Motor Unit Potential Analysis Research Articles

Value of paraspinal muscle myography in diagnosing L5 radiculopathy

Introduction. Electromyography (EMG) is an important diagnostic tool for the evaluation of radiculopathy. Since 1990s a paraspinal mapping technique is used, which detects spontaneous activity in paraspinal muscles (PM) at the level of several vertebral segments. This modality seems to be highly conclusive for diagnosing radicular lesions. The main limitation of this method is spontaneous activity dependence on the disease duration.
 The aim of the study is to assess if PM EMG with motor unit potential (MUP) analysis is conclusive for diagnosing lumbar radiculopathy.
 Materials and methods. The study examined 58 patients (26 men and 32 women) aged 2673 years with MRI-confirmed symptomatic L5 mono-radiculopathy due to L4L5 herniated discs. The study assessed the neurological status and needle EMG of m. tensor fasciae latae (TFL) and PM at L4L5 and L3L4 levels on both symptomatic and healthy sides immediately before radicular microscopic decompression surgery. Surgery outcomes were evaluated by early and late postoperative questioning.
 Results. In PMs of the affected level and side, the average MUP duration was significantly different from opposite MUPs at the higher segment (р 0.001). At 3-month disease duration, a neurogenic pattern was significantly more frequent in affected PMs (p = 0.031) with neurogenic PM MUP rearrangement in 73.3% of patients. In the TFL (L5), neurogenic changes were reported only in 47.4% of patients. When compared to normal values, significant differences were found in the average duration of TFL MUPs (р = 0.001) and PM MUPs of the affected level and side (р 0.001) both in patients with motor disorders and those with isolated pain syndrome or sensory disorders.
 Conclusions. For diagnosing radiculopathy, the sensitivity of needle PM EMG is 82.6% (48/58; 95% CI 70.691.4%). Compared to limb myotome assessment, the highest informative value of PM EMG was reported in patients with the disease duration for up to 3 months. PM EMG was conclusive for diagnosing radicular lesions in patients with isolated pain syndrome or sensory disorders.

Increased prevalence of mild myopathic changes in the post-COVID-19 duration

ABSTRACT Objective There are reports of peripheral nerve and muscle involvement during or after coronavirus disease 2019 (COVID-19), even following a mild infection. Here, we aimed to analyze the objective findings regarding peripheral nerve, neuromuscular junction, and muscle function using electrophysiology in patients with a previous COVID-19 infection. Methods All consecutive patients with a history of COVID-19 were questioned for post-COVID-19 duration-related neurological complaints via Composite Autonomic Symptom Score-31 (COMPASS-31), modified Toronto Neuropathy score (mTORONTO), and Fatigue Severity Scale (FSS). Patients were dichotomized into two groups based on their scores in the questionnaire. Group 1 (patients with high scores in any area of the questionnaire) and Group 2 (patients with normal scores in all sections of the questionnaire). In the second step, Group 1 was invited to a preplanned hospital visit for electrophysiological analysis, including nerve conduction studies, repetitive nerve stimulation, needle electromyography (EMG), quantitative motor unit potential analysis (qMUP), and single fiber EMG. We included 106 patients in the study. According to the questionnaire, 38 patients constituted Group 1, and 68 formed Group 2. Results Of the 38 patients, 14 accepted and underwent preplanned electrophysiological examinations. Needle EMG revealed small, short, polyphasic MUPs with early recruitment, and qMUP analysis demonstrated an increased percentage of polyphasic potentials in three patients. The examinations in other patients were unremarkable. Conclusions The high prevalence of complaints and objective myopathic findings in our cohort implicated the role of muscle involvement in the post-COVID-19 duration. Considering the socioeconomic and psychological burden of the post-COVID-19 duration among individuals and societies, a better understanding of the symptoms and myopathy is warranted.

Efficacy of pyridostigmine (Mestinon) in the relief of patients with epiphora.

Although the mechanism is not clear, the inability of the orbicularis oculi muscle, especially the deeper segment (Horner muscle), is thought to be responsible in epiphora. This study evaluates the effect of the anticholinergic drug pyridostigmine (Mestinon) in patients with patent but dysfunctional lacrimal drainage system. Twenty patients with bilateral epiphora (mean age:60.78±6.49 yrs) were included in this study. Patients with a patent lacrimal irrigation test based on persistent and symptomatic epiphora, wiping >10 times daily or continuous tearing and grade 4-5 epiphora according to Munk scale, showing neuropathic involvement in the orbicularis oculi muscle by the quantitative motor unit potential (MUP) analysis method were evaluated prospectively. Fluorescein dye disappearance test (a semi-quantitative assessment of delayed tear outflow) together with a Schirmer test reading were performed in order to detect dry eye. The patients were evaluated for tear meniscus measurements by anterior segment optical coherence topography (OCT) and non-invasive tear break-up time (NI-BUT) was measured by Oculus Keratograph 5 M. Those with a NI-BUT value above 10s, without eyelid laxity, previous ocular surgery or ocular surface disease, or nasolacrimal duct obstruction, and who agreed to use the drug were included in the study. Each subject underwent OCT measurements of the lower tear meniscus of both eyes before and 15mins after taking Mestinon (1×60mg tablet). Upon measurement of the positive effect of the drug on tear meniscus height (TMH), the patients were asked to continue this regime daily for 1 month and then evaluated for relief in their epiphora complaints and any systemic drug side effects. A total of 20 patients (40 eyes) with bilateral epiphora were included in the study. All eyes had grade 4 Munk-score epiphora, Schirmer's test was within the normal range in all eyes (mean, 14±4mm), and patent lacrimal irrigation test. The lower mean TMH reductions 15min after Mestinon in the right and left eyes were 135.41±85.47 and 55.44±61.56mm, respectively, a statistically significant decrease in both eyes (p=0.001, p<0.01). The mean tear meniscus area (TMA) in the right and left eyes was 131.83±68.27mm2 and 62.72±50.57mm2, respectively; 15 mins after administration of Mestinon, the mean TMA in the right and left eyes was 77.27±48.34 and 59.18±44.74mm2, respectively (p=0.001, p<0.01). The mean decreases of 54.56±39.34mm2 in the right eye area and 3.53±42.32mm2 in the left eye area were statistically significant (p=0.041, p<0.05). Symptomatic relief for epiphora cannot be achieved with known treatment options due to lacrimal pump dysfunction. We found that pyridostigmine (Mestinon) provided relief in patients' complaints of epiphora consistent with a significant reduction in TMH levels.

Neurophysiological Hallmarks of Axonal Degeneration in CIDP Patients: A Pilot Analysis.

In this work, we aim to identify sensitive neurophysiological biomarkers of axonal degeneration in CIDP patients. A total of 16 CIDP patients, fulfilling the clinical and neurophysiological criteria for typical CIDP, treated with subcutaneous immunoglobulin (ScIg) (0.4 g/kg/week) were evaluated at baseline (before ScIg treatment) and after long-term treatment with ScIg (24 months) by clinical assessment scales, nerve conduction studies (NCS) and electromyography (EMG). Conventional and non-conventional neurophysiological parameters: motor unit potential (MUP) analysis, MUP thickness and size index (SI)] and interference pattern (IP) features were evaluated after long-term treatment (24 months) and compared with a population of 16 healthy controls (HC). An increase of distal motor latency (DML) and reduced compound motor action potential (CMAP) amplitude and area in CIDP patients suggest axonal damage of motor fibers, together with a significant increase of MUP amplitude, duration and area. Analysis of non-conventional MUP parameters shows no difference for MUP thickness; however, in CIDP patients, SI is increased and IP area and amplitude values are lower than HC. Despite clinical and neurophysiological improvement after ScIg treatment, neurophysiological analysis revealed axonal degeneration of motor fibers and motor unit remodeling. Correlation analysis shows that the axonal degeneration process is related to the diagnostic and therapeutic delay. MUP area and SI parameters can detect early signs of axonal degeneration, and their introduction in clinical practice may help to identify patients with the worst outcome.

Commentary: The electromyographic analysis of orbicularis oculi muscle in epiphora.

The simplest description of functional epiphora is “epiphora in the presence of a patent lacrimal drainage system, absence of any demonstrable anatomical abnormality, and absence of alternative etiology.”[1] It is a complex and underdiagnosed entity. Jones, in 1957, suggested dysfunctions of the lacrimal pump as the major aberration in functional epiphora.[2] Ali et al.,[3] in 2020, presented a new theory of lacrimal pump functions based on their anatomical, ultrastructural, and immunohistochemical studies of the Horner–Duverney (HD) muscle. The diagnosis of functional epiphora is by a series of examinations and imaging to exclude other causes. In essence, it is a diagnosis of exclusion. Hence, a careful clinical examination along with magnetic resonance dacryocystography or dacryoscintigraphy are helpful.[4] The data on the use of electromyography (EMG) and its characteristics in such cases is evolving. The present study succinctly described the electromyographic response of the deeper heads of the orbicularis oculi muscle using the motor unit potential (MUP) analysis.[5] A statistically significant change in the amplitude, duration, number of phases, turns, and rise time were noted between the functional epiphora cohort and normal volunteers. The EMG was suggestive of a neurogenic origin of lacrimal pump weakness in patients with functional epiphora. Apart from the earlier known motor innervation by the branches of the facial nerve, recent other explorations have pointed to the presence of an extensive network of additional sensory, sympathomimetic, and parasympathetic innervation of the HD muscle.[3] Hence, the EMG needs to be further explored. Although the present study had several limitations, including difficulties with the not very conclusive results, it is nevertheless an excellent strategy to begin answering the proposed research query. To what extent can an EMG help appreciate the complex physiology of the HD muscle is yet to be deciphered. Although EMG partly enhances our understanding of the orbicularis oculi behavior in different clinical settings, it does not directly assess the lacrimal pump mechanisms of tear flow. Besides, it is unhelpful to assess other mechanisms in tear flow dynamics such as capillary action, gravity, and pressure gradient. At present, EMG of the HD muscle has limited clinical worth and, at best, can be of adjunctive value. However, its utility as a research tool has the potential to further our understanding of the lacrimal pump. Financial disclosure Mohammad Javed Ali receives royalties from Springer for the textbook “Principles and Practice of Lacrimal Surgery,” “Atlas of Lacrimal Drainage Disorders,” and “Video Atlas of Lacrimal Surgery.”

The electromyographic analysis of orbicularis oculi muscle in epiphora.

Purpose:Functional epiphora is a clinical condition that presents with the complaint of watery eyes, but without anatomical stenosis in the lacrimal drainage system. Although the mechanism is not clear, there are various possibilities involving the movement of the orbicularis oculi muscle, especially its deeper segment (Horner’s muscle). We aimed to evaluate the function of the orbicularis oculi muscle in patients with patent, but dysfunctional lacrimal drainage system using a quantitative motor unit potential (MUP) analysis.Methods:Twenty-eight patients with functional epiphora (mean age = 59 years) and a control group of 28 volunteers were included in the study. Inclusion criteria were persistent and symptomatic epiphora or wiping >10 times per day and diagnosis confirmation by lacrimal irrigation test. Electromyography (EMG) was performed on the deeper segment of the orbicularis oculi muscle (medial and lateral parts). MUP parameters (duration time, amplitude, number of phases, number of turns, area, rise time, and thickness) were evaluated in both groups. Any increase in amplitude, prolongation time (>14 ms), number of turns, and satellite potential was taken as characteristic of the neurogenic type of epiphora, whereas shortened motor unit duration time, increased phase number, and low amplitude are the features of myopathic type.Results:Upon MUP analysis of the medial and lateral orbicularis oculi muscle, the increase in duration and thickness values in the medial part and the increase in duration, amplitude, area, and thickness values of the lateral part were found to be statistically significant in the patient group compared to the control group (P < 0.001). In the evaluation of the patients’ medial and lateral orbicularis oculi muscle, the increase in phase values and decrease in amplitude, area, and rise time values were found to be statistically significant (P = 0.024, P < 0.001, P < 0.001, and P = 0.010, respectively).Conclusion:These data show that functional epiphora is due to neurogenic damage of the orbicularis oculi muscle and should be investigated in more detail.

Motor unit potential analysis in Myasthenia gravis disease

Motor unit action potential (MUAP) analysis is a test used to evaluate neuromuscular diseases (myopathy, neuropathy and neuromuscular junction disorders). Myasthenia gravis is an autoimmune disease affects neuromuscular junction that is diagnosed by clinical, pharmacological, serological and electrophysiological tests. This study was conducted to estimate parameters of MUAP analysis test in myasthenic patients based on our own control values.

WS4.2. My Approach to Quantitative EMG (with Demonstration)

The routine needle EMG examination is usually performed by observing the waveforms on the display screen and listening to their sound. It is subjective. Quantitative analysis (QA) is considered time consuming and not used. In this workshop, I will describe the “objective and interactive” approach. It adds elements of QA to record and measure EMG signals. It does not add time for analysis, and provides quantitative data to document abnormalities. The techniques of recording and measurements will be demonstrated. This includes use of dual time base, amplitude trigger, cascaded traces, etc. The “quality” control of the recording will be emphasized. The various signal displays help better assessment of amplitude, duration, phases, turns, stability, and firing rate of motor unit potentials (MUPs). It is also useful to assess the fullness of the interference pattern and its amplitude. The additional information captured by this approach will improve the quality of the needle EMG examination. Finally, I will demonstrate the fully automated methods for MUP analysis (Multi-motor unit analysis) and IP (Turns & amplitude). This requires just a few minutes per muscles. Using modern algorithms, QA is not time consuming. It should be included in the laboratory routine.

Quantitative motor unit potential analysis and nerve conduction studies for detection of subclinical peripheral nerve dysfunction in patients with compensated liver cirrhosis

BackgroundPeripheral neuropathy is an underestimated problem of compensated liver cirrhosis despite its negative effect on quality of life. The aim was to assess the role of meticulous electrophysiological screening (nerve conduction responses and quantitative motor unit potential analysis) of subclinical peripheral nerve dysfunction in patients with compensated cirrhosis and also to explore its relations with different characteristics of liver disease. Severity of cirrhosis was assessed by Child–Pugh and albumin-bilirubin (ALBI) scores.ResultsPrevalence of hepatic neuropathy (HN) was 82%. It involved sensory and motor fibers (66%), and its pathophysiology was axonal (53.7%) or mixed axonal and demyelinating (46.3). The most sensitive discriminating tests were ulnar sensory conduction velocity (area under curve (AUC) = 0.915) and peak latency (AUC = 0.887), peroneal motor conduction velocity (AUC = 0.885), ulnar distal motor latency (AUC = 0.842), and first dorsal interosseous number of phases (AUC = 0.736). HN showed significant correlation with the severity of liver disease assessed by both child (P = 0.029) and ALBI (P = 0.016) scores and also correlated with the low serum albumin level (P = 0.001).ConclusionsSubclinical mild axonal polyneuropathy is very common in post-hepatitis C compensated cirrhosis picked up by meticulous electrophysiological testing, and it is related to severity of liver cirrhosis and low serum albumin level.

Motor Unit Potential Analysis of the Palatal Muscles in Obstructive Sleep Apnea Syndrome

Objectives: Among different theories about pathogenesis of obstructive sleep apnea syndrome (OSAS), dysfunction of upper airway muscles still awaits to be delineated. The aim of this study is to examine differences in motor unit potential (MUP) parameters of upper airway muscles between OSAS patients and healthy controls. Methods: Ten male patients diagnosed as OSAS by whole-night polysomnography were analyzed for MUP parameters of genioglossus (GG) muscle, palatoglossus muscle (PG), palatopharyngeus muscle, and uvular (U) muscle. Eight healthy volunteer men matched by age were enrolled as a control group. Results: In PG muscle parameters, the mean MUP area was significantly smaller (P = 0.040) in OSAS patients than those in controls. On the other hand, U muscle parameters showed a significantly larger mean MUP area (P = 0.022) in OUAS patients compared to those in the control group. In OSAS patients, the percentages of polyphasic MUPs of GG and PG muscles were significantly high (P &lt; 0.001 and P = 0.05, respectively). Body mass index was positively correlated with number of phases of GG muscle (r s = 0.63, P &lt; 0.05) and duration of U muscle (r s = 0.71, P &lt; 0.05) in OSAS patients. Other MUP parameters of palatal muscles were similar between the two groups. Conclusion: Our results showed that, although mild in severity, structural neurogenic and myogenic changes characterized as mild and nonuniform MUP changes may co-exist in OSAS patients. These changes in palatal muscles may be attributed to compensatory adaptation of muscle fibers to other precipitating factors in OSAS.

Absence of hyperexcitability of spinal motoneurons in patients with amyotrophic lateral sclerosis.

•Amyotrophic lateral sclerosis (ALS) motoneurons become hypoexcitable with disease progression in experimental models, raising questions about the neural hyperexcitability supported by clinical observations. •A variant of the ∆F method, based on motor unit discharge frequency modulations during recruitment and derecruitment, has been developed to investigate the motoneuron capacity to self-sustained discharge in patients. •The modulation of motor unit firing rate during ramp contraction and vibration-induced recruitment are modified in ALS, suggesting lower motoneuron capacity to self-sustained discharge, which is a sign of hypoexcitability. •∆F-D decreases with functional impairment and its reduction is more pronounced in fast progressors. •In patients with ALS, motoneurons exhibit hypoexcitability, which increases with disease progression. Experimental models have primarily revealed spinal motoneuron hypoexcitability in amyotrophic lateral sclerosis (ALS), which is contentious considering the role of glutamate-induced excitotoxicity in neurodegeneration and clinical features rather supporting hyperexcitability. This phenomenon was evaluated in human patients by investigating changes in motor unit firing during contraction and relaxation. Twenty-two ALS patients with subtle motor deficits and 28 controls performed tonic contractions of extensor carpi radialis, triceps brachialis, tibialis anterior and quadriceps, aiming to isolate a low-threshold unit (U1) on the electromyogram (EMG). Subsequently, they performed a stronger contraction or tendon vibration was delivered, to recruit higher threshold unit (U2) for 10s before they relaxed progressively. EMG and motor unit potential analyses suggest altered neuromuscular function in all muscles, including those with normal strength (Medical Research Council score at 5). During the preconditioning tonic phase, U1 discharge frequency did not differ significantly between groups. During recruitment, the increase in U1 frequency (∆F-R) was comparable between groups both during contraction and tendon vibration. During derecruitment, the decrease in U1 frequency (∆F-D) was reduced in ALS regardless of the recruitment mode, particularly for ∆F-R<8Hz in the upper limbs, consistent with the muscle weakness profile of the group. ∆F-D was associated with functional disability and its reduction was more pronounced in patients with more rapid disease progression rate. This in vivo study has demonstrated reduced motoneuron capacity for self-sustained discharge, and further supports that motoneurons are normo- to hypoexcitable in ALS patients, similar to observations in experimental models.

Platform Session – Electromyography: Two novel electrophysiological methods: In the evaluation of ALS patients – MScan MUNE and MVRC

Introduction Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive loss of motor units, but electromyography (EMG) with quantitative motor unit potential (MUP) analysis does not directly quantify the denervation process. A more extensive clinical use of Motor Unit Estimation Methods: (MUNE), like MScan MUNE, could hence be of potentially great value. Muscle Velocity Recovery Cycle (MVRC) recordings can provide in vivo information about changes in muscle fiber membrane properties, and may enlighten the effect of the denervation process on the muscle fibers. The aim of this study was to examine the clinical utility of MScan MUNE and MVRC in ALS patients; which also contribute to a better understanding of disease pathophysiology. Methods 27 ALS patients and 23 age and sex-matched healthy control subjects were included. All participants were evaluated electrophysiologically by a standard quantitative EMG and by the two novel methods: MScan MUNE and MVRC, all in the anterior tibial muscle (TA). MScan MUNE, MVRC and EMG parameters were compared between ALS patients and healthy controls using parametric unpaired t-tests. ROC curves were used to test how these methods distinguish patients from healthy controls. MVRC parameters were correlated to EMG results and MScan parameters using linear regression analysis. Results The MScan MUNE value for ALS patients (55 (95% CI: 42–68)) was significantly lower than for the healthy controls (108 (95% CI: 98–117)) (p 5 sites) and controls. And there was no significant correlation between MVRC and MUP parameters or incidence of spontaneous activity. Conclusion The novel MScan MUNE method is a sensitive quantitative measure of loss of motor units in ALS patients in TA. The finding of no difference in MVRC for ALS patients compared to healthy controls indicate, that the muscle fiber membranes are not prominently affected by the denervation process. This may be explained by the compensatory process of collateral reinnervation, which initially is strong and ensures that the vast majority of muscle fibers are innervated and behave normally.

S130. Muscle velocity recovery cycles in intensive care unit patients

Introduction Critical illness myopathy is a disabling condition that develops in critically ill patients and presents as diffuse muscle weakness and failure to wean from mechanical ventilation. Muscle Velocity Recovery Cycles (MVRC) enable in vivo assessment of muscle membrane properties. We aimed in this study to examine whether MVRC may detect changes in patients with delayed wean from mechanical ventilation. Methods Six patients (mean age: 52.4 ± 5.8) with failure to wean from mechanical ventilation and 24 healthy controls (mean age: 53.2 ± 3.2) were prospectively included. In addition to conventional nerve conduction studies (NCS) and electromyography, all patients were examined by MVRC in the anterior tibial muscle using Qtrac-software. MVRC parameters consisted of muscle relative refractory period (MRRP) and early and late supernormality after 1, 2 or 5 conditioning stimuli. Results Motor NCS of peroneal and tibial and sensory NCS of sural nerves were normal. None of the patients had spontaneous activity and quantitative motor unit potential analysis was normal. MRRP was significantly prolonged in patients (5.9 ± 0.7) compared to healthy controls (3.6 ± 0.09), and early supernormality was lower in patients than healthy controls after 2 (5.1 ± 1.1 vs 11.3 ± 0.4) and 5 (4.6 ± 1.1 vs 13.5 ± 0.4) conditioning stimuli. Similarly, late supernormality was decreased in patients compared to healthy controls after 1 (2.4 ± 0.5 vs 3.9 ± 0.2), 2 (1.4 ± 0.4 vs 2.8 ± 0.1) and 5 (3.1 ± 0.8 vs 7.9 ± 0.2) conditioning stimuli (t test, p Conclusion Changes in MVRC in patients with failure to wean from mechanical ventilation may suggest critical illness myopathy in these patients. MVRC may detect changes in the muscle membrane before spontaneous activity and motor unit potential changes are seen. Future studies with larger patient groups and follow-up examinations are needed.

The utility of motor unit number estimation methods versus quantitative motor unit potential analysis in diagnosis of ALS

ObjectiveTo compare the diagnostic utility of motor unit number estimation (MUNE) methods to motor unit potential (MUP) analysis in amyotrophic lateral sclerosis (ALS). MethodsTwenty-five patients (1 definite, 11 probable, 9 possible ALS and 4 progressive muscular atrophy) and 22 healthy controls were prospectively included. Quantitative MUP analysis and three MUNE methods; Multiple Point Stimulation MUNE (MPS), Motor Unit Number Index (MUNIX) and MScanFit MUNE (MScan) were done in abductor pollicis brevis muscle. The sensitivities were compared by McNemar chi-square test. MUNE, MUP and revised ALS Functional Rating Scale (ALSFRS-R) parameters were correlated by regression analysis. ResultsThe sensitivities of MPS (76%) and MScan (68%) were higher than MUP duration (36%) and amplitude (40%) in detecting motor unit loss (p < 0.05). MUNE methods increased the categorical probability from possible to probable ALS in 4 patients (16%). There was only significant correlation between ALSFRS-R and MScan (r = 0.443, p = 0.027) among the electrophysiological tests. MUNE methods did not correlate to MUP parameters. ConclusionsMUNE methods are more sensitive in showing abnormality than MUP analysis. SignificanceMUNE methods, in particular MScan, may have the potential to be implemented in the clinical practice for diagnosis and follow-up of neuromuscular disorders particularly ALS.

Quantitative facial electromyography monitoring after hypoglossal-facial jump nerve suture.

Objectives/HypothesisThe time course of the reinnervation of the paralyzed face after hypoglossal‐facial jump nerve suture using electromyography (EMG) was assessed. The relation to the clinical outcome was analyzed.Study DesignRetrospective single‐center cohort studyMethodsReestablishment of motor units was studied by quantitative EMG and motor unit potential (MUP) analysis in 11 patients after hypoglossal‐facial jump nerve suture. Functional recovery was evaluated using the Stennert index (0 = normal; 10 = maximal palsy).ResultsClinically, first movements were seen between 6 and >10 months after surgery in individual patients. Maximal improvement was achieved at 18 months. The Stennert index decreased from 7.9 ± 2.0 preoperatively to a final postoperative score of 5.8 ± 2.4. EMG monitoring performed for 2.8 to 60 months after surgery revealed that pathological spontaneous activity disappeared within 2 weeks. MUPs were first recorded after the 2nd month and present in all 11 patients 8–10 months post‐surgery. Polyphasic regeneration potentials first appeared at 4–10 months post‐surgery. The MUP amplitudes increased between the 3rd and 15th months after surgery to values of control muscles. The MUP duration was significantly increased above normal values between the 3rd and 24th months after surgery.ConclusionReinnervation can be detected at least 2 months earlier by EMG than by clinical evaluation. Changes should be followed for at least 18 months to assess outcome. EMG changes reflected the remodeling of motor units due to axonal regeneration and collateral sprouting by hypoglossal nerve fibers into the reinnervated facial muscle fibers.Level of Evidence3b.

Template-operated MUP analysis is not accurate in the diagnosis of myopathic or neuropathic changes in the diaphragm

The aim of this study was to evaluate the quantitative motor unit potential (MUP) analysis in the diagnosis of myopathy and neuropathy of the diaphragm. Diaphragm template-operated quantitative EMG were performed in 30 patients with myotonic dystrophy type 1 (DM1), 17 with myotonic dystrophy type 2 (DM2) and 40 with amyotrophic lateral sclerosis (ALS). Low MUP amplitude precluded MUP analysis in 21% of DM1 patients. Only a single DM1 patient had EMG findings consistent with myopathy. In this patient, and another 4 DM1 and 3 DM2 patients, findings were consistent with neuropathy. Neuropathic MUP changes were found in 92% of ALS patients, but due to motor neuron cell loss in only 60% MUPs analyses could be done. Phrenic nerve conduction studies correlated with respiratory function tests, whereas MUP parameters did not. Quantitative MUP analysis was not able to adequately sample diaphragm MUPs in patients with chronic myopathy or motor neuronopathy.

O25 Motor unit number estimation methods compared to quantitative motor unit potential analysis in amyotrophic lateral sclerosis

Objectives To compare the sensitivity of MUNE methods to quantitative motor unit potential (MUP) analysis in amyotrophic lateral sclerosis (ALS). Methods Twenty-four patients (1 definite, 11 probable and 8 possible ALS according to awaji criteria as reference standard, and 4 progressive muscular atrophy) were included. Patients were evaluated by revised ALS functional rating scale (ALSFRS-R). In all patients, quantitative MUP analysis and three MUNE methods; MScanFit MUNA (MScan), multiple point stimulation MUNE (MPS), and Motor Unit Number Index (MUNIX) were done in abductor pollicis brevis (APB). MUNE results were compared to 20 age-matched healthy controls and EMG to laboratory controls. The sensitivity of each methods was compared using McNemar chi-square test. MUNE values and MUP parameters were correlated to ALSFRS-R by regression analysis. Results MScan (70%) and MPS (61%) more frequently showed abnormality than MUP duration (35%) whereas only MScan was more often abnormal than MUP amplitude (39%) ( p r = 0.42, p = 0.03) but not MPS ( r = 31), MUNIX ( r = 35), MUP duration ( r = 0.19) or amplitude ( r = 0.09). Discussion MUP analysis gives information about reinnervation, but not about loss of motor units. Therefore MUNE methods may be preferable in ALS electrodiagnosis. Conclusions MUNE methods, particularly MScan, had higher sensitivities than MUP analysis in detection of abnormality in APB and were correlated better to ALSFRS-R. Significance MScan is a promising novel method which should be considered in diagnosis and monitoring disease progression in ALS.

O21 Peak ratio and motor unit potential analyses in detection of chronic neurogenic changes in amyotrophic lateral sclerosis

Objectives Peak ratio analysis is a quantitative way of analyzing interference pattern by turns-amplitude analysis. We aimed in this study to compare the sensitivities of peak ratio analysis and quantitative motor unit potential (MUP) analysis in detecting chronic neurogenic changes in amyotrophic lateral sclerosis (ALS). Methods Twenty-two patients (1 definite, 7 probable, and 9 possible ALS according to Awaji criteria as reference standard, and 5 progressive muscular atrophy) were prospectively included. Quantitative MUP and peak ratio analyses were done in 22 biceps brachialis (BB), 22 tibialis anterior (TA) and 18 abductor pollicis brevis (APB) muscles on the least affected side. Results were compared to laboratory controls. The sensitivity of MUP duration and peak ratio was compared using the McNemar chi-square test. Results Peak ratio analysis was more frequently abnormal than MUP analysis in BB (59% vs. 23%), and TA (59% vs. 18%) muscles ( p Discussion Peak ratio analysis sampled at stronger effort detected more frequently chronic neurogenic changes than MUP analysis recruited at weak effort. Conclusions Peak ratio analysis may provide earlier detection of chronic neurogenic changes, thereby facilitating earlier diagnosis of ALS. Significance Peak ratio analysis which is available in commercial EMG machines should be considered in the electrodiagnostic investigation of ALS.

O128 Evaluation of muscle fibers diameter using analysis of motor unit potentials

Objectives The study was to develop a method for evaluation of muscle fibers diameter by application an approximation of motor unit morphology using analysis of motor unit potentials (MUPs). Verify the utility and reliability. Method The principle of the approximation method rests upon decomposition of MUP into single fiber potentials to determine the morphology of muscle fibers generating these potentials and their diameters and distribution within motor unit territory. The typical and atypical MUPs of various shapes have been analysed. Results Using approximation method the morphology of motor unit generating the selected MUP has been determined including muscle fibers diameter. Contribution of each fiber to the MUP waveforms has been evaluated. Correlation between some characteristic MUP’s parameters and morphological features has been indicated. Conclusion MUP analysis using an approximation method emerged as a useful tool for the interpretation of MUPs. It enables to get an insight into motor unit morphology and therefore increases understanding of the way the motor unit structure correlates with function. The ability to quantify the fibers diameter can add significantly to the motor unit potentials examination. It may help study of muscle fiber diameter variability and thus compliment the muscle biopsy studies. Significance Extending the amount of information available from EMG examinations.

3-2-12. Size index revisited: Verification by increased number of subjects

Size Index (SI) is a motor unit potential (MUP) parameter in concentric needle EMG, which can sensitively discriminate between control and neurogenic MUPs. We also proposed the revised SI (rSI) using a logarithmic scale for area/amp. In this study, we greatly increased the number of patients, and investigated the utility of SI and rSI for both neurogenic and myogenic MUPs. The biceps brachii (BB) and tibialis anterior (TA) muscles were investigated. The study population was 1619 control MUPs (26 subjects), 340 neurogenic MUPs (10 subjects), and 498 myogenic MUPs (14 subjects) in BB, and 1245 control MUPs (23 subjects), 566 neurogenic MUPs (19 subjects), and 473 myogenic MUPs (13 subjects) in TA. The coefficient for area/amp was variously changed for SI and rSI. As results, the maximum sensitivity of SI for neurogenic MUPs was 84% for BB and 66% for TA. Similar sensitivity was achieved using rSI. That for rSI for myogenic MUPs was 9% for BB and 25% for TA. These were higher than any other conventional parameters. By choosing appropriate coefficients, SI (for neurogenic MUPs) and rSI (for both neurogenic and myogenic MUPs) will enhance the utility of MUP analyses.