Magnetoencephalography in the detection of focal lesions in West syndrome

Hattori, Hideji; Yamano, Tsunekazu; Tsutada, Tsuyoshi; Tsuyuguchi, Naohiro; Kawawaki, Hisashi; Shimogawara, Masahiro

doi:10.1016/s0387-7604(01)00311-4

Cited by 15 publications

(7 citation statements)

References 16 publications

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“…3 Magnetoencephalography (MEG), a non-invasive tool for the assessment of focal epileptic activity, has been reported to accurately localise specific epileptic discharges in a variety of publications [4][5][6][7][8][9] and to be particularly useful in combination with MRI data-known as ''magnetic source imaging'' (MSI). [10][11][12][13][14][15][16][17] Although MEG has been successfully applied in presurgical evaluation of lesional epilepsies, [18][19][20][21][22][23] no systematic studies have as yet been conducted about the spatial relation between MEG localisation of spike activity, MRI localisation of lesions, histological examination, and surgical outcome in patients with cavernomas. Therefore, we conducted a study to investigate whether MEG spike localisations were able to locate the epileptic tissue in focal epilepsies associated with cavernomas.…”

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Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

Stefan

2004

Journal of Neurology, Neurosurgery & Psychiatry

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Objective: The aim of this study was to identify the irritative epileptic zone in patients with cavernomas by means of magnetoencephalography (MEG). Method: Among 82 patients operated for epilepsy, whose presurgical evaluation had included MEG, histological assessment of the tissue removed had confirmed cavernomas in eight. These eight patients had epilepsy since 18.6 (SD 12.7) years on average. The monitoring lasted about 2.1 (SD 1.3) hours and a median 20.9 (SD 14.3) spikes per hour were recorded. Spontaneous brain activity was recorded by means of a 74 channel dual unit MEG system (Magnes II, 4-D Neuroimaging) with simultaneous EEG recording (31 scalp electrodes). Spike analysis was performed using different source (moving dipole, current density reconstruction) and head models (spherical shells, BEM). Co-registration of neurophysiological and imaging data (MRI) was based upon anatomical landmarks. Results: In 6/8 patients co-localisation from the cavernoma and epileptic zone was found. In two patients the focus was localised in the parieto-occipital lobe, in three patients in the frontal lobe and in three patients in the temporal lobe. In one case of temporal and one case of frontal lobe focus localisation there was no spatial relationship to the cavernoma. Conclusion: In cases of focal seizures due to a single cavernoma, MEG may precisely delineate the epileptogenic tissue bordering the lesion. In patients with multiple cavernomas or dual pathology, MSI may reveal the complexity of the case, and contribute to the decision about further invasive diagnostics and more sophisticated therapeutic measures. MEG is a promising method for prediction of the epileptic zone in cavernoma related epilepsies, and thus it can contribute to decision making about and planning of epilepsy surgery. C avernous angiomas represent about 5-20% of all vascular malformations in the central nervous system. Multiple cavernomas may occur in 20-40% of affected patients. Magnetic resonance imaging (MRI) is the most appropriate method to identify cavernomas. Microhaemorrhages within and around the lesions are an integral diagnostic feature that can usually only be inferred from irregular haemosiderin deposits detectable in T1 and T2 weighted MR images.Seizures are estimated to occur in 40-70% of patients with cavernomas. Most of the seizures are focal, without or with secondary generalisation.1 A number of different mechanisms have been proposed to cause epilepsy: mass effects on, gliosis of, or haemosiderin deposition in the surrounding brain tissue. Studies using neocortical seizure models indicated that the tissue adjacent to rather than within the lesion exhibits hyperexcitability and thus may be critical in seizure generation. Intracellular neuronal recordings showed that especially neocortical neurones in the vicinity of cavernous malformations had a greater propensity for large complex spontaneous synaptic events than neurones neighbouring tumours. These data also revealed that occurrence of these abnormalities was proportional to ...

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Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

Stefan

2004

Journal of Neurology, Neurosurgery & Psychiatry

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“…Although some studies reporting MEG findings in pediatric epilepsy populations do not provide details of the procedure pertaining to use of sedation and /or anesthesia, 20,21 others do report the necessity of general anesthesia for successful MEG recording. 22,23 Some other studies included mostly older children who could cooperate. 24,25 In the current study, we took special care to conduct the MEG recording for the infants and children included in the most natural conditions, with post-feeding natural sleep, and ensuring presence of a parent in the magnetically shielded room, to maximize yield without use of sedative or anesthetic medications.…”

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Magnetoencephalographic Identification of Epileptic Focus in Children With Generalized Electroencephalographic (EEG) Features but Focal Imaging Abnormalities

et al. 2017

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“…The single-ECD method may fail to give meaningful results in the case of widespread or propagating epileptic activity (see, e.g., Ossenblok et al, 1999; Hisada et al, 2001; Hattori et al, 2001, Shiraishi et al, 2005a, Oishi et al, 2006). Clusters of ECDs may reflect both the initial and propagated activity (Bast et al, 2006; Ossenblok et al 2007).…”

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confidence: 99%

Comparison of Three Methods for Localizing Interictal Epileptiform Discharges With Magnetoencephalography

Shiraishi

Ahlfors²,

Stufflebeam³

et al. 2011

Journal of Clinical Neurophysiology

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Purpose To compare three methods of localizing the source of epileptiform activity recorded with magnetoencephalography (MEG): equivalent current dipole (ECD), minimum current estimate (MCE), and dynamic statistical parametric mapping (dSPM), and to evaluate the solutions by comparison with clinical symptoms and other electrophysiological and neuroradiological findings. Methods Fourteen children of 3 to 15 years old were studied. MEG was collected with a whole-head 204-channel helmet-shaped sensor array. We calculated ECDs and made MCE and dSPM movies to estimate the cortical distribution of interictal epileptic discharges (IED) in these patients. Results The results for 4 patients with localization related epilepsy (LRE) and 1 patient with Landau-Kleffner Syndrome were consistent among all 3 analysis methods. In the rest of the patients MCE and dSPM suggested multifocal or widespread activity; in these patients the ECD results were so scattered that interpretation of the results was not possible. For 9 patients with LRE and generalized epilepsy, the epileptiform discharges were wide-spread or only slow waves, but dSPM suggested a possible propagation path of the IED. Conclusion MCE and dSPM could identify the propagation of epileptiform activity with high temporal resolution. The results of dSPM were more stable because the solutions were less sensitive to background brain activity.

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Magnetoencephalography in the detection of focal lesions in West syndrome

Cited by 15 publications

References 16 publications

Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

Magnetoencephalographic Identification of Epileptic Focus in Children With Generalized Electroencephalographic (EEG) Features but Focal Imaging Abnormalities

Comparison of Three Methods for Localizing Interictal Epileptiform Discharges With Magnetoencephalography

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