Clinical applications of rTMS in parkinson’s disease

Abstract

Parkinson’s disease (PD) has wide-ranging clinical features, and repetitive transcranial magnetic stimulation (rTMS) therapy has been tried for many aspects of PD. Underlying mechanism of rTMS therapy in PD remains unclear, but several possibilities are proposed such as endogenous dopamine release or restoration of neural plasticity or network activity. Motor symptoms are a cardinal feature of PD, for which evidence suggested moderate efficacy of rTMS. High-frequency (HF) rTMS over the M1 including less focal stimulation (e.g., leg and bilateral hand M1 rTMS) or over the DLPFC, and low-frequency (LF) rTMS over the SMA were most favorable. Long-term administration of levodopa, a major agent for medical therapy of PD, can induce a motor complication called levodopa-induced dyskinesia (LID). Several types of rTMS were reported to be effective for the LID. rTMS has also been tried for non-pharmacological treatment of non-motor symptoms of PD including depression. A “weak recommendation” in favor of HF rTMS of the left DLPFC can be given for the treatment of depressive symptoms associated with PD. These are examples of growing application of rTMS therapy to PD for symptoms other than the classical motor symptoms. As such, rTMS has a potential to become an important adjunctive treatment for PD. Well-designed large clinical trials are needed to establish its utility in the clinical settings.