Four-Way Wada: SEEG-based mapping with electrical stimulation, high frequency activity, and phase amplitude coupling to complement traditional Wada and functional MRI prior to epilepsy surgery

Abstract

Presurgical evaluation of refractory epilepsy involves functional investigations to minimize postoperative deficit. Assessing language and memory is conventionally undertaken using Wada and fMRI, and occasionally supplemented by data from invasive intracranial electroencephalography, such as electrical stimulation, corticortical evoked potentials, mapping of high frequency activity and phase amplitude coupling. We describe the comparative and complementary role of these methods to inform surgical decision-making and functional prognostication. We used Wada paradigm to standardize testing across all modalities. Postoperative neuropsychological testing confirmed deficit predicted based on these methods.

Keywords: Electrical stimulation mapping; Epilepsy surgery; High frequency activity; Phase amplitude coupling; Stereoelectroencephalography; Temporal lobe epilepsy.

Fig. 1.

HFA/PAC comparisons of three tasks: 1) confrontation naming, 2) word-list recall, and 3) word-list encoding with MaxPAC values projected to the cortex including a) left lateral view and b) left inferior oblique view. Analyses are displayed using MaxPAC as Delta-HFA, Theta-HFA, Alpha-HFA, and Beta-HFA.

Fig. 2.

HFA/PAC comparisons of three tasks: 1) confrontation naming, 2) word-list recall, and 3) word-list encoding with fLow of MaxPAC values projected to the cortex including a) left lateral view and b) left inferior oblique view. Analyses are displayed using fLow of MaxPAC as Delta-HFA, Theta-HFA, Alpha-HFA, and Beta-HFA.