Intracerebral Electrical Stimulation and the Optimisation of Presurgical Planning in Drug-refractory Partial Epilepsy

Patients with drug-refractory epilepsy sometimes need to be implanted with intracerebral electrodes in order to identify their seizure onset zone. During this procedure, direct brain electrical stimulations is a standard clinical practice to assess seizure sensitivity and for functional mapping. However the efficiency of these stimulations can be questioned and could potentially be improved. Indeed, only two typical frequencies are commonly used in our epilepsy centre, 1Hz and 50Hz, without clear clinical or scientific justification for these specific frequencies.

This study aims at assessing if extending the range of stimulation frequencies of the usual clinical frequencies could improve the definition of the seizure onset zone and hence the presurgical planning. We will maintain the usual stimulation frequencies (standard clinical stimulations condition) and add new frequencies to the protocol (research stimulations condition). The choice of these new frequencies will be based either on the spontaneous frequency of the onset of the patients' typical seizures or on physiological frequencies depending on the brain structures stimulated (i.e., theta in the medial temporal lobe).

The protocol will be proposed to all patients undergoing a stereo-electro-encephalography (SEEG) in our epilepsy center and the efficiency of the two conditions (standard clinical stimulations condition vs research stimulations condition) will be compared. The efficiency will be assessed as any epileptic event, recorded in the intracerebral EEG or symptom induced by the stimulations. This project will last 36 months. 20 patients will be included.

Inclusion criteria

• all patients undergoing a stereo-electro-encephalography (SEEG), age 12 to 65 years old.

Exclusion criteria

• usual excluding criteria for a SEEG.