Implanted electrodes for multi-month EEG.

Area of Science:

• Biomedical Engineering
• Neuroscience
• Medical Devices

Background:

• Diagnosing infrequent seizure-like events is challenging with current monitoring methods.
• Implantable electroencephalogram (EEG) recorders offer a potential solution for continuous, long-term monitoring.
• Proof-of-concept studies are essential to validate novel medical device technologies.

Purpose of the Study:

• To evaluate the electrical characteristics and clinical utility of electrodes for a proposed implantable EEG recorder.
• To assess the feasibility of long-term implantation and performance in a relevant animal model.

Main Methods:

• Electrodes were implanted in an ovine model for an eight-week study period.
• Electrode impedance was measured, and frequency-domain analysis was used to assess sedation.
• Time-domain correlation was calculated between implanted and surface electrodes.
• EEG-certified clinicians qualitatively assessed the performance and data quality of implanted electrodes.

Main Results:

• Electrode impedance remained below 800 Ohms throughout the study.
• Frequency-domain sedation determination was comparable between surface and implanted electrodes.
• High time-domain correlation (0.86) was observed between implanted and surface electrodes.
• Clinicians rated implanted electrode quality as adequate to excellent, providing similar clinical information to surface electrodes, with only a minor amplitude difference.

Conclusions:

• The tested electrodes exhibit suitable electrical characteristics for an implantable EEG recorder.
• Implanted electrodes provide clinically relevant EEG data, supporting their use in diagnosing infrequent seizures.
• No significant obstacles were identified, indicating the proposed EEG recorder is viable for further development.