Modulation of motor cortical plasticity after BIG-physiotherapy in patients suffering from Parkinson's Disease

Research question: The study aims to examine the influence of a two or four week LSVT-BIG-physiotherapy on motor cortical plasticity using neurophysiological parameters of transcranial magnetic stimulation (TMS) in patients suffering from Parkinson's disease (PD).

Methodology: TMS was applied in 16 PD patients before and at the end of the physiotherapy period. The TMS research protocol comprised parameters evaluating corticospinal excitability (resting motor threshold, RMT; stimulus-response curve), intracortical inhibition and facilitation (Short-Interval Cortical inhibition, SICI; Intracortical Facilitation, ICF) as well as neuroplasticity (paired-associated stimulation, PAS).

Results: In line with previous results, the majority of patients responded to BIG therapy with an improvement in motor UPDRS (11 out of 16 responder). We found a significant decrease in cortical excitability with smaller MEP amplitude in the stimulus-response curve at 140% and 150% RMT (mean amplitude 1.65+ 0.32 mV vs. 1.09+ 0.18 mV, p = 0.01) and a decrease in ICF (mean 138.5%+ 11.1% vs. 116.2%+ 5.4%, p = 0.03) after therapy in patients with clinical benefit to LSVT-BIG therapy. Moreover, we found a significant increase in PAS effect after LSVT-BIG therapy that correlated with clinical improvement (r =-0.567, p = 0.02). Changes after LSVT-BIG therapy showed a shift towards values obtained in a group of 10 normal controls.

Conclusion: In summary, we could show that clinical improvement during LSVT-BIG-physiotherapy is associated with modulation of motor cortex excitability/plasticity showing a partial normalization of altered TMS parameters in PD patients.