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

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.

Comparison of muscle ultrasound and needle electromyography findings in neuromuscular disorders

INTRODUCTION/AIMS

Needle electromyography (EMG) and muscle ultrasound can be used to evaluate patients with suspected neuromuscular disorders. The relation between muscle ultrasound pathology and the corresponding needle EMG findings is unknown. In this study we compared the results of concurrent ultrasound and needle EMG examinations in patients suspected of a neuromuscular disorder.

METHODS

Retrospective data from 218 patients with pairwise ultrasound and EMG results of 796 muscles were analyzed. We compared overall quantitative and visual muscle ultrasound results to EMGs with neurogenic and myopathic abnormalities and assessed the congruency of both methods in the different clinical diagnosis categories.

RESULTS

In muscles of patients with a neuromuscular disorder, abnormalities were found with EMG in 71.8%, and quantitative and visual muscle ultrasound results were abnormal in 19.3% and 35.4% respectively. In muscles with neurogenic EMG abnormalities, quantitative and visual muscle ultrasound results were abnormal in 18.9% versus 35.6%, increasing up to 43.7% versus 87.5% in muscles with the most pronounced signs of denervation. Congruency of EMG and ultrasound was better for more proximal and cranial muscles than for muscles in the hand and lower limb.

DISCUSSION

Needle EMG and muscle ultrasound typically produce disparate results and identify different aspects of muscle pathology. Muscle ultrasound seems less suited for detecting mild neurogenic abnormalities. As the severity of neurogenic needle EMG abnormalities increased, muscle ultrasound abnormalities were also increasingly found. Visual analysis seems better suited than grayscale quantification for detecting neurogenic abnormalities.

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.

The cross-sectional area of peripheral nerve in amyotrophic lateral sclerosis: A case-control study

OBJECTIVE

A growing body of literature recognises the importance of peripheral nerve ultrasound in neuromuscular disorders. Several attempts have been made to differentiate amyotrophic lateral sclerosis (ALS) from multifocal motor neuropathy (MMN) using peripheral nerve ultrasound. A much-debated question is whether the cross-sectional area (CSA) of peripheral nerve in ALS patients is significantly smaller compared to healthy controls. This study aims to determine the CSA of peripheral nerves in patients with ALS.

METHODS

One hundred and thirty-nine patients with ALS and 75 healthy controls were recruited. Ultrasound of the median, ulnar, and trunks of the brachial plexus and cervical nerve roots was undertaken in ALS patients and controls.

RESULTS

Compared to controls, ALS patients had mild reductions of the median nerve, most sites of the ulnar nerve, trunks of the brachial plexus and cervical nerve roots. Another important finding of this study is that the median nerve tends to have a more significant reduction than the ulnar nerve in ALS patients, especially at the proximal.

CONCLUSIONS

Ultrasound could be sensitive to nerve motor fibre loss in patients with ALS. CSA at the proximal Median nerve may be a promising biomarker in patients with ALS.

Abdominal Muscle Fasciculations and Amyotrophic Lateral Sclerosis Diagnosis in a Patient Unable to Perform Sit-Ups

While performing sit-ups, a 70-year-old man was unable to lift his upper body. The abdominal skin reflex was absent, and abdominal ultrasonography showed intermittent, irregular, and localized muscle twitches of the abdominal muscles. Further, electromyography (EMG) detected widespread fasciculations. Amyotrophic lateral sclerosis (ALS) was diagnosed. Muscle ultrasonography (MU) is useful in detecting fasciculations. This technique allows for repeated non-invasive imaging and the assessment of an expansive range of muscles in real-time. It also detects deep abdominal muscles, which are difficult to assess using EMG. MU is particularly beneficial to patients with atypical ALS who experience truncal muscle weakness.

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.

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.

Ultrasound Detection of Vagus Nerve Atrophy in Bulbar Amyotrophic Lateral Sclerosis

BACKGROUND AND PURPOSE

Neuromuscular ultrasound in amyotrophic lateral sclerosis (ALS) is of increasing interest. As bulbar symptoms are commonly developed by most ALS patients during disease, the aim of our study was to find possible sonographic changes of vagus nerve size in bulbar affected ALS patients.

METHODS

We investigated 24 ALS patients and 19 controls without neuromuscular disorders. In ALS patients, bulbar affection was documented clinically (eg, dysarthria, dysphagia, and fasciculations) or subclinically using ultrasound and electromyography of bulbar muscles. Vagus nerve ultrasound was performed in all participants bilaterally at the level of the thyroid gland.

RESULTS

The cross-sectional area (CSA) of the vagus nerve in bulbar affected ALS patients (mean CSA right/left 1.9 ± .7 mm²/1.8 ± .6 mm²) was significantly reduced on both sides compared to controls (mean CSA right/left 2.2 ± .6 mm²/2.0 ± .3 mm²) - right: P = .0387, left: P = .0386. Receiver operating characteristic curve analysis of the vagus nerve CSA yielded a sensitivity of 66.7% and a specificity of 63.2% (cutoff value 1.85 mm²). Vagus nerve CSA did not correlate significantly with age in controls (right: P = .45, left: P = .66). In controls and ALS patients, there was no significant difference of vagus nerve CSA between the right and left sides (controls: P = .43; patients: P = .86).

CONCLUSION

Our study demonstrates vagus nerve atrophy in bulbar affected ALS patients. Further studies are warranted investigating the relevance of our finding for monitoring disease progression in ALS.

Difference in distribution of fasciculations between multifocal motor neuropathy and amyotrophic lateral sclerosis

OBJECTIVE

To examine differences in fasciculation distribution between patients with multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS) based on muscle ultrasound.

METHODS

Forty-one muscles (tongue muscle and 40 muscles of the trunk and limbs on both sides) in 5 MMN patients and 21 muscles (tongue muscle and 20 muscles on the onset side) in 21 ALS patients were subjected to muscle ultrasound individually for 60 seconds to detect the presence of fasciculations.

RESULTS

Fasciculation detection rates on the onset side were significantly higher in ALS (42.4 ± 18.3%, mean ± SD) than in MMN (21.9 ± 8.8%) patients (p < 0.05). In MMN patients, no fasciculation was detected in the tongue or truncal muscles. There was no difference in the fasciculation detection rate between the onset and non-onset sides or between upper and lower limbs in MMN patients.

CONCLUSIONS

In MMN patients, fasciculations were detected extensively in the limbs. However, the detection rate in patients with MMN was lower than in those with ALS.

SIGNIFICANCE

Demonstration of the absence of fasciculations in the tongue and truncal muscles in MMN patients by extensive muscle ultrasound examination may help distinguish MMN from ALS.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

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.

The evolving role of surface electromyography in amyotrophic lateral sclerosis: A systematic review

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease that leads to inexorable motor decline and a median survival of three years from symptom onset. Surface EMG represents a major technological advance that has been harnessed in the development of novel neurophysiological biomarkers. We have systematically reviewed the current application of surface EMG techniques in ALS.

METHODS

We searched PubMed to identify 42 studies focusing on surface EMG and its associated analytical methods in the diagnosis, prognosis and monitoring of ALS patients.

RESULTS

A wide variety of analytical techniques were identified, involving motor unit decomposition from high-density grids, motor unit number estimation and measurements of neuronal hyperexcitability or neuromuscular architecture. Some studies have proposed specific diagnostic and prognostic criteria however clinical calibration in large ALS cohorts is currently lacking. The most validated method to monitor disease is the motor unit number index (MUNIX), which has been implemented as an outcome measure in two ALS clinical trials.

CONCLUSION

Surface EMG offers significant practical and analytical flexibility compared to invasive techniques. To capitalise on this fully, emphasis must be placed upon the multi-disciplinary collaboration of clinicians, bioengineers, mathematicians and biostatisticians.

SIGNIFICANCE

Surface EMG techniques can enrich effective biomarker development in ALS.

Quantitative sonographic evaluation of muscle thickness and fasciculation prevalence in healthy subjects

BACKGROUND

In the current study, we aimed to determine normative values for muscle thickness and fasciculation prevalence in healthy subjects.

METHODS

We performed a prospective study from October to December 2018 in 65 healthy subjects. All subjects underwent quantitative sonographic evaluation of muscle thickness and fasciculation prevalence in the following 8 muscles: Biceps brachii, abductor pollicis brevis, first dorsal interosseous, abductor digiti minimi, quadriceps, tibialis anterior, extensor digitorum brevis, and abductor hallucis brevis.

RESULTS

Subject ages ranged from 21 to 82 years, with 63% women. Normative values for muscle thickness were determined using the fifth percentile. Multivariate regression analysis showed that sex, age, body mass index, and hand dominance affected muscle thickness. Fasciculations were observed frequently only in distal muscles.

CONCLUSIONS

Normal values for muscle thickness were determined, and may enhance neuromuscular ultrasound sensitivity and serve as a basis for future studies. Larger series are needed to confirm these values.

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.

Neuromuscular ultrasound in clinical practice: A review

Neuromuscular ultrasound (NMUS) is becoming a standard element in the evaluation of peripheral nerve and muscle disease. When obtained simultaneously to electrodiagnostic studies, it provides dynamic, structural information that can refine a diagnosis or identify a structural etiology. NMUS can improve patient care for those with mononeuropathies, polyneuropathy, motor neuron disease and muscle disorders. In this article, we present a practical guide to the basics of NMUS and its clinical application. Basic ultrasound physics, scanning techniques and clinical applications are reviewed, along with current challenges.

SPiQE: An automated analytical tool for detecting and characterising fasciculations in amyotrophic lateral sclerosis

OBJECTIVES

Fasciculations are a clinical hallmark of amyotrophic lateral sclerosis (ALS). Compared to concentric needle EMG, high-density surface EMG (HDSEMG) is non-invasive and records fasciculation potentials (FPs) from greater muscle volumes over longer durations. To detect and characterise FPs from vast data sets generated by serial HDSEMG, we developed an automated analytical tool.

METHODS

Six ALS patients and two control patients (one with benign fasciculation syndrome and one with multifocal motor neuropathy) underwent 30-minute HDSEMG from biceps and gastrocnemius monthly. In MATLAB we developed a novel, innovative method to identify FPs amidst fluctuating noise levels. One hundred repeats of 5-fold cross validation estimated the model's predictive ability.

RESULTS

By applying this method, we identified 5,318 FPs from 80 minutes of recordings with a sensitivity of 83.6% (+/- 0.2 SEM), specificity of 91.6% (+/- 0.1 SEM) and classification accuracy of 87.9% (+/- 0.1 SEM). An amplitude exclusion threshold (100 μV) removed excessively noisy data without compromising sensitivity. The resulting automated FP counts were not significantly different to the manual counts (p = 0.394).

CONCLUSION

We have devised and internally validated an automated method to accurately identify FPs from HDSEMG, a technique we have named Surface Potential Quantification Engine (SPiQE).

SIGNIFICANCE

Longitudinal quantification of fasciculations in ALS could provide unique insight into motor neuron health.

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.