Comparison of magnetoencephalographic spikes with and without concurrent electroencephalographic spikes in extratemporal epilepsy

Hyeon Mi Park, Nobukazu Nakasato, Masaki Iwasaki, Hiroshi Shamoto, Teiji Tominaga, Takashi Yoshimoto

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Interictal spikes in patients with epilepsy may be detected by either electroencephalography (EEG) (E-spikes) or magnetoencephalography (MEG) (M-spikes), or both MEG and EEG (E/M-spikes). Localization and amplitude were compared between E/M-spikes and M-spikes in 7 adult patients with extratemporal epilepsy to evaluate the clinical significance of MEG spikes. MEG and EEG were simultaneously measured using a helmet-shaped MEG system with planar-type gradiometers and scalp electrodes of the international 10-20 system. Sources of E/M-spikes and M-spikes were estimated by an equivalent current dipole (ECD) model for MEG at peak latency. Each subject showed 9 to 20 (mean 13.4) E/M-spikes and 9 to 31 (mean 16.3) M-spikes. No subjects showed significant differences in the ECD locations between E/M- and M-spikes. ECD moments of the E/M-spikes were significantly larger in 2 patients and not significantly different in the other 5 patients. The similar localizations of E/M-spikes and M-spikes suggest that combination of MEG and EEG is useful to detect more interictal spikes in patients with extratemporal epilepsy. The smaller tendency of ECD amplitude of the M-spikes than E/M-spikes suggests that scalp EEG may overlook small tangential spikes due to background brain noise. Localization value of M-spikes is clinically equivalent to that of E/M-spikes.

Original languageEnglish
Pages (from-to)165-174
Number of pages10
JournalTohoku Journal of Experimental Medicine
Volume203
Issue number3
DOIs
Publication statusPublished - 2004 Jul

Keywords

  • Electroencephalography
  • Epilepsy
  • Equivalent current dipole
  • Interictal spike
  • Magnetoencephalography

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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