Cortical Excitability Assessment Using Paired Pulses

Study Overview
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Brief Summary
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The identification of the epileptogenic zone (EZ) during pharmacoresistant focal epilepsy presurgical assessment frequently requires intracranial recordings like stereo-electroencephalography (SEEG). Cortical direct electrical stimulation (DES) is commonly used during SEEG for functional mapping or to induce seizure. However, the recording of seizures is sometimes insufficient to circumscribe the EZ and development of new biomarkers is necessary. The cortex within the EZ is thought to be hyperexcitable. The paired pulses paradigm, using transcranial magnetic stimulation (TMS), allows determining the hemispheric cortical excitability level. The investigators hypothesize that paired pulses DES during SEEG could provide useful information for EZ identification.

Official Title
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Cortical Excitability Assessment of Pharmacoresistant Focal Epilepsy Using Direct Electrical Stimulation During Stereo-electroencephalography

Conditions
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Focal Epilepsy

Intervention / Treatment
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* Other: paired pulses cortical electrical stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age above 18 years old Pharmacoresistant focal epilepsy patients undergoing a stereo-electroencephalographic recording Provide written consent to the study after receiving clear information Be a beneficiary or member of health insurance plan Exclusion Criteria: Patient with contraindication for MRI scanning Pregnancy Prohibition on participation in other research, apart from any other non-interventional research

Ages Eligible for Study
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Minimum Age: 18 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: paired pulses cortical electrical stimulation<br> | Other: paired pulses cortical electrical stimulation<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Presence of a significant difference between the evoked responses to paired pulses cortical electrical stimulation of epileptogenic zone cortex and of normal cortex | Low frequency single pulse electrical stimulation induces several cortico-cortical electroencephalographic responses: early-physiological and/or late-pathological. We expect different paired pulses modulation of those responses according the excitability level of the stimulated cortex (in terms of latency, amplitude, surface, frequency power) | between Day 7 and 21 (End of the stereoelectroencephalographic recordings) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Presence of a difference of responses patterns between anatomic regions and/or lesion type |  | between Day 7 and 21 (End of the stereoelectroencephalographic recordings ) | 
| Presence of a difference between transcranial magnetic paired pulses stimulations and intracranial paired pulses cortical direct electrical stimulations |  | Between Day 7 and 21 (End of the stereoelectroencephalographic recordings) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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TMS, pharmacoresistant focal epilepsy, cortical excitability, paired pulses, SEEG, DES