Neuroplasticity mediated by motor rehabilitation in Parkinson's disease: A systematic review on structural and functional MRI markers

Parkinson's disease (PD) is the second most common neurological disease affecting the elderly population. Pharmacological and surgical interventions usually employed for PD treatment show transient effectiveness and are associated with the insurgence of side effects. Therefore, motor rehabilitation has been proposed as a promising supplement in the treatment of PD, reducing the global burden of the disease and improving patients quality of life. The present systematic review aimed to critically analyse the literature concerning MRI markers of brain functional and structural response to motor rehabilitation in PD. Fourteen out of 1313 studies were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Despite the limited number of retrieved studies coupled with their heterogeneity prevent ultimate conclusions from being drawn, motor rehabilitation seems to have beneficial effects on PD as measured both with clinical outcomes and MRI derived indices. Interestingly, consistent results seem to indicate that motor rehabilitation acts via a dual mechanism of strengthening cortico-subcortical pathways, restoring movements automaticity, or activating compensatory networks such as the fronto-parietal one. The employment of more advanced and quantitative MRI methods is warranted to establish and validate standardized metrics capable of reliably determining the changes induced by rehabilitative intervention.