Clinical Utility of ESI in Presurgical Evaluation of Patients With Epilepsy

Study Overview
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Brief Summary
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This study evaluates to what extend electrical source imaging (ESI) provides nonredundant information in the evaluation of epilepsy surgery candidates. Epilepsy surgery normally requires an extensive multimodal workup to identify the epileptic focus. This workup includes Magnetic Resonance Imaging (MRI), electroencephalography (EEG) without source imaging, video monitoring and when needed Positron Emission Tomography (PET), Magnetoencephalography (MEG), Single Photon Emission Computed Tomography (SPECT) and invasive EEG recordings using implanted electrodes. ESI estimates the location of the epileptic source with a high sensitivity and specificity using inverse source estimation methods on non-invasive EEG recordings. This study aims to investigate the clinical utility of ESI using low-density (LD, 25 channels) and high-density (HD, 256 channels) EEG. Clinical utility is defined in this study as the proportion of patients in whom the patient management plan was changed, based on the results of ESI. Should ESI be added to the routine work-up of epilepsy surgery candidates.

Detailed Description
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Patients with drug resistant epilepsy can be offered resective neurosurgery if seizure semiology, video-EEG and MRI points to a focal origin in the brain. Are these investigations not concordant or is the MRI without a lesion, then additional investigations such as PET, SPECT and MEG can be performed before deciding upon operation or further, invasive investigation, using intracranial EEG recordings. If a single hypothesis can be made the patient can be operated. In case of one main hypothesis and additional hypothesis, intracranial EEG registration can be performed. If there are no hypothesis or too many hypotheses the patient cannot be offered surgery. In the present study electrical source imaging (ESI) will be performed in epilepsy surgery candidates on low density (LD, 25 channels) and high density (HD, 256 channels) electroencephalography (EEG). In the analysis of LD-EEG, a template brain and template electrode position will be used. In the analysis of HD-EEG an individual MRI scan and individual electrode position will be used. The multidisciplinary epilepsy surgery team will be blinded to the results of the ESI, until based on MRI, LD EEG (without source imaging), video monitoring and optionally PET, MEG and ictal-SPECT, the investigators have decided whether a patient 1) is ready for surgery, 2) should be evaluated with intracranial electrodes or 3) cannot be offered operation. This decision is registered. Then LD ESI is presented. It is registered whether any change in the patient management plan was made, based on the ESI data. Further, for 1) it is registered whether the planned extend of the surgical resection is changed and whether intraoperative EEG recording is needed; for 2) it is registered if the planned implantation strategy of intracranial electrodes is changed; and for 3) whether other additional evaluation is needed. Finally, HD ESI is presented and it is registered if this changes the decision made without ESI, according to the above-mentioned categories. Clinical utility of LD ESI and of HD ESI is defined as the proportion of patients in whom the patient management plan was changed, based on the LD ESI and respectively HD ESI. The investigators will use McNemar test to compare the proportion of changes based on LD ESI with those based on HD ESI. The localization provided by the ESI methods, will be compared with the conclusion of the multidisciplinary team, on the localization of the epileptic focus. In patients having intracranial EEG performed within the study period, the results will be compared to the ESI results. In patients having one-year follow-up after operation and being seizure free, it will be evaluated if the location of the ESI was within the operation area.

Official Title
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Electrical Source Imaging in Presurgical Evaluation of Patients With Focal Epilepsy: A Prospective Study of Clinical Utility

Conditions
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Electroencephalography, Refractory Epilepsy, Brain Imaging, Surgery

Intervention / Treatment
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* Diagnostic Test: Low-density ESI (LD ESI)
* Diagnostic Test: High-density ESI (HD ESI)
* Diagnostic Test: No electrical source imaging (ESI)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Drug resistant epilepsy Potential candidates for epilepsy surgery Exclusion Criteria: Can not cooperate for EEG recording

Ages Eligible for Study
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Minimum Age: 10 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
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Evaluation of low-density (LD, 25 channels) and high-density (HD, 256 channels) electrical source imaging (ESI) in epilepsy surgery
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: No electrical source imaging (ESI)<br>In all patients, the multidisciplinary epilepsy surgery team will make a conclusion on management plan, based on all non-invasive presurgical data, except for ESI. | Diagnostic Test: No electrical source imaging (ESI)<br>* For all patients: MRI, semiology, visual interpretation of EEG. When needed: PET, SPECT.<br>|
| Experimental: Low-density ESI (LD ESI)<br>The multidisciplinary epilepsy surgery team will make a conclusion on management plan, based on all non-invasive presurgical data, including ESI using LD EEG recordings. | Diagnostic Test: Low-density ESI (LD ESI)<br>* Electrical source imaging using low density EEG<br>|
| Experimental: High-density ESI (HD ESI)<br>The multidisciplinary epilepsy surgery team will make a conclusion on management plan, based on all non-invasive presurgical data, including ESI using HD EEG recordings. | Diagnostic Test: High-density ESI (HD ESI)<br>* Electrical source imaging using high density EEG<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Clinical utility of LD ESI and of HD ESI: change in clinical decision following ESI | Defined as the proportion of patients in whom the patient management plan was changed, based on the LD ESI and respectively HD ESI | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change to stop | The patient is not offered surgery. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 
| Change from stop to implantation of intracranial electrodes | Without ESI the patient is not offered surgery. Based on ESI, implantation of intracranial recordings is offered. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 
| Change in the strategy (location) of implanted intracranial electrodes | Additional intracranial electrodes are implanted, based on the results of ESI. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 
| Change from stop to operation | Without ESI, the patient is not offered operation. Based on ESI, operation is offered. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 
| Change from implantation of intracranial electrodes to operation | Without ESI, implantation of intracranial electrodes is offered. Based on ESI, operation is offered. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 
| Change from operation to implantation of intracranial electrodes | Without ESI, operation is offered. Based on ESI this is changed to implantation of intracranial electrodes. | Through study completion - an average 1 year - at the end of the presurgical work-up of each patient, at the multidisciplinary epilepsy surgery meeting. The timeframe of completing the presurgical evaluation varies from 6 months to 24 month. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Electrical source imaging