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MEG May Reveal Hidden Population of Spikes in Epilepsy With Porencephalic Cyst/Encephalomalacia

Kakisaka, Yosuke*,†; Wang, Zhong I.*; Shibata, Sumiya*; Takahashi, Yoko*,†; Mosher, John C.*; Alexopoulos, Andreas V.*; Burgess, Richard C.*

Journal of Clinical Neurophysiology: November 2017 - Volume 34 - Issue 6 - p 546–549
doi: 10.1097/WNP.0000000000000362
Case Report

Summary: Porencephalic cyst/encephalomalacia is often associated with intractable epilepsy. A limited number of studies reported magnetoencephalography's (MEG's) potential to help construct treatment strategy for epilepsies associated with porencephalic cyst/encephalomalacia. The authors present here simultaneous electroencephalography (EEG) and MEG findings in three adult patients with pediatric-onset epilepsy due to porencephalic cyst/encephalomalacia. There were two types of spikes: one type was detected by MEG only (EEG−/MEG+), and the other detected by both EEG and MEG (EEG+/MEG+). Both types were seen in all three cases. The EEG−/MEG+ spikes all formed tight clusters; in contrast, the majority of EEG+/MEG+ spikes formed loose clusters. These data suggest that MEG may be helpful to better identify spike populations in epilepsy patients with porencephalic cyst/encephalomalacia. If hidden spike populations were to be found by MEG, this information would affect the interpretation of patient's pathophysiology and planning of intracranial electrode placement.

*Epilepsy Center, Department of Neurology, Cleveland Clinic, Cleveland, Ohio, U.S.A.; and

Department of Epileptology, Tohoku University School of Medicine, Sendai, Japan.

Address correspondence and reprint requests to Yosuke Kakisaka, MD, PhD, Department of Epileptology, Tohoku University School of Medicine, Sendai 980-8575, Japan; e-mail:

The authors have no funding or conflicts of interest to disclose.

© 2017 by the American Clinical Neurophysiology Society