REGIONAL VARIATION IN BILATERAL SYNCHRONY OF SPIKE-WAVE DISCHARGE BEFORE AND AFTER CORPUS CALLOSOTOMY

In patients undergoing corpus callosotomy (CC), we investigated whethe r regions with a high degree of bilateral synchrony of spike-wave disc harge correspond to the regions with major epileptogenic abnormalities and whether these regions are included within the cortical distributi on of callosal fibers bisectioned. We studied 16 patients who underwen t anterior (ant 2/3-4/5) CC for intractable symptomatic generalized ep ilepsies (SGE) with preoperative interictal generalized synchronous sp ike-wave discharges (GSSW). The degree of bisynchrony and synmorphism (i.e., similarity of wave form) was measured using cross-correlation a nalysis and the measurement of amplitude differences between homologou s regions. Preoperatively, frontocentral regions had higher values of correlation coefficient (R) and interhemispheric synchrony (IS) than t emporal and occipital regions. Furthermore, the temporal region, as co mpared with the other regions, had higher value of interhemispheric ti me difference (ITD). Postoperatively, the GSSW were disrupted and ther e was a significant decrease in the levels of R and IS, and a signific ant increase in amplitude difference in all regions, especially in the frontocentral regions where many of the lateralized spike-wave discha rges were observed in routine electroencephalograms (EEGs). In our pat ients with SGE, the regions with a high degree of bilateral synchrony correspond to the regions with major epileptogenic abnormalities. They are predominantly frontocentral regions, and are included in the exte nt of the cortical distribution affected by the bisection of callosal fibers. These analyses will provide additional information regarding p atient selection, the extent of callosal bisection, and seizure outcom e. (C) 1998 by Elsevier Science Inc. All rights reserved.