Contribution of High Resolution EEG Functional Connectivity Measures to Presurgical Evaluation of Patients With Intractable Epilepsy

Study Overview
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Brief Summary
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Electroencephalography (EEG) with very high spatial resolution (HR-EEG, 256 electrodes) allow for better analysis of local and global activity of the cerebral cortex, as compared with conventional EEG. Since January 2012, the Neurology Department of CHU Rennes is the first clinical service in France equipped with such a system. Applied to HR-EEG recordings, brain connectivity methods are likely to provide essential information (in the form of connectivity graphs) on cortical networks, either dysfunctional or not, involved in the generation of interictal paroxysms (like spikes or spike-waves) and during seizures. So far, many methods have been proposed (see for a review: Wendling et al., 2009; Wendling et al., 2010). However, since each method is highly sensitive to the type of model that is assumed for the underlying relationship between distinct brain regions (Ansari-Asl et al., 2006), none of them has yet demonstrated its effectiveness.

Official Title
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Contribution of High Resolution EEG Functional Connectivity Measures to Presurgical Evaluation of Patients With Intractable Epilepsy

Conditions
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Epilepsy

Intervention / Treatment
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* Procedure: Electroencephalography
* Procedure: Electroencephalography and additional experimental tasks


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria Patients: Being more than 18 years old, Having a chronic partial epilepsy resistant to medical treatments well administered and well followed in the course of pre-surgical assessment. Inclusion Criteria Healthy Volunteers: Being French native speaker, Being more than 18 years old, Being right-handed. Exclusion Criteria Patients: All patients for whom a preoperative surgical exam is not suitable, Any patient with psychiatric disease or intellectual disorder such that informed consent could not be obtained, Any patient with no abnormal EEG during intercritical phases, All patients presenting psychiatric, neuropsychological or developmental difficulties in addition to epilepsy, Adult persons subject to legal protection (judicial protection, temporary guardianship/guardianship, administrative supervision), persons deprived of their liberty and pregnant or lactating women. Exclusion Criteria Healthy Volunteers: The presence of any psychiatric, neuropsychological, and developmental disorder, Any uncorrected visual impairment, Any trouble or delay in learning to read / speak or write French, Being fully bilingual or multilingual Medication, treatment and / or substances that may alter or modify brain functions, Adult persons subject to legal protection (judicial protection, temporary guardianship/guardianship, administrative supervision), persons deprived of their liberty and pregnant or lactating women.

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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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: epileptic patients<br>Electroencephalography | Procedure: Electroencephalography<br>* Epileptic patients, as in healthy volunteers will be offered a review of EEG recording equipment resting on EEG-HR 256-channel EGI © in operation since January 2012 in the Van Gogh Service Unit of Neurology Rennes University Hospital (hospital Pontchaillou). The EEG is a routine now included in the Phase I report some epileptic patients during presurgical investigation. Patients to be included in this research protocol pass all review on the new device EEG-HR 256 channels. In addition to the rest condition, shared by both groups of participants, the healthy control subjects participate in two additional experimental tasks to be performed during recording. A picture naming task and a task of spelling words represented by these images.<br>|
| Other: Healthy Volunteers<br>Electroencephalography and additional experimental tasks | Procedure: Electroencephalography and additional experimental tasks<br>* Epileptic patients, as in healthy volunteers will be offered a review of EEG recording equipment resting on EEG-HR 256-channel EGI © in operation since January 2012 in the Van Gogh Service Unit of Neurology Rennes University Hospital (hospital Pontchaillou). The EEG is a routine now included in the Phase I report some epileptic patients during presurgical investigation. Patients to be included in this research protocol pass all review on the new device EEG-HR 256 channels. In addition to the rest condition, shared by both groups of participants, the healthy control subjects participate in two additional experimental tasks to be performed during recording. A picture naming task and a task of spelling words represented by these images.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The quality of matching between i) the graphs produced by the evaluated connectivity method(s) applied to the HR-EEG and ii) the results of the visual analysis typically performed by an expert on the standard EEG recorded during intercritical phase. | Main objective :To determine which functional connectivity estimation method(s) show(s) best performance(s) for the identification of epileptogenic networks from the HR-EEG recording performed in epileptic patients. | 2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The quality of matching between i) the connectivity graphs obtained from control subjects performing a well defined cognitive task to ii) data from the literature on networks activated and sustaining these cognitive processes. | Our secondary objectives are: The application of linear, non-linear and phase synchronization methods in digital signal processing on broadband band analysis or on band-filtered EEG signals acquired during HR-EEG explorations of patients with epilepsy, The evaluation of the performance of these methods by comparing the resulting connectivity graphs with those expected in healthy subjects (controls), The application of the methods offering the best performances to data acquired in patients. | 2 years |