Single-Institutional Experience of Chronic Intracranial Electroencephalography Based on the Combined Usage of Subdural and Depth Electrodes.

Yutaro Takayama,Masaki Iwasaki,Suguru Yokosako,Naoki Ikegaya,Tetsuya Yamamoto,Keiya Iijima,Kenzo Kosugi,Yuu Kaneko,Yuiko Kimura,Norihiro Muraoka

doi:10.3390/brainsci11030307

Yutaro Takayama, Masaki Iwasaki + Show 8 more

Open Access

https://doi.org/10.3390/brainsci11030307

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Abstract

Implantation of subdural electrodes on the brain surface is still widely performed as one of the “gold standard methods” for the presurgical evaluation of epilepsy. Stereotactic insertion of depth electrodes to the brain can be added to detect brain activities in deep-seated lesions to which surface electrodes are insensitive. This study tried to clarify the efficacy and limitations of combined implantation of subdural and depth electrodes in intractable epilepsy patients. Fifty-three patients with drug-resistant epilepsy underwent combined implantation of subdural and depth electrodes for long-term intracranial electroencephalography (iEEG) before epilepsy surgery. The detectability of early ictal iEEG change (EIIC) were compared between the subdural and depth electrodes. We also examined clinical factors including resection of MRI lesion and EIIC with seizure freedom. Detectability of EIIC showed no significant difference between subdural and depth electrodes. However, the additional depth electrode was useful for detecting EIIC from apparently deep locations, such as the insula and mesial temporal structures, but not in detecting EIIC in patients with ulegyria (glial scar). Total removal of MRI lesion was associated with seizure freedom. Depth electrodes should be carefully used after consideration of the suspected etiology to avoid injudicious usage.

Highlights

Chronic intracranial electroencephalography is performed to investigate patients with drug-resistant epilepsy in whom the epileptogenic zone is not clearly identified by non-invasive presurgical evaluations
The indications and approaches for intracranial electroencephalography (iEEG) are changing based on the recent introduction of less invasive therapeutic devices and robotassisted stereotactic implantation systems for stereo-electroencephalography (SEEG) [1,2,3]
The fluorodeoxyglucose-positron emission tomography (FDG-PET) abnormalities were consistent with the magnetic resonance imaging (MRI) abnormalities in 39 patients (73.6%)

Summary

Introduction

Chronic intracranial electroencephalography (iEEG) is performed to investigate patients with drug-resistant epilepsy in whom the epileptogenic zone is not clearly identified by non-invasive presurgical evaluations. The indications and approaches for iEEG are changing based on the recent introduction of less invasive therapeutic devices and robotassisted stereotactic implantation systems for stereo-electroencephalography (SEEG) [1,2,3]. Implantation of subdural electrodes through craniotomy is still widely performed in Japan, partly because of the limited availability of these new devices. Stereotactic implantation of depth electrodes is frequently combined with subdural electrodes to explore deep-seated activities. The primary aim of this study is to clarify the efficacy and limitations of the combined implantation of subdural and depth electrodes under craniotomy for presurgical evaluation of epilepsy

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