Stimulation Mapping Using Stereoelectroencephalography: Current and Future Directions

Abstract

Electrical stimulation mapping (ESM) using stereoelectroencephalography (SEEG) is an essential component in the workup of surgical epilepsy. Since the initial application of ESM in the mid-1960s, it remains unparalleled in defining eloquent brain areas and delimiting seizure foci for the purposes of surgical planning. Here, we briefly review the current state of SEEG stimulation, with a focus on the techniques used for identifying the epileptogenic zone and eloquent cortex. We also summarize clinical data on the efficacy of SEEG stimulation in surgical outcomes and functional mapping. Finally, we briefly highlight future applications of SEEG ESM, including novel functional mapping approaches, identifying rare seizure semiologies, neurophysiologic investigations for understanding cognitive function, and its role in SEEG-guided radiofrequency thermal coagulation.

Keywords: electrical stimulation mapping; epilepsy; epileptogenic zone; functional neurosurgery; review; stereoelectroencephalography; subdural grid.

Figure 1

An overview of the two common invasive EEG (iEEG) techniques, subdural grids (SD) and Stereoelectroencephalography (SEEG), including the criteria for iEEG, electrical stimulation mapping (ESM) applications, advantages and disadvantages of both techniques. We also demonstrate the relationship of the epileptogenic zone (EZ) to eloquent cortex (EC), highlighting that SEEG is useful for understanding network connectivity.