Authors :
Presenting Author: Keita Fujii, MD – Yokohama City University Graduate School of Medicine
Masaki Sonoda, MD, PhD – Yokohama City University Graduate School of Medicine
Yosuke Masuda, MD PhD – University of Tsukuba
Taisuke Akimoto, MD, PhD – Yokohama City University Graduate School of Medicine
Kota Araki, MD – University of Tsukuba
Naoki Ikegaya, MD, PhD – Yokohama City University Graduate School of Medicine
Yasunobu Nakai, MD, PhD – Yokohama City University Graduate School of Medicine
Yuji Matsumaru, MD PhD – University of Tsukuba
Tetsuya Yamamoto, MD, PhD – Yokohama City University Graduate School of Medicine
Rationale: Endovascular EEG (eEEG) is an emerging technique that enables the recording of brain signals via the venous system. This study aimed to characterize the recording properties of the eEEG EP-01 device by analyzing the data obtained during simultaneous recordings using stereo-EEG (SEEG) and endovascular electrodes in a clinical trial setting.
Methods: This is a single-case report of the ongoing "eEEG EP-01 Phase 2/3 clinical trial" conducted in Japan. A 27-year-old male with drug-resistant focal epilepsy underwent robot-assisted stereotactic implantation of SEEG electrodes along with endovascular placement of an EP-01 electrode. Simultaneous recordings were obtained for both the modalities. The EP-01 electrode was positioned in the left cavernous-inferior petrosal sinus. A sliding-window correlation analysis was performed to evaluate the signal similarity between channels. Pearson correlation coefficients were calculated within 60-second windows, advanced in 30-second steps. For each selected target channel, the mean absolute correlation with all other channels was computed. The correlation values across the four windows were Z-scored for normalization and further analysis.
Results:
The EP-01 electrode was placed in six venous locations, including the bilateral transverse sinuses, cavernous sinuses, and anterior and posterior segments of the superior sagittal sinus. SEEG electrodes were implanted based on clinical indications, with a total of 10 depth electrodes targeting the left frontotemporal cortex and various cortical and subcortical regions, including the bilateral amygdala and hippocampus. Recordings were obtained from 100 electrode sites. Among the Z-transformed correlation values, three SEEG sites exceeded the threshold of 1.96, and all were located in the ipsilateral (left) hemisphere. These sites included the left amygdala (Z = 2.55, r = 0.37), anterior middle temporal gyrus (Z = 2.14, r = 0.33), and lateral middle temporal gyrus (Z = 5.61, r = 0.66). The Euclidean distances between the EP-01 electrode and these correlated SEEG sites were 32.26 mm, 58.55 mm, and 55.57 mm, respectively.
Conclusions:
We identified SEEG recording sites with a strong correlation to signals from the eEEG electrode, suggesting that endovascular recordings can reflect nearby intracranial activity. Further studies are warranted to validate the recording characteristics and clinical utility of eEEG in the diagnosis of epilepsy.
Funding:
This work was supported by KAKENHI Grant JP24K19533 (to M.S.).