What percentage represents the distance from O1/O2 to Oz?

The distance from the O1 and O2 EEG electrode positions to Oz is commonly defined in terms of percentage of the interelectrode distance on the International 10-20 system for electrode placement. The distance from the lateral occipital sites (O1 and O2) to the midline occipital site (Oz) represents a relatively small percentage of the total distance.

Specifically, it is understood that the distance from O1 or O2 to Oz is approximately 5% of the total distance between O1 and O2. This is a standard reference point utilized in the field of electroencephalography (EEG), where accurate placement of electrodes is crucial for reliable data collection and interpretation.

In this context, recognizing the precise measurements and their relevance in EEG monitoring can help clinicians and technicians ensure that electrode placements are consistent with standard practices, thereby promoting the quality of sleep studies and other related assessments.