ECoG, or intracranial electroencephalography (iEEG), is a type of electrophysiological monitoring that uses electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral cortex.


ECoG, also referred to as Intracranial EEG (iEEG) or Subdural EEG (sdEEG), intraoperatively records potentials from the cortical surface. It is used as part of an evaluation for epilepsy surgery, where electrodes may be placed near the surface of the brain. Depth electrodes may also be placed into brain structures which are common epileptic foci and may not be seen clearly by scalp EEG. ECoG can:

  • Locate epileptogenic lesions

  • Locate brain regions (e.g. speech)

  • Brain mapping (e.g. sensorimotor cortex)