Authors :
Presenting Author: Laurent KOESSLER, PhD – CNRS - Lorraine University
Sophie COLNAT-COULBOIS, MD, PhD – Epilepsy unit & Neuroscience – University Hospital of Nancy & CNRS - Lorraine University; Samuel LOUVIOT, PhD – CNRS - Lorraine University; Louis MAILLARD, MD, PhD – Epilepsy unit & Neuroscience – University Hospital of Nancy & CNRS - Lorraine University; Louise TYVAERT, MD, PhD – Epilepsy unit & Neuroscience – University Hospital of Nancy & CNRS - Lorraine University; Jean-Pierre VIGNAL, MD – Epilepsy unit – University Hospital of Nancy
Rationale: Despite the development of several new antiseizure drugs, thirty to forty percent of epileptic patients are still refractory to medications or report major side effects. Epilepsy including recurrent seizures resulting from excessive neuronal discharges should be an ideal candidate for tDCS. Here, thanks to a rare opportunity of simultaneous tDCS and iEEG recordings, we investigated the effect of an anodal tDCS on focal epileptic seizure with direct and online video-iEEG recordings in a drug-resistant epileptic patient. Our first aim was to demonstrate that ictal epileptic discharges recorded during tDCS were significantly reduced as compared to those recorded without tDCS. Our second aim was to compare the clinical symptoms of the epileptic seizure during tDCS with those recorded whithout tDCS
Methods: MC is a female (19-year-old) suffering from refractory insulo-opercular epilepsy (study NCT03644732). The patient was stereotactically implanted with seventeen multi-contact iEEG electrodes. Five spontaneous epileptic seizure occurred during the week with one under tDCS. The tDCS parameters were +1mA over T7 electrode and -1mA over the C6 electrode and a 20-minute total duration was set. The seizure was recorded after 8m3s of a-tDCS stimulation. Amplitude spectrum of the ictal epileptic discharges and video-recorded ictal symptoms before and during eight minutes of 1mA-intensity tDCS were compared. In addition, using a semi-automatic procedure, epileptogenic indexes were calculated for all seizures.
Results: Significant modulation of ictal spectrums was observed. Most of all, disappearance of the ictal low amplitude fast discharge was observed during tDCS. In the beta and gamma bands, seizure under tDCS had significantly lower amplitude distribution by comparison to the other seizures. For the seizure recorded during tDCS, no seizure detection was obtained (EI = 0) at the opposite to the other ones without tDCS with EI > 0.3). The duration of the clinical symptoms of the seizure recorded during tDCS (22 seconds) was significantly reduced compared to the others (p=0.005).
For the seizure recorded during tDCS, the beginning and the end of the clinal symptoms were like the first four epileptic seizures. However, strikingly, the major disabling motor symptoms disappeared.
Conclusions: Thanks to a rare combination of simultaneous tDCS and iEEG investigation, we provide here original evidence of both electrophysiological and clinical epilepsy symptoms reductions during a single transcranial electrical brain stimulation at low intensity and for few minutes duration. During the tDCS session, both intracerebral interictal and ictal epileptic discharges were neuromodulated. The most crucial feature of the epileptic seizure (i.e., the low amplitude fast discharge) was completely cancelled. Moreover, the cancellation of the most disabling and dangerous part of the clinical symptoms (i.e., the motor symptoms) reduce the risk of traumatic injuries for the patient (Koessler et al., Brain Stimulation, 2022). Funding: Lorraine University of Excellence Initiative (France) and the City College of New-York (USA) (DrEAM mobility grant) and the Region Grand Est (France)