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Re‐emergent Tremor in Parkinson's Disease: The Role of the Motor Cortex
Author(s) -
Leodori Giorgio,
Belvisi Daniele,
De Bartolo Maria I.,
Fabbrini Andrea,
Costanzo Matteo,
Vial Felipe,
Conte Antonella,
Hallett Mark,
Berardelli Alfredo
Publication year - 2020
Publication title -
movement disorders
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.352
H-Index - 198
eISSN - 1531-8257
pISSN - 0885-3185
DOI - 10.1002/mds.28022
Subject(s) - transcranial magnetic stimulation , essential tremor , motor cortex , postural tremor , psychology , neuroscience , resting tremor , physical medicine and rehabilitation , primary motor cortex , cortex (anatomy) , deep brain stimulation , medicine , stimulation , parkinson's disease , disease , dopaminergic , pathology , dopamine
Background Parkinson's disease patients may show a tremor that appears after a variable delay while the arms are kept outstretched (re‐emergent tremor). The objectives of this study were to investigate re‐emergent tremor pathophysiology by studying the role of the primary motor cortex in this tremor and making a comparison with rest tremor. Methods We enrolled 10 Parkinson's disease patients with both re‐emergent and rest tremor. Tremor was assessed by spectral analysis, corticomuscular coherence and tremor‐resetting produced by transcranial magnetic stimulation over the primary motor cortex. We also recorded transcranial magnetic stimulation‐evoked potentials generated by motor cortex stimulation during rest tremor, tremor suppression during wrist extension, and re‐emergent tremor. Spectral analysis, corticomuscular coherence, and tremor resetting were compared between re‐emergent tremor and rest tremor. Results Re‐emergent tremor showed significant corticomuscular coherence, causal relation between motor cortex activity and tremor muscle and tremor resetting. The P60 component of transcranial magnetic stimulation‐evoked potentials reduced in amplitude during tremor suppression, recovered before re‐emergent tremor, was facilitated at re‐emergent tremor onset, and returned to values similar to those of rest tremor during re‐emergent tremor. Compared with rest tremor, re‐emergent tremor showed similar corticomuscular coherence and tremor resetting, but slightly higher frequency. Conclusions Re‐emergent tremor is causally related with the activity of the primary motor cortex, which is likely a convergence node in the network that generates re‐emergent tremor. Re‐emergent tremor and rest tremor share common pathophysiological mechanisms in which the motor cortex plays a crucial role. © 2020 International Parkinson and Movement Disorder Society