Intracerebral Epileptic Discharges Without and During Concurrent tDCS in an Epileptic Patient

Intracerebral EEG recordings of a patient (female, 19 yo) suffering from refractory insulo-opercular epilepsy.
She gave informed consent to participate in this study (NCT03644732).
Intracerebral electrode positions (see also Figure):
A’, B’, C’ and P’, targeted the temporal pole, the mesial and neocortical temporal lobe.
H’, I’, L’, O’, R’, S’ and T’ targeted the insular cortex and the operculum.
G’, J’, K’, M’, W’ and X’ targeted the mesial and neocortical frontal lobe.
IEEG signals were recorded at a 1024 Hz sampling rate with a 256-channel amplifier (SD LTM 256 Headbox, Micromed, Italy).
The reference electrode was an iEEG contact located in the white matter.
The tDCS parameters were +1mA over the anode (T7 electrode) and -1mA over the cathode (C6 electrode) and a 20-minute total duration was set.
Two HD electrodes (12mm external diameter; Soterix Medical®, New York, NY, USA) were used (with Z < 5 kOhms).
During the four days of iEEG investigation, five spontaneous epileptic seizures occurred, and ictal epileptic discharges were recorded in S’1-2 to 8-9 and O’5-6 to O’9-10 contacts.
Seizure#5 occured after 8min of tDCS.
Five datasets of ictal epileptic discharges outside (IED1-4) and during tDCS (IED*) were identified and selected during tDCS with the same 60 seconds duration (bipolar montage).