Brain Dynamics in Different Stages of Arousal and Anesthesia

Brain Dynamics in Different Stages of Arousal and Anesthesia

The principle aim of this project is to characterize the changes in relative stability of the intrinsic brain dynamics during onset of sleep and induction of general anesthesia. The investigators hypothesize that brain dynamics in the awake state are critical akin to physical systems close to a second order phase transition and that during loss of consciousness the dynamics move away from the critical point.

1. Once the electrode array is placed during the first surgery (on the day of admission) we will record brain activity as subjects are waking up from anesthesia
2. While subjects are staying at New York Presbyterian hospital before the second surgery we will record brain activity. Most of the recordings will be performed as subjects are going to sleep naturally, but other recordings will be acquired during waking hours. This will not interfere with normal monitoring of seizure activity.
3. Final recording session is immediately before the second operation as general anesthesia is gradually induced. During this time subjects may be asked to follow simple commands like: "Open your eyes" in order to determine the level of consciousness. Also during this session, if arterial line is placed by the anesthesiologist for real-time blood pressure monitoring we will collect several small (~1 ml) blood samples to determine blood concentration of anesthetics. Approximately 1 teaspoon of blood will be obtained in total. No additional venipuncture will be necessary.

No additional invasive procedures will be performed for the purposes of the study. We will use the same electrode array as is typically used for monitoring and mapping of epilepsy. Subjects will receive the same anesthetic agent as is commonly used for induction of anesthesia for this surgery (propofol). Subjects will be monitored in the same way as is normally done during surgical procedures and during your stay at New York Presbyterian hospital.

As a part of the study subjects may be asked simple questions as they go under anesthesia.

We may collect several small blood samples (described above) to determine the concentration of anesthetic agents.

Inclusion Criteria:

1.Patients referred for epilepsy resection surgery with Dr. Theodore Schwartz

Exclusion Criteria:

1. Patient refusal.
2. Patients requiring rapid sequence induction because of concerns about delayed gastric emptying as a result of diabetes or other medical conditions.
3. Age less than 15 or greater than 65 years old.
4. Pregnant or nursing.
5. Inability to follow simple commands such as "Open your eyes" and "Squeeze my hand" for any reason.
6. Severe mental disability.
7. Allergy to propofol or any components of the formulation.
8. Poor suitability for propofol infusion because of other medical concerns such as severe heart disease.
9. Patients deemed to have a difficult airway thus necessitating awake fiberoptic intubation.
10. Patients with severe sleep apnea requiring CPAP/BiPAP.