scholarly journals Monitoring Involuntary Muscle Activity in Acute Patients with Upper Motor Neuron Lesion by Wearable Sensors: A Feasibility Study

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3120
Author(s):  
Andrea Merlo ◽  
Maria Giulia Montecchi ◽  
Francesco Lombardi ◽  
Xhejsi Vata ◽  
Aurora Musi ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Biceps Brachii ◽  
Wearable Sensors ◽  
Surface Emg ◽  
Motor Unit Action Potential ◽  
Involuntary Muscle ◽  
Neurological Patients ◽  
Huge Impact ◽  
Motor Unit Action ◽  
Acute Rehabilitation

Sustained involuntary muscle activity (IMA) is a highly disabling and not completely understood phenomenon that occurs after a central nervous system lesion. We tested the feasibility of in-field IMA measuring at an acute rehabilitation ward. We used wearable probes for single differential surface EMG (sEMG), inclusive of a 3D accelerometer, onboard memory and remote control. We collected 429 h of data from the biceps brachii of 10 patients with arm plegia. Data quality was first verified in the time and frequency domains. Next, IMA was automatically identified based on the steady presence of motor unit action potential (MUAP) trains at rest. Feasibility was excellent in terms of prep time and burden to the clinical staff. A total of 350.5 h of data (81.7%) were reliable. IMA was found in 85.9 h (25%). This was often present in the form of exceedingly long-lasting trains of one or a few MUAPs, with differences among patients and variability, both within and between days in terms of IMA duration, root mean square (RMS) and peak-to-peak amplitude. Our results proved the feasibility of using wearable probes for single differential sEMG to identify and quantify IMA in plegic muscles of bedridden acute neurological patients. Our results also suggest the need for long-lasting acquisitions to properly characterize IMA. The possibility of easily assessing IMA in acute inpatients can have a huge impact on the management of their postures, physiotherapy and treatments.

Models of recruitment and rate coding organization in motor-unit pools

1993 ◽  
Vol 70 (6) ◽  
pp. 2470-2488 ◽  
Author(s):  
A. J. Fuglevand ◽  
D. A. Winter ◽  
A. E. Patla
Keyword(s):  
Action Potential ◽  
Firing Rate ◽  
Motor Unit ◽  
Action Potentials ◽  
Surface Emg ◽  
Motor Unit Action Potential ◽  
Rate Coding ◽  
Motor Unit Action ◽  
Unit Action ◽  
Excitatory Drive

1. Isometric muscle force and the surface electromyogram (EMG) were simulated from a model that predicted recruitment and firing times in a pool of 120 motor units under different levels of excitatory drive. The EMG-force relationships that emerged from simulations using various schedules of recruitment and rate coding were compared with those observed experimentally to determine which of the modeled schemes were plausible representations of the actual organization in motor-unit pools. 2. The model was comprised of three elements: a motoneuron model, a motor-unit force model, and a model of the surface EMG. Input to the neuron model was an excitatory drive function representing the net synaptic input to motoneurons during voluntary muscle contractions. Recruitment thresholds were assigned such that many motoneurons had low thresholds and relatively few neurons had high thresholds. Motoneuron firing rate increased as a linear function of excitatory drive between recruitment threshold and peak firing rate levels. The sequence of discharge times for each motoneuron was simulated as a random renewal process. 3. Motor-unit twitch force was estimated as an impulse response of a critically damped, second-order system. Twitch amplitudes were assigned according to rank in the recruitment order, and twitch contraction times were inversely related to twitch amplitude. Nonlinear force-firing rate behavior was simulated by varying motor-unit force gain as a function of the instantaneous firing rate and the contraction time of the unit. The total force exerted by the muscle was computed as the sum of the motor-unit forces. 4. Motor-unit action potentials were simulated on the basis of estimates of the number and location of motor-unit muscle fibers and the propagation velocity of the fiber action potentials. The number of fibers innervated by each unit was assumed to be directly proportional to the twitch force. The area of muscle encompassing unit fibers was proportional to the number of fibers innervated, and the location of motor-unit territories were randomly assigned within the muscle cross section. Action-potential propagation velocities were estimated from an inverse function of contraction time. The train of discharge times predicted from the motoneuron model determined the occurrence of each motor-unit action potential. The surface EMG was synthesized as the sum of all motor-unit action-potential trains. 5. Two recruitment conditions were tested: narrow (limit of recruitment < 50% maximum excitation) and broad recruitment range conditions (limit of recruitment > 70% maximum excitation).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Multi-Channel Surface EMG Spatio-Temporal Image Enhancement Using Multi-Scale Hessian-Based Filters

2020 ◽  
Vol 10 (15) ◽  
pp. 5099 ◽  
Author(s):  
Khalil Ullah ◽  
Khalil Khan ◽  
Muhammad Amin ◽  
Muhammad Attique ◽  
Tae-Sun Chung ◽  
...  
Keyword(s):  
Action Potential ◽  
Motor Unit ◽  
Linear Structure ◽  
Surface Emg ◽  
Motor Unit Action Potential ◽  
Multi Scale ◽  
Motor Unit Action ◽  
Spatio Temporal ◽  
Unit Action ◽  
Semg Signals

Surface electromyography (sEMG) signals acquired with linear electrode array are useful in analyzing muscle anatomy and physiology. Most algorithms for signal processing, detection, and estimation require adequate quality of the input signals, however, multi-channel sEMG signals are commonly contaminated due to several noise sources. The sEMG signal needs to be enhanced prior to the digital signal and image processing to achieve the best results. This study is using spatio-temporal images to represent surface EMG signals. The motor unit action potential (MUAP) in these images looks like a linear structure, making certain angles with the x-axis, depending on the conduction velocity of the MU. A multi-scale Hessian-based filter is used to enhance the linear structure, i.e., the MUAP region, and to suppress the background noise. The proposed framework is compared with some of the existing algorithms using synthetic, simulated, and experimental sEMG signals. Results show improved detection accuracy of the motor unit action potential after the proposed enhancement as a preprocessing step.

A new surface electromyography analysis method to determine spread of muscle fiber conduction velocities

2002 ◽  
Vol 93 (2) ◽  
pp. 759-764 ◽  
Author(s):  
Fiete Lange ◽  
Tiemen W. Van Weerden ◽  
Johannes H. Van Der Hoeven
Keyword(s):  
Motor Unit ◽  
Muscle Fiber ◽  
Biceps Brachii ◽  
Young Male ◽  
Motor Unit Action Potential ◽  
Conduction Velocities ◽  
Motor Unit Action ◽  
Interpeak Latency ◽  
Unit Action

Muscle fiber conduction velocity (MFCV) estimation from surface signals is widely used to study muscle function, e.g., in neuromuscular disease and in fatigue studies. However, most analysis methods do not yield information about the velocity distribution of the various motor unit action potentials. We have developed a new method–the interpeak latency method (IPL)–to calculate both the mean MFCV and the spread of conduction velocities in vivo, from bipolar surface electromyogram (sEMG) during isometric contractions. sEMG was analyzed in the biceps brachii muscle in 15 young male volunteers. The motor unit action potential peaks are automatically detected with a computer program. Associated peaks are used to calculate a mean MFCV and the SD. The SD is taken as a measure of the MFCV spread. The main finding is that the IPL method can derive a measure of MFCV spread at different contraction levels. In conclusion, the IPL method provides accurate values for the MFCV and additionally gives information about the scatter of conduction velocities.

scholarly journals Sustained involuntary muscle activity in cerebral palsy and stroke: same symptom, diverse mechanisms

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Christian Riis Forman ◽  
Christian Svane ◽  
Christina Kruuse ◽  
Jean-Michel Gracies ◽  
Jens Bo Nielsen ◽  
...  
Keyword(s):  
Cerebral Palsy ◽  
Muscle Activity ◽  
Surface Emg ◽  
Passive Movement ◽  
Gamma Band ◽  
Involuntary Muscle ◽  
Extended Position ◽  
Cross Correlation Analysis ◽  
Stroke Group ◽  
Spinal Stretch Reflex

Abstract Individuals with lesions of central motor pathways frequently suffer from sustained involuntary muscle activity. This symptom shares clinical characteristics with dystonia but is observable in individuals classified as spastic. The term spastic dystonia has been introduced, although the underlying mechanisms of involuntary activity are not clarified and vary between individuals depending on the disorder. This study aimed to investigate the nature and pathophysiology of sustained involuntary muscle activity in adults with cerebral palsy and stroke. Seventeen adults with cerebral palsy (Gross Motor Function Classification System I–V), 8 adults with chronic stroke and 14 control individuals participated in the study. All individuals with cerebral palsy or stroke showed increased resistance to passive movement with Modified Ashworth Scale &gt;1. Two-minute surface EMG recordings were obtained from the biceps muscle during attempted rest in three positions of the elbow joint; a maximally flexed position, a 90-degree position and a maximally extended position. Cross-correlation analysis of sustained involuntary muscle activity from individuals with cerebral palsy and stroke, and recordings of voluntary isometric contractions from control individuals were performed to examine common synaptic drive. In total, 13 out of 17 individuals with cerebral palsy and all 8 individuals with stroke contained sustained involuntary muscle activity. In individuals with cerebral palsy, the level of muscle activity was not affected by the joint position. In individuals with stroke, the level of muscle activity significantly (P &lt; 0.05) increased from the flexed position to the 90 degree and extended position. Cumulant density function indicated significant short-term synchronization of motor unit activities in all recordings. All groups exhibited significant coherence in the alpha (6–15 Hz), beta (16–35 Hz) and early gamma band (36–60 Hz). The cerebral palsy group had lower alpha band coherence estimates, but higher gamma band coherence estimates compared with the stroke group. Individuals with increased resistance to passive movement due to cerebral palsy or stroke frequently suffer sustained involuntary muscle activity, which cannot exclusively be described by spasticity. The sustained involuntary muscle activity in both groups originated from a common synaptic input to the motor neuron pool, but the generating mechanisms could differ between groups. In cerebral palsy it seemed to originate more from central mechanisms, whereas peripheral mechanisms likely play a larger role in stroke. The sustained involuntary muscle activity should not be treated simply like the spinal stretch reflex mediated symptom of spasticity and should not either be treated identically in both groups.

scholarly journals Two-Source Validation of Progressive FastICA Peel-Off for Automatic Surface EMG Decomposition in Human First Dorsal Interosseous Muscle

2018 ◽  
Vol 28 (09) ◽  
pp. 1850019 ◽  
Author(s):  
Maoqi Chen ◽  
Xu Zhang ◽  
Zhiyuan Lu ◽  
Xiaoyan Li ◽  
Ping Zhou
Keyword(s):  
Motor Unit ◽  
Electrode Array ◽  
Surface Emg ◽  
High Density ◽  
Motor Unit Action Potential ◽  
First Dorsal Interosseous ◽  
First Dorsal Interosseous Muscle ◽  
Density Surface ◽  
Motor Unit Action ◽  
Semg Signals

This study aims to assess the accuracy of a novel high density surface electromyogram (SEMG) decomposition method, namely automatic progressive FastICA peel-off (APFP), for automatic decomposition of experimental electrode array SEMG signals. A two-source method was performed by simultaneous concentric needle EMG and electrode array SEMG recordings from the human first dorsal interosseous (FDI) muscle, using a protocol commonly applied in clinical EMG examination. The electrode array SEMG was automatically decomposed by the APFP while the motor unit action potential (MUAP) trains were also independently identified from the concentric needle EMG. The degree of agreement of the common motor unit (MU) discharge timings decomposed from the two different categories of EMG signals was assessed. A total of 861 and 217 MUs were identified from the 114 trials of simultaneous high density SEMG and concentric needle EMG recordings, respectively. Among them 168 common (MUs) were found with a high average matching rate of [Formula: see text] for the discharge timings. The outcomes of this study show that the APFP can reliably decompose at least a subset of MUs in the high density SEMG signals recorded from the human FDI muscle during low contraction levels using a protocol analog to clinical EMG examination.

Analysis of Temporalis and Masseter adaptation after routine dental treatment in the horse via surface electromyography

2014 ◽  
Vol 10 (4) ◽  
pp. 223-232 ◽  
Author(s):  
J.M. Williams ◽  
C. Johnson ◽  
R. Bales ◽  
G. Lloyd ◽  
L. Barron ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Surface Electromyography ◽  
Dental Treatment ◽  
Post Treatment ◽  
Motor Unit Action Potential ◽  
Dental Pathology ◽  
Time Period ◽  
Motor Unit Action ◽  
The Right ◽  
Activity Decrease

Limited knowledge of how routine dental treatment (rasping) alters the mastication cycle exists. To our knowledge, Masseter and Temporalis muscle activity after rasping has not been previously evaluated. A descriptive, experimental study compared muscle activity pre- and post-routine dental treatment using surface electromyography (sEMG) to investigate the hypothesis that Masseter activity would increase and Temporalis activity decrease, over a 6 week time period after routine dentistry. Motor unit action potential amplitude (MUAP) and peak amplitude contraction (PAC), for 5 chewing cycles, were measured using sEMG in the right and left Masseter and Temporalis muscles of 10 horses, selected opportunistically due to their dental pathology that required routine rasping (week 0). Routine dental treatment was undertaken and sEMG measurements repeated at 1, 3 and 6 weeks post treatment. Mean MUAP and PAC were calculated for each week and compared both across the cohort and for each horse. For the cohort: Temporalis MUAP fluctuated after rasping, but was only significant in the left muscle between weeks 0 and 6, and weeks 1 and 6 (P<0.02). PAC did not differ significantly, with the exception of a decrease occurring on the left from week 0 to 1 (P<0.01). Masseter activity varied throughout the investigation, but few significant differences were found. A non-significant but consistent reduction in magnitude of PAC was found. For the individuals: MUAP and PAC in the Masseter and Temporalis muscles varied (increased / decreased) on an individual basis throughout the six weeks post rasping, although only MUAP fluctuations between weeks were significant (P<0.01). Adaptation occurs in the Masseter and Temporalis of individual horses after routine rasping; this appears to be associated with kinematic changes within the chewing cycle and is still occurring 6 weeks post-treatment.

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