TABLE 1.

Techniques for Intracranial Electrode Placement

	Surface electrode grids (eg, 8 × 8, 16 × 16)	Surface electrode strips (eg, 1 × 6, 2 × 14)	Penetrating electrodes (eg DBS electrode, depth electrode for sEEG)
Placement	Placed directly over cortical surface after craniotomy	Narrow profile allows for manipulation beyond craniotomy margin or through burr holes	Stereotactic placement under imaging guidance through burr holes or craniotomy
Risks	Cortical surface exposure; hemorrhage; infection	Cortical surface exposure (if craniotomy is used); hemorrhage; infection; risk of injury to bridging veins when manipulated beyond craniotomy margins	Infection; hemorrhage; local tissue injury from penetrating probes
Advantages	Extensive exposure of multiple cortical regions simultaneously; usually gyral surface only	Coverage of targeted cortical surface regions not covered by grids or beyond the margins of a craniotomy; reduced cortical surface exposure	3-D selective sampling of deep and superficial cortex; access to sulci
Disadvantages	Limited coverage of sulci and areas not directly exposed by craniotomy	Limited coverage of targeted regions	Limited coverage of targeted regions (eg, typically < 5 electrodes in regions of interest)