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F. Brighina · M. Romano · G. Giglia · V. Saia · A. Puma · F. Giglia · B. Fierro

Recent evidence suggests a role for cerebellum in pathophysiology of dystonia. Here we explored, the cere- bellar modulation of motor cortex in patients with focal upper limb dystonia. Eight patients and eight controls underwent a transcranial magnetic stimulation protocol to study the cerebellar-brain-inhibition (CBI): a conditioning cerebellar stimulus (CCS) was followed 5 ms after by the contralateral motor cortex stimulation (test stimulus: TS). We explored the eVects of CBI on MEP amplitude, short intracortical inhibition (SICI) and intracortical facilitation (ICF) measures. At baseline no diVerences in TS-MEP amplitude, SICI or ICF were found between patients and controls. Cerebellar-conditioning signiWcantly reduced TS- MEP amplitude, increased ICF, and decreased SICI in con- trol subjects. In contrast, no changes in these neurophysio- logical measures were observed in the motor cortex of patients, regardless of which side was tested. If further con- Wrmed, these Wndings suggest a reduced cerebellar modula- tion of motor cortex excitability in patients with focal dystonia.