EEG Characteristics of Different Sedation Depths in Neurosurgery Patients

Study Overview
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Brief Summary
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Gliomas are the most common primary intracranial malignancy, and behavioral experiments in patients with supratentorial gliomas under sedation have shown potential neurological abnormalities; however, these behavioral experiments are susceptible to external influences. Therefore, more objective evidence is needed to support and extend the existing conclusions. The purpose of this study is to compare the EEG signatures (such as the EEG signal power) at various levels of anesthetics induced sedation in patients with supratentorial glioma in frontal lobe and in patients without intracranial-occupying lesion.

Official Title
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EEG Characteristics of Different Sedation Depths in Patients With Supratentorial Glioma in Frontal Lobe

Conditions
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Electroencephalography

Intervention / Treatment
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* Other: OAA/S=5
* Other: OAA/S=3
* Other: OAA/S=1


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with supratentorial glioma in right frontal lobe, and patients requiring general anesthesia without intracranial-occupying lesion; Aged 18-60 years; ASA I to II; All those who sign the informed consent form. Exclusion Criteria: Obese patients, BMI>30kg/m2; Patients with Mallampati class III to IV airway anatomy; Combined with other neurological or psychiatric diseases; Combined with disturbance of consciousness; Previous intracranial surgery; Known or suspected cardiac dysfunction; Allergic to intravenous general anesthetics; Long-term history of analgesia, sedation and drug abuse.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 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 |
| --- | --- |
| Awake State<br>OAA/S=5 | Other: OAA/S=5<br>* Prior to anesthesia induciton, EEG signatures will be recorded at Observer's Assessment of Alertness/Sedation (OAA/S) score of 5 (awake, eye-close state) for few minutes.<br>|
| Sedation State<br>OAA/S=3 | Other: OAA/S=3<br>* Given sedative anesthetics (propofol, midazolam or dexmetomidine), EEG signatures will be recorded after reaching steady state of OAA/S=3 (responds only after name called loudly and/or repeatedly) for few minutes.<br>|
| Unconsciousness State<br>OAA/S=1 | Other: OAA/S=1<br>* Increasing drug concentration, EEG signatures will be recorded after reaching steady state of OAA/S=1 (does not respond to noxious stimuli) for few minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 1. The time-frequency characteristics of EEG power changes at different sedation depths in neurosurgical patients. | The EEG power will be calculated by raw signal at awake, eye-closed state and after reaching the steady-state sedation depths of OAA/S=3 and OAA/S=1. | Prior to anesthesia induction, three minutes after reaching the target level of sedation |