Neuromagnetic Classification of Rolandic Discharges.
Abstract number :
1.183
Submission category :
Year :
2001
Submission ID :
2731
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
M. Ishitobi, MD, Pediatrics, Tohoku University School of Medicine, Sendai, Miyagi, Japan; N. Nakasato, PhD, Neurosurgery, Kohnan Hospital, Sendai, Miyagi, Japan; K. Yamamoto, PhD, Pediatrics, Sendai City Hospital, Sendai, Miyagi, Japan; K. Iinuma, PhD, Pe
RATIONALE: Rolandic discharges (RDs) appear in patients with benign rolandic epilepsy (BRE) and other epilepsies. However, physiological background and clinical significance of RDs remains unknown. We applied magnetoencephalography (MEG) to classify RDs' location and orientation.
METHODS: Subjects were 15 patients with BRE aging between 7 and 15 years old. Interictal epileptic discharges were sampled simultaneously by MEG (helmet-shaped 122 channel system) and EEG (international 10-20 system). Equivalent current dipoles (ECDs) of RDs were calculated using MEG data. Location and orientation of RD-ECDs were compared with conventional scalp EEG findings. Somatosensory evoked fields were used to identify the central sulcus and somatotopic organization of the primary sensory area.
RESULTS: Each subject showed 1 to 5 independent groups of RDs, which were estimated in neighboring areas of the central sulcus. According to location of ECDs, we classified into face, hand and foot groups, which included 15, 13 and 5 spike groups respectively. These spike groups were further classified into subgroups according to orientation of ECDs, and each subgroup had a relation to particular finding of conventional scalp EEG.
CONCLUSIONS: RDs were neuromagnetically originated from nearby areas of the central sulcus. RD-ECDs with same location showed different EEG distribution according to their orientation. Midline spikes of EEG were considered as RDs as well as centroparietal or midtemporal EEG spikes. It is important to know that both location and orientation of dipoles are responsible for distribution in conventional scalp EEG.[table]