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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Epilepsy

Intervention / Treatment
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* Diagnostic Test: StiMiC stimulation condition


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

Ages Eligible for Study
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Minimum Age: 12 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: StiMic stimulation condition<br>StiMic stimulation condition will be evaluate during stereo-electro-encephalography and this condition will be compare to standard stimulation condition | Diagnostic Test: StiMiC stimulation condition<br>* This new condition of stimulation of electrical Brain Stimulation will be evaluate to determine if this stimulation is more efficient that standard stimulation condition<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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). | 22 days after implantation of electrode | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| efficient stimulation for each frequency of stimulation | Distribution of efficient stimulations (assessed as any stimulation having yielded an electrical or clinical effect) for each frequency of stimulation. | 22 days after implantation of electrode | 
| efficient stimulation for each type of brain area stimulated | 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). | 22 days after implantation of electrode | 
| percentage change in the neuronal discharge rate | 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. | 30 second after stimulation | 
| percentage change in the neuronal discharge rate for stimic stimulation condition | 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) | 30 second after stimulation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Epilepsy, Electrical Brain stimulation, Neurosurgery, stereo-electro-encephalography (SEEG)