Comparison of Magnetoencephalographic Spikes with and without Concurrent Electroencephalographic Spikes in Extratemporal Epilepsy

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

doi:10.1620/tjem.203.165

Cited by 32 publications

(15 citation statements)

References 19 publications

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“…In our study, the fraction of the commonly detected interictal spikes in both EEG and MEG was comparable to previous studies [i.e., here 44 vs. 41% in Ramantani et al (2006) and 51.1% in Park et al (2004)]. For source localizations to interictal epileptiform activity, it is recommended to perform the analysis during the upslope of the spike since source propagation can already occur during this interval (Alarcon et al, 1994; Lantz et al, 2003; Ray et al, 2007).…”

Section: Discussionsupporting

confidence: 91%

Localization of the Epileptogenic Foci in Tuberous Sclerosis Complex: A Pediatric Case Report

Hunold

Haueisen

Ahtam

et al. 2014

Front. Hum. Neurosci.

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Tuberous sclerosis complex (TSC) is a rare disorder of tissue growth and differentiation, characterized by benign hamartomas in the brain and other organs. Up to 90% of TSC patients develop epilepsy and 50% become medically intractable requiring resective surgery. The surgical outcome of TSC patients depends on the accurate identification of the epileptogenic zone consisting of tubers and the surrounding epileptogenic tissue. There is conflicting evidence whether the epileptogenic zone is in the tuber itself or in abnormally developed surrounding cortex. Here, we report the localization of the epileptiform activity among the many cortical tubers in a 4-year-old patient with TSC-related refractory epilepsy undergoing magnetoencephalography (MEG), electroencephalography (EEG), and diffusion tensor imaging (DTI). For MEG, we used a prototype system that offers higher spatial resolution and sensitivity compared to the conventional adult systems. The generators of interictal activity were localized using both EEG and MEG with equivalent current dipole (ECD) and minimum norm estimation (MNE) methods according to the current clinical standards. For DTI, we calculated four diffusion scalar parameters for the fibers passing through four ROIs defined: (i) at a large cortical tuber identified at the right quadrant, (ii) at the normal appearing tissue contralateral to the tuber, (iii) at the cluster formed by ECDs fitted at the peak of interictal spikes, and (iv) at the normal appearing tissue contralateral to the cluster. ECDs were consistently clustered at the vicinity of the large calcified cortical tuber. MNE and ECDs indicated epileptiform activity in the same areas. DTI analysis showed differences between the scalar values of the tracks passing through the tuber and the ECD cluster. In this illustrative case, we provide evidence from different neuroimaging modalities, which support the view that epileptiform activity may derive from abnormally developed tissue surrounding the tuber rather than the tuber itself.

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Section: Discussionsupporting

confidence: 91%

Localization of the Epileptogenic Foci in Tuberous Sclerosis Complex: A Pediatric Case Report

Hunold

Haueisen

Ahtam

et al. 2014

Front. Hum. Neurosci.

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“…However, presumably MEG detected the tangential current produced by the insular cortex possibly distorted by the structural lesion (Park et al 2002). Previously, M-spikes were considered to have similar localization to E/M-spikes in patients with TLE or extratemporal epilepsy (Park et al 2002(Park et al , 2004. However, the present findings in our Patient 1 suggest that the M-spikes may be earlier and more localized, and so may provide important localization information about the epileptic origin.…”

Section: Discussioncontrasting

confidence: 51%

“…The ECDs of M-spikes may be scattered due to poor signal-to-noise ratios, and the orientation could be random if such restricted focal activity has multiple sources around the insular lesion. Scalp EEG cannot detect M-spike activity because the amplitude is too small to overcome the background brain noise resulting from the poor spatial resolution of scalp EEG (Park et al 2004). The larger ECD moments of the E/M-spikes may reflect more extended sources compared to the M-spikes.…”

Section: Discussionmentioning

confidence: 99%

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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“…In a study by Ramantani et al (2006), more spikes were detected in the MEG compared with the simultaneously recorded EEG in 14 patients. A similar argumentation was put forward earlier by Park et al (2004). A similar argumentation was put forward earlier by Park et al (2004).…”

supporting

confidence: 70%

Tangential and Radial Epileptic Spike Activity

Haueisen

Funke

Güllmar

et al. 2012

Journal of Clinical Neurophysiology

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Comparison of Magnetoencephalographic Spikes with and without Concurrent Electroencephalographic Spikes in Extratemporal Epilepsy

Cited by 32 publications

References 19 publications

Localization of the Epileptogenic Foci in Tuberous Sclerosis Complex: A Pediatric Case Report

Localization of the Epileptogenic Foci in Tuberous Sclerosis Complex: A Pediatric Case Report

Localization of Abnormal Discharges Causing Insular Epilepsy by Magnetoencephalography

Tangential and Radial Epileptic Spike Activity

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