The programming of subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson's disease (PD) is complex work because the parameter setting has not been standardized so far. The objective of the present study is to set up a standardized programming algorithm for Chinese PD patients treated with bilateral STN DBS.

A total of 150 subjects will be recruited from the concurrent NCT01922388 study and followed up for four years. All patients will be evaluated using the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III at baseline (one week before surgery) and at 12 and 48 months postoperatively.

Stimulation parameters setting: The first programming is performed at 4 weeks after surgery. Bilateral contacts are as cathode for monopolar configuration. The initial voltage, pulse width and frequency are bilaterally 1.0-1.5 V, 60 μs and 130 Hz for each individual, respectively. Voltage is gradually increased to a stable level first, until the optimal efficacy is achieved. Two weeks later, when patients came back to hospital for reprogramming, the voltage is also first adjusted to optimize the stimulation parameters. Either pulse width or frequency will be adjusted when increasing voltage more than 0.4 V for one time still can not get satisfactory outcomes. The frequency is adjusted when bilateral symptoms are unresponsive to voltage. Frequency is increased by 15-20 Hz for each time. Pulse width is then adjusted for the satisfactory clinical response of unilateral symptoms which are not satisfied after increasing voltage or frequency. Pulse width is increased to 90 μs if necessary (e.g. severe tremor).

Groups: Patients are divided into two groups according to the parameter settings during follow-up. Group I: patients with voltage adjustment only. The pulse width is kept to 60 μs and frequency to 130 Hz constant throughout the follow-up period. Group II: patients with adjustment of more than two stimulation parameters (voltage, pulse width or frequency) during the follow-up.

Inclusion Criteria:

1. The patients with the idiopathic Parkinson's disease with good response to levodopa medication (i.e. more than 30% improvement in the MDS-UPDRS Part III score of the motor function examination(Goetz et al., 2008b) after an acute levodopa medication challenge);
2. Disease duration ≥4 years;
3. The patients with the fluctuations and/or dyskinesias;
4. The patients with age ranging from 18 to 75 years old;
5. The patients with normal brain on the MRI;
6. The patients with the absence of dementia (Mini-Mental State Examination scores of≥ 26) ;
7. The patients with the absence of severe psychiatric diseases;
8. The patients who provided the written informed consent

Exclusion Criteria:

1. The patients with severe metabolic diseases;
2. The patients with severe cardiac/respiratory/renal/hepatic diseases;
3. The patients having secondary parkinsonism or multiple system atrophies;
4. The patients who illiterate or having insufficient language skills to complete the questionnaires;
5. The patients who had poor compliance and unreasonable expectation;
6. Women who were pregnant or breast feeding;
7. The patients with the simultaneous participation in another clinical trial

PD Patients are selected from the outpatient department of three centres.