At present, there is no cure for Parkinson's disease. The standard treatment involves taking dopaminergic drugs. When drugs lose their effectiveness, they can be supplemented by Deep Brain Stimulation (DBS) therapy. Medication and deep brain stimulation are effective for motor problems such as tremors, slowness of movement, and muscle stiffness. However, there is no effective treatment for walking and balance problems that occur during the course of the disease.

DBS neurostimulators not only stimulate, but also record brain activity in the region in which the electrodes are implanted. This brain activity changes over time, depending on the individual's general state (i.e., medication, eating), movements (sitting, standing or walking) and motor problems (i.e., problems of gait initiation and termination, balance problems and freezing of gait).

Adaptive deep brain stimulation (aDBS) makes it possible to change the stimulation according to brain activity, and thus to these different states. This method involves using the usual Medtronic Percept neurostimulator with its adaptive therapy active. Additional investigational features for adaptive therapy are available within the study.

In this study, we want to evaluate whether adaptive deep brain stimulation is safe and effective in improving walking problems in people with Parkinson's disease.

The hypotheses of the current study are that:

HYPOTHESIS 1: Adaptive DBS, aligned in time to the occurrence of locomotor states, facilitates gait initiation, termination, turning, symmetry and adaptations to obstacles by titrating the delivery of stimulation to the dynamics of gait.

HYPOTHESIS 2: Enforcing that biomarkers of FoG never exceed an abnormally-high value prevents the occurrence of freezing of gait.

The resulting observations will establish a rigorous understanding of motor state-dependent DBS modulations that will open new avenues for the design of evidence-based DBS strategies for locomotor deficits.

The study is divided into 3 different phases, which will take place on 3 different days at CHUV, and will be spread over a maximum of 5 weeks:

PHASE 1: Eligibility (1 day at CHUV)

• Evaluate Feasibility for aDBS
• Characterize DBS and Movement Modulations
• Assess Global Parkinsonian State

PHASE 2: aDBS therapy setup and efficacy evaluation in different conditions (between 2 to 3 days at CHUV)

• Optimize aDBS Parameters
• Test Safety and Performance
• Evaluate Stability and Robustness
• Daily Life Use of aDBS

The 2 to 3 days of Phase 2 will happenoccur within 10 days.

Inclusion Criteria:

• Diagnosed with typical or atypical forms of Parkinson's disease; Suffering from gait or balance disorders;
• Implanted with a full Medtronic Percept suite (neurostimulator Percept PC Model B35200 or Percept RC Model B35300; with bilateral leads (Medtronic Legacy leads (Models 3387 and 3389) or Medtronic SenSightTM Directional Lead (models B33015 and B33005)) and lead extensions (Medtronic extensions (Model 37085 and 37086) or SenSightTM extension (model B34000)), or Medtronic SenSightTM Connector Plug (Model B31061));
• Exhibit modulations in at least one frequency band of the LFP that are related to locomotor states or gait deficits.
• Aged 18 years-old or more;
• Must provide and sign the study's Informed Consent prior to any study-related procedures;
• Able to understand and interact with the study team in French;
• Agree to comply in good faith with all conditions of the recordings, and to attend all required study procedures

Exclusion Criteria:

• Exclusive use of interleaved DBS programs that are incompatible with aDBS;
• High impedances or artefacts in neural signals that obstruct the detection of motor-related biomarkers for adaptive DBS;
• Changes in DBS amplitudes (increase/decrease) not well tolerated;
• Secondary causes of gait problems independent of PD;
• Inability to follow the procedures of the study independently;
• History of major psychiatric disorders or major neurocognitive disorders, as considered by the investigators in according with treating physicians;
• Major changes in PD treatments planned within the course of the study;
• History of drug or alcohol abuse in the past 5 years;
• Pregnancy;
• Participation in another investigational study in the preceding 30 days or during the study