Invasive and Non-Invasive Stimulation in Parkinson’s Disease

The ability of the brain to process information relies on its control of the conduction of electric currents. Brain diseases invariably affect this capability. One of the therapeutic approaches to a variety of neurological disorders therefore includes the application of electric currents and fields to the brain. A successful example of this strategy is the introduction of deep brain stimulation which has become a cornerstone of the therapy of advanced Parkinson’s disease (PD), dystonia and essential tremor. Several studies have proven its effectiveness and often patients respond immediately to this therapy. Invasiveness and complexity of this treatment restrict its indication. On the other hand, there are techniques for the non-invasive modulation of cortical excitability namely transcranial magnetic stimulation (TMS) as well as transcranial direct current stimulation (tDCS). These techniques have been investigated in several studies including patients with PD. However results so far are heterogeneous and limit their therapeutic value. In the following chapter the basic principles of as well as therapeutic experiences with invasive and non-invasive electrical stimulation techniques and their applications in patients with PD will be discussed.