A new ground and reference technique for invasive EEG recordings.

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Long-term EEG monitoring (LTM) with intracranial electrodes typically requires a separate ground (GND) and reference (REF).
• Traditional GND & REF methods using invasive electrode arrays or surface discs often need frequent maintenance and can suffer from impedance issues.

Purpose of the Study:

• To evaluate the efficacy of chronic subdermal wire electrodes (SWE) as a combined GND and REF system for LTM.
• To demonstrate a novel, low-maintenance technique for establishing stable electrical references during invasive EEG.

Main Methods:

• A prospective study involving nine patients undergoing invasive EEG monitoring.
• A pair of subdermal wire electrodes (SWE) were utilized as the GND & REF.
• Impedance monitoring of SWE was performed in two patients and compared against standard disc electrodes.

Main Results:

• Subdermal wire electrodes (SWE) demonstrated consistently low and stable impedances throughout the recording period (up to 20 days) without maintenance.
• In contrast, disc electrodes exhibited a rapid increase in impedance after the first day.
• All nine patients achieved good quality EEG recordings with the SWE GND & REF system, showing no local skin complications.

Conclusions:

• Chronic subdermal wire electrodes (SWE) provide a simple, maintainable, and stable GND & REF system for LTM.
• This technique ensures high-quality EEG recordings when used with referential-based systems and invasive electrodes.
• The study presents a more efficient method for establishing GND & REF pairs in patients requiring invasive EEG monitoring.