Ictal and Interictal Activity in Partial Epilepsy Recorded with Multichannel Magnetoelectroencephalography: Correlation of Electroencephalography/Electrocorticography, Magnetic Resonance Imaging, Single Photon Emission Computed Tomography, and Positron Emission Tomography Findings

Stefan, Hermann; Schneider, Siegfried; Feistel, H.; Pawlik, G.; Schüler, P.; Abraham-Fuchs, K.; Schlegel, T; Neubauer, U.; Huk, W.

doi:10.1111/j.1528-1157.1992.tb02195.x

Cited by 146 publications

(68 citation statements)

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“…Spike localization by magnetoencephalography (MEG) has been compared with localization by intracranial EEG (2,(9)(10)(11)(12)(13)(14), positron emission tomography (PET) (15) and single-photon emission computed tomography (SPECT) (9). Previous studies suggested that the localization accuracy of MEG was higher than that of conventional scalp EEG (10,14) because of the absence of disturbance by the inhomogeneous conductivity of cranial tissues.…”

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Surgical Implications of Neuromagnetic Spike Localization in Temporal Lobe Epilepsy

et al. 2002

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Summary:Purpose: To investigate the clinical usefulness of magnetoencephalography (MEG) as a guide to the surgical treatment of temporal lobe epilepsy (TLE).Methods: Preoperative spike localization by MEG was compared with seizure outcome and postoperative spike localization at 12 months after resective surgery in 16 patients with TLE. Spike localization was classified into anterior temporal (AT) and non-AT localization in 11 patients without neocortical lesion treated with anterior temporal lobectomy (ATL); and lesion and lobar localization in five patients with neocortical lesion treated with lesionectomy (n ‫ס‬ 3) or lesionectomy with medial temporal resection (n ‫ס‬ 2).Results: All five patients with AT localization became seizure free and spike free after surgery. Among the six patients with non-AT localization, two became seizure free and spike free, two became seizure free with residual spikes, one had residual seizures but no spikes, and one had both residual seizures and spikes. All three patients with lesion localization and two with lobar localization had favorable seizure outcome and became spike free after surgery.Conclusions: MEG spike localization can identify neocortical sources remote from the presumed epileptogenic area. Favorable seizure outcome can be expected in patients with AT localization after ATL and patients with lesion localization after lesionectomy. In contrast, non-AT localization indicates either nonmedial TLE or spike propagation to the posterior and extratemporal neocortex. Similarly, lobar localization indicates spike propagation from an epileptogenic lesion or extensive epileptogenicity. Patients with non-AT localization or lobar localization should undergo intensive evaluations, such as intracranial EEG, for improved seizure outcome.

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Surgical Implications of Neuromagnetic Spike Localization in Temporal Lobe Epilepsy

et al. 2002

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“…Magnetoencephalography (MEG) is a noninvasive neurophysiologic technique to detect the magnetic fields generated by electric currents in the brain, and has been frequently used to localize the epileptic discharges in patients with focal epilepsy (Stefan et al 1992;Nakasato et al 1994;Knowlton et al 1997;Jin et al 2007), but not in patients with insular epilepsy.…”

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Localization of Abnormal Discharges Causing Insular Epilepsy by Magnetoencephalography

Park

Nakasato

Tominaga

2012

Tohoku J. Exp. Med.

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The insula, one of the five cerebral lobes of the brain, is located deep within the brain and lies mainly beneath the temporal lobe. Insular epilepsy can be easily confused and misdiagnosed as temporal lobe epilepsy (TLE) because of the similar clinical symptoms and scalp electroencephalography (EEG) findings due to the insula location and neuronal connections with the temporal lobe. Magnetoencephalography (MEG) has higher sensitivity and spatial resolution than scalp EEG, and thus can often identify epileptic discharges not revealed by scalp EEG. Simultaneous scalp EEG and MEG were performed to detect and localize epileptic discharges in two patients known to have insular epilepsy associated with cavernous angioma in the insula. Epileptic discharges were detected as abnormal spikes in the EEG and MEG findings. In Patient 1, the sources of all MEG spikes detected simultaneously by EEG and MEG (E/ M-spikes) were localized in the anterior temporal lobe, similar to TLE. In contrast, the sources of all MEG spikes detected only by MEG (M-spikes) were adjacent to the insular lesion. In Patient 2, the sources of all MEG spikes detected simultaneously by EEG and MEG (E/M-spikes) were localized in the anterior temporal lobe. These findings indicate that MEG allows us to detect insular activity that is undetectable by scalp EEG. In conclusion, simultaneous EEG and MEG are helpful for detecting spikes and obtaining additional information about the epileptic origin and propagation in patients with insular epilepsy.

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“…Several noninvasive and interictal diagnostic approaches have been implemented in the presurgical evaluation programs in intractable epilepsy syndromes of uniregional origin, all of them with the intention (a) to add to the complementary information about a regional functional deficit or morphologic lesion corresponding to the hypothesized primary epileptogenic zone, and (b) to reduce the number of invasive EEG recordings (26)(27)(28)(29). For this purpose, the most promising aspect of EEG dipole-source analysis is the theoretic possibility to ameliorate the poor spatial resolution of spikes recorded from the scalp in depth.…”

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Dipole‐Source Analysis in a Realistic Head Model in Patients with Focal Epilepsy

et al. 2000

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Summary:Purpose: By the use of three different head models in EEG dipole analysis, we tried to model the origin of interictal and ictal epileptic activity as precisely as possible. Further, as a control, a second evaluation was made by an independent group to control for interindividual reliability of the dipole source analysis. With the realistic head model (CURRY) considering cortex, skull, and skin segmentation, the spike source was located.Methods: In five patients with mesial temporal epileptogenesis, confirmed by successful epilepsy surgery, the spike source was close to the hippocampus, with a mean distance of the dipole source from the hippocampus of 13.6 mm (range, 9-17.2 mm). In one case the ictal EEG also could be analyzed and resulted in a dipole-source localization comparable to the interictal source. Results:In both head models using either pure cortex segmentation only or a concentric three-shell model, the dipole source was systematically dislocated in a more superior position. Data analysis by a second group with independently chosen EEG samples and identical individual head model resulted in deviations of 4 . 3 mm. Data analysis using independently selected spikes and independently segmented head models resulted in deviations 5 16.7 mm.Conclusions: In four cases of extratemporal epileptogenesis, the origin of interictal epileptiform discharges was localized to the suspected primary epileptogenic zone.

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Ictal and Interictal Activity in Partial Epilepsy Recorded with Multichannel Magnetoelectroencephalography: Correlation of Electroencephalography/Electrocorticography, Magnetic Resonance Imaging, Single Photon Emission Computed Tomography, and Positron Emission Tomography Findings

Cited by 146 publications

References 14 publications

Surgical Implications of Neuromagnetic Spike Localization in Temporal Lobe Epilepsy

Surgical Implications of Neuromagnetic Spike Localization in Temporal Lobe Epilepsy

Localization of Abnormal Discharges Causing Insular Epilepsy by Magnetoencephalography

Dipole‐Source Analysis in a Realistic Head Model in Patients with Focal Epilepsy

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