Magnetoencephalographic analysis of bilaterally synchronous discharges in benign rolandic epilepsy of childhood.
The purpose of this study was to examine the spatial and temporal relationship between bilateral foci of bilaterally synchronous discharges in benign rolandic epilepsy of childhood (BREC) using a whole-scalp neuromagnetometer. We simultaneously recorded interictal magnetoencephalographic (MEG) and electroencephalographic (EEG) signals in six children with BREC. Interictal spikes were classified into three groups: bilaterally synchronous discharges (BSDs), unilateral discharges on right side (UD-R), and unilateral discharges on left side (UD-L). We used equivalent current dipole (ECD) modelling to analyse the cortical sources of interictal spikes. Both BSDs and UDs were found in Patients 1-4, whereas only UDs were identified in Patients 5 and 6. The ECDs of interictal spikes were located in rolandic regions, 10-20mm anterior and lateral to hand somatosensory cortices. Multi-dipole analysis of BSDs showed two ECDs in homotopic motor areas of the hemispheres. During BSDs, the right-sided activation preceded the left-sided activation by 15-21 milliseconds in Patients 1 and 2. In Patients 3 and 4, the activation occurred 17-20 milliseconds earlier in the left than the right hemisphere. Within the same hemisphere, the sources of BSDs and UDs were located in similar areas. In conclusion, our results imply the cortical epileptogenicity in bilateral perirolandic areas in BREC. The sequential activation during BSDs in both hemispheres suggest the existence of synaptic connections, possibly via the corpus callosum, between bilateral irritative foci.
Lin
Yung-Yang
YY
Integrated Brain Research Unit, Department of Medical Research and Education, Taipei Veterans General Hospital, No 201, Sector 2, Shih-Pai Road, Taipei 11217, Taiwan, ROC. yylin@vghtpe.gov.tw
Chang
Kai-Ping
KP
Hsieh
Jen-Chuen
JC
Yeh
Tzu-Chen
TC
Yu
Hsiang-Yu
HY
Kwan
Shang-Yeong
SY
Yen
Der-Jen
DJ
Yiu
Chun-Hing
CH
Hari
Riitta
R
D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D002648:Child; D004558:Electric Stimulation; D004569:Electroencephalography / Q000145:classification / Q000706:statistics & numerical data; D019305:Epilepsy, Rolandic / Q000175:diagnosis* / Q000503:physiopathology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008959:Models, Neurological; D012535:Scalp; D013997:Time Factors