Cortical Excitability Assessment Using Paired Pulses

Hospices Civils de Lyon60 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

Purpose

DIAGNOSTIC

Masking

NONE

Enrollment

Conditions

Focal Epilepsy

Interventions

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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)

Time frame: between Day 7 and 21 (End of the stereoelectroencephalographic recordings)

Secondary Outcomes

Presence of a difference of responses patterns between anatomic regions and/or lesion type

Time frame: 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

Time frame: Between Day 7 and 21 (End of the stereoelectroencephalographic recordings)