileptogenic area as well as to further confirm the conventional initial ictal EEG change, and that scalp-recorded ictal slow shifts also have high specificity although their low sensitivity is to be taken into account.

Original languageEnglish (US)
Pages (from-to)827-838
Number of pages12
JournalBrain
Volume122
Issue number5
DOIs
StatePublished - 1999
Externally publishedYes

Keywords

  • Epilepsy
  • Ictal DC shift
  • Ictal EEG
  • Scalp recording
  • Subdural recording

ASJC Scopus subject areas

  • Neuroscience(all)

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  • Cite this

    Ikeda, A., Taki, W., Kunieda, T., Terada, K., Mikuni, N., Nagamine, T., Yazawa, S., Ohara, S., Hori, T., Kaji, R., Kimura, J., & Shibasaki, H. (1999). Focal ictal direct current shifts in human epilepsy as studied by subdural and scalp recording. Brain, 122(5), 827-838. https://doi.org/10.1093/brain/122.5.827