title: Effects of cerebellar continuous theta burst stimulation on resting tremor in Parkinson's disease.
abstract: BACKGROUND
  Recent studies have suggested that the cerebellum may be involved in the pathophysiology of resting tremor in patients with Parkinson's disease (PD). The aim of the study was to investigate the effects of cerebellar continuous theta burst stimulation (cTBS) on cerebello-thalamo-cortical connectivity and resting tremor in PD patients.
  
  
  METHODS
  Thirteen PD patients and ten healthy subjects underwent two experimental sessions: (i) 'real' cTBS, delivered over the cerebellar hemisphere and (ii) 'sham' cerebellar cTBS, delivered over the neck muscles. The two sessions were performed at least one week apart. The effects of 'real' and 'sham' cerebellar cTBS were quantified as excitability changes in the contralateral primary motor cortex or as possible changes in resting tremor in the ipsilateral hand. Primary motor cortex excitability was assessed by recording the input/output curve of the motor-evoked potentials from the contralateral first dorsal interosseous muscle.
  
  
  RESULTS
  Resting tremor was rated clinically and objectively assessed by means of kinematic techniques. 'Real' cerebellar cTBS, though not 'sham' cerebellar cTBS, reduced the excitability in the contralateral primary motor cortex both in healthy subjects and in patients with PD. There was no significant change in rest tremor severity, as assessed by a clinical examination or kinematic techniques, after either 'real' or 'sham' cerebellar cTBS in patients. Lastly, there was no correlation between individual changes in M1 excitability and clinical or kinematic measures of resting tremor in patients.
  
  
  CONCLUSIONS
  The cerebello-thalamo-cortical connectivity, as tested by cTBS, is not predominantly involved in the generation of resting tremor in PD.
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Bologna
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Di Biasio
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Conte
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy.
authors.forename: Ennio
authors.initials: E
authors.lastname: Iezzi
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Modugno
authors.affiliation: Neuromed Institute IRCCS, Pozzilli, IS, Italy; Department of Neurology and Psychiatry, Sapienza University of Rome, Italy. Electronic address: alfredo.berardelli@uniroma1.it.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Berardelli
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016022:Case-Control Studies; D002531:Cerebellum / Q000502:physiology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications*; D018709:Statistics, Nonparametric; D065908:Transcranial Direct Current Stimulation / Q000379:methods; D014202:Tremor / Q000209:etiology* / Q000628:therapy*
keywords: Cerebellum; Parkinson's disease; Transcranial magnetic stimulation; Tremor