Benefit of simultaneous recording of EEG and MEG in dipole localization

Harumi Yoshinaga, Tomoyuki Nakahori, Yoko Ohtsuka, Eiji Oka, Yoshihiro Kitamura, Hideki Kiriyama, Kazumasa Kinugasa, Keiichi Miyamoto, Toru Hoshida

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)


Purpose: In this study, we tried to show that EEG and magnetoencephalography (MEG) are clinically complementary to each other and that a combination of both technologies is useful for the precise diagnosis of epileptic focus. Methods: We recorded EEGs and MEGs simultaneously and analyzed dipoles in seven patients with intractable localization-related epilepsy. MEG dipoles were analyzed by using a BTI Magnes 148-channel magnetometer. EEG dipoles were analyzed by using a realistically shaped four-layered head model (scalp-skull-fluid-brain) built from 2.0-mm slice magnetic resonance imaging (MRI) images. Results: (a) In two of seven patients, MEG could not detect any epileptiform discharges, whereas EEG showed clear spikes. However, dipoles estimated from the MEG data corresponding to the early phase of EEG spikes clustered at a location close to that of the EEG-detected dipole. (b) In two of seven patients, EEG showed only intermittent high-voltage slow waves (HVSs) without definite spikes. However, MEG showed clear epileptiform discharges preceding these EEG-detected HVSs. Dipoles estimated for these EEG-detected HVSs were located at a location close to that of the MEG-detected dipoles. (c) Based on the agreement of the results of these two techniques, surgical resection was performed in one patient with good results. Conclusions: Dipole modeling of epileptiform activity by MEG and EEG sometimes provides information not obtainable with either modality used alone.

Original languageEnglish
Pages (from-to)924-928
Number of pages5
Issue number8
Publication statusPublished - 2002


  • Dipole
  • EEG
  • Localization-related epilepsy
  • MEG

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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