ABSTRACT
OBJECTIVE & BACKGROUND: There have been reports on the lateralizing value of temporal lobe interictal epileptiform discharge(IED), yet it is a matter of debate till now. We studied our patients focusing on the degree of lateralization by which accurate lateralization was possible and also on the significance of bisynchronous IED(BIED) in the lateralization of temporal lobe epilepsy. METHOD: Fifty two patients were included in the study who were diagnosed as having medial temporal lobe epilepsy through video-EEG monitoring and brain MRI. Twenty four hour sleep-deprived interictal scalp EEG was checked for all of them. After that, we counted the number of independent IED(IIED) and BIED originating from anterior temporal areas. Then we tried to find a reasonable degree of IED above which correct lateralization of epileptogenic area was possible by using brain MRI as a standard. We also tried to find a significance of BIED in the lateralization of temporal lobe epilepsy by comparing the result excluding patients with BIED to that includig patients with BIED. RESULT: Lateralization of IED was over 80% accurate if the cutoff point was set at 70% and patients with BIED were included, but nearly 100% accurate of the cutoff point was set at 80% and patients with BIED were excluded. CONCLUSION: Influence of BIED on the accuracy of lateralization by IED is significant, and if the lateralization of IED is over 80% in patients with no BIED, the chance of true lateralization is very high.