Re-emergent Tremor in Parkinson's Disease: The Role of the Motor Cortex.

Abstract

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.

• Authors: Giorgio Leodori, Daniele Belvisi, Maria I De Bartolo, Andrea Fabbrini, Matteo Costanzo, Felipe Vial, Antonella Conte, Mark Hallett, Alfredo Berardelli
• Journal: Movement disorders : official journal of the Movement Disorder Society (Mov Disord) Vol. 35 Issue 6 Pg. 1002-1011 (06 2020) ISSN: 1531-8257 [Electronic] United States
• PMID: 32175656 (Publication Type: Journal Article)
• Copyright: © 2020 International Parkinson and Movement Disorder Society.

Topics

• Humans
• Motor Cortex
• Parkinson Disease (complications)
• Transcranial Magnetic Stimulation
• Tremor (etiology)
• Wrist