10-20 EEG system

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The 10-20 system is used to measure 19 channel (q)EEG.  The 10-20 EEG system is a widely used method to place electrodes on the scalp in a standardized way for electroencephalography (EEG) recordings. This system ensures that electrodes are placed in consistent and reproducible locations across different subjects and sessions.

Key Points of the 10-20 System

  1. Nomenclature: The name "10-20" refers to the distances between adjacent electrodes, which are either 10% or 20% of the total front-back or right-left distance of the skull.

  2. Landmarks: The system uses several anatomical landmarks for placement:

    • Nasion: The indentation between the forehead and the nose.
    • Inion: The prominent point on the lower back of the skull.
    • Preauricular Points: Points just in front of the ears.

  3. Electrode Labels: Electrodes are labeled with a combination of letters and numbers:

    • Letters indicate the region of the brain: F (frontal), T (temporal), P (parietal), O (occipital), C (central).
    • Numbers indicate the hemisphere and position: Even numbers (2, 4, 6, 8) are on the right hemisphere, odd numbers (1, 3, 5, 7) are on the left hemisphere, and the letter 'z' (zero) indicates the midline (Fpz, Fz, Cz, Pz, Oz).

  4. Placement:

    • Electrodes are placed at intervals of 10% or 20% of the total length of specific anatomical measurements.
    • The distances are measured between the nasion and inion for the longitudinal axis and between the preauricular points for the transverse axis.

  5. Electrode Positions:

    • Fp: Frontal pole (Fp1, Fp2)
    • F: Frontal (F3, F4, F7, F8, Fz)
    • T: Temporal (T3, T4, T5, T6)
    • C: Central (C3, C4, Cz)
    • P: Parietal (P3, P4, Pz)
    • O: Occipital (O1, O2)

Advantages of the 10-20 System

  • Standardization: Provides a consistent framework for electrode placement, allowing for reproducibility in research and clinical settings.
  • Comparison: Facilitates comparison of EEG results across different studies and subjects.
  • Clinical Use: Helps in diagnosing and monitoring neurological disorders, such as epilepsy, sleep disorders, and brain injuries.