Gait disorders are symptoms that significantly compromise the quality of life and functionality of patients with Parkinson's disease (PD). When they are not responsive to drug dopaminergic therapy and deep brain stimulation (DBS), the management of these symptoms is a challenge in clinical practice. Although deep brain stimulation is useful in the motor symptoms of Parkinson's disease, gait symptoms remains a challenge in patients undergoing this therapy. This is because, in addition to adjustments in the DBS programming not adding evident benefit in some patients with gait disorders, motor symptoms tend to progress over the years. In this context, spinal cord invasive electrical stimulation was proposed as a potential and effective therapy in a group of patients with PD who presented with gait impairment. More recently, the application of transcutaneous magnetic stimulation of the spinal cord has emerged as a possible therapeutic option, as it could stimulate neural elements in a non-invasive way. The general objective will be to study the effect of transcutaneous magnetic stimulation of the spinal cord on gait in PD patients with deep brain stimulation refractory to dopaminergic therapy. The method of the present study will be a randomized, double-blind, placebo-controlled, parallel, phase II clinical trial that will evaluate the efficacy of transcutaneous magnetic stimulation of the spinal cord in patients with PD and deep brain stimulation who present gait disorders refractory to dopaminergic therapy. The primary outcome will be the change in gait speed between pre-stimulation and post-stimulation conditions between the two groups (active and placebo) assessed using the Timed Up and Go Test (TUG). Secondary outcomes will be the effects of stimulation on other gait measures (speed, step length, stride length, cadence, step width, sway time, support time and the presence of blocks), other motor symptoms (Unified Parkinson's Disease Rating Scale), cognitive alterations, quality of life and side effects. Statistical analysis will be performed using ANOVA for repeated measures and 38 patients will be included. The expected results are supported by transcutaneous magnetic stimulation of the spinal cord, which may improve gait disorders in participants with PD and DBS.

Inclusion Criteria:

1. Men and women (non-pregnant) aged between 21 and 80 years;
2. Presence of deep brain stimulation in the subthalamic nucleus or globus pallidus
3. Participants with idiopathic Parkinson's disease at Hoehn Yahr stages between 2 and 4 during off-medication, whose primary symptom includes altered gait and/or balance (score equal to or greater than 1 on sub-item 2.12 of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) ["gait and balance"]). Patients should present the above symptoms even though they are optimized from a drug point of view and with optimized programming. The criteria to be optimized will be defined by a neurologist specialized in movement disorders who will evaluate the case.
4. Able to give informed consent in accordance with institutional policies;
5. Able to meet all testing and follow-up requirements as defined by the study protocol

Exclusion Criteria:

1. Patients with unstabilized psychiatric comorbidities;
2. Impossibility to consent to their participation in the study;
3. Patients with uncontrolled infection or other uncontrolled pre-existing medical conditions (eg, decompensated diabetes, high blood pressure, symptomatic pneumo or heart disease);
4. Concurrent treatment with other experimental drugs;
5. Pregnant or breastfeeding women;
6. Patients who cannot walk, not even with unilateral aid of a walking aid device or another person, when they are without their medication for Parkinson's Disease (off-medication);
7. Presence of cardiac pacemaker.