Evaluation of the Risk of Cognitive Deficit After Surgery of Epilepsy by Dynamic Spectral Imaging (ISD) of the Cognitive Functions in Patients Explored in StereoElectroEncephaloGraphy (SEEG)

Study Overview
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Brief Summary
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Epilepsy affects between 0.5 and 0.7% of the European population. Despite the availability of numerous drug treatments, one third of patients still have seizures, which are associated with significant cognitive and social complications and excess mortality. In these patients, surgical treatment to remove the epileptogenic zone (EZ), the region of the brain responsible for seizures, is the only approach that can allow control of the disease. However, before investigating this surgery, investigations have to answer two questions: (i) what is the location and extension of the EZ and (ii) what functional risks, both motor and cognitive, would represent the resection of this Cortical region? As it is a functional surgery, it is in fact inconceivable that the surgery will result in an over-handicap. For these reasons, all candidates for surgery benefit from a complete assessment including imaging examinations, a neuropsychological assessment and a long-term video-EEG recording to record seizures. Nevertheless, in some patients, this assessment does not give us a formal answer. In these subjects, it is then necessary to carry out a second step, consisting of an invasive exploration by implantation of intracerebral electrodes during a stereoencephalography (SEEG). Due to its temporal and spatial resolution, the SEEG allows, besides the precise determination of the EZ, to carry out a functional mapping of the cortical regions likely to be included in cortectomy. Conventionally, this mapping is carried out on the basis of the cortical electrical stimulations applied to the implanted electrodes. If this approach is very robust for exploring primary functions such as motor skills or language, it cannot be used to evaluate more complex cognitive tasks such as face recognition or attention Effective cognitive treatment on a daily basis. This has led to the development in recent years, in Lyon and Grenoble, of a complementary approach to cerebral stimulation: dynamic spectral imaging (ISD). Numerous experimental paradigms have demonstrated that the realization of a cognitive task associates with the generation within the cortical regions involved in its treatment of a particular cortical activity. This activity is characterized by oscillations of the cortical rhythm in high frequencies (> 30 Hz), called gamma activities. The ISD thus consists in mapping this gamma activity during various cognitive tasks, thus making it possible to study more widely the complexity of the cognitive functions. Correlations between gamma activity and cognitive tasks have so far been exclusively performed in the non-epileptic cortex explored at the periphery of the EA during SEEG. Nevertheless, the cortical oscillatory pattern study associated with a specific cognitive task within the EZ could better anticipate complex cognitive deficits that could be generated by the resection of a cortical region. The main objective of this project is to establish the predictive character of the gamma cortical oscillatory pattern associated with a specific cognitive task on the risk of occurrence of a cognitive disorder after surgery of epilepsy.

Official Title
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Evaluation of the Risk of Cognitive Deficit After Surgery of Epilepsy by Dynamic Spectral Imaging (ISD) of the Cognitive Functions in Patients Explored in StereoElectroEncephaloGraphy (SEEG)

Conditions
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Epilepsy

Intervention / Treatment
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* Procedure: Dynamic Spectral Imaging (ISD)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patient adult (18-65 y/o) without legal protection measures Patient with a drug-resistant focal epilepsy Patient with a SEEG exploration as part of pre-surgical assessment of epilepsy patient with a consent form signed Intellectual capacities compatible with cognitive tasks and the signing of informed consent Affiliation to the social security Exclusion Criteria: Pregnant women: this is already a contraindication to the realization of a SEEG study Subjects under 18 years of age or over 65 years of age Patient not suffering from EFPR, or not scheduled for SEEG Intellectual capacities incompatible with the cognitive tasks and / or the signature of a consent

Ages Eligible for Study
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Minimum Age: 18 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: Dynamic Spectral Imaging (ISD)<br>Evaluation of cognitive functions by ISD | Procedure: Dynamic Spectral Imaging (ISD)<br>* cerebral stimulation: dynamic spectral imaging (ISD)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| predictive character of the cortical gamma oscillatory pattern associated with a specific cognitive task on the risk of occurrence of a cognitive disorder after epilepsy surgery | Relation between the presence in the epileptogenic zone of a gamma activation in at least 1 of the cognitive tasks performed during the ISD and the occurrence of a postoperative neuropsychological deficit (Wilcoxon test) | 12 months post-surgery compare to preoperative assessment (SEEG) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| database on the dynamics of large cerebral networks underlying the main cognitive functions | Comparison of mapping of pre-surgical gamma activity with preoperative neu-ropsychological evaluation | pre-surgical assessment (SEEG) | 
| spatio-temporal organization of these networks with that predicted by fMRI | Pre-surgical comparison of the performances for the functional cartography of gamma activity performed during SEEG, fMRI and cortical stimulation at preoperative assessment. | preoperative assessment (SEEG, fMRI and cortical stimulations) | 
| effect of intracerebral electrical stimulations | Pre-surgical comparison of the performances for the functional cartography of gamma activity performed during SEEG, fMRI and cortical stimulation at preoperative assessment. | preoperative assessment (SEEG, fMRI and cortical stimulations) | 
| macro-electrophysiological recordings | The relation between the presence in the epileptogenic zone of an activation in the other frequency bands (theta, alpha, beta) in at least 1 of the cognitive tasks performed during the ISD and the occurrence of a post neuropsychological deficit | 12 months post-surgery compare to preoperative assessment (SEEG) | 
| micro-electrophysiological recordings | The relation between the presence in the epileptogenic zone of an activation in the other frequency bands (theta, alpha, beta) in at least 1 of the cognitive tasks performed during the ISD and the occurrence of a post neuropsychological deficit | 12 months post-surgery compare to preoperative assessment (SEEG) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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SEEG, ISD, cognitive disorder, epilepsy surgery