Directionality of corticomuscular coupling in essential tremor and cortical myoclonic tremor

S. Sharifi; F. Luft; S. Potgieter; T. Heida; W. Mugge; A.C. Schouten; L.J. Bour; A.F. van Rootselaar

doi:10.1016/j.clinph.2021.04.011

Directionality of corticomuscular coupling in essential tremor and cortical myoclonic tremor

S. Sharifi^*, F. Luft, S. Potgieter, T. Heida, W. Mugge, A.C. Schouten, L.J. Bour, A.F. van Rootselaar

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

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Abstract

Objective
A major role of the motor cortex in tremor generation in essential tremor (ET) is assumed, yet the directionality of corticomuscular coupling is unknown. Our aim is to clarify the role of the motor cortex. To this end we also study ‘familial cortical myoclonic tremor with epilepsy’ (FCMTE) and slow repetitive voluntary movements with a known cortical drive.

Methods
Directionality of corticomuscular coupling (EEG-EMG) was studied with renormalized partial directed coherence (rPDC) during tremor in 25 ET patients, 25 healthy controls (mimicked) and in seven FCMTE patients; and during a self-paced 2Hz task in eight ET patients and seven healthy controls.

Results
Efferent coupling around tremor frequency was seen in 33% of ET patients, 45.5% of healthy controls, all FCMTE patients, and, around 2Hz, in all ET patients and all healthy controls. Ascending coupling, seen in the majority of all participants, was weaker in ET than in healthy controls around 5-6Hz.

Conclusions
Possible explanations are that tremor in ET results from faulty subcortical output bypassing the motor cortex; rate-dependent transmission similar to generation of rhythmic movements; and/or faulty feedforward mechanism resulting from decreased afferent (sensory) coupling.

Significance
A linear cortical drive is lacking in the majority of ET patients.

Original language	English
Pages (from-to)	1878-1886
Number of pages	9
Journal	Clinical neurophysiology
Volume	132
Issue number	8
Early online date	8 May 2021
DOIs	https://doi.org/10.1016/j.clinph.2021.04.011
Publication status	Published - Aug 2021

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Cite this

@article{38148f7417944723bcd313426b007879,

title = "Directionality of corticomuscular coupling in essential tremor and cortical myoclonic tremor",

abstract = "ObjectiveA major role of the motor cortex in tremor generation in essential tremor (ET) is assumed, yet the directionality of corticomuscular coupling is unknown. Our aim is to clarify the role of the motor cortex. To this end we also study {\textquoteleft}familial cortical myoclonic tremor with epilepsy{\textquoteright} (FCMTE) and slow repetitive voluntary movements with a known cortical drive.MethodsDirectionality of corticomuscular coupling (EEG-EMG) was studied with renormalized partial directed coherence (rPDC) during tremor in 25 ET patients, 25 healthy controls (mimicked) and in seven FCMTE patients; and during a self-paced 2Hz task in eight ET patients and seven healthy controls. ResultsEfferent coupling around tremor frequency was seen in 33% of ET patients, 45.5% of healthy controls, all FCMTE patients, and, around 2Hz, in all ET patients and all healthy controls. Ascending coupling, seen in the majority of all participants, was weaker in ET than in healthy controls around 5-6Hz. ConclusionsPossible explanations are that tremor in ET results from faulty subcortical output bypassing the motor cortex; rate-dependent transmission similar to generation of rhythmic movements; and/or faulty feedforward mechanism resulting from decreased afferent (sensory) coupling.SignificanceA linear cortical drive is lacking in the majority of ET patients. ",

author = "S. Sharifi and F. Luft and S. Potgieter and T. Heida and W. Mugge and A.C. Schouten and L.J. Bour and Rootselaar, {A.F. van}",

note = "Funding Information: This study was performed in cooperation with the technical universities of Delft and Twente, and with financial support of the NWO technology foundation STW (NeuroSIPE 10739, www.neurosipe.nl). The authors thank L.I.M. Jansen Holleboom, C.W.M. van den Hoven, A.H. Jonkman, dr. H. Meijer for their contribution to the development of the rPDC toolbox. We also thank dr. J.D. Speelman for his clinical evaluation of the participants. Publisher Copyright: {\textcopyright} 2021 International Federation of Clinical Neurophysiology",

year = "2021",

month = aug,

doi = "10.1016/j.clinph.2021.04.011",

language = "English",

volume = "132",

pages = "1878--1886",

journal = "Clinical neurophysiology",

issn = "1388-2457",

publisher = "Elsevier Ireland Ltd",

number = "8",

}

TY - JOUR

T1 - Directionality of corticomuscular coupling in essential tremor and cortical myoclonic tremor

AU - Sharifi, S.

AU - Luft, F.

AU - Potgieter, S.

AU - Heida, T.

AU - Mugge, W.

AU - Schouten, A.C.

AU - Bour, L.J.

AU - Rootselaar, A.F. van

N1 - Funding Information: This study was performed in cooperation with the technical universities of Delft and Twente, and with financial support of the NWO technology foundation STW (NeuroSIPE 10739, www.neurosipe.nl). The authors thank L.I.M. Jansen Holleboom, C.W.M. van den Hoven, A.H. Jonkman, dr. H. Meijer for their contribution to the development of the rPDC toolbox. We also thank dr. J.D. Speelman for his clinical evaluation of the participants. Publisher Copyright: © 2021 International Federation of Clinical Neurophysiology

PY - 2021/8

Y1 - 2021/8

N2 - ObjectiveA major role of the motor cortex in tremor generation in essential tremor (ET) is assumed, yet the directionality of corticomuscular coupling is unknown. Our aim is to clarify the role of the motor cortex. To this end we also study ‘familial cortical myoclonic tremor with epilepsy’ (FCMTE) and slow repetitive voluntary movements with a known cortical drive.MethodsDirectionality of corticomuscular coupling (EEG-EMG) was studied with renormalized partial directed coherence (rPDC) during tremor in 25 ET patients, 25 healthy controls (mimicked) and in seven FCMTE patients; and during a self-paced 2Hz task in eight ET patients and seven healthy controls. ResultsEfferent coupling around tremor frequency was seen in 33% of ET patients, 45.5% of healthy controls, all FCMTE patients, and, around 2Hz, in all ET patients and all healthy controls. Ascending coupling, seen in the majority of all participants, was weaker in ET than in healthy controls around 5-6Hz. ConclusionsPossible explanations are that tremor in ET results from faulty subcortical output bypassing the motor cortex; rate-dependent transmission similar to generation of rhythmic movements; and/or faulty feedforward mechanism resulting from decreased afferent (sensory) coupling.SignificanceA linear cortical drive is lacking in the majority of ET patients.

AB - ObjectiveA major role of the motor cortex in tremor generation in essential tremor (ET) is assumed, yet the directionality of corticomuscular coupling is unknown. Our aim is to clarify the role of the motor cortex. To this end we also study ‘familial cortical myoclonic tremor with epilepsy’ (FCMTE) and slow repetitive voluntary movements with a known cortical drive.MethodsDirectionality of corticomuscular coupling (EEG-EMG) was studied with renormalized partial directed coherence (rPDC) during tremor in 25 ET patients, 25 healthy controls (mimicked) and in seven FCMTE patients; and during a self-paced 2Hz task in eight ET patients and seven healthy controls. ResultsEfferent coupling around tremor frequency was seen in 33% of ET patients, 45.5% of healthy controls, all FCMTE patients, and, around 2Hz, in all ET patients and all healthy controls. Ascending coupling, seen in the majority of all participants, was weaker in ET than in healthy controls around 5-6Hz. ConclusionsPossible explanations are that tremor in ET results from faulty subcortical output bypassing the motor cortex; rate-dependent transmission similar to generation of rhythmic movements; and/or faulty feedforward mechanism resulting from decreased afferent (sensory) coupling.SignificanceA linear cortical drive is lacking in the majority of ET patients.

U2 - 10.1016/j.clinph.2021.04.011

DO - 10.1016/j.clinph.2021.04.011

M3 - Article

SN - 1388-2457

VL - 132

SP - 1878

EP - 1886

JO - Clinical neurophysiology

JF - Clinical neurophysiology

IS - 8

ER -

Directionality of corticomuscular coupling in essential tremor and cortical myoclonic tremor

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