Choice of Anesthesia in Microelectrode Recording Guided Deep Brain Stimulation for Parkinson's Disease (CHAMPION)

Choice of Anesthesia in Microelectrode Recording Guided Deep Brain Stimulation for Parkinson's Disease

Choice of Anesthesia in Microelectrode Recording Guided Deep Brain Stimulation for Parkinson's Disease (CHAMPION)：A Randomized Controlled, Non-Inferiority Study

Subthalamic nucleus (STN)-deep brain stimulation (DBS) under general anesthesia has been applied to PD patients who cannot tolerate awake surgery, but general anesthesia will affect the electrical signal in microelectrode recording (MER) to some degree. This study is a prospective randomized controlled, noninferiority study, open label, endpoint outcome evaluator blinded, two-arm study. Parkinson's disease patients undergoing STN-DBS are randomly divided into a conscious sedation group (dexmedetomidine) and a general anesthesia group (desflurane). Normalized root mean square (NRMS) is used to compare the difference of neuronal activity between the two groups. The primary outcome is the percentage of high NRMS recorded by the MER signal (with the average NRMS recorded by MER after entering the STN greater than 2.0). The secondary outcomes are the NRMS, length of the STN, number of MER tracks, and differences in clinical outcomes 6 months after the operation.

STN-DBS under general anesthesia has been applied to PD patients who cannot tolerate awake surgery, but general anesthesia will affect the electrical signal in microelectrode recording (MER) to some degree. At present, there are some studies on the effects of desflurane on neuronal signal amplitude and discharge characteristics during STN-DBS in PD patients but there is no definite conclusion. This study compares the influence of MER mapping during STN-DBS and the differences in postoperative clinical outcomes between desflurane general anesthesia and conscious sedation anesthesia to explore alternative anesthesia for DBS in PD patients who cannot tolerate local anesthesia or conscious sedation and to provide feasible anesthesia techniques for the application of MER during DBS under general anesthesia. This study is a prospective randomized controlled, noninferiority study, open label, endpoint outcome evaluator blinded, two-arm study. Parkinson's disease patients undergoing STN-DBS are randomly divided into a conscious sedation group (dexmedetomidine) and a general anesthesia group (desflurane). The primary outcome is the percentage of high NRMS recorded by the MER signal (with the average NRMS recorded by MER after entering the STN greater than 2.0), which is used to compare the differences in neuronal electrical activities between conscious sedation and general anesthesia via desflurane groups. The secondary outcomes are the NRMS, length of the subthalamic nucleus, number of MER tracks, and differences in clinical outcomes 6 months after the operation.

The patients did not use any preoperative sedative drugs and were given sufentanil citrate 0.1-0.2 µg/kg, cisatracurium 0.2 mg/kg and propofol 1.5-2.0 mg/kg during anesthesia induction. After the patients were unconscious, oral endotracheal intubation was performed. Anesthesiologists should continuously monitor PetCO2 and maintain PetCO2 at 30-35 mmHg. During the operation, patients are treated with remifentanil, cisatracurium, and desflurane inhalation at 0.5-1.0 minimum alveolar concentration (MAC). In the MER process, the desflurane concentration is adjusted to maintain 0.5-0.6 MAC. If the desflurane concentration needs to be adjusted to less than 0.5 MAC during MER for various reasons, remedial measures will be implemented.

A loading dose of DEX 0.5 µg/kg was infused intravenously at a constant speed within 15 min after the patients entered the operating room, and the DEX maintenance dose was infused at 0.2-0.5 µg/kg/h until the end of the first stage (deep-brain stimulation implantation) of the operation. Maintain the BIS value at 60-80.

The proportion of high-normalized root mean square (high-NRMS) recorded by the MER signal (with the average NRMS recorded by MER after entering the STN greater than 2.0).

We will use the root mean square (RMS) value of the MER sampled signal as the main parameter for evaluating electrode position. RMS values change with the electrode properties and other external drives related to the operating room; therefore, it is crucial to normalize the RMS to comparable values. Thus, each session's RMS in a trajectory is divided by the mean RMS of the first five stable sessions in the same trajectory. This normalized RMS (NRMS) is found to be a good measure as it reflects the relative change in the total power of the signal, which elevates dramatically entering the STN.

We will use the root mean square (RMS) value of the MER sampled signal as the main parameter for evaluating electrode position. RMS values change with the electrode properties and other external drives related to the operating room; therefore, it is crucial to normalize the RMS to comparable values. Thus, each session's RMS in a trajectory is divided by the mean RMS of the first five stable sessions in the same trajectory. This normalized RMS (NRMS) is found to be a good measure as it reflects the relative change in the total power of the signal, which elevates dramatically entering the STN. We will stratify the mean NRMS of the two groups at the level of 0.5, and calculate the stratified proportions.

The STN pass length is determined as the distance from entry to exit of the STN based on the significant, clear increase in baseline unit activity and FR changes unique to STN.

Total electrode path times are the total number of paths actually selected, which can be used as an indirect indicator to judge the accuracy of positioning.

Power spectrum will be calculated using a discrete Fourier transform of the sampling windows to allow evaluation of change in oscillatory activity along time. Synchronized beta band (13-30 Hz) oscillations are often observed in the dorsolateral region of the STN of PD patients and are thought to play a role in the disease pathophysiology. The power of beta band will be calculated by averaging the power across the corresponding frequency band.

If the characteristic discharge activity of neurons cannot be recovered after maintaining the target anaesthetic concentration during MER, the following procedures should be implemented: ① Reduce the concentration of anaesthetics for a short time and wait for the recovery of electrical signals; ② Readjust the target position; and ③ If the STN cannot be successfully identified by MER, implant electrodes with preoperative imaging localization.

The accuracy of the target location is defined by the neurosurgeon's review of the postoperative CT scan.

Clinical efficacy measured with the improvement of the United Parkinson's Disease Rating Scale (UPDRS)-III (conditions: med on/off, stim on/off)

UPDRS -III is the standard test used by movement disorders neurologists to measure balance impairment in PD.

Dopaminergic medication is converted into levodopa equivalent, which is assessed the degree of medication reduction.

Cognitive function as measured by the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA)

Surgical experience satisfaction 24 hours after the operation and DBS satisfaction 6 months after the operation evaluated by the seven-point Likert scale

The seven-point Likert scale will be used in the present trial. It is a questionnaire answered by the patient 24 hours after the operation. The scale reported the experience of the patient from very dissatisfied to very satisfied, as graded from 1-7.

24 hours after operation for surgical experience satisfaction and 6 months after STN-DBS for DBS satisfaction

Inclusion Criteria: 1.50-80 years old, ASA grade II-III; 2.Bilateral STN-DBS of patients with Parkinson's disease; 3.Signed informed consent. Exclusion Criteria: Obstructive sleep apnea; BMI > 30kg/m2; Estimated difficult airway; Severe preoperative anxiety; Serious dysfunction of important organs (i.e. heart failure, renal or liver dysfunction) A history of allergy to the anaesthetics.