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

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 firing rates will be calculated using customized scripts developed from the Osort toolbox.

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 operation time and MER recording time from the start to the end.

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

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.

MMSE and MoCA will be used to assess cognitive function

PDQ-39 will be used to assess changes in the quality of life of the patients.

Second operation, infection, intracranial haemorrhage, etc.

Nausea, vomiting and intraoperative awareness.

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.