Lateralization discordance between stereo EEG and scalp EEG in temporal epilepsy: A case report

A 34-year-old woman with drug-resistant epilepsy underwent simultaneous scalp and stereo-EEG (sEEG) and had seven seizures, three of them without visibility on the scalp EEG. Of the four seizures seen on both sEEG and scalp EEG, the seizure onset in the scalp EEG was ipsilateral to the seizure onset in the sEEG in two seizures and contralateral to the sEEG onset in two seizures. This unusual lateralization discordance of scalp EEG and sEEG highlights the importance of bilateral lead placement in stereo EEG to accurately identify the seizure onset zone.