Muscle ultrasonography as an additional diagnostic tool for the diagnosis of amyotrophic lateral sclerosis

Neuromuscular Ultrasound in Polyneuropathies

Neuromuscular ultrasound is a painless, radiation-free, high-resolution imaging technique for assessing the peripheral nervous system. It can accurately depict changes in the nerves and muscles of individuals with neuromuscular conditions, and it is therefore a robust diagnostic tool for the assessment of individuals with polyneuropathies. This review will outline the typical ultrasonographic changes found in a wide variety of polyneuropathies. In general, demyelinating conditions result in greater nerve enlargement than axonal conditions, and acquired conditions result in more patchy nerve enlargement compared to diffuse nerve enlargement in hereditary conditions. This review is data-driven, but more nuanced anecdotal findings are also described. The overall goal of this paper is to provide clinicians with an accessible review of the ultrasonographic approaches and findings in a wide variety of polyneuropathies.

Neurophysiological and imaging biomarkers of lower motor neuron dysfunction in motor neuron diseases/amyotrophic lateral sclerosis: IFCN handbook chapter

This chapter discusses comprehensive neurophysiological biomarkers utilised in motor neuron disease (MND) and, in particular, its commonest form, amyotrophic lateral sclerosis (ALS). These encompass the conventional techniques including nerve conduction studies (NCS), needle and high-density surface electromyography (EMG) and H-reflex studies as well as novel techniques. In the last two decades, new methods of assessing the loss of motor units in a muscle have been developed, that are more convenient than earlier methods of motor unit number estimation (MUNE),and may use either electrical stimulation (e.g. MScanFit MUNE) or voluntary activation (MUNIX). Electrical impedance myography (EIM) is another novel approach for the evaluation that relies upon the application and measurement of high-frequency, low-intensity electrical current. Nerve excitability techniques (NET) also provide insights into the function of an axon and reflect the changes in resting membrane potential, ion channel dysfunction and the structural integrity of the axon and myelin sheath. Furthermore, imaging ultrasound techniques as well as magnetic resonance imaging are capable of detecting the constituents of morphological changes in the nerve and muscle. The chapter provides a critical description of the ability of each technique to provide neurophysiological insight into the complex pathophysiology of MND/ALS. However, it is important to recognise the strengths and limitations of each approach in order to clarify utility. These neurophysiological biomarkers have demonstrated reliability, specificity and provide additional information to validate and assess lower motor neuron dysfunction. Their use has expanded the knowledge about MND/ALS and enhanced our understanding of the relationship between motor units, axons, reflexes and other neural circuits in relation to clinical features of patients with MND/ALS at different stages of the disease. Taken together, the ultimate goal is to aid early diagnosis, distinguish potential disease mimics, monitor and stage disease progression, quantify response to treatment and develop potential therapeutic interventions.

Whole-body fasciculation detection in amyotrophic lateral sclerosis using motor unit MRI

OBJECTIVE

Compare fasciculation rates between amyotrophic lateral sclerosis (ALS) patients and healthy controls in body regions relevant for diagnosing ALS using motor unit MRI (MUMRI) at baseline and 6 months follow-up, and relate this to single-channel surface EMG (SEMG).

METHODS

Tongue, biceps brachii, paraspinals and lower legs were assessed with MUMRI and biceps brachii and soleus with SEMG in 10 healthy controls and 10 patients (9 typical ALS, 1 primary lateral sclerosis [PLS]).

RESULTS

MUMRI-detected fasciculation rates in typical ALS patients were higher compared to healthy controls for biceps brachii (2.40 ± 1.90 cm-3min-1vs. 0.04 ± 0.10 cm-3min-1, p = 0.004), paraspinals (1.14 ± 1.61 cm-3min-1vs. 0.02 ± 0.02 cm-3min-1, p = 0.016) and lower legs (1.42 ± 1.27 cm-3min-1vs. 0.13 ± 0.10 cm-3min-1, p = 0.004), but not tongue (1.41 ± 1.94 cm-3min-1vs. 0.18 ± 0.18 cm-3min-1, p = 0.556). The PLS patient showed no fasciculation. At baseline, 6/9 ALS patients had increased fasciculation rates compared to healthy controls in at least 2 body regions. At follow-up every patient had increased fasciculation rates in at least 2 body regions. The MUMRI-detected fasciculation rate correlated with SEMG-detected fasciculation rates (τ = 0.475, p = 0.006).

CONCLUSION

MUMRI can non-invasively image fasciculation in multiple body regions and appears sensitive to disease progression in individual patients.

SIGNIFICANCE

MUMRI has potential as diagnostic tool for ALS.

Neuromuscular ultrasound in combination with nerve conduction studies helps identify inflammatory motor neuropathies from lower motor neuron syndromes

BACKGROUND AND PURPOSE

Identifying patients with inflammatory motor neuropathies (IMNs) is warranted since effective treatments are available and the prognosis of these patients differs from that of amyotrophic lateral sclerosis patients.

METHODS

Between January 2019 and May 2022, 102 consecutive treatment-naïve lower motor neuron syndrome (LMNS) patients were recruited; these patients were suspected of having multifocal motor neuropathy, pure motor chronic inflammatory demyelinating polyneuropathy or amyotrophic lateral sclerosis with initial lower motor neuron presentation. Neuromuscular ultrasound (US) and nerve conduction studies (NCSs) were conducted at baseline. Relevant diagnostic investigations were performed if clinically warranted. The proposed US evidence of IMN was as follows: (i) nerve enlargement at ≥1 of the predetermined sites or (ii) absence of high intensity fasciculations in predefined muscle groups. Final diagnoses were made by experienced physicians after a prolonged follow-up period (≥12 months). IMN patients were defined as LMNS patients who experienced convincing improvements in response to immunotherapies. IMN patients without electrodiagnostic demyelinating features were diagnosed with treatment-responsive LMNS (TR-LMNS).

RESULTS

In total, 16 patients were classified as IMN, including nine chronic inflammatory demyelinating polyneuropathy/multifocal motor neuropathy patients and seven TR-LMNS patients. Six TR-LMNS patients were identified by neuromuscular US. The sensitivity and specificity of NCSs, nerve US and muscle US were 56.3% and 100%, 43.8% and 90.7% and 68.8% and 97.7%, respectively. When these three modalities were combined, the sensitivity and specificity were 93.8% and 88.4%, respectively.

CONCLUSION

Neuromuscular US studies are supplementary modalities to NCSs, and the combined use of these techniques might improve the identification of IMNs in LMNS patients.

Nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies

PURPOSE OF REVIEW

The purpose if this review is to provide an overview of the available data on the use of nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies.

RECENT FINDINGS

During the last decade, nerve ultrasound has been established as a complementary tool for the evaluation of morphological changes mostly for immune-mediated polyneuropathies. Through the development of ultrasound protocols for evaluation of disease-specific sites, nerve ultrasound has proven to be a practical, widely available, reproducible diagnostic tool with no relevant contraindications.

SUMMARY

Cross-sectional area, echogenicity, morphology of the individual nerve fascicles, thickness of the epineurium, vascularization and mobility of the nerve are the main parameters evaluated with nerve ultrasound in polyneuropathies. Patients with typical chronic inflammatory demyelinating polyneuropathy show multifocal nerve enlargements easily visible on the upper extremities and the brachial plexus, whereas its variants show focal nerve enlargements. On the other hand, axonal neuropathies including diabetic neuropathy present with isolated nerve enlargement mostly in compression sites.

The Sensitivity of Quantitative Sonographic Assessment of Muscle Thickness for Amyotrophic Lateral Sclerosis Diagnosis

PURPOSE

In the current proof-of-concept study, we aimed to examine the sensitivities and specificities of previously reported normal values for muscle ultrasound thickness in amyotrophic lateral sclerosis.

METHODS

Muscle ultrasound was performed in 65 healthy control subjects and 91 amyotrophic lateral sclerosis patients using a standardized assessment of eight relaxed muscles and four contracted muscles. Normal values for muscle thickness were determined as values above the 5th percentile stratified by age and gender using the weighted average method. Sensitivity for amyotrophic lateral sclerosis diagnosis was determined for muscles with and without the addition of muscle contraction.

RESULTS

Amyotrophic lateral sclerosis patients showed reduced muscle sum thickness both in relaxed and in contracted states compared with control subjects. Muscle ultrasound of muscles with and without contraction showed excellent diagnostic accuracy for differentiating amyotrophic lateral sclerosis patients from control subjects (area under curve = 0.96, sensitivity: 93%-95%, specificity: 84-87). Muscle ultrasound sensitivity was lower within 6 months of symptom onset (83%) compared with longer disease duration (>92%).

CONCLUSIONS

Quantitative sonographic assessment of muscle thickness can be complementary in the diagnosis of amyotrophic lateral sclerosis with excellent accuracy for differentiating patients from healthy subjects, and might be useful in other neuromuscular disorders, although additional studies are required.

Sitting vs. supine ultrasound measurements of the vastus medialis: correlations with MRI measurements and age considerations

BACKGROUND

Muscle thickness (MT) and echo intensity (EI) measurements are ultrasound alternatives to magnetic resonance imaging (MRI) for evaluating muscle quantity and quality. The vastus medialis (VM) is a clinically important muscle, and assessment methods that most accurately reflect its quantity and quality are required. This study aimed to examine the correlation between MT and EI measured in the supine and sitting postures with corresponding MRI-measured muscle quantity and quality indices.

METHODS

In total, 134 adults (91 older and 43 young) participated in this study. Ultrasound images of the VM were acquired in the supine and sitting postures, and MT and EI were measured. The cross-sectional area (CSA), muscle volume (MV), and intramuscular adipose tissue (intraMAT) of the VM were evaluated from MRI images using T1-weighted and Dixon methods. Pearson's coefficients were used to quantify the correlation strength amongst pairs of dependent variables. Meng's test was used to test for correlation coefficient differences between the two measurement postures (supine and sitting).

RESULTS

The correlation coefficients amongst MT, CSA, and MV were significantly higher in the sitting posture than in the supine posture. EI measured in the supine and sitting postures correlated significantly with intraMAT, and in young individuals, these correlation coefficients were significantly higher in the sitting posture than in the supine posture.

CONCLUSIONS

These findings suggest that assessment of VM muscle quantity in the sitting posture is superior for young and older individuals, and assessment of VM muscle quality in the sitting posture is most effective in younger individuals.

Bedeutung der Muskelsonographie in der Detektion von Faszikulationen bei der ALS

Bei der amyotrophen Lateralsklerose sind Faszikulationen häufig bereits in frühen Stadien in mehreren Körperregionen vorzufinden und haben daher Eingang in die entsprechenden Leitlinien und Diagnosekriterien gefunden. Während die invasive EMG-Diagnostik unverzichtbar zum Nachweis von akut- und chronisch-neurogenen Veränderungen des elektrischen Signalverhaltens motorischer Einheiten und zur Bestätigung von Faszikulationspotenzialen bleibt, bietet die Muskelsonographie ein hochsensitives Verfahren, um schnell und nicht-invasiv Faszikulationen in den verschiedenen Muskel-Etagen zu erfassen. In dieser Übersichtsarbeit stellen wir die bisherigen Daten zum Einsatz der Muskelsonographie zur Faszikulationsdetektion dar. Durch ihren Einsatz ermöglicht die Muskelsonographie im klinischen Alltag eine zielgerichtete und hierdurch aussagekräftigere EMG-Diagnostik. Aktuelle Forschungsstudien zielen darauf ab, Faszikulationen sonomorphologisch genauer zu charakterisieren, zu quantifizieren und als Verlaufsparameter zu untersuchen.

Muscle ultrasonography in detecting fasciculations: A noninvasive diagnostic tool for amyotrophic lateral sclerosis

BACKGROUND AND OBJECTIVES

Muscle ultrasound (MUS) is an emerging noninvasive tool to identify fasciculations in amyotrophic lateral sclerosis (ALS). We assessed the utility of MUS in detecting fasciculations in suspected ALS patients.

METHODS

Thirty-three patients (25 men) with possible (n = 7), probable (n = 12), or definite ALS according to Awaji criteria were studied. Electromyography was done in biceps brachii, quadriceps, and thoracic paraspinal muscles and MUS in biceps, triceps, deltoid, abductor-digiti-minimi, quadriceps, hamstrings, tibialis anterior, thoracic paraspinal, and tongue muscles.

RESULTS

The age at onset and illness duration was 49.73 ± 12.7 years and 13.57 ± 9.7 months, respectively. Limb-onset = 24 patients (72.7%) and bulbar-onset = 9 (27.3%). Totally 561 muscles were examined by MUS. Fasciculations were detected in 84.3% of muscles, 98.4% with and 73% without clinical fasciculations (p < 0.001). Fasciculation detection rate (FDR) by MUS was significantly higher in muscles with wasting (95.6%) than without wasting (77.6%, p < 0.001). Compared with EMG, FDR was significantly higher with MUS in quadriceps (81.8% vs. 51.5%, p = 0.002) and thoracic paraspinal muscles (75.8% vs. 42.4%, p = 0.013). The proportion of patients with definite ALS increased from 42% by clinical examination to 70% after combining EMG and MUS findings.

CONCLUSIONS

MUS is more sensitive in detecting fasciculations than electromyography (EMG) and provides a safer, faster, painless, and noninvasive alternative to EMG in detecting fasciculations in ALS.

Fasciculation differences between ALS and non-ALS patients: an ultrasound study

Background

Fasciculation is an important sign for the diagnosis of amyotrophic lateral sclerosis (ALS). Our study aimed to analyze the difference in fasciculation detected with muscle ultrasonography (MUS) between ALS patients and non-ALS patients with symptoms resembling ALS.

Methods

Eighty-eight ALS patients and fifty-four non-ALS (eight multifocal motor neuropathy, 32 chronic inflammatory demyelinating polyneuropathy/Charcot-Marie-Tooth, and 14 cervical spondylopathy or lumbar spondylopathy) patients were recruited. MUS was performed on 19 muscle groups in cervical, lumbosacral, bulbar, and thoracic regions for each patient. The intensity of fasciculation was divided into five grades based on firing frequency and number in the involved muscle groups.

Results

The overall detection rates were 72.8% in ALS and 18% in non-ALS patients. The fasciculation grades (median [IQR]) were 2 (0–3) in ALS and 0 (0–0) in non-ALS patients (P < 0.001). Fasciculations were observed in four regions for ALS patients and primarily distributed in proximal limbs. Fasciculations in non-ALS patients were primarily low-grade and mostly distributed in distal limbs.

Discussion

The fasciculation grade was higher in ALS than non-ALS patients. The distribution pattern of fasciculation was different between ALS and non-ALS patients.

Conclusions

The fasciculation grade and distribution pattern detected with MUS could help distinguish ALS from non-ALS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02473-5.

Demystifying the spontaneous phenomena of motor hyperexcitability

Possessing a discrete functional repertoire, the anterior horn cell can be in one of two electrophysiological states: on or off. Usually under tight regulatory control by the central nervous system, a hierarchical network of these specialist neurons ensures muscular strength is coordinated, gradated and adaptable. However, spontaneous activation of these cells and their axons can result in abnormal muscular twitching. The muscular twitch is the common building block of several distinct clinical patterns, namely fasciculation, myokymia and neuromyotonia. When attempting to distinguish these entities electromyographically, their unique temporal and morphological profiles must be appreciated. Detection and quantification of burst duration, firing frequency, multiplet patterns and amplitude are informative. A common feature is their persistence during sleep. In this review, we explain the accepted terminology used to describe the spontaneous phenomena of motor hyperexcitability, highlighting potential pitfalls amidst a bemusing and complex collection of overlapping terms. We outline the relevance of these findings within the context of disease, principally amyotrophic lateral sclerosis, Isaacs syndrome and Morvan syndrome. In addition, we highlight the use of high-density surface electromyography, suggesting that more widespread use of this non-invasive technique is likely to provide an enhanced understanding of these motor hyperexcitability syndromes.

Muscle ultrasound: Present state and future opportunities

Muscle ultrasound is a valuable addition to the neuromuscular toolkit in both the clinic and research settings, with proven value and reliability. However, it is currently not fulfilling its full potential in the diagnostic care of patients with neuromuscular disease. This review highlights the possibilities and pitfalls of muscle ultrasound as a diagnostic tool and biomarker, and discusses challenges to its widespread implementation. We expect that limitations in visual image interpretation, posed by user inexperience, could be overcome with simpler scoring systems and the help of deep-learning algorithms. In addition, more information should be collected on the relation between specific neuromuscular disorders, disease stages, and expected ultrasound abnormalities, as this will enhance specificity of the technique and enable the use of muscle ultrasound as a biomarker. Quantified muscle ultrasound gives the most sensitive results but is hampered by the need for device-specific reference values. Efforts in creating dedicated muscle ultrasound systems and artificial intelligence to help with image interpretation are expected to improve usability. Finally, the standard inclusion of muscle and nerve ultrasound in neuromuscular teaching curricula and guidelines will facilitate further implementation in practice. Our hope is that this review will help in unleashing muscle ultrasound's full potential.

Fasciculation score: a sensitive biomarker in amyotrophic lateral sclerosis

OBJECTIVE

The aim of our study was to elucidate the characteristic of fasciculation distributions in amyotrophic lateral sclerosis (ALS) using a fasciculation score (FS) of muscle ultrasound (MUS) and to compare the diagnostic values of three MUS fasciculation parameters in patients.

METHODS

Thirty ALS patients, 16 ALS mimics, and 10 healthy subjects were involved. MUS of unilateral 10 muscles in each patient and needle electromyography (EMG) of total 204 muscles were performed to detect fasciculations and spontaneous activity respectively in ALS. Control groups underwent only MUS. Fasciculation was graded semiquantitatively with FS.

RESULTS

Three hundred fifty muscles in ALS and 260 in controls were examined. The fasciculation detection rates, total FS, the number of muscles with fasciculation, and the total number of fasciculations in ALS were all significantly higher than those of controls (P < 0.001). ALS patients exhibited a multifocal continuous pattern of fasciculation in limbs, whereas there were few fasciculations in controls. Compared with other parameters, total FS had the largest area under the curve (AUC) (AUC = 0.899, P < 0.001) in ALS diagnosis. The detection rates of lower motor neuron (LMN) acute lesions by MUS (70.6%) and EMG (72.1%) were nearly the same, and a positive correlation between the FS and spontaneous activity grades (P < 0.001, r = 0.359) was proved.

CONCLUSIONS

ALS patients exhibited the multifocal continuous pattern of fasciculation in limbs. FS showed high sensitivity and specificity in differentiating ALS from non-ALS patients, and the optimal cut-off value was determined as 4. The combination of MUS and EMG can provide additional information about specific muscles.

Utility of transoral motion-mode ultrasonography to detect tongue fasciculation in patients with amyotrophic lateral sclerosis

INTRODUCTION

Increasing evidence suggests the utility of the submandibular approach for ultrasonography to detect tongue fasciculation in amyotrophic lateral sclerosis (ALS). We hypothesized that transoral motion-mode ultrasonography (TOMU) would be useful to detect tongue fasciculation in patients with ALS.

METHODS

Patients with sporadic ALS showing clinically definite tongue fasciculation were enrolled, and the ultrasonography findings of patients' tongues on TOMU and ultrasonography by the conventional submandibular approach were analyzed.

RESULTS

Six patients with clinically definite ALS were enrolled in this study. Although small, irregular muscle movements of 5 to 10 mm in amplitude and 0.1 to 0.2 second in duration were detected in all patients by TOMU, similar muscle movements were detected in only two of the six patients by the submandibular approach.

DISCUSSION

TOMU appeared to be useful for detecting tongue fasciculation in ALS patients. Further study is needed to better determine its role as a diagnostic tool for ALS.

Ultrasound Imaging as a Diagnostic Tool to Assess the Functional Status of Muscles after a Spinal Cord Injury

The aim of this study was to evaluate the use of ultrasound imaging (USI) as a diagnostic tool to assess muscle function after a spinal cord injury (SCI). Ultrasound videos of the gastrocnemius medialis muscle were recorded both at rest and during attempted maximum voluntary contraction (MVC) for fifteen participants with a SCI and fifteen able-bodied controls. Measurements were repeated at monthly intervals for participants in the SCI group during their inpatient stay. Differences in muscle echogenicity and thickness were detected between both able-bodied and SCI groups and subgroups of SCI participants, suggesting USI can detect and monitor changes in muscle structure which are characteristic of atrophy. Decreased muscle movement in the SCI groups was also detected during attempted MVC. The ability of USI to distinguish between different levels of function demonstrates the potential of USI as a quantitative tool to assess muscles.

Non-invasive measurement of fasciculation frequency demonstrates diagnostic accuracy in amyotrophic lateral sclerosis

Delayed diagnosis of amyotrophic lateral sclerosis prevents early entry into clinical trials at a time when neuroprotective therapies would be most effective. Fasciculations are an early hallmark of amyotrophic lateral sclerosis, preceding muscle weakness and atrophy. To assess the potential diagnostic utility of fasciculations measured by high-density surface electromyography, we carried out 30-min biceps brachii recordings in 39 patients with amyotrophic lateral sclerosis, 7 patients with benign fasciculation syndrome, 1 patient with multifocal motor neuropathy and 17 healthy individuals. We employed the surface potential quantification engine to compute fasciculation frequency, fasciculation amplitude and inter-fasciculation interval. Inter-group comparison was assessed by Welch’s analysis of variance. Logistic regression, receiver operating characteristic curves and decision trees discerned the diagnostic performance of these measures. Fasciculation frequency, median fasciculation amplitude and proportion of inter-fasciculation intervals <100 ms showed significant differences between the groups. In the best-fit regression model, increasing fasciculation frequency and median fasciculation amplitude were independently associated with the diagnosis of amyotrophic lateral sclerosis. Fasciculation frequency was the single best measure predictive of the disease, with an area under the curve of 0.89 (95% confidence interval 0.81–0.98). The cut-off of more than 14 fasciculation potentials per minute achieved 80% sensitivity (95% confidence interval 63–90%) and 96% specificity (95% confidence interval 78–100%). In conclusion, non-invasive measurement of fasciculation frequency at a single time-point reliably distinguished amyotrophic lateral sclerosis from its mimicking conditions and healthy individuals, warranting further research into its diagnostic applications.

Application of muscle ultrasound for the evaluation of patients with amyotrophic lateral sclerosis: An observational cross-sectional study

INTRODUCTION

We evaluated the association between muscle ultrasound, number of motor units, and clinical parameters, and assessed their utility for distinguishing amyotrophic lateral scleorisis (ALS) patients from healthy individuals.

METHODS

Three muscle pairs (abductor pollicis brevis, abductor digiti minimi, and tibialis anterior) of 18 ALS patients and 18 controls underwent muscle ultrasound (echointensity and thickness) and assessment of motor unit number index (MUNIX). The clinical and functional status of participants were also assessed.

RESULTS

Mean age of the patients was 53.8 ± 12.1 years, and score on the ALS Functional Rating Scale-Revised was 38.9 ± 4.1. Echointensity of all tested muscles of ALS participants was significantly higher than that of controls, but there was no significant difference in muscle thickness. Muscle echointensity correlated significantly with clinical and electrophysiological parameters.

CONCLUSION

Echointensity of muscles was highly associated with clinical scales and MUNIX, confirming its relevance as an ancillary diagnostic test in ALS patients.

Quantitative ultrasound of the tongue: Echo intensity is a potential biomarker of bulbar dysfunction in amyotrophic lateral sclerosis

OBJECTIVES

To learn if quantitative ultrasound (QUS) distinguishes the tongues of healthy participants and amyotrophic lateral sclerosis (ALS) patients by echo intensity (EI) and to evaluate if EI correlates with measures of bulbar function.

METHODS

Ultrasound was performed along the midline of the anterior tongue surface in 16 ALS patients and 16 age-matched controls using a linear hockey stick 16-7 MHz transducer. A region of interest was manually drawn and then EI was determined for the upper 1/3 of the muscle. For patients, the ALS functional rating scale - revised (ALSFRS-R) was used to calculate bulbar sub-scores and the Iowa Oral Performance Instrument (IOPI) was used to measure tongue strength.

RESULTS

EI was significantly higher in ALS patients than in healthy participants (49.8 versus 37.8 arbitrary units, p < 0.01). In the patient group, EI was negatively correlated with ALSFRS-R bulbar sub-score (R_S = -0.65, p < 0.01). An inverse correlation between EI and tongue strength did not reach significance (R_S = -0.34, p = 0.28).

CONCLUSIONS

This study suggests that EI can differentiate healthy from diseased tongue muscle, and correlates with a standard functional measure in ALS patients.

SIGNIFICANCE

Tongue EI may represent a novel biomarker for bulbar dysfunction in ALS.

Ultrasound versus electromyography for the detection of fasciculation in amyotrophic lateral sclerosis: systematic review and meta-analysis

The objective of this study was to determine the diagnostic accuracy of ultrasound and electromyography for the detection of fasciculation in patients with amyotrophic lateral sclerosis and to compare detection rates between the two methods. By searching the Cochrane Library, MEDLINE, Excerpta Medica, and Latin-American and Caribbean Health Sciences Literature databases, we identified studies evaluating the diagnostic accuracy and fasciculation detection rates of ultrasound and electromyography. The Quality Assessment of Diagnostic Accuracy Studies, version 2, and RTI item bank tools were used for the evaluation of methodological quality. Ultrasound, for 10 s or 30 s, had a higher detection rate than did electromyography in all muscles evaluated. The overall detection rate (in patients) did not differ significantly between ultrasound for 10 s and ultrasound for 30 s. The accuracy of ultrasound for 10 s was 70% in muscles and 85% in patients. The accuracy of ultrasound for 30 s was 82% in patients. Ultrasound provided detection rates superior to those achieved with electromyography, independent of the examination time and muscles evaluated.

Identification of muscle fasciculations from surface EMG: comparison with ultrasound-based detection

The clinical standard for the identification of muscle fasciculations is needle electromyography. However, both surface electromyograms (sEMG) and ultrasound imaging (US) have been recently proposed as alternative and more sensitive approaches. The aims of this study were to: (i) compare the sensitivity to muscle fasciculations of sEMG and US, (ii) assess the rate of agreement (RoA) between the two approaches, and (iii) investigate how much sensitivity and RoA are affected by the selectivity of sEMG detection. Surface EMGs were collected concurrently with US images using an array of 32 electrodes spanning the whole, posterior aspect of the leg. Muscle fasciculations were identified from US videos and from monopolar and single differential sEMGs computed between electrodes spaced by 1, 2, and 3 cm. Results from five healthy subjects showed that US detected as many fasciculations as single differential EMGs, but always less than monopolar sEMGs. However, monopolar sEMGs exhibited a very poor spatial selectivity, likely responsible for the small RoA with US measures. The RoA was maximal for single differential recordings with 3cm inter-electrode distance, however, it was always smaller than 75% (median=30%). Although preliminary, these results suggest that sEMG and US are sensitive to different events in the muscle volume and that their integration may increase the detection sensitivity to muscle fasciculations.

Relationship between EMG-detected and ultrasound-detected fasciculations in amyotrophic lateral sclerosis: A prospective cohort study

OBJECTIVES

Fasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).

METHODS

Thirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.

RESULTS

The mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch's t-test).

CONCLUSION

Small FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.

SIGNIFICANCE

Clinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Clinical and research applications of neuromuscular ultrasound in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterized by dysfunction at multiple levels of the neuraxis. It remains a clinical diagnosis without a definitive diagnostic investigation. Electrodiagnostic testing provides supportive information and, along with imaging and biochemical markers, can help exclude mimicking conditions. Neuromuscular ultrasound has a valuable role in the diagnosis and monitoring of ALS and provides complementary information to clinical assessment and electrodiagnostic testing as well as insights into the underlying pathophysiology of this disease. This review highlights the evidence for ultrasound in the evaluation of bulbar, limb and respiratory musculature and peripheral nerves in ALS. Further research in this evolving area is required.

Foreground Detection Analysis of Ultrasound Image Sequences Identifies Markers of Motor Neurone Disease across Diagnostically Relevant Skeletal Muscles

Diagnosis of motor neurone disease (MND) includes detection of small, involuntary muscle excitations, termed fasciculations. There is need to improve diagnosis and monitoring of MND through provision of objective markers of change. Fasciculations are visible in ultrasound image sequences. However, few approaches that objectively measure their occurrence have been proposed; their performance has been evaluated in only a few muscles; and their agreement with the clinical gold standard for fasciculation detection, intramuscular electromyography, has not been tested. We present a new application of adaptive foreground detection using a Gaussian mixture model (GMM), evaluating its accuracy across five skeletal muscles in healthy and MND-affected participants. The GMM provided good to excellent accuracy with the electromyography ground truth (80.17%-92.01%) and was robust to different ultrasound probe orientations. The GMM provides objective measurement of fasciculations in each of the body segments necessary for MND diagnosis and hence could provide a new, clinically relevant disease marker.

ULTRASOUND IN THE DIAGNOSIS AND MONITORING OF AMYOTROPHIC LATERAL SCLEROSIS: A REVIEW

Neuromuscular ultrasound is complementary to electrodiagnostic (EDx) testing and is useful in enhancing the diagnosis of mononeuropathies, peripheral nerve trauma, and demyelinating polyneuropathies. There is increasing interest in using ultrasound both to aid in the diagnosis of amyotrophic lateral sclerosis (ALS) and to monitor its progression. In this article we review the relevant literature on ultrasound in ALS. Ultrasound is more sensitive than EDx in identifying fasciculations in patients with ALS. It can detect decreased muscle thickness, increased muscle echointensity and echovariance, and reduced peripheral nerve size in these patients. Ultrasound is also a helpful tool in assessment of diaphragm function. Although additional studies are required to define the exact role of ultrasound in the evaluation and monitoring of ALS, it can improve the diagnostic yield in patients when ALS is suspected, but insufficiently supported, by clinical and EDx examinations. Muscle Nerve 60: 114-123, 2019.

Quantitative neuromuscular ultrasound analysis as biomarkers in amyotrophic lateral sclerosis

OBJECTIVES

To assess the differences in morphological and texture parameters of median nerve (MN) and abductor pollicis brevis (APB) between amyotrophic lateral sclerosis (ALS) patients and controls.

METHODS

The cross-sectional area (CSA) of the MN and the muscle thickness (MTh) of APB were measured bilaterally in 59 recently diagnosed ALS patients and 20 matched healthy controls. Echointensity (EI), echovariation (EV) and grey-level co-occurrence matrix (GLCM) texture features of both structures were also analysed. Correlations between these parameters and clinical variables (muscle strength and disability) were analysed.

RESULTS

The CSA of MN was significantly lower in ALS patients (MD = - 1.83 mm² [95% CI = 2.89; - 0.77 mm²]; p = 0.01). ALS patients showed significantly lower MTh (- 2.23 mm [3.16; - 1.30 mm]; p < 0.001) and EV (- 7.40 [11.5; - 3.33]; p = 0.004) and higher EI (21.2 [11.9; 30.6]; p < 0.001) in the APB muscle. No relevant differences were detected in GLCM features for this muscle. The model including all parameters (CSA for MN and MTh, EI and EV for APB) showed an AUC of 82% (sensitivity 87%; specificity 42%). Muscle strength and disability correlated with APB muscle ultrasound parameters but not with those of the MN.

CONCLUSIONS

APB muscle ultrasound biomarkers (especially MTh and EI) showed better discrimination capacity and correlation with clinical variables than MN biomarkers. However, the combination of both biomarkers increased their ability to detect LMN impairment, suggesting that both biomarkers could be used in a complementary manner for the diagnosis and progression monitoring in ALS.

KEY POINTS

• Abductor pollicis brevis muscle and median nerve impairment is detectable by ultrasound in amyotrophic lateral sclerosis patients, even in those without clinical impairment. • Muscle ultrasound biomarkers show better discrimination capacity than nerve biomarkers in amyotrophic lateral sclerosis. • Quantitative neuromuscular ultrasound biomarkers could be useful in a general amyotrophic lateral sclerosis population early on the disease.

A pilot study of neuromuscular ultrasound as a biomarker for amyotrophic lateral sclerosis

INTRODUCTION

This study explores the reliability and responsiveness of neuromuscular ultrasound in amyotrophic lateral sclerosis (ALS).

METHODS

Investigations were conducted with 10 healthy controls, 10 patients with ALS (single point in time), and 10 different patients with ALS (followed over 6 months; 4 completed follow-up). Ultrasound was used to measure the thickness of the geniohyoid, bilateral biceps/brachialis, bilateral tibialis anterior, and bilateral hemidiaphragms (at inspiration and expiration). Interrater and intrarater reliability and change in muscle thickness over 6 months were measured.

RESULTS

Interrater correlation coefficients ranged between 0.80 and 0.99 in healthy controls and between 0.78 and 0.97 in patients with ALS. Intrarater correlation coefficients ranged between 0.83 and 0.98 in healthy controls. The mean percentage decline in muscle thickness over 6 months was 20.25%.

DISCUSSION

Muscle ultrasound appears to be a reliable technique for measuring important muscles in patients with ALS. Larger studies with age-matched controls should be conducted to assess further the responsiveness of this biomarker in ALS. Muscle Nerve 59:181-186, 2019.

Diagnostic criteria for amyotrophic lateral sclerosis: A multicentre study of inter-rater variation and sensitivity

OBJECTIVE

This study assesses inter-rater agreement and sensitivity of diagnostic criteria for amyotrophic lateral sclerosis (ALS).

METHODS

Clinical and electrophysiological data of 399 patients with suspected ALS were collected by eleven experienced physicians from ten different countries. Eight physicians classified patients independently and blinded according to the revised El Escorial Criteria (rEEC) and to the Awaji Criteria (AC). Inter-rater agreement was assessed by Kappa coefficients, sensitivity by majority diagnosis on 350 patients with follow-up data.

RESULTS

Inter-rater agreement was generally low both for rEEC and AC. Agreement was best on the categories "Not-ALS", "Definite", and "Probable", and poorest for "Possible" and "Probable Laboratory-supported". Sensitivity was equal for rEEC (64%) and AC (63%), probably due to downgrading of "Probable Laboratory-supported" patients by AC. However, AC was significantly more effective in classifying patients as "ALS" versus "Not-ALS" (p < 0.0001).

CONCLUSIONS

Inter-rater variation is high both for rEEC and for AC probably due to a high complexity of the rEEC inherent in the AC. The gain of AC on diagnostic sensitivity is reduced by the omission of the "Probable Laboratory-supported" category.

SIGNIFICANCE

The results highlight a need for initiatives to develop simpler and more reproducible diagnostic criteria for ALS in clinical practice and research.

Computer-aided detection of fasciculations and other movements in muscle with ultrasound: Development and clinical application

OBJECTIVE

To develop an automated algorithm for detecting fasciculations and other movements in muscle ultrasound videos. Fasciculation detection in muscle ultrasound is routinely performed online by observing the live videos. However, human observation limits the objective information gained. Automated detection of movement is expected to improved sensitivity and specificity and increase reliability.

METHODS

We used 42 ultrasound videos from 11 neuromuscular patients for an iterative learning process between human observers and automated computer analysis, to identify muscle ultrasound movements. Two different datasets were selected from this, one to develop the algorithm and one to validate it. The outcome was compared to manual movement identification by clinicians. The algorithm also quantifies specific parameters of different movement types, to enable automated differentiation of events.

RESULTS

The algorithm reliably detected fasciculations. With algorithm guidance, observers found more fasciculations compared to visual analysis alone, and prescreening the videos with the algorithm saved clinicians significant time compared to reviewing full video sequences. All videos also contained other movements, especially contraction pseudotremor, which confused human interpretation in some.

CONCLUSIONS

Automated movement detection is a feasible and attractive method to screen for fasciculations in muscle ultrasound videos.

SIGNIFICANCE

Our findings affirm the potential clinical usefulness of automated movement analysis in muscle ultrasound.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Muscular cramp: causes and management

Muscular cramp is a common symptom in healthy people, especially among the elderly and in young people after vigorous or peak exercise. It is prominent in a number of benign neurological syndromes. It is a particular feature of chronic neurogenic disorders, especially amyotrophic lateral sclerosis. A literature review was undertaken to understand the diverse clinical associations of cramp and its neurophysiological basis, taking into account recent developments in membrane physiology and modulation of motor neuronal excitability. Many aspects of cramping remain incompletely understood and require further study. Current treatment options are correspondingly limited.

Split hand muscle echo intensity index as a reliable imaging marker for differential diagnosis of amyotrophic lateral sclerosis

OBJECTIVE

The objective of this study was to investigate the usefulness of muscle ultrasound in evaluating dissociated small hand muscle atrophy, termed 'split hand', and its feasibility in the diagnosis of amyotrophic lateral sclerosis (ALS).

METHODS

Forty-four patients with ALS, 18 normal subjects and 9 patients with other neuromuscular disorders were included in this study. The hand muscles were divided into three regions, the median-innervated lateral hand muscle group (ML), the ulnar-innervated lateral hand muscle (UL) and the ulnar-innervated medial hand muscle (UM), and the muscle echo intensity (EI) and compound muscle action potential (CMAP) were measured. We calculated the split hand index (SHI) using muscle EI (SHI_mEI) and CMAP (SHI_CMAP) for comparison among groups. The SHI was derived by dividing muscle EI (or CMAP) measured at the ML and UL by that measured at the UM.

RESULTS

The SHI_mEI was significantly higher in patients with ALS (51.7±28.3) than in normal controls (29.7±9.9) and disease controls with other neuromuscular disorders (36.5±7.3; P<0.001), particularly in upper limb-onset ALS (66.5±34.0; P<0.001). Receiver operating characteristic curve analysis indicated that the SHI_mEI had significantly better diagnostic accuracy than the SHI_CMAP.

CONCLUSIONS

The SHI_mEI was more sensitive in evaluating dissociated small hand muscle atrophy compared with the SHI_CMAP and may be a reliable diagnostic marker for differentiating ALS from other neuromuscular disorders and healthy controls.

Baclofen Pump Replacement in a Patient With End-Stage Amyotrophic Lateral Sclerosis: A Case Report Demonstrating Transversus Abdominis Plane Block as the Sole Anesthetic

A patient with end-stage amyotrophic lateral sclerosis (ALS) presented for Baclofen pump replacement. She underwent a left transversus abdominis plane block to anesthetize the left lower quadrant of the abdomen. No sedatives or analgesics were administered, and the procedure was successfully completed without complication. It is prudent to consider anesthetic plans that avoid complications associated with general or neuraxial anesthesia in patients with ALS. This case report demonstrates successful placement of a transversus abdominis plane block in a patient with ALS and offers a safe anesthetic technique that can be performed in other high-risk patients.

Detection radius of EMG for fasciculations: Empiric study combining ultrasonography and electromyography

OBJECTIVE

The aims of this study were to investigate the detection radius and sensitivity of EMG for fasciculations.

METHODS

Muscle ultrasonography was performed simultaneously to EMG recordings in patients with fasciculations in the context of amyotrophic lateral sclerosis. Ultrasonography and EMG parameters were analyzed for selected fasciculations.

RESULTS

A total of 381 fasciculations were detected by ultrasonography in 18 muscles of 10 patients. Out of these, 125 (33%) were EMG-negative. In contrast, none of the fasciculations detected by EMG were ultrasonography-negative. EMG detection probability decreased significantly with increasing distance from the center of the fasciculation. EMG detection rate was 98% when the EMG needle was located within the fasciculation and 50% at 7.75 mm distance from the fasciculation center. In addition, EMG detection depended significantly on cross-sectional area of the fasciculation and presence of neurogenic changes.

CONCLUSIONS

For detecting the same fasciculations, EMG is less sensitive than ultrasonography. EMG detection probability decreases sharply at a distance comparable to motor unit size.

SIGNIFICANCE

These results extend previous knowledge about superior sensitivity of ultrasonography for fasciculations. Moreover, our novel bimodal detection method provides first in vivo data about the EMG detection radius for fasciculations in a clinical setting.

Amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is characterised by the progressive loss of motor neurons in the brain and spinal cord. This neurodegenerative syndrome shares pathobiological features with frontotemporal dementia and, indeed, many patients show features of both diseases. Many different genes and pathophysiological processes contribute to the disease, and it will be necessary to understand this heterogeneity to find effective treatments. In this Seminar, we discuss clinical and diagnostic approaches as well as scientific advances in the research fields of genetics, disease modelling, biomarkers, and therapeutic strategies.

Quantitative Muscle Ultrasonography Using Textural Analysis in Amyotrophic Lateral Sclerosis

The purpose of this study was to analyze differences in gray-level co-occurrence matrix (GLCM) parameters, as assessed by muscle ultrasound (MUS), between amyotrophic lateral sclerosis (ALS) patients and healthy controls, and to compare the diagnostic accuracy of these GLCM parameters with first-order MUS parameters (echointensity [EI], echovariation [EV], and muscle thickness [MTh]) in different muscle groups. Twenty-six patients with ALS and 26 healthy subjects underwent bilateral and transverse ultrasound of the biceps/brachialis, forearm flexor, quadriceps femoris, and tibialis anterior muscle groups. MTh was measured with electronic calipers, and EI, EV, and GLCM were obtained using Image J (v.1.48) software. Sensitivity, specificity, likelihood ratios, and area under the curve (AUC) were performed by logistic regression models and receiver operating characteristic curves. GLCM parameters showed reduced granularity in the muscles of ALS patients compared with the controls. Regarding the discrimination capacity, the best single diagnostic parameter in forearm flexors and quadriceps was GLCM and in biceps brachialis and tibialis anterior was EV. The respective combination of these two parameters with MTh resulted in the best AUC (over 90% in all muscle groups and close to the maximum combination model). The use of new textural parameters (EV and GLCM) combined with usual quantitative MUS variables is a promising biomarker in ALS.

Fasciculations in nerve and muscle disorders - A prospective study of muscle ultrasound compared to electromyography

OBJECTIVES

We examined the clinical utility of muscle ultrasound (MUS) in detecting fasciculations in patients with nerve and muscle disorders (NMD) and investigated the impact on diagnostic sensitivity when combining electromyography (EMG) and MUS.

METHODS

We included 58 consecutive patients suspected to have NMD and 38 healthy subjects (HS). Patients and HS underwent MUS in 14 skeletal and two bulbar muscles and the video recordings of the MUS were anonymised. Only patients underwent EMG.

RESULTS

The follow-up diagnoses were: 15 Amyotrophic lateral sclerosis (ALS), 15 polyneuropathy, 14 patients had other diagnoses (disease-control group) and 14 patients had no pathological findings. MUS detected more muscles with fasciculations among ALS patients compared to all other groups. In ALS patients, the dominating pattern of fasciculations was continuous (45%). More proximal muscles showed fasciculations among ALS patients compared to all other patient groups. MUS was more sensitive than EMG in detecting fasciculations (58% vs. 48%). When combining the two methods, the sensitivity in detecting fasciculations increased to 65%. Fasciculations in nine muscles could predict the ALS diagnosis with high sensitivity and specificity.

CONCLUSIONS

MUS is a sensitive tool in detecting fasciculations in patients with NMD and performs well compared to EMG in diagnosing ALS.

SIGNIFICANCE

MUS may add valuable information in the clinic, especially in diagnosing ALS.