Mild cerebello-thalamo-cortical impairment in patients with normal dopaminergic scans (SWEDD). (July 2016)

• Record Type: Journal Article
• Authors: Schirinzi, Tommaso; Di Lorenzo, Francesco; Ponzo, Viviana; Palmieri, Maria Giuseppina; Bentivoglio, Anna Rita; Schillaci, Orazio; Pisani, Antonio; Koch, Giacomo
• Is Part Of: Parkinsonism & related disorders. Volume 28(2016)
• Page Start: 23
• Page End: 28
• Publication Date: 2016-07
• Subjects: SWEDD -- Parkinson's disease -- Dystonia -- Tremor -- Cerebello thalamo cortical; Parkinson's disease -- Periodicals; Movement disorders -- Periodicals; Movement Disorders -- Periodicals; Nerve Degeneration -- Periodicals; Nervous System Diseases -- Periodicals; Parkinson Disease -- Periodicals; Tremor -- Periodicals; Parkinson, Maladie de -- Périodiques; Parkinson's disease; 616.833
• DOI: 10.1016/j.parkreldis.2016.03.023
• Languages: English
• ISSNs: 1353-8020

Abstract

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. Highlights: Many SWEDD patients often present asymmetric rest tremor. Dysfunction of the CTC circuit is involved in the pathogenesis of tremor. By cerebellar TMS we evaluated the CTC in SWEDD, PD and dystonia. SWEDDs show a mild impairment in CTC circuit different from PD and dystonic patients.