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. 2007 Jun;24(3):215-31.
doi: 10.1097/WNP.0b013e3180556095.

Concordance between routine interictal magnetoencephalography and simultaneous scalp electroencephalography in a sample of patients with epilepsy

Heidi E Kirsch  1 , Mary Mantle, Srikantan S Nagarajan
Affiliations

Concordance between routine interictal magnetoencephalography and simultaneous scalp electroencephalography in a sample of patients with epilepsy

Heidi E Kirsch et al. J Clin Neurophysiol. 2007 Jun.

Abstract

Both electroencephalography (EEG) and magnetoencephalography (MEG) localize epileptiform activity but may yield different results. This discordance may arise from different detection capabilities or from different data collection and interpretation techniques. Comparisons of MEG and EEG have focused on detection of individual spikes. However, side-by-side comparisons of results as used in the clinical setting is lacking. In this report, we present our empirical comparison. We reviewed 58 simultaneous MEG-EEG recordings (35 paired-sensors, 23 whole-head) from a diverse epilepsy population, comparing previous clinical MEG interpretations with new blinded EEG interpretations, noting lobar concordance of readers' judgments of regional abnormalities. A second-pass unblinded analysis, using all available clinical data, assessed the relative contribution and plausibility of the results of each technique. Concordance was high (85%) overall. Discordance was sometimes caused by constraints imposed by MEG dipole fitting techniques. Even when results of the techniques did not match, MEG often disambiguated the clinical scenario, especially when combined with imaging information. Thoughtful analysis of combined MEG-EEG datasets, beyond algorithm-based interictal spike detection, can help guide clinical decision-making even when concordance between techniques is imperfect. In some cases, EEG and MEG are synergistic and provide complementary information.

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Figures

FIGURE 1
FIGURE 1
Paired-sensor MEG, simultaneous scalp EEG, and MSI for case 17. Dipoles in this and following figures are shown as triangles with vector tails indicating orientation and strength (proportional to length).
FIGURE 2
FIGURE 2
Paired-sensor MEG, simultaneous scalp EEG, and MSI for case 23.
FIGURE 3
FIGURE 3
Whole-head MEG, EEG, and MSI for case 53. Top panel: Left frontal and temporal MEG channels (left column and top of right column), ECG, and EEG (bottom of right column) for left frontal spikes (marked with gray dashed vertical cursors) along with MSI showing left frontal dipoles. Bottom panel: Left frontal and temporal MEG channels, ECG, and EEG for generalized spike and slow wave bursts that could not be reliably modeled for MSI.
FIGURE 4
FIGURE 4
Paired-sensor MEG and simultaneous scalp EEG and MSI for case 10; the same epoch of MEG and EEG (limited to bilateral temporal longitudinal bipolar montage) is shown at normal (left) and increasingly expanded time scales (marked with blue cursor to show lead/lag).
FIGURE 5
FIGURE 5
Paired-sensor MEG, simultaneous scalp EEG, and MSI for case 30.
FIGURE 6
FIGURE 6
Paired-sensor MEG, simultaneous scalp EEG, and MSI for case 15.
See this image and copyright information in PMC

References

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