J Korean Neurol Assoc.  2004 Oct;22(5):459-464.

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

Affiliations
  • 1Department of Neurology, Yonsei University College of Medicine, Seoul, Korea. Kheo@yumc.yonsei.ac.kr
  • 2Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Korea.
  • 3Department of Neurology, Soonchunhyang University College of Medicine, Bucheon, Korea.
  • 4Department of Neurology, National Health Insurance Corporation Ilsan Hospital, Ilsan, Korea.
  • 5Department of Neurology, Hallym University College of Medicine, Seoul, Korea.

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.

Keyword

Temporal lobe epilepsy; Interictal epileptiform discharges; Lateralization of ictal scalp EEG

MeSH Terms

Electroencephalography*
Epilepsy, Temporal Lobe*
Humans
Scalp*
Seizures
Temporal Lobe*
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