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Rubin DI, Lamb CJ. Motor unit potential recruitment reference values in common upper and lower extremity muscles. Clin Neurophysiol 2024:S1388-2457(24)00150-0. [PMID: 38777641 DOI: 10.1016/j.clinph.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/30/2024] [Accepted: 05/04/2024] [Indexed: 05/25/2024]
Abstract
OBJECTIVE To define reference values for motor unit (MU) recruitment during needle EMG of six commonly examined muscles at low to moderate contraction. METHODS Needle examination was performed for each muscle in a total of 111 subjects without neuromuscular disorders. Fastest firing rates and recruitment ratios (RRs) were calculated in at least 5 sites within each muscle. Upper limits of normal based on 97th percentile for fastest MU firing rates and RRs were calculated for each muscle. The means of fastest firing rates were compared among muscles using the Friedman and Wilcoxon signed rank tests. RESULTS The upper limits of normal were 12-15 Hz for fastest firing rates and were slightly higher in the deltoid and triceps than the other muscles. CONCLUSION Firing rates >15 Hz recorded at multiple sites within a single muscle exceed the 97th percentile of normal subjects and may suggest reduced MU recruitment. In some muscles, rates >12 Hz might support mildly reduced recruitment. Recruitment ratios varied depending on number of firing MUs, whereas the fastest firing MU rate did not. SIGNIFICANCE The determination of reference values for fastest MU firing rates can help to identify mild reduction in recruitment with more accuracy.
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Affiliation(s)
- Devon I Rubin
- Electromyography Laboratory, Department of Neurology, Mayo Clinic, Jacksonville, FL, USA.
| | - Christopher J Lamb
- Electromyography Laboratory, Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
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Rubin DI, Lamb CJ. The role of electrodiagnosis in focal neuropathies. HANDBOOK OF CLINICAL NEUROLOGY 2024; 201:43-59. [PMID: 38697746 DOI: 10.1016/b978-0-323-90108-6.00010-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Electrodiagnostic (EDX) testing plays an important role in confirming a mononeuropathy, localizing the site of nerve injury, defining the pathophysiology, and assessing the severity and prognosis. The combination of nerve conduction studies (NCS) and needle electromyography findings provides the necessary information to fully assess a nerve. The pattern of NCS abnormalities reflects the underlying pathophysiology, with focal slowing or conduction block in neuropraxic injuries and reduced amplitudes in axonotmetic injuries. Needle electromyography findings, including spontaneous activity and voluntary motor unit potential changes, complement the NCS findings and further characterize chronicity and degree of axon loss and reinnervation. EDX is used as an objective marker to follow the progression of a mononeuropathy over time.
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Affiliation(s)
- Devon I Rubin
- Department of Neurology, Mayo Clinic, Jacksonville, FL, United States.
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Ferrante MA. Neuromuscular electrodiagnosis. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:251-270. [PMID: 37562871 DOI: 10.1016/b978-0-323-98818-6.00019-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
The electrodiagnostic (EDX) study is an extension of the clinical examination, which means that the clinical features dictate the initial nerve conduction studies (NCS) performed. However, once the EDX study is started, it continues in an independent manner, meaning that the initial NCS findings dictate the subsequent studies performed. Because competent EDX study performance requires considerable knowledge (and special training), it is not possible to convey all of the basic and advanced concepts in a single chapter. Nonetheless, the most important concepts are easily conveyed by a discussion limited to EDX-pertinent anatomical, physiological, pathological, pathophysiological, and basic electrical concepts. The focus of this chapter will be on the standard NCS and needle EMG measurements made during EDX studies and their significance with regard to lesion localization and characterization. Because the most challenging portion of EDX study is motor unit action potential analysis, this topic is more extensively reviewed. The utility of the sensory NCS for identifying focal axon loss, the utility of the motor NCS for screening long nerve segments for focal demyelination and for determining lesion severity, and the utility of the needle EMG for confirming the NCS findings, better defining lesion localization, and identifying the temporal features (e.g., chronicity) and rate of progression of the lesion are also reviewed.
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Affiliation(s)
- Mark A Ferrante
- Electromyography Laboratory, Department of Neurology, Veterans Administration Medical Center, University of Tennessee, Memphis, TN, United States.
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Nandedkar SD, Barkhaus PE, Stålberg EV. Motor unit recruitment and firing rate at low force of contraction. Muscle Nerve 2022; 66:750-756. [PMID: 36214178 DOI: 10.1002/mus.27737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/28/2022] [Accepted: 10/04/2022] [Indexed: 12/14/2022]
Abstract
INTRODUCTION/AIMS A prevailing concept of motor unit (MU) recruitment used for calculating recruitment ratio (RR) suggests a progressive linear increase in firing rate (FR). The objective of this study is to assess its validity. METHODS Concentric needle electromyography (EMG) recordings were made in normal muscle and abnormal muscle of patients with neurogenic findings. Signals recorded at low force were visually decomposed to study MU FR at onset, recruitment of a second MU, and recruitment of more MUs with further increases in force. RESULTS We observed one to six MUs discharging at a rate < 15 Hz in normal muscles at low force. The MU FR was 5-8 Hz at onset. With increasing force, FR increased by 3-5 Hz and then idled at <15 Hz while other MUs were recruited. The recruitment frequency (RF) and RR had low sensitivity and were abnormal mainly in moderately to severely weak muscles. DISCUSSION Our data are consistent with FR analysis results described by other investigators. It does not support a progressive linear increase in MU FR with recruitment. A revised model for MU recruitment at low effort during gradual increase in force is presented. On subjective assessment, the FR of the fastest firing MU can help detect MU loss in neurogenic processes.
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Affiliation(s)
- Sanjeev D Nandedkar
- Clinical Applications, Natus Medical Inc, Hopewell Junction, New York, USA.,Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Paul E Barkhaus
- Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Erik V Stålberg
- Academic Hospital, Dept Clin Neurophysiology, Uppsala University, Uppsala, Sweden
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Rong P, Pattee GL. A multidimensional facial surface EMG analysis for objective assessment of bulbar involvement in amyotrophic lateral sclerosis. Clin Neurophysiol 2022; 135:74-84. [DOI: 10.1016/j.clinph.2021.11.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/01/2021] [Accepted: 11/07/2021] [Indexed: 11/03/2022]
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Abstract
Needle electromyography (EMG) waveforms recorded during needle EMG help to define the type, temporal course, and severity of a neuromuscular disorder. Accurate interpretation of EMG waveforms is a critical component of an electrodiagnostic examination. This article reviews the significance of spontaneous EMG waveforms and changes in voluntary motor unit potentials in neuromuscular disorders.
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Stålberg E, van Dijk H, Falck B, Kimura J, Neuwirth C, Pitt M, Podnar S, Rubin DI, Rutkove S, Sanders DB, Sonoo M, Tankisi H, Zwarts M. Standards for quantification of EMG and neurography. Clin Neurophysiol 2019; 130:1688-1729. [DOI: 10.1016/j.clinph.2019.05.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/07/2019] [Accepted: 05/09/2019] [Indexed: 12/11/2022]
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Motor unit recruitment in myopathy: The myopathic EMG reconsidered. J Electromyogr Kinesiol 2019; 45:41-45. [PMID: 30798164 DOI: 10.1016/j.jelekin.2019.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 02/16/2019] [Accepted: 02/18/2019] [Indexed: 12/11/2022] Open
Abstract
Motor unit recruitment is abnormal in myopathies. We have addressed this subject by recording motor unit potentials (MUPs) using a standard concentric needle electrode in tibialis anterior muscles of clinically normal strength in a group of patients with myopathy (15 with myositis and 4 with facioscapulohumeral muscular dystrophy Type 1). In each recording site, a minimal voluntary contraction was sought in order to activate only 2 MUPs. At least 5 pairs of MUPs were recorded in each muscle. We analysed the recruitment rate of the first activated MUP and the mean consecutive difference (MCD) of firing frequency between the individual MUPs of each recruited pair. Results were compared with 30 healthy control subjects. In myopathy the first recorded MUs fired at similar rates to controls (8.2 vs 8.0 Hz, respectively), but the MCD of the firing rate difference between the first two recruited MUPs was less than in controls (median difference 1.78 Hz vs median difference 2.47 Hz, p = 0.02). This change suggests increased lower motor neuron excitability as a functional adaptation, since muscle strength was normal in the studied muscles. These findings are consistent with spinal cord adaptation to the functional changes associated with myopathic muscle disease, although a primary muscle fibre feedback sensing mechanism could also be involved.
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Normal and abnormal voluntary activity. HANDBOOK OF CLINICAL NEUROLOGY 2019; 160:281-301. [PMID: 31277854 DOI: 10.1016/b978-0-444-64032-1.00018-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
An important component of needle EMG entails recording and interpreting the electrical signals generated from motor units during voluntary contraction. The recorded motor unit potentials (MUPs) reflect the number of motor units within a muscle and the distribution and density of muscle fibers within a motor unit within a portion of a muscle. Various MUP parameters are assessed to determine the integrity of the motor units, including recruitment, stability, phases and turns, duration, and amplitude. Each of these parameters is altered in a different way in various neuromuscular diseases. In neurogenic disorders, the earliest changes occur in the recruitment pattern of motor units followed by MUP morphologic changes (increased MUP phases and duration) as reinnervation occurs. MUP instability, indicating impaired neuromuscular transmission, also occurs in reinnervating neurogenic disorders as well as in neuromuscular junction disorders. In myopathies, a reduction in the size of the motor unit is manifested by MUPs of low amplitude and short duration. Interpreting the voluntary MUP changes along with spontaneous activity helps to determine the type, severity, and temporal course of neuromuscular diseases.
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Scheidegger O, Kamber N, Rösler KM. Estimation of voluntary elicited motor neuron discharge using a peripheral nerve collision technique at different contraction strengths. Clin Neurophysiol 2018; 129:1579-1587. [PMID: 29885647 DOI: 10.1016/j.clinph.2018.04.751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/24/2018] [Accepted: 04/25/2018] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To estimate non-invasively the amount, recruitment pattern and discharge frequency of spinal motor neurons (MN) at contraction strength >20% of maximal voluntary contraction (MVC) of small hand muscles. METHODS A peripheral collision technique was used and consisted of supramaximal electrical stimuli at Erb's point and at the wrist, synchronizing descending volleys of action potential during voluntary isometric contractions of the abductor digiti minimi muscle at 20-80% of MVC strength and 1-8 s of contraction duration. Responses of 13 healthy volunteers were quantified and analysed using a recently described model of MN behaviour. RESULTS A linear relationship between MN discharge and force generation was noticed with R2 = 0.996, and was confirmed using the simulation results (R2 = 0.997) for contraction durations up to 8 s. For each investigated force level, discharge frequency and recruitment pattern were calculated for individual MN. CONCLUSIONS Using this method, MN discharge properties during voluntary activity can be estimated non-invasively. SIGNIFICANCE This method provides new opportunities for the non-invasive study of MN behaviour, and could be expanded to patients with conduction failure and during fatigue.
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Affiliation(s)
- Olivier Scheidegger
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.
| | - Nicole Kamber
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Kai Michael Rösler
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
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Yalinay Dikmen P, Kocasoy Orhan E, Baslo MB. Analysis of motor unit firing characteristics in patients with motor neuron diseases. Somatosens Mot Res 2016; 33:16-9. [PMID: 26911921 DOI: 10.3109/08990220.2016.1142437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This study was designed to evaluate firing rate variability in patients with upper/lower motor neuron disorders. Twenty healthy subjects and 19 patients with motor neuron disorders participated in the study. Consecutive motor unit action potential pairs from extensor digitorum communis (EDC) muscle were recorded from each subject with trigger-delay line mode. Patients with motor neuron disorders (17.7 ± 10.8 ms) showed significantly higher mean time variability of interpotential interval value than healthy volunteers (10.3 ± 0.1 ms) (p < 0.001).
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Affiliation(s)
- Pınar Yalinay Dikmen
- a Department of Neurology, Acibadem University School of Medicine , Istanbul , Turkey
| | - Elif Kocasoy Orhan
- b Department of Neurology, Istanbul University, Istanbul Faculty of Medicine , Istanbul , Turkey
| | - M Barış Baslo
- b Department of Neurology, Istanbul University, Istanbul Faculty of Medicine , Istanbul , Turkey
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de Carvalho M, Eisen A, Krieger C, Swash M. Motoneuron firing in amyotrophic lateral sclerosis (ALS). Front Hum Neurosci 2014; 8:719. [PMID: 25294995 PMCID: PMC4170108 DOI: 10.3389/fnhum.2014.00719] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 08/27/2014] [Indexed: 01/09/2023] Open
Abstract
Amyotrophic lateral sclerosis is an inexorably progressive neurodegenerative disorder involving the classical motor system and the frontal effector brain, causing muscular weakness and atrophy, with variable upper motor neuron signs and often an associated fronto-temporal dementia. The physiological disturbance consequent on the motor system degeneration is beginning to be well understood. In this review we describe aspects of the motor cortical, neuronal, and lower motor neuron dysfunction. We show how studies of the changes in the pattern of motor unit firing help delineate the underlying pathophysiological disturbance as the disease progresses. Such studies are beginning to illuminate the underlying disordered pathophysiological processes in the disease, and are important in designing new approaches to therapy and especially for clinical trials.
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Affiliation(s)
- Mamede de Carvalho
- Institute of Physiology and Institute of Molecular Medicine, Faculty of Medicine, University of Lisbon Lisbon, Portugal ; Department of Neurosciences, Hospital Santa Maria, Faculty of Medicine, University of Lisbon Lisbon, Portugal
| | - Andrew Eisen
- Emeritus Professor of Neurology, University of British Columbia Vancouver, BC, Canada
| | - Charles Krieger
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby BC, Canada ; Department of Medicine (Neurology), University of British Columbia, Vancouver BC, Canada
| | - Michael Swash
- Institute of Physiology and Institute of Molecular Medicine, Faculty of Medicine, University of Lisbon Lisbon, Portugal ; Department of Neurosciences, Hospital Santa Maria, Faculty of Medicine, University of Lisbon Lisbon, Portugal ; Institute of Neuroscience, Barts and The London School of Medicine, Queen Mary University of London London, UK
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Latronico N, Nattino G, Guarneri B, Fagoni N, Amantini A, Bertolini G. Validation of the peroneal nerve test to diagnose critical illness polyneuropathy and myopathy in the intensive care unit: the multicentre Italian CRIMYNE-2 diagnostic accuracy study. F1000Res 2014; 3:127. [PMID: 25309729 PMCID: PMC4184363 DOI: 10.12688/f1000research.3933.1] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/13/2014] [Indexed: 11/15/2023] Open
Abstract
OBJECTIVES To evaluate the accuracy of the peroneal nerve test (PENT) in the diagnosis of critical illness polyneuropathy (CIP) and myopathy (CIM) in the intensive care unit (ICU). We hypothesised that abnormal reduction of peroneal compound muscle action potential (CMAP) amplitude predicts CIP/CIM diagnosed using a complete nerve conduction study and electromyography (NCS-EMG) as a reference diagnostic standard. DESIGN prospective observational study. SETTING Nine Italian ICUs. PATIENTS One-hundred and twenty-one adult (≥18 years) neurologic (106) and non-neurologic (15) critically ill patients with an ICU stay of at least 3 days. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS PATIENTS underwent PENT and NCS-EMG testing on the same day conducted by two independent clinicians who were blind to the results of the other test. Cases were considered as true negative if both NCS-EMG and PENT measurements were normal. Cases were considered as true positive if the PENT result was abnormal and NCS-EMG showed symmetric abnormal findings, independently from the specific diagnosis by NCS-EMG (CIP, CIM, or combined CIP and CIM). All data were centrally reviewed and diagnoses were evaluated for consistency with predefined electrophysiological diagnostic criteria for CIP/CIM. During the study period, 342 patients were evaluated, 124 (36.3%) were enrolled and 121 individuals with no protocol violation were studied. Sensitivity and specificity of PENT were 100% (95% CI 96.1-100.0) and 85.2% (95% CI 66.3-95.8). Of 23 patients with normal results, all presented normal values on both tests with no false negative results. Of 97 patients with abnormal results, 93 had abnormal values on both tests (true positive), whereas four with abnormal findings with PENT had only single peroneal nerve neuropathy at complete NCS-EMG (false positive). CONCLUSIONS PENT has 100% sensitivity and high specificity, and can be used to diagnose CIP/CIM in the ICU.
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Affiliation(s)
- Nicola Latronico
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
| | - Giovanni Nattino
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
| | - Bruno Guarneri
- Department of Neuroscience, Section of Clinical Neurophysiology, Spedali Civili, Brescia, 25123, Italy
| | - Nazzareno Fagoni
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Anesthesia and Critical Care Medicine, Section of Neuroanesthesia and Neurocritical Care, University of Brescia at Spedali Civili, Brescia, 25123, Italy
| | - Aldo Amantini
- Department of Neuroscience, Section of Clinical Neurophysiology, Azienda Ospedaliero-Universitaria Careggi, Firenze, 50134, Italy
| | - Guido Bertolini
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
| | - and GiVITI Study Investigators
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
- Department of Neuroscience, Section of Clinical Neurophysiology, Spedali Civili, Brescia, 25123, Italy
- Department of Anesthesia and Critical Care Medicine, Section of Neuroanesthesia and Neurocritical Care, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Neuroscience, Section of Clinical Neurophysiology, Azienda Ospedaliero-Universitaria Careggi, Firenze, 50134, Italy
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Latronico N, Nattino G, Guarneri B, Fagoni N, Amantini A, Bertolini G. Validation of the peroneal nerve test to diagnose critical illness polyneuropathy and myopathy in the intensive care unit: the multicentre Italian CRIMYNE-2 diagnostic accuracy study. F1000Res 2014; 3:127. [PMID: 25309729 PMCID: PMC4184363 DOI: 10.12688/f1000research.3933.3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/21/2014] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES To evaluate the accuracy of the peroneal nerve test (PENT) in the diagnosis of critical illness polyneuropathy (CIP) and myopathy (CIM) in the intensive care unit (ICU). We hypothesised that abnormal reduction of peroneal compound muscle action potential (CMAP) amplitude predicts CIP/CIM diagnosed using a complete nerve conduction study and electromyography (NCS-EMG) as a reference diagnostic standard. DESIGN prospective observational study. SETTING Nine Italian ICUs. PATIENTS One-hundred and twenty-one adult (≥18 years) neurologic (106) and non-neurologic (15) critically ill patients with an ICU stay of at least 3 days. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS PATIENTS underwent PENT and NCS-EMG testing on the same day conducted by two independent clinicians who were blind to the results of the other test. Cases were considered as true negative if both NCS-EMG and PENT measurements were normal. Cases were considered as true positive if the PENT result was abnormal and NCS-EMG showed symmetric abnormal findings, independently from the specific diagnosis by NCS-EMG (CIP, CIM, or combined CIP and CIM). All data were centrally reviewed and diagnoses were evaluated for consistency with predefined electrophysiological diagnostic criteria for CIP/CIM. During the study period, 342 patients were evaluated, 124 (36.3%) were enrolled and 121 individuals with no protocol violation were studied. Sensitivity and specificity of PENT were 100% (95% CI 96.1-100.0) and 85.2% (95% CI 66.3-95.8). Of 23 patients with normal results, all presented normal values on both tests with no false negative results. Of 97 patients with abnormal results, 93 had abnormal values on both tests (true positive), whereas four with abnormal findings with PENT had only single peroneal nerve neuropathy at complete NCS-EMG (false positive). CONCLUSIONS PENT has 100% sensitivity and high specificity, and can be used as a screening test to diagnose CIP/CIM in the ICU.
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Affiliation(s)
- Nicola Latronico
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
| | - Giovanni Nattino
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
| | - Bruno Guarneri
- Department of Neuroscience, Section of Clinical Neurophysiology, Spedali Civili, Brescia, 25123, Italy
| | - Nazzareno Fagoni
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Anesthesia and Critical Care Medicine, Section of Neuroanesthesia and Neurocritical Care, University of Brescia at Spedali Civili, Brescia, 25123, Italy
| | - Aldo Amantini
- Department of Neuroscience, Section of Clinical Neurophysiology, Azienda Ospedaliero-Universitaria Careggi, Firenze, 50134, Italy
| | - Guido Bertolini
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
| | - and GiVITI Study Investigators
- Department of Anesthesia and Critical Care Medicine, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Clinical Epidemiology, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Ranica (BG), 24020, Italy
- Department of Neuroscience, Section of Clinical Neurophysiology, Spedali Civili, Brescia, 25123, Italy
- Department of Anesthesia and Critical Care Medicine, Section of Neuroanesthesia and Neurocritical Care, University of Brescia at Spedali Civili, Brescia, 25123, Italy
- Department of Neuroscience, Section of Clinical Neurophysiology, Azienda Ospedaliero-Universitaria Careggi, Firenze, 50134, Italy
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Matsumoto H, Tokushige SI, Hashida H, Hanajima R, Terao Y, Ugawa Y. Focal Lesion in Upper Part of Brachial Plexus can be Detected by Magnetic Cervical Motor Root Stimulation. Brain Stimul 2013; 6:538-40. [DOI: 10.1016/j.brs.2012.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/22/2012] [Accepted: 09/21/2012] [Indexed: 11/24/2022] Open
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Recurrent CSPs after Transcranial Magnetic Stimulation of Motor Cortex in Restless Legs Syndrome. Neurol Res Int 2012; 2012:628949. [PMID: 23213521 PMCID: PMC3507135 DOI: 10.1155/2012/628949] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/20/2012] [Accepted: 10/20/2012] [Indexed: 11/21/2022] Open
Abstract
Aims. The aim of this study was to investigate the motor control and central silent period (CSP) in restless legs syndrome (RLS). Methods. Transcranial magnetic stimulation was focused on the dominant and nondominant hemispheric areas of motor cortex in six subjects with RLS and six controls. The responses were recorded on the contralateral abductor digiti minimi (ADM) and tibialis anterior (TA) muscles with intramuscular needle electrodes. Results. No significant differences were found in the motor conduction or central motor conduction time, in the latency, or in the duration of the CSPs between or within the groups, but multiple CSPs were observed in both groups. The number of the CSPs was significantly higher in both ADMs and in the dominant TA (P ≤ 0.01) in the RLS group compared to the controls. Conclusion. Descending motor pathways functioned correctly in both groups. The occurrence of the recurrent CSPs predominantly in the RLS group could be a sign of a change of function in the inhibitory control system. Further research is needed to clarify the role of the intramuscular recording technique and especially the role of the subcortical generators in the feedback regulation of the central nervous system in RLS.
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Abstract
Electrodiagnostic studies play an important role in the evaluation of patients suspected of having a myopathic disorder. They are used to exclude alternative diagnoses, confirm the presence of muscle disease, narrow down the differential, and identify an appropriate biopsy site. The most informative part of the electrodiagnostic study is needle electromyography. This allows for the analysis of spontaneous activity and motor unit action potential morphology and recruitment patterns. This article proposes a practical electrodiagnostic approach and describes the electrophysiologic patterns of the most commonly encountered myopathies.
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Affiliation(s)
- Sabrina Paganoni
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Boston, MA 02114, USA.
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de Carvalho M, Turkman A, Swash M. Motor unit firing in amyotrophic lateral sclerosis and other upper and lower motor neurone disorders. Clin Neurophysiol 2012; 123:2312-8. [PMID: 22627021 DOI: 10.1016/j.clinph.2012.04.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2012] [Revised: 02/25/2012] [Accepted: 04/01/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVE Motor unit recruitment order and firing rate was investigated in healthy subjects, and in small numbers of patients 50years ago. We aimed to investigate firing rate in different disorders, testing the same target muscle with normal strength, to evaluate possible application in diagnosing upper motor neuron (UMN) lesion. METHODS We studied motor unit firing in the tibialis anterior muscle in six groups of subjects; normal subjects (n=45), patients with amyotrophic lateral sclerosis (ALS) (n=36), primary lateral sclerosis (PLS) (n=21), progressive muscular atrophy (PMA) (n=14), various upper motor neurone lesions (n=16) and polyneuropathy (n=42). In all these subjects the tibialis anterior muscle was of normal strength. Motor units were recruited during slight contraction in order to study 2-5 motor units at each recording site, using a standard concentric needle electrode, so that 20-22 motor units were recorded in each muscle. We analysed the coefficient of variation (CV) for amplitude, area, duration and firing rate in these motor units, and the correlation between motor unit potential size and recruitment order. RESULTS The mean MU firing rate in this task was similar in each group. No recruitment order was disclosed within the limits of the study task. The CV of firing rate was decreased in UMN and PLS groups. ALS patients with marked spasticity showed a lower CV of motor unit firing rate. The CV of amplitude, area and duration was similar between groups. CONCLUSIONS These results in tibialis anterior indicate that physiological modulation of lower motor neuron (LMN) firing rate is decreased in patients with lower limb spasticity. The variability of MU discharges tends to be greater in diseases affecting the LMN. SIGNIFICANCE These results suggest that, notwithstanding the simplicity of the task we have used, the physiological variability of motor unit firing may be a useful variable in assessing UMN involvement in motor system disorders.
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Electrodiagnostic Medicine Skills Competency in Physical Medicine and Rehabilitation Residents. Am J Phys Med Rehabil 2008; 87:654-65. [DOI: 10.1097/phm.0b013e31816de0f2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Fuglsang-Frederiksen A. The role of different EMG methods in evaluating myopathy. Clin Neurophysiol 2006; 117:1173-89. [PMID: 16516549 DOI: 10.1016/j.clinph.2005.12.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 11/22/2005] [Accepted: 12/17/2005] [Indexed: 10/25/2022]
Abstract
For the diagnosis of myopathy, EMG may have an important role along with blood tests, muscle biopsies and genetic testing. This review evaluates different EMG methods in the diagnosis of myopathy. These include manual analysis of individual motor unit potentials and multi-motor unit potential analysis sampled at weak effort. At high effort, turns-amplitude analyses such as the cloud analysis and the peak ratio analysis have a high diagnostic yield. The EMG can seldom be used to differentiate between different types of myopathy. In the channelopathies, myotonia, exercise test and cooling of the muscle are helpful. Macro-EMG, single-fibre EMG and muscle fibre conduction velocity analysis have a limited role in myopathy, but provide information about the changes seen. Analysis of the firing rate of motor units, power spectrum analysis, as well as multichannel surface EMG may have diagnostic potential in the future. EMG is of great importance in the diagnosing of patients with myopathy, preferably a needle electrode and quantitative analyses should be used. A combination of a method at weak effort as well as a method at stronger effort seems optimal.
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Affiliation(s)
- Anders Fuglsang-Frederiksen
- Department of Clinical Neurophysiology, Aarhus University Hospital, Nørrebrogade 44, DK-8000 Aarhus C, Denmark.
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Abstract
Quantitation has become an increasingly important part of clinical EMG. Most aspects of peripheral nerve and muscle function can be evaluated quantitatively using commonly available neurophysiologic methods. Because of the effects of collateral sprouting and reinnervation, techniques to measure the number of motor units supplying a muscle have been more difficult to develop. Motor unit number estimation (MUNE) consists of a number of different methods that evaluate the last unmeasured variable in nerve disease. The various MUNE techniques and their common technical issues will be reviewed, and potential clinical and research applications emphasized.
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Affiliation(s)
- Jasper R Daube
- Mayo Clinic Department of Neurology, 200 First Street SW, E8B, Rochester, MN 55905-0001, USA.
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McNulty PA, Macefield VG. Intraneural microstimulation of motor axons in the study of human single motor units. Muscle Nerve 2005; 32:119-39. [PMID: 15880485 DOI: 10.1002/mus.20324] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Single motor unit activity has been studied in depth since the first intramuscular electrodes were developed more than 70 years ago. Many techniques have been combined or used in isolation since then. Intraneural motor axon microstimulation allows the detailed study of single motor units in awake human subjects in a manner most analogous to that used in reduced animal preparations. A microelectrode, inserted percutaneously into a peripheral nerve, stimulates the axon of a single alpha-motoneuron at a site remote from the contracting muscle, allowing detailed analyses of the contractile properties of a single motor unit in an otherwise quiescent muscle, that is, without interference of simultaneously active motor units or the presence of an electrode within the muscle. The methods and results obtained using this technique are described and compared to those of other studies of single motor units in human subjects. Differences have been found between human and animal motor units and between motor units of various muscles. Studying human and animal motor units using an analogous technique provides insight into the interpretation of human data when results differ from animal data, and when human motor units cannot be examined in the same way, or at a similar level of detail, as animal motor units.
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Affiliation(s)
- Penelope A McNulty
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, NSW, Australia.
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Stålberg E, Fuglsang-Frederiksen A, Bischoff C. Quantitation and standardization in EMG and neurography. SUPPLEMENTS TO CLINICAL NEUROPHYSIOLOGY 2003; 53:101-11. [PMID: 12740983 DOI: 10.1016/s1567-424x(09)70144-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Affiliation(s)
- E Stålberg
- Department of Clinical Neurophysiology, University Hospital, S-75185 Uppsala, Sweden.
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24
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Abstract
Electrodiagnostic studies comprising electromyography (EMG) and nerve conduction studies (NCS) are well-established objective methods for the diagnosis, quantification and classification of polyneuropathies (PNP). This paper reviews examination techniques, their pathophysiological interpretation, examination strategies and diagnostic criteria for the diagnosis and classification of a PNP. The routine electrodiagnostic evaluation includes sensory NCSs performed with surface or needle electrodes, motor NCSs, F-wave studies and EMG by qualitative or quantitative techniques. Sensory NCSs and F-wave studies have a high sensitivity in PNPs and the different techniques complement each other. The distinction between a PNP with predominantly axonal loss and a PNP with predominantly demyelination is one of the major aims of the electrophysiological examination. There are, however, large variation in suggested criteria for predominantly demyelination. The degree of slowing in conduction taken to indicate demyelination varies between a decrease of 50 to 30% from mean of controls, distal latency prolongation criteria vary from 35% to 70% of mean of controls, F-wave latency prolongation criteria vary from 120% to 150% of upper limit of controls, and criteria for partial motor conduction block vary from 11 to 50% reduction of CMAP amplitude and/or area between proximal and distal stimulation. Needle EMG studies may be valuable in order to detect and quantify denervation activity, to assess chronicity by an evaluation of the extent of reinnervation, and to evaluate the topographical distribution of changes. It is concluded that electrodiagnostic studies are valuable in patients with suspected PNP and the results may have consequences for prognosis and therapy of individual patients. Large variation in examination techniques, strategies, interpretations and diagnostic criteria have been found among electromyographers and it is suggested that the value of electrodiagnostic studies may be further improved by international standardisation.
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Affiliation(s)
- B Johnsen
- Department of Clinical Neurophysiology, University Hospital, Nørrebrogade HH, DK 8000, Aarhus, Denmark
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Schulte-Mattler WJ, Georgiadis D, Tietze K, Zierz S. Relation between maximum discharge rates on electromyography and motor unit number estimates. Muscle Nerve 2000; 23:231-8. [PMID: 10639616 DOI: 10.1002/(sici)1097-4598(200002)23:2<231::aid-mus14>3.0.co;2-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
To improve quantitative assessment of motor unit recruitment by standard concentric needle electromyography (CNEMG), hypothenar muscles of 22 healthy subjects, 18 with denervation, and 10 with a myopathy were studied. Discharge rates of motor units were measured in CNEMG recordings comprising action potentials of, at most, 4 motor units. Motor unit number estimation (MUNE) was done using the manual incremental method. In controls, the upper 95% limit of the discharge rate was 16.2/s. In all subjects, a strong nonlinear correlation between the number of motor units and the maximal discharge rate was found (r = 0.88, P < 0.0001). Increased discharge rates were found in all but one of the paretic muscles with denervation, but in none of the myopathic muscles. Measurement of the discharge rate is a simple and reliable procedure. If the discharge rate is high in a hypothenar muscle, loss of motor units can be inferred. Moreover, the discharge rate value gives an estimate of the number of motor units in that muscle. Thus, we suggest that maximal discharge rate be included in electromyographic reports.
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Affiliation(s)
- W J Schulte-Mattler
- Neurologische Klinik und Poliklinik, Martin-Luther-Universität, Halle-Wittenberg, Ernst-Grube-Strasse 40, D-06097 Halle, Germany.
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Abstract
The interference pattern of the electrical activity of muscle can be quantified by amplitude measurements, different spike counting methods, and power spectrum analyses. Interference pattern analysis (IPA) methods are used to describe the degree of activation of different muscles, muscle fatigue, occupational work, muscles in chronic pain syndromes, disused muscle, and dystonic muscle treated with botulinum toxin. In patients with neuromuscular disorders, the turns/amplitude analysis is useful for diagnosis. High diagnostic yields can be obtained without force measurements, for example, by using the amplitude as an indicator of force (the peak ratio method) or plotting the amplitude against the turns (cloud analysis). The diagnostic possibilities of the power spectrum analysis and the motor unit firing rate obtained by decomposition techniques are still unclear.
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Affiliation(s)
- A Fuglsang-Frederiksen
- Department of Clinical Neurophysiology, Gentofte Hospital, Niels Andersens Vej 65, DK 2900 Hellerup, Denmark.
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Kamen G, Du DC. Independence of motor unit recruitment and rate modulation during precision force control. Neuroscience 1999; 88:643-53. [PMID: 10197782 DOI: 10.1016/s0306-4522(98)00248-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The vertebrate motor system chiefly employs motor unit recruitment and rate coding to modulate muscle force output. In this paper, we studied how the recruitment of new motor units altered the firing rate of already-active motor units during precision force production in the first dorsal interosseous muscle. Six healthy adults performed linearly increasing isometric voluntary contractions while motor unit activity and force output were recorded. After motor unit discharges were identified, motor unit firing rates were calculated before and after the instances of new motor unit recruitment. Three procedures were applied to compute motor unit firing rate, including the mean of a fixed number of inter-spike intervals and the constant width weighted Hanning window filter method, as well as a modified boxcar technique. In contrast to previous reports, the analysis of the firing rates of over 200 motor units revealed that reduction of the active firing rates was not a common mechanism used to accommodate the twitch force produced by the recruitment of a new motor unit. Similarly, during de-recruitment there was no tendency for motor unit firing rates to increase immediately following the cessation of activity in other motor units. Considerable consistency in recruitment behavior was observed during repeated contractions. However, firing rates during repeated contractions demonstrated considerably more fluctuation. It is concluded that the neuromuscular system does not use short-term preferential motor unit disfacilitation to effect precise regulation of muscular force output.
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Affiliation(s)
- G Kamen
- Department of Exercise Science, University of Massachusetts, Amherst 01003, USA
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Abstract
The purpose of this review is to consider some issues in the interpretation of the electromyogram (EMG) and to discuss current areas of controversy regarding use of the EMG. We consider the underlying physiology and origin of the EMG signal and offer an abbreviated discussion of measurement issues and selected factors that affect the characteristics of the EMG signal. We discuss many of the problems affecting interpretation, including normalization, crosstalk, and issues specific to contraction. In the final section, we consider topics of current interest in electromyography, such as muscle fatigue, task specificity, multichannel representations, and muscle fiber conduction velocity. We present, in addition, alternative analysis techniques. This review should interest researchers and clinicians who seek to obtain the valuable information inherent in the EMG while respecting the potential sources of variance and misinterpretation.
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Affiliation(s)
- G Kamen
- Department of Exercise Science, University of Massachusetts, Amherst 01003, USA
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Lefaucheur JP, Verroust J, Gherardi RK. Turns-amplitude analysis assessment of myopathies in HIV-infected patients. J Neurol Sci 1996; 136:148-53. [PMID: 8815162 DOI: 10.1016/0022-510x(95)00302-i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Electromyographic interference patterns during a gradual increase in force were studied by means of the turns-amplitude analysis in a series of HIV-infected patients with and without clinical, biological and histological signs of myopathy. Different parameters were evaluated to determine their sensitivity for the diagnosis of the myopathies that occur in this context. The studied parameters were the number of turns (NT), the mean amplitude of the turns (MA) and the ratio NT/MA (RTA). For each parameter, we compared the interest of mean values, calculated at moderate contraction, to that of peak values. In addition, the shape of the cloud of MA plotted versus NT data points was analyzed. The sensitivity of the turns-amplitude analysis was 95% for the diagnosis of myopathy when NT, MA and RTA were taken together into account, versus 80% in the cloud studies. Peak values were the most sensitive criteria, but mean values abnormalities were observed in some cases of zidovudine myopathy, indicating a potential usefulness of this quantitative EMG method in the differential diagnosis among myopathies in HIV-infected patients.
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Affiliation(s)
- J P Lefaucheur
- Department of Physiology, Centre Hospitalo-Universitaire Henri Mondor, Créteil, France
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Hassoun MH, Wang C, Spitzer AR. NNERVE: neural network extraction of repetitive vectors for electromyography--Part I: Algorithm. IEEE Trans Biomed Eng 1994; 41:1039-52. [PMID: 8001993 DOI: 10.1109/10.335842] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Artificial neural network (ANN) based signal processing methods have been shown to have significant robustness in processing complex, degraded, noisy, and unstable signals. A novel approach to automated electromyogram (EMG) signal decomposition, using an ANN processing architecture, is presented in this paper. Due to the lack of a priori knowledge of motor unit action potential (MUAP) morphology, the EMG decomposition must be performed in an unsupervised manner. An ANN classifier, consisting of a multilayer perceptron neural network and employing a novel unsupervised training strategy, is proposed. The ANN learns repetitive appearances of MUAP waveforms from their suspected occurrences in a filtered EMG signal in an autoassociative learning task. The same training waveforms are fed into the trained ANN and the output of the ANN is fed back to its input, giving rise to a dynamic retrieval net classifier. For each waveform in the data, the network discovers a feature vector associated with that waveform. For each waveform, classification is achieved by comparing its feature vector with those of the other waveforms. Firing information of each MUAP is further used to refine the classification results of the ANN classifier. Then, individual MUAP waveform shapes are derived and their firing tables are created.
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Affiliation(s)
- M H Hassoun
- Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI 48202
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