The effects of transcranial magnetic stimulation in motor symptoms of Parkinson’s disease: an overview of systematic reviews with meta-analysis

Background: Parkinson’s disease is a progressive neurodegenerative disorder that causes significant motor function limitations, substantially impacting the quality of life of affected individuals and their caregivers. While the currently available pharmacological therapy with levodopa can alleviate symptoms, identifying a treatment that achieves similar results with fewer adverse effects would be highly beneficial. Transcranial Magnetic Stimulation is a non-invasive stimulation of brain tissue that generates a magnetic field to modulate cortical excitability. To date, it has primarily been validated for the treatment of psychiatric conditions, but it is increasingly being used in the management of movement disorders. Objective: Although several systematic reviews with meta-analysis have been conducted on this topic, discrepancies remain in their findings. To address these inconsistencies, we conducted this overview of systematic reviews with meta-analyses to synthesise the available evidence and provide a comprehensive summary that can guide clinicians in their practice. Results: Evidence from 21 systematic reviews with meta-analyses, including 107 unique primary studies, suggests, with low to moderate certainty, that high-frequency stimulation of the primary and supplementary motor cortex significantly improves general motor impairment, gait, functional mobility, and balance in patients with Parkinson’s disease, with minimal side effects. Other stimulation parameters, such as a higher number of sessions, a greater number of pulses per session, and the use of the F8 coil type, appear to enhance these effects. However, further research is needed to strengthen these findings. Currently, definitive conclusions cannot be drawn regarding the influence of patient characteristics on treatment outcomes.