Overview of EEG Montages and Principles of Localization.

Area of Science:

• Neuroscience
• Clinical Electrophysiology

Background:

• Electroencephalogram (EEG) montages are systematic arrangements of electrode derivations used to visualize brain activity across the scalp.
• Bipolar and referential montages are standard for routine EEG, while common average and Laplacian montages offer additional utility.
• Each montage type possesses unique strengths and limitations, necessitating a varied approach.

Purpose of the Study:

• To emphasize the importance of utilizing multiple EEG montage classes for comprehensive brain activity display and localization.
• To provide guidance on selecting and designing appropriate montages for clinical EEG interpretation.

Main Methods:

• Review of existing literature and guidelines, including those from the American Clinical Neurophysiology Society (ACNS).
• Discussion of factors influencing scalp EEG localization.
• Description of a practical three-step visual inspection method for localizing interictal epileptiform discharges using conventional montages and the 10-20 electrode system.

Main Results:

• The ACNS guidelines advocate for the use of diverse montage types in EEG recordings.
• A structured three-step approach facilitates the localization of epileptiform discharges via visual inspection.
• Standard and suggested montages are available, with flexibility for custom designs using the 10-20 system.

Conclusions:

• Optimal EEG interpretation and localization rely on the strategic application of multiple montage types.
• Clinical practice can effectively employ a systematic approach for identifying the origin of epileptiform discharges.
• Adherence to guidelines and understanding montage characteristics are key for accurate neurophysiological assessment.