Evaluate the Effectiveness and Safety of Variable Frequency Stimulation Compared With Constant Frequency Stimulation for Patients With Idiopathic Parkinson's Disease

In advanced stages of PD, motor symptoms and dyskinesia are effectively treated by deep brain stimulation (DBS) targeting the subthalamic nucleus (STN) . Traditionally, in this procedure, stimulation is set to a constant frequency electrical stimulation with the physician programming the parameters of stimulation frequency, pulse width and amplitude, and stimulated patients' brain nuclei with single frequency, single pulse width and single amplitude of the electric stimulation. Indeed, high frequency stimulation (HFS) of the STN provides consistent, long-term improvement of the cardinal signs of PD . However, the treatment effects of HFS on the axial symptoms of PD, specifically FOG can be poor often causing further impairment. While this can be alleviated by using relatively low frequency stimulation (LFS) , major concerns in the clinical application of LFS exist in regards to its duration of therapeutic benefit. Previous studies have shown that LFS of the STN improves the axial motor signs in some PD patients, but a loss of therapeutic efficacy is seen in the short term. Thereafter, patients may present increased tremor, rigidity and bradykinesia, which is often intolerable outweighing the initial benefits of LFS therapy for FOG. As such, a suitable treatment strategy for FOG remains to be established. Based on previous findings on the relationships between stimulation frequency and movement rhythm regulation in the human body, The National Engineering Laboratory for Neuromodulation, Tsinghua University, proposes a method of variable frequency stimulation (VFS) for aiding movement.