TY - JOUR
T1 - Demystifying the spontaneous phenomena of motor hyperexcitability
AU - Bashford, James
AU - Chan, Weng Kit
AU - Freitas Barbosa Pereira Coutinho, Maria Ester
AU - Norwood, Fiona
AU - Mills, Kerry
AU - Shaw, Christopher
N1 - Funding Information:
JB acknowledges funding from the Medical Research Council and Motor Neurone Disease Assocation (Lady Edith Wolfson Clinical Research Training Fellowship; MR/P000983/1), Sattaripour Charitable Foundation and UK Dementia Research Institute. WKC contributed during his MSc qualification in Clinical Neuroscience. EC received funding through a clinical fellowship from the MRC Centre for Neurodevelopmental disorders.
Publisher Copyright:
© 2021 International Federation of Clinical Neurophysiology
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/8
Y1 - 2021/8
N2 - Possessing a discrete functional repertoire, the anterior horn cell can be in one of two electrophysiological states: on or off. Usually under tight regulatory control by the central nervous system, a hierarchical network of these specialist neurons ensures muscular strength is coordinated, gradated and adaptable. However, spontaneous activation of these cells and their axons can result in abnormal muscular twitching. The muscular twitch is the common building block of several distinct clinical patterns, namely fasciculation, myokymia and neuromyotonia. When attempting to distinguish these entities electromyographically, their unique temporal and morphological profiles must be appreciated. Detection and quantification of burst duration, firing frequency, multiplet patterns and amplitude are informative. A common feature is their persistence during sleep. In this review, we explain the accepted terminology used to describe the spontaneous phenomena of motor hyperexcitability, highlighting potential pitfalls amidst a bemusing and complex collection of overlapping terms. We outline the relevance of these findings within the context of disease, principally amyotrophic lateral sclerosis, Isaacs syndrome and Morvan syndrome. In addition, we highlight the use of high-density surface electromyography, suggesting that more widespread use of this non-invasive technique is likely to provide an enhanced understanding of these motor hyperexcitability syndromes.
AB - Possessing a discrete functional repertoire, the anterior horn cell can be in one of two electrophysiological states: on or off. Usually under tight regulatory control by the central nervous system, a hierarchical network of these specialist neurons ensures muscular strength is coordinated, gradated and adaptable. However, spontaneous activation of these cells and their axons can result in abnormal muscular twitching. The muscular twitch is the common building block of several distinct clinical patterns, namely fasciculation, myokymia and neuromyotonia. When attempting to distinguish these entities electromyographically, their unique temporal and morphological profiles must be appreciated. Detection and quantification of burst duration, firing frequency, multiplet patterns and amplitude are informative. A common feature is their persistence during sleep. In this review, we explain the accepted terminology used to describe the spontaneous phenomena of motor hyperexcitability, highlighting potential pitfalls amidst a bemusing and complex collection of overlapping terms. We outline the relevance of these findings within the context of disease, principally amyotrophic lateral sclerosis, Isaacs syndrome and Morvan syndrome. In addition, we highlight the use of high-density surface electromyography, suggesting that more widespread use of this non-invasive technique is likely to provide an enhanced understanding of these motor hyperexcitability syndromes.
KW - hyperexcitabiltiy
KW - motor unit
KW - Amyotrophic lateral sclerosis (ALS)
UR - http://www.scopus.com/inward/record.url?scp=85107762795&partnerID=8YFLogxK
U2 - 10.1016/j.clinph.2021.03.053
DO - 10.1016/j.clinph.2021.03.053
M3 - Review article
SN - 1388-2457
VL - 132
SP - 1830
EP - 1844
JO - Clinical Neurophysiology
JF - Clinical Neurophysiology
IS - 8
ER -