Magnetoencephalographic analysis of roland discharges in benign childhood epilepsy

Abstract

We report the detailed analysis of the generator and propagation of rolandic discharges in benign childhood epilepsy with centrotemporal spikes by means of 37-channel magnetoencephalography with neuromagnetic three-dimensional dipole localization. Equivalent current dipoles of prominent negative sharp waves of rolandic discharges appeared as tangential dipoles in the rolandic region, positive poles being situated anteriorly. These equivalent current dipoles showed a relatively limited localization and regular directions compared with other components. Equivalent current dipoles of preceding small positive waves, positive waves following negative sharp waves, and negative slow waves appeared in the vicinity of negative sharp waves. Equivalent current dipoles of rolandic discharges were located around the generator of somatosensory evoked magnetic fields stimulated at the lower lip. These findings suggest that rolandic discharges are generated through basically a mechanism similar to that for the middle-latency components of somatosensory evoked responses.

Focal epileptiform spikes do not show a canonical BOLD response in patients with benign rolandic epilepsy (BECTS)

“…The CTS of BECTS show a characteristic phase-reversal over the central sulcus (Beaussart, 1972;Gregory and Wong, 1984) that suggests a generator somewhere within the face area of the sensorimotor cortex. This localisation is also supported by EEG and MEG source-modelling results (Wong, 1991;Minami et al, 1996;Baumgartner et al, 1996;Manganotti et al, 1998a;Huiskamp et al, 2004). We aimed to characterise the event-related BOLD signal changes associated with focal epileptiform spikes in this patient group.…”

Benign Rolandic Epilepsy investigated by Magnetoencephalography

“…We suppose that both motor and somatosensory cortex might have a possibility of generating the RDs. With regard to dipole directions of the negative sharp waves, there have been reported two different directions, one with anterior positivity [3,7] and the other with posterior positivity [5]. Our study constantly manifested tangential dipoles with anterior positivity and it is noteworthy to identify not only the dipole localization but also the dipole direction for a diagnosis of BECRS.…”

Idiopathic focal epilepsies: the “lost tribe”

“…Studies have focused on spike localisation, their relationship to clinical features, and more recently time‐frequency analyses of oscillatory rhythms. In an early MEG study on five patients, the spike ECDs were localised to the same area as lower lip stimulation (Minami et al ., ). Subsequently, a study of seven cases reported spikes with an anterior positivity in the superior Rolandic (hand motor) region in four patients and in the inferior Rolandic (oromotor) region in three patients (Kamada et al ., ).…”