Invasive epilepsy surgery evaluation.

Area of Science:

• Neurosurgery
• Epileptology
• Neurology

Background:

• Intracranial EEG (iEEG) is essential for evaluating pharmacoresistant epilepsy.
• Various iEEG techniques (grids, strips, depth electrodes, SEEG) offer distinct advantages and limitations.
• Individualized patient approaches are employed by epilepsy centers skilled in multiple iEEG methods.

Purpose of the Study:

• To review indications for iEEG in pharmacoresistant epilepsy work-up.
• To describe key iEEG recording techniques: grid electrodes, depth electrodes, and SEEG.
• To outline preferred technical approaches for iEEG in specific clinical scenarios.

Main Methods:

• Review of current literature on iEEG techniques for epilepsy surgery.
• Description of subdural grids, depth electrodes, and stereoencephalography (SEEG).
• Analysis of clinical scenarios influencing the choice of iEEG technique.

Main Results:

• iEEG helps map the seizure onset zone, approximating the epileptogenic zone for potential resection.
• Direct cortical stimulation via implanted electrodes can define eloquent cortex.
• Clinical factors, such as proximity to eloquent cortex, guide the selection between techniques like grids and SEEG.

Conclusions:

• This review updates clinicians on the diagnostic utility of iEEG for epilepsy surgery.
• Understanding patient selection for iEEG can optimize referral patterns.
• Advances in iEEG technology are expected to further enhance clinical applications.