Continuous Dopaminergic Stimulation Improves Cortical Maladaptive Changes in Advanced Parkinson's Disease

Background With the progression of Parkinson's disease (PD), pulsatile treatment with oral levodopa causes maladaptive changes within basal ganglia‐thalamo‐cortical circuits, which are clinically expressed as motor fluctuations and dyskinesias. At the level of the motor cortex, these changes may be detected using transcranial magnetic stimulation (TMS), as abnormal corticospinal and intracortical excitability and absent response to plasticity protocols. Objective We investigated the effect of continuous dopaminergic stimulation on cortical maladaptive changes related to oral levodopa treatment. Methods Twenty patients with advanced PD were tested using TMS within 1 week before and again 6 months after the introduction of levodopa‐carbidopa intestinal gel. We measured resting and active motor thresholds, input/output curve, short interval intracortical inhibition curve, cortical silent period, and response to intermittent theta burst stimulation. Patients were clinically assessed with Part III and Part IV of the Movement Disorders Society Unified Parkinson's Disease Rating Scale. Results Six months after the introduction of levodopa‐carbidopa intestinal gel, motor fluctuations scores (P = 0.001) and dyskinesias scores (P