The dynamics of finger tremor in multiple sclerosis is affected by whole body position

Morrison, Shannon; Sosnoff, Jacob J.; Sandroff, Brian M.; Pula, John H.; Motl, Robert W.

doi:10.1016/j.jns.2012.10.007

Cited by 7 publications

(1 citation statement)

References 49 publications

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“…Importantly, this is, to date, the only clinical motor function measure that has been correlated with changes in neuromuscular output complexity, though this does come with the caveats associated with analysing complexity of bipolar surface EMG discussed above. Further neurological conditions, such as stroke (Chow & Stokic, 2014) and multiple sclerosis (Morrison et al., 2013), have been demonstrated to result in decreased force complexity compared with healthy controls. It has also recently been observed that the peripheral neuropathy associated with diabetes results in decreased complexity of muscle force and surface EMG outputs during lower limb contractions (Suda et al., 2017).…”

Section: Loss Of Complexity Hypothesismentioning

confidence: 99%

Physiological complexity: influence of ageing, disease and neuromuscular fatigue on muscle force and torque fluctuations

Pethick

Winter

2021

Experimental Physiology

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New Findings What is the topic of this review?Physiological complexity in muscle force and torque fluctuations, specifically the quantification of complexity, how neuromuscular complexityis altered by perturbations and the potential mechanism underlying changes in neuromuscular complexity. What advances does it highlight?The necessity to calculate both magnitude‐ and complexity‐based measures for the thorough evaluation of force/torque fluctuations. Also the need for further research on neuromuscular complexity, particularly how it relates to the performance of functional activities (e.g. manual dexterity, balance, locomotion). Abstract Physiological time series produce inherently complex fluctuations. In the last 30 years, methods have been developed to characterise these fluctuations, and have revealed that they contain information about the function of the system producing them. Two broad classes of metrics are used: (1) those which quantify the regularity of the signal (e.g. entropy metrics); and (2) those which quantify the fractal properties of the signal (e.g. detrended fluctuation analysis). Using these techniques, it has been demonstrated that ageing results in a loss of complexity in the time series of a multitude of signals, including heart rate, respiration, gait and, crucially, muscle force or torque output. This suggests that as the body ages, physiological systems become less adaptable (i.e. the systems’ ability to respond rapidly to a changing external environment is diminished). More recently, it has been shown that neuromuscular fatigue causes a substantial loss of muscle torque complexity, a process that can be observed in a few minutes, rather than the decades it requires for the same system to degrade with ageing. The loss of torque complexity with neuromuscular fatigue appears to occur exclusively above the critical torque (at least for tasks lasting up to 30 min). The loss of torque complexity can be exacerbated with previous exercise of the same limb, and reduced by the administration of caffeine, suggesting both peripheral and central mechanisms contribute to this loss. The mechanisms underpinning the loss of complexity are not known but may be related to altered motor unit behaviour as the muscle fatigues.

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Section: Loss Of Complexity Hypothesismentioning

confidence: 99%

Physiological complexity: influence of ageing, disease and neuromuscular fatigue on muscle force and torque fluctuations

Pethick

Winter

2021

Experimental Physiology

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Differences in postural tremor dynamics with age and neurological disease

2017

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The overlap of dominant tremor frequencies and similarly amplified tremor observed for Parkinson's disease (PD) and essential tremor (ET) means differentiating between these pathologies is often difficult. As tremor exhibits non-linear properties, employing both linear and non-linear analyses may help distinguish between the tremor dynamics of aging, PD and ET. This study was designed to examine postural tremor in healthy older adults, PD and ET using standard linear and non-linear metrics. Hand and finger postural tremor was recorded in 15 healthy older adults (64 ± 6 years), 15 older individuals with PD (63 ± 6 years), and 10 persons with ET (68 ± 7 years). Linear measures of amplitude, frequency, and between-limb coupling (coherence) were performed. Non-linear measures of regularity (ApEn) and coupling (Cross-ApEn) were also used. Additionally, receiver operating characteristic analyses were performed for those measures that were significantly different between all groups. The results revealed that the linear measures only showed significant differences between the healthy adults and ET/PD persons, but no differences between the two neurological groups. Coherence showed higher bilateral coupling for ET but no differences in inter-limb coupling between PD and healthy subjects. However, ApEn values for finger tremor revealed significant differences between all groups, with tremor for ET persons being more regular (lower ApEn) overall. Similarly, Cross-ApEn results also showed differences between all groups, with ET persons showing strongest inter-limb coupling followed by PD and elderly. Overall, our findings point to the diagnostic potential for non-linear measures of coupling and tremor structure as biomarkers for discriminating between ET, PD and healthy persons.

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Distinction between essential and physiological tremor using Hilbert-Huang transform

Ayache

Al-Ani

Lefaucheur

2014

Neurophysiologie Clinique/Clinical Neurophysiology

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The dynamics of finger tremor in multiple sclerosis is affected by whole body position

Cited by 7 publications

References 49 publications

Physiological complexity: influence of ageing, disease and neuromuscular fatigue on muscle force and torque fluctuations

Physiological complexity: influence of ageing, disease and neuromuscular fatigue on muscle force and torque fluctuations

Differences in postural tremor dynamics with age and neurological disease

Distinction between essential and physiological tremor using Hilbert-Huang transform

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