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Technical Description of Long-Term High-Density EEG Monitoring Using 128-Channel Cap Applied With a Conductive Paste

Ochoa, Juan G.; Rini, James; Diaz, Judy; Botwell, Jennifer

Journal of Clinical Neurophysiology: May 2019 - Volume 36 - Issue 3 - p 175–180
doi: 10.1097/WNP.0000000000000557
Original Research

Purpose: EEG is a common diagnostic tool to localize epileptic activity with excellent temporal resolution and, however, with relatively low spatial resolution. High-density EEG recording is limited in clinical practice, mainly because of electrode placement difficulties, need of high technical skills, and advanced equipment requirement.

Methods: We described the technique of long-term EEG recording using a 128-channel neoprene cap placed with a dielectric paste in 7 patients with refractory epilepsy. We captured electrographic seizures in six of seven patients. The 128-channel EEG cap was well tolerated except for a mild headache. Daily impedance checks and reapplication of the high impedance leads maintained the recording with impedances below 10 kΩ.

Results: Successful long-term recording of high-density EEG was able to capture seizures in six of seven patients. The time needed to apply the electrodes was approximately 1 hour and approximately 30 minutes daily for maintenance. The EEG source localization was obtained in six of seven patients, concordant within the sublobar region for both standard and high-density EEG recordings. Three patients reported a mild headache not leading to discontinuation of the recording.

Conclusions: In general, long-term high-density scalp EEG recording with a dielectric paste is well tolerated and allows capturing both interictal and ictal data for localization. This small sample does not show a significant advantage in terms of sublobar localization when high-density EEG source is compared with standard 10 to 20 placement as long as the subtemporal areas are recorded.

Department of Neurology, University of South Alabama, Mobile, Alabama, U.S.A.

Address correspondence and reprint requests to Juan G. Ochoa, MD, University of South Alabama, 2451 Fillingim St, 10-E, Mobile, AL, U.S.A.; e-mail:

J. G. Ochoa is a consultant for Compumedics and not related to the issues discussed in this article. The remaining authors have no funding or conflicts of interest to disclose.

© 2019 by the American Clinical Neurophysiology Society