Discrepancy between Ictal Scalp EEG and Neuroimaging Findings in Mesial Temporal Lobe Epilepsy : A Case Report

• Published in: Japanese Journal of Neurosurgery Vol. 21; no. 9; pp. 736 - 740
• Main Authors: Muramoto, Emiko, Nakamura, Hirohiko, Mizobuchi, Masahiro, Sumi, Yoshihiro, Shiraishi, Hideaki, Usui, Reiko
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Congress of Neurological Surgeons 2012
• Subjects: hippocampal sclerosis; ictal monitoring; selective amygdalo-hippocampectomy; subdural electrode; temporal lobe epilepsy
• ISSN: 0917-950X; 2187-3100
• DOI: 10.7887/jcns.21.736

Introduction : The purpose of this study was to evaluate the epileptogenic zone in a patient with unilateral hippocampal sclerosis, whose ictal discharges on scalp EEG indicated onset on the contralateral side.   Case presentation : A 34-year-old man had intractable complex partial seizures since six years of age. His seizures presented with automatism of both arms with mild dystonia on the right side. Scalp ictal EEG revealed rhythmic theta waves over the left anterior temporal region, indicating left temporal lobe origin. On the contrary, neuroimaging findings of right hippocampal sclerosis on MRI, hypo-metabolism in the right temporal lobe on 18F-FDG-PET, and hypo-accumulation in the right mesial temporal lobe on 11C-FMZ-PET strongly support right mesial temporal lobe origin. Invasive EEG monitoring revealed that ictal discharges originated from the right mesial temporal lobe and immediately propagated to the left temporal lobe. The patient became seizure-free after selective right amygdalo-hippocampectomy.   Conclusion : Although this case showed a discrepancy between neuroimaging and other findings such as semiology and scalp ictal EEG, consistent findings on both MRI and PET should be a strong indicator in deciding the side of surgery.