Mild cerebello-thalamo-cortical impairment in patients with normal dopaminergic scans (SWEDD)

Tommaso Schirinzi, Francesco Di Lorenzo, Viviana Ponzo, Maria Giuseppina Palmieri, Anna Rita Bentivoglio, Orazio Schillaci, Antonio Pisani, Giacomo Koch

Research output: Contribution to journalArticle

Abstract

Introduction: Patients with Scans-Without-Evidence-of-Dopaminergic-Deficit (SWEDD) often present asymmetric rest tremor not responsive to levodopa. Although a dystonic origin of this tremor has been proposed, the underlying pathophysiology of such condition is still unclear. An abnormal activity in the Cerebello-Thalamo-Cortical circuit is involved in the pathogenesis of tremor and other movement disorders. Here we used different paradigms of cerebellar transcranial magnetic stimulation to evaluate the Cerebello-Thalamo-Cortical functioning in patients with normal scans. Methods: Cerebello-Thalamo-Cortical circuit was investigated in 12 patients with normal scans, 8 patients with Parkinson's Disease (PD), 8 patients with adult-onset isolated dystonia and 9 healthy controls. We studied the effects of a single cerebellar magnetic pulse over the excitability of the contralateral primary motor cortex tested with Motor-Evoked-Potentials (Cerebellar-Inhibition) both at rest and during arm extension. Furthermore, we also tested the effects of cerebellar continuous-Theta-Burst-Stimulation on Motor-Evoked-Potentials amplitude. Results: patients with normal scans compared to controls show a deficient Cerebellar-Inhibition at rest but not in arm extension; in both conditions they differ from PD but not from dystonic patients. Cerebellar Continuous-Theta-Burst-Stimulation induced the expected long-lasting cortical inhibition of Motor-Evoked-Potentials amplitude in patients with normal scans differently from PD and dystonic patients. Conclusions: patients with normal scans show a mild impairment in Cerebello-Thalamo-Cortical circuit that emerges only at rest. Such neurophysiological phenotype differs from the one observed in PD and dystonic patients, suggesting a distinct involvement of this pathway in the pathophysiology of these disorders.

Original languageEnglish
Pages (from-to)23-28
Number of pages6
JournalParkinsonism and Related Disorders
Volume28
DOIs
Publication statusPublished - Jul 1 2016

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Keywords

  • Cerebello thalamo cortical
  • Dystonia
  • Parkinson's disease
  • SWEDD
  • Tremor

ASJC Scopus subject areas

  • Geriatrics and Gerontology
  • Clinical Neurology
  • Neurology

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