Subthalamic nucleus deep brain stimulation (STN-DBS) has become a choice treatment for fluctuating Parkinson's disease (PD) patients, inducing remarkable improvement in motor symptoms. However, as PD is a complex neuropsychiatric disease, it has been hypothesized that in some patients, non-motor features, i.e. dysfunctional expectations for the result of neurosurgery, could interfere with postoperative result of DBS, even in case of motor improvement. Recent literature highlights the necessity to take these preoperative expectations into account, but to our knowledge, no specific scale investigating these cognitions in this PD-specific condition is available. So, the investigators developped the DBS-PS, a self-scale constructed to measure preoperative expectations for DBS, with 11 questions and visuo-analogical responses (1 to 10), theorically divided in three domains investigating the expectations concerning symptoms of PD, postoperative social-life and leisures, and postoperative familial and marital sphere. The investigators would like to validate this new-developped scale in the preoperative subthalamic nucleus deep brain stimulation population through patients recruited in the Predistim study, whereas the investigators did not recruite sufficiently patients through the PsyParkinson study, the one in which the DBS-PS scale was developed. The DBS-PS constitutes an interesting basis for the consideration of these cognitive and affective factors in preoperative PD patients.

Inclusion Criteria:

• Parkinson's disease patients included in the Predistim study and having completed the DBS-PS scale during the preoperative phase

Exclusion Criteria:

• Parkinson's disease patients not included in the Predistim study or not having completed the DBS-PS scale during the preoperative phase

- Parkinson's disease patients selected for STN DBS and participating to the Predistim study