Directional PSA Versus STN DBS for TD-PD

This single-center trial utilizes directional deep brain stimulation (DBS) current-steering technology to compare the clinical efficacy and tolerability of the posterior subthalamic area (PSA) versus the subthalamic nucleus (STN) for the treatment of tremor-dominant Parkinson's disease (TD-PD) within the same subject. The study is optimized into a two-phase framework to maximize patient safety and protocol compliance:

Phase 1: Two-month post-implantation, acute mapping is conducted to define the therapeutic window for PSA and STN configurations in a blinded randomized order. If a configuration induces immediate, unmanageable adverse events before reaching efficacy, it is classified as "intolerant" and excluded from that participant's subsequent chronic phase.

Phase 2 (Chronic Crossover): Participants with tolerated configurations are entered into a chronic randomized phase with a blinded sequence of 2-month PSA or STN chronic stimulation. Following the core two-arm crossover, all eligible patients transition into an open-label, exploratory sequential add-on phase of 2-month with combined PSA+STN stimulation to evaluate potential synergistic benefits.

All participants will then be followed-up up to 12 months after surgery.

Inclusion criteria

• diagnosis of idiopathic Parkinson's disease
• tremor-dominant subtype in the off-medication condition
• modified Hoehn-Yahr scale of 2 to 4 in the off-medication condition
• receiving regular anti-parkinsonian drugs for more than 6 weeks
• good compliance and written informed consent provided

Exclusion criteria

• Atypical parkinsonism
• History of stroke, encephalitis, neuroleptic uses, MRI scan with evidence of significant brain atrophy, lacunar infracts, or other conditions that might interfere with the intracranial surgery
• Presence of cognitive, or psychiatric or other co-morbidities (e.g., dementia, epilepsy, cranial traumatism, brain tumor, schizophrenia, severe depression or bipolar disorder, personality disorder, etc.) that might interfere with the patient's ability to complete the evaluations or to provide informed consent
• Presence of anatomical abnormalities in the target region
• Clinically significant medical history that would increase pre-/post-operative complications
• Other conditions considered by the investigators that might interfere with the surgery procedure, the follow-ups, and the interpretation of the data