Differential Effects of Propofol on Scalp and Intracranial EEG

Study Overview
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Brief Summary
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The anesthetic propofol has a dose-depending effect on the EEG, which differs in comparison between scalp and intracerebral electrodes

Detailed Description
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The electrical activity of the brain (electroencephalogram EEG) is usually assessed from the surface of the head, which is approximately 1-2 cm above the cerebral cortex. Thus, the spatial resolution of the EEG is low, and the electrical activity recorded originates from a multitude of neurons. Deep brain structures such as the hippocampus also generate electrical activity which cannot be assessed from the surface of the head. However, in some patients electrodes are implanted into the brain to look for the origin of epileptic seizures. Along the way, these intracerebral electrodes enable to record the EEG from intracerebral structures which are generated from few neurons only. Once the origin of epilepsy has been identified, the intracerebral electrodes are removed under general anesthesia. Anesthetics such as propofol characteristically modify the EEG in a dose-dependant manner. More over, the propofol effect on the EEG recorded from the surface is likely to be different from the intracerebral EEG, however little is known so far. Therefore we aim to investigate the differential effect of propofol on the superficial versus intracerebral recorded EEG.

Official Title
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Differential Effects of Propofol on Scalp and Intracranial Electroencephalogram

Conditions
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General Anesthesia

Intervention / Treatment
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* Other: differences between surface and intracerebral EEG


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with implanted intracerebral EEG electrodes Exclusion Criteria: Pregnancy

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| epilepsy patients<br>The group consists of patients with therapy refractory epilepsy, in which intracerebral electrodes were implanted to locate the seizure origin and to determine whether the patients are eligible for epilepsy surgery. In an observational study, differences between surface and intracerebral EEG are recorded. | Other: differences between surface and intracerebral EEG<br>* No intervention is performed. Im- and explantation of intracerebral electrodes is performed for clinical and not for study purposes. The only difference between study and non-study patients is that the surface as well as the intracerebral EEG is recorded and stored in the former, while it is discarded in the latter.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| EEG amplitude | EEG amplitude in comparison between scalp and intracranial recordings | up to two hours of EEG recording | 
| EEG frequency spectrum | EEG frequency spectrum in comparison between scalp and intracranial recordings | up to two hours of EEG recording | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| EEG Burst Suppression Ratio | EEG Burst Suppression Ratio in comparison between scalp and intracranial recordings | up to two hours of EEG recording | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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propofol, electroencephalogram