1Hz rTMS Preconditioned by tDCS Over the Primary Motor Cortex in Parkinson’s Disease: Absence of Effect on Arm Lift and Hand Grip Force Control

in Motor Control
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This study investigated whether a period of low frequency rTMS preconditioned by tDCS over the primary motor cortex modulates control of grip force in Parkinson’s disease. The presented results are from the same patient cohort tested in an earlier study (Gruner et al. J Neural Transm 2010: 117: 207–216). 15 patients with Parkinson’s disease (mean age: 69 ±8 years; average disease duration: 5 ±3 years) on dopaminergic drugs performed a grasp-lift task with either hand before (baseline) and after a period of 1Hz rTMS (90% of the resting motor threshold; 900 pulses) preconditioned by sham, anodal or cathodal tDCS (1mA, 10 min) over the primary motor cortex. We found that compared with baseline, none of the grip force parameters was significantly influenced by either stimulation session and concluded that grasping is a higher order motor skill, which cannot be modulated by tDCS preconditioned 1Hz rTMS in PD.

Eggers, Grüner, and Ameli are with the Department of Neurology, University of Cologne, Cologne, Germany. Sarfeld is with the Department of Neurology, University of Cologne and Max-Planck-Institute for Neurological Research, Neuromodulation and Neurorehabilitation, Cologne, Germany. Nowak is with the Department of Neurology, University of Cologne; Department of Neurology, Philipps-University Marburg Marburg, Germany and Neurologische Fachklinik Kipfenberg, Kipfenberg, Germany.