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

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

A Study of the Effect of Intracerebral Electrical Stimulation on the Optimisation of Presurgical Planning in Drug-refractory Partial Epilepsy (StiMiC)

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 electrical brain stimulations represent a standard clinical practice to assess seizure sensitivity and for functional mapping. This study aims at assessing if extending the range of stimulation frequencies of the usual clinical frequencies is of benefit for the definition of the seizure onset zone and hence for the presurgical planning.

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.

StiMic stimulation condition will be evaluate during stereo-electro-encephalography and this condition will be compare to standard stimulation condition

This new condition of stimulation of electrical Brain Stimulation will be evaluate to determine if this stimulation is more efficient that standard stimulation condition

Comparison of the index of efficient stimulation between standard clinical stimulation condition and StiMic stimulation condition

Comparison for each patient of the index of efficient stimulations (assessed as any stimulation having yielded an electrical or clinical effect over the total number of stimulations) for each condition (standard clinical stimulations condition vs research stimulations condition).

Distribution of efficient stimulations (assessed as any stimulation having yielded an electrical or clinical effect) for each frequency of stimulation.

Distribution of efficient stimulations (assessed as any stimulation having yielded an electrical or clinical effect) for each type of brain area stimulated (i.e, anatomical brain area, seizure onset zone, primary seizure propagation zone, healthy brain area or lesion).

Percentage change in the neuronal discharge rate 30 seconds after the stimulation compared to the 30 seconds before the stimulation, depending on the frequency of stimulations.

Percentage change in the neuronal discharge rate 30 seconds after the stimulation compared to the 30 seconds before the stimulation, depending on the effect of the stimulation (electrical or clinical as defined in the primary outcome)

Inclusion Criteria: all patients undergoing a stereo-electro-encephalography (SEEG), age 12 to 65 years old. Exclusion Criteria: usual excluding criteria for a SEEG.