The purpose of this study was to describe the methodology necessary for simultaneous recording of intracranial EEG (ICEEG) and magnetoencephalography (MEG) and to assess the sensitivity of whole-head MEG versus depth electrode EEG in the detection and localization of epileptic spikes. Interictal MEG and depth electrode activities from the temporal mesial and occipital lobes were simultaneously recorded from four candidates for epilepsy surgery. Implanted depth electrodes identified neocortical and mesial structures of ictal onset. Interictal spikes detected by these same depth electrodes were compared with simultaneous MEG events. MEG detections of ICEEG spikes, ICEEG versus MEG spike amplitudes, number of ICEEG contacts involved in the spike, and anatomic locations of MEG equivalent current dipoles were analyzed. MEG detected and localized 95% of the neocortical spikes, but only 25% to 60% of spikes from mesial structures. Mesial temporal spikes resulted in lower MEG spike amplitudes, when compared with neocortical spikes. Equivalent current dipoles of MEG spikes localized to the ictal onset zones in all four patients. MEG can detect and localize interictal epileptiform spikes that are recorded from depth electrodes in both neocortical and mesial structures, despite the lesser amplitude of spikes of mesial origin.

The PK profile of gadobutrol in children aged younger than 2 years including newborns is similar to that in older children and adults. At the dose of 0.1 mmol/kg BW, gadobutrol had a favorable safety profile and was well tolerated with similar profile across the age range 0 to younger than 2 years and compared with older children and adults. Extrapolation of efficacy data from adults to the younger pediatric population, including term newborns, is justified. The recommended standard dose of gadobutrol (0.1 mmol/kg BW), as used in the population aged 2 years and older, is also appropriate in children aged younger than 2 years.

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Using magnetoencephalography, we investigated the spatiotemporal patterns of brain magnetic activity responsible for maintaining verbal and spatial information in either an integrated or an unintegrated fashion. Considering time dimension, we noted a greater activation of a fronto-parietal network in early latencies during the maintenance of integrated information, and a different pattern during the maintenance of unintegrated material, showing a greater activation in a fronto-posterior network in late latencies. The greater activation found in certain areas which are traditionally reported as being engaged in spatial working memory (i.e. superior frontal gyri, dorsolateral prefrontal cortex, superior and inferior parietal lobes) when subjects maintained integrated information could be explained by a greater weight of the spatial dimension. It is as if words somehow acquired a spatial attribute, thus exerting a greater load in a neural network specialized in spatial working memory. Alternatively, and not mutually exclusive, we also propose that during the maintenance of integrated information the allocation of cognitive resources is less interfering than during the maintenance of unintegrated information, making it easier.

There is not yet a formal definition of magnetoencephalography (MEG) spike. This study provides a parametric description and definition of clear-cut MEG spikes recorded simultaneously by MEG and depth electrodes (iEEG). A total number of 367 simultaneous MEG/iEEG spikes were selected for analysis. Distribution of morphologic spike parameters and detailed quantitative analysis of the basic morphologic characteristics of MEG spikes is provided.

The results indicate a more intense cortical response to main speech frequencies (0.5 to 2 kHz) as compared with other frequencies not involved in human conversation.

RESUMEN -La localización del inicio de las crisis es un factor importante para la evaluación prequirúrgica de la epilepsia. En este trabajo se describe la localización del inicio de una crisis registrada mediante magnetoencefalografía (MEG) en un niño de 12 años que presenta crisis parciales complejas farmacorresistentes. La RM muestra una lesión de 20mm de diámetro en el hipocampo izquierdo. EEG de superficie con ondas theta temporales izquierdas. Registro MEG interictal con punta-onda aislada posterior e inferior a la lesión de la RM. Registro MEG ictal con punta-onda (2 Hz). La localización de los dipolos indica el inicio de la crisis en la circunvolución temporal inferior en la misma localización que la actividad interictal MEG. Esta actividad ictal se propaga bilateralmente a áreas frontales. El registro corticográfico intraquirúrgico confirma los resultados de la localización interictal mediante MEG.PALABRAS CLAVE: electrocorticografía, inicio ictal, magnetoencefalografía, propagación. Temporal lobe seizure recorded by magnetoencephalography: case reportABSTRACT -Ictal onset localization is a important factor in presurgical evaluation of epilepsy. This paper describes the localization of a seizure onset recorded by magnetoencephalography (MEG) from a 12-year-old male patient who suffered from complex partial drug-resistant seizures. MRI revealed a 20mm diameter lesion located in left hippocampus. Scalp EEG showed left temporal theta waves. Interictal MEG registrations detected isolated spike-wave activity posterior and inferior to the MRI lesion. Ictal MEG showed continuous spike-wave activity (2 Hz). Dipole localization sited seizure onset in the inferior left temporal gyrus, the same localization of the interictal MEG activity. This ictal activity spreads bilaterally to frontal areas. Intrasurgical electrocorticography recording confirmed interictal MEG results.KEY WORDS: electrocorticography, magnetoencephalography, seizure onset, spreading.La magnetoencefalografía (MEG) en combinación con las imágenes de resonancia magnética (RM) proporciona excelente resolución espacial (milíme-tros) y temporal (milisegundos) en el diagnóstico de la epilepsia, aumentando la capacidad de localización anatómica de la actividad en episodios clíni-cos y subclínicos 1 . La localización del foco epiléptico mediante MEG ha sido confirmada con técnicas intraquirúrgicas tal como la estimulación eléctrica cortical 2 , la electrocorticografía (ECoG) 3 y la monitorización invasiva con electrodos subdurales 4 . A pesar de que la capacidad de localización espacial se reduce por los movimientos de la cabeza durante la crisis generalizadas, bajo condiciones especiales se pueden obtener del trazado MEG datos sobre el inicio ictal 5 . Así la localización basada en datos ictales claramente definidos es considerada como superior a la basada en datos intercríticos 6 y puede aportar información equivalente o superior a la de los registros EEG invasivos 7 . En este artículo se describe la localización anatómica del inicio de una crisis parc...

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