Objective: To evaluate the effect of a single intermittent theta burst stimulation (iTBS) session on objective markers of physical fatigue of fatigue in patients with Parkinson’s disease (PD) under dopaminergic treatment and fatigue symptoms.

Background: The factors that drive towards greater physical fatigability in PD have not been fully elucidated and, as a consequence of this lack of knowledge, there are no optimal therapeutic targets for the symptomatic treatment of physical fatigue.

Method: This single-blind, randomized study with sham cross-over condition included 10 PD patients 10 healthy controls subjects.  Participants completed an exhausting whole-body physical task intended to induce fatigue and different variables were calculated at recovery times (4min, 12min and 20min after the task). iTBS/sham was applied after this task and neuromuscular fatigue was assessed using a dynamometer and analyzing different physiological measurements: maximal voluntary contraction (MVC) and power at one maximal bicep curl concentric contraction and its correlation with EMG by analysis of root-mean square (RMS), median frequency, power spectral density (PSD) at lower frequencies, and EMG coherences of biceps brachii with triceps and forearm muscles. Moreover, single-pulse transcranial magnetic stimulation over the biceps brachii ‘hot spot’ and peripheral nerve stimulation were used to obtain measures of the motor evoked potential (MEP), cortical silent period (CSP) and voluntary activation (VA).

Results: Analysis during the sham condition revealed a similar decrease in both groups in power, MVC, MEP, and VA. These variables were recovered to baseline levels after applying iTBS in both groups, but PD patients showed a higher rate of recovery for some of these measures. Changes in objective markers of physical fatigue parallelized proportional changes in cortical excitability and CSP. EMG-related measures were also affected by iTBS, showing RMS, median frequency, PSD in beta band and beta-range corticomuscular coherence in agonist vs. antagonist muscles significant changes after stimulation.

Conclusion: One session of iTBS over primary motor cortex ameliorates the effect of the induced fatigue in different neuromuscular and neurophysiological variables after a exhaustive whole-body exercise, recovering faster to baseline values after the treatment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/intermittent-theta-burst-stimulation-over-primary-motor-cortex-ameliorates-physical-fatigue-in-parkinsons-disease-patients/