Abstracts

Rationale: Electroencephalography (EEG) is an essential modality for monitoring interictal epileptiform discharges (IEDs) in patients with epilepsy. However, monitoring IEDs in these patients in daily life is challenging. Various wearable EEGs have recently been developed. They have been designed for minimally invasive monitoring of epileptic seizures and demonstrate a potential for home-based applications. However, the accuracy of wearable EEGs for detecting IEDs has not been verified. Specifically, a non-medical two-channel in-ear EEG (VIE ZONE, VIE Inc., Tokyo, Japan) (fig.1), is already being used in neurofeedback studies ^[1]; however, its accuracy has not yet been evaluated in clinical settings. In this study, we compared the recordings between scalp and in-ear EEG in an epilepsy outpatient setting.

[1] Chang, M et al., “Pretraining alpha rhythm enhancement by neurofeedback facilitates short-term perceptual learning and improves visual acuity by facilitated consolidation”, Front. Neuroergonomics, Volume5, 2024




Methods: This study included five patients at an epilepsy outpatient clinic, two with Lennox–Gastaut syndrome, two with idiopathic generalized epilepsy, and one with frontal epilepsy. In each patient, concurrent 30-minute EEG recordings using conventional scalp EEG (Nihon Kohden Corporation, Tokyo, Japan) and in-ear EEG were performed. The ground and reference electrodes of in-ear EEG were placed on the back of the left and right sides of the neck, respectively. Data from both EEGs were anonymized and converted to the European Data Format. A certified epileptologist visually reviewed the conventional scalp EEG recordings, which detected IEDs. The in-ear EEG waveforms corresponding to the IEDs in the scalp EEG recordings were extracted and reviewed.


Results: In two of the five patients whose epileptic discharges were clearly visible in the temporal regions, the IEDs detected in scalp EEG recordings were also reflected in the in-ear EEG recordings (fig.2). However, the frontal dominant IEDs were difficult to identify in the in-ear EEG recordings. Thus, IED detection using the in-ear EEG depended on the epileptic foci.


Conclusions: The results demonstrated that IEDs in the temporal region can be identified using the in-ear EEG, indicating its utility in monitoring temporal lobe and generalized epilepsy and reflecting prominent spikes in temporal lesions. Further studies with a larger cohort of temporal and non-temporal epilepsies are required to verify the accuracy of IED detection using the in-ear EEG system and its feasibility for evaluating epilepsy in clinical practice.


Funding: This work was supported in part by Japan Foundation of Institute for Neuropsychiatry Epilepsy Research Grant for Young Researchers and Japan Society for the Promotion of Science (Grant Number: 23K21867).