Ictal Scalp EEG in Mesial Temporal Lobe Epilepsy Patients with Unilateral versus Bilateral Interictal Epileptiform Discharges

J Korean Neurol Assoc > Volume 22(5); 2004 > Article

Journal of the Korean Neurological Association 2004;22(5): 459-464.

내측두엽간질 환자에서 일측성과 양측성 발작간 간질양파 간의 발작중 두피뇌파의 측위화 비교

조정희, 허 경 박수철 장진우* 박선아† 김규식‡ 주민경§ 이병인

연세대학교 의과대학 신경과학교실, 신경외과학교실*, 순천향대학교 의과대학 신경과학교실† 국민건강보험공단 일산병원 신경과‡, 한림대학교 의과대학 신경과학교실§

Ictal Scalp EEG in Mesial Temporal Lobe Epilepsy Patients with Unilateral versus Bilateral Interictal Epileptiform Discharges

Jeong Hee Cho

Ictal Scalp EEG in Mesial Temporal Lobe Epilepsy Patients with Unilateral versus Bilateral Interictal Epileptiform Discharges

Abstract

Background: Interictal and ictal scalp EEG is the most often used and relied-on method of noninvasive presurgical evaluation in temporal lobe epilepsy. We attempted to compare unitemporal interictal epileptiform discharges (UIED) with bitemporal interictal epileptiform discharges (BIED) groups for lateralizing value and propagation patterns of ictal scalp EEGs.
Methods: We investigated ictal scalp EEGs in 48 patients who had undergone anterior temporal lobectomies. We divided them into UIED and BIED groups by cut-off value of 90% in the laterality of IED.
Results: We analyzed ictal EEG patterns in 201 seizures of 32 patients with UIED and 86 seizures of 16 patients with BIED. Ictal scalp EEG was correctly lateralized significantly more often in the UIED group compared with the BIED group; 93.5% versus 57.0% in seizures and 93.8% versus 62.5% in patients, respectively. Bilateral independent onset was seen more frequently in the BIED group whereas the maintenance of ictal discharges in the unilateral temporal or hemisphere occurred more frequently in the UIED group. Lateralization by a later significant pattern (LSP) presents additional value of correct lateralization rather than pattern at onset (PAO) only.
Conclusions: Interpretation of ictal scalp EEGs must be considered more cautiously in patients with BIED because BIED may be correlated with bitemporal excitability. Key Words: Temporal lobe epilepsy, Interictal epileptiform discharges, Lateralization of ictal scalp EEG