Fasciculation in amyotrophic lateral sclerosis: origin and pathophysiological relevance

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.

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.

Contribution of neurophysiology to the diagnosis and monitoring of ALS

This chapter describes the role of neurophysiological techniques in diagnosing and monitoring amyotrophic lateral sclerosis (ALS). Despite many advances, electromyography (EMG) remains a keystone investigation from which to build support for a diagnosis of ALS, demonstrating the pathophysiological processes of motor unit hyperexcitability, denervation and reinnervation. We consider development of the different diagnostic criteria and the role of EMG therein. While not formally recognised by established diagnostic criteria, we discuss the pioneering studies that have demonstrated the diagnostic potential of transcranial magnetic stimulation (TMS) of the motor cortex and highlight the growing evidence for TMS in the diagnostic process. Finally, accurately monitoring disease progression is crucial for the successful implementation of clinical trials. Neurophysiological measures of disease state have been incorporated into clinical trials for over 20 years and we review prominent techniques for assessing disease progression.

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.

Neuromuscular organoids model spinal neuromuscular pathologies in C9orf72 amyotrophic lateral sclerosis

Hexanucleotide repeat expansions in the C9orf72 gene are the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Due to the lack of trunk neuromuscular organoids (NMOs) from ALS patients' induced pluripotent stem cells (iPSCs), an organoid system was missing to model the trunk spinal neuromuscular neurodegeneration. With the C9orf72 ALS patient-derived iPSCs and isogenic controls, we used an NMO system containing trunk spinal cord neural and peripheral muscular tissues to show that the ALS NMOs could model peripheral defects in ALS, including contraction weakness, neural denervation, and loss of Schwann cells. The neurons and astrocytes in ALS NMOs manifested the RNA foci and dipeptide repeat proteins. Acute treatment with the unfolded protein response inhibitor GSK2606414 increased the glutamatergic muscular contraction 2-fold and reduced the dipeptide repeat protein aggregation and autophagy. This study provides an organoid system for spinal neuromuscular pathologies in ALS and its application for drug testing.

Split Phenomenon of Fasciculation between Antagonistic Muscles in Amyotrophic Lateral Sclerosis: An Ultrasound Study

OBJECTIVE

Paresis of muscle groups in patients with amyotrophic lateral sclerosis (ALS) tends to present split phenomena. We explored the split phenomenon of fasciculation in multiple antagonistic muscle groups in ALS patients.

METHODS

One hundred and forty ALS patients and 66 non-ALS patients were included from a single ALS center. Muscle ultrasonography (MUS) was performed to detect fasciculation in elbow flexor-extensor, wrist flexor-extensor, knee flexor-extensor, and ankle flexor-extensor. Split phenomena of fasciculation between different antagonistic muscle groups were summarized, and the possible influence factors were analyzed through stratified analysis.

RESULTS

The frequency of split phenomenon of fasciculation intensity was significantly higher than those of muscle strength (26.1% vs. 7.1% for elbow flexor-extensor, 38.3% vs. 5.7% for wrist flexor-extensor, 37.9% vs. 3.0% for knee extensor-flexor, and 33.6% vs. 14.4% for ankle flexor-extensor) (P < 0.01). For muscles with 0-1 level of muscle strength (the Medical Research Council, MRC, score), significance difference in mean fasciculation intensity was observed only in ankle flexor-extensor. For muscles with 2-5 level of muscle strength, significant dissociation of fasciculation grade was common, especially among patients with slow rapid progression rate and both upper and lower motor neuron (UMN and LMN) involvement. As for non-ALS patients, no significant difference was observed in fasciculation intensity between antagonistic muscles.

CONCLUSION

Split phenomenon of fasciculation between antagonistic muscles was common and relatively specific in ALS patients. Muscle strength, progression rate, and UMN involvement were influence factors of the split phenomenon of fasciculation intensity.

Novel approaches to motoneuron disease/ALS treatment using non-invasive brain and spinal stimulation: IFCN handbook chapter

Non-invasive brain stimulation techniques have been exploited in motor neuron disease (MND) with multifold objectives: to support the diagnosis, to get insights in the pathophysiology of these disorders and, more recently, to slow down disease progression. In this review, we consider how neuromodulation can now be employed to treat MND, with specific attention to amyotrophic lateral sclerosis (ALS), the most common form with upper motoneuron (UMN) involvement, taking into account electrophysiological abnormalities revealed by human and animal studies that can be targeted by neuromodulation techniques. This review article encompasses repetitive transcranial magnetic stimulation methods (including low-frequency, high-frequency, and pattern stimulation paradigms), transcranial direct current stimulation as well as experimental findings with the newer approach of trans-spinal direct current stimulation. We also survey and discuss the trials that have been performed, and future perspectives.

Clinical Neurology in Practice: The Tongue (part 2)

BACKGROUND

The tongue is an essential organ for the development of certain crucial functions such as swallowing and speech. The examination of the tongue can be very useful in neurology, as the various types of lingual alterations can lead to certain specific diagnoses, the tongue being a kind of 'mirror' of some neurological function.

REVIEW SUMMARY

To discuss the elements of clinical examination of the tongue in relation to neurological disorders. After reviewing the different superficial lesions of the tongue, we deal with various movement disorders of the tongue (fasciculations/myokimia, orolingual tremor, choreic movements of the tongue, dystonia of the tongue, lingual myoclonus, and psychogenic movements), disorders of taste and lingual sensitivity and lingual pain.

CONCLUSIONS

Examination of the tongue should not be limited to studying its motility and trophicity. It is equally important to check the sensory function and understand how to interpret abnormal movements involving the tongue. This study also aimed to demonstrate the importance of nonmotor tongue function in neurological practice.

Aberrant axon initial segment plasticity and intrinsic excitability of ALS hiPSC motor neurons

Dysregulated neuronal excitability is a hallmark of amyotrophic lateral sclerosis (ALS). We sought to investigate how functional changes to the axon initial segment (AIS), the site of action potential generation, could impact neuronal excitability in ALS human induced pluripotent stem cell (hiPSC) motor neurons. We find that early TDP-43 and C9orf72 hiPSC motor neurons show an increase in the length of the AIS and impaired activity-dependent AIS plasticity that is linked to abnormal homeostatic regulation of neuronal activity and intrinsic hyperexcitability. In turn, these hyperactive neurons drive increased spontaneous myofiber contractions of in vitro hiPSC motor units. In contrast, late hiPSC and postmortem ALS motor neurons show AIS shortening, and hiPSC motor neurons progress to hypoexcitability. At a molecular level, aberrant expression of the AIS master scaffolding protein ankyrin-G and AIS-specific voltage-gated sodium channels mirror these dynamic changes in AIS function and excitability. Our results point toward the AIS as an important site of dysfunction in ALS motor neurons.

Diagnosis and differential diagnosis of MND/ALS: IFCN handbook chapter

•Accurate and rapid diagnosis of amyotrophic lateral sclerosis (ALS) is important to prevent erroneous interventions. •The recent Gold Coast criteria are easily applicable and have high sensitivity and specificity. •Future developments will help to distinguish ALS as a specific clinical-pathologic entity.

Accurate and rapid diagnosis of amyotrophic lateral sclerosis (ALS) is essential in order to provide accurate information for patient and family, to avoid time-consuming investigations and to permit an appropriate management plan. ALS is variable regarding presentation, disease progression, genetic profile and patient reaction to the diagnosis. It is obviously important to exclude treatable conditions but, in most patients, for experienced neurologists the diagnosis is clear-cut, depending on the presence of progressive upper and lower motor neuron signs. Patients with signs of restricted lower motor neuron (LMN) or upper motor neuron (UMN) dysfunction may present diagnostic difficulty, but electromyography (EMG) is often a determinant diagnostic test since it may exclude other disorders. Transcranial magnetic stimulation may aid detection of UMN dysfunction, and brain and spinal cord MRI, ultrasound and blood neurofilament measurements, have begun to have clinical impact, although none are themselves diagnostic tests. Several sets of diagnostic criteria have been proposed in the past; all rely on clinical LMN and UMN signs in different anatomic territories, EMG changes, exclusion of other disorders, and disease progression, in particular evidence of spreading to other anatomic territories. Fasciculations are a characteristic clinical feature and increased importance is now attached to fasciculation potentials detected by EMG, when associated with classical signs of denervation and reinnervation. The Gold Coast diagnostic criteria rely on the presence of UMN and LMN signs in one (or more) anatomic territory, or LMN signs in two (or more) anatomic territories, recognizing the fundamental clinical requirements of disease progression and exclusion of other diseases. Recent studies confirm a high sensitivity without loss of specificity using these Gold Coast criteria. In considering the diagnosis of ALS a critical question for future understanding is whether ALS should be considered a syndrome or a specific clinico-pathologic entity; this can only be addressed in the light of more complete knowledge.

Diagnostic accuracy of nerve excitability and compound muscle action potential scan derived biomarkers in amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

The lack of reliable early biomarkers still causes substantial diagnostic delays in amyotrophic lateral sclerosis (ALS). The aim was to assess the diagnostic accuracy of a novel electrophysiological protocol in patients with suspected motor neuron disease (MND).

METHODS

Consecutive patients with suspected MND were prospectively recruited at our tertiary referral centre for MND in Utrecht, The Netherlands. Procedures were performed in accordance with the Standards for Reporting of Diagnostic Accuracy. In addition to the standard diagnostic workup, an electrophysiological protocol of compound muscle action potential (CMAP) scans and nerve excitability tests was performed on patients' thenar muscles. The combined diagnostic yield of nerve excitability and CMAP scan based motor unit number estimation was compared to the Awaji and Gold Coast criteria and their added value was determined.

RESULTS

In all, 153 ALS or progressive muscular atrophy patients, 63 disease controls and 43 healthy controls were included. Our electrophysiological protocol had high diagnostic accuracy (area under the curve [AUC] 0.85, 95% confidence interval [95% CI] 0.80-0.90), even in muscles with undetectable axon loss (AUC 0.78, 95% CI 0.70-0.85) and in bulbar-onset patients (AUC 0.85, 95% CI 0.73-0.95). Twenty-four of 33 (73%) ALS patients who could not be diagnosed during the same visit were correctly identified, as well as 8/13 (62%) ALS patients not meeting the Gold Coast criteria and 49/59 (83%) ALS patients not meeting the Awaji criteria during this first visit.

CONCLUSIONS

Our practical and non-invasive electrophysiological protocol may improve early diagnosis in clinically challenging patients with suspected ALS. Routine incorporation may boost early diagnosis, enhance patient selection and generate baseline measures for clinical trials.

A Glutamate Scavenging Protocol Combined with Deanna Protocol in SOD1-G93A Mouse Model of ALS

Amyotrophic lateral sclerosis (ALS) is a progressive disease of neuronal degeneration in the motor cortex, brainstem, and spinal cord, resulting in impaired motor function and premature demise as a result of insufficient respiratory drive. ALS is associated with dysfunctions in neurons, neuroglia, muscle cells, energy metabolism, and glutamate balance. Currently, there is not a widely accepted, effective treatment for this condition. Prior work from our lab has demonstrated the efficacy of supplemental nutrition with the Deanna Protocol (DP). In the present study, we tested the effects of three different treatments in a mouse model of ALS. These treatments were the DP alone, a glutamate scavenging protocol (GSP) alone, and a combination of the two treatments. Outcome measures included body weight, food intake, behavioral assessments, neurological score, and lifespan. Compared to the control group, DP had a significantly slower decline in neurological score, strength, endurance, and coordination, with a trend toward increased lifespan despite a greater loss of weight. GSP had a significantly slower decline in neurological score, strength, endurance, and coordination, with a trend toward increased lifespan. DP+GSP had a significantly slower decline in neurological score with a trend toward increased lifespan, despite a greater loss of weight. While each of the treatment groups fared better than the control group, the combination of the DP+GSP was not better than either of the individual treatments. We conclude that the beneficial effects of the DP and the GSP in this ALS mouse model are distinct, and appear to offer no additional benefit when combined.

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.

Fasciculation electromechanical latency is prolonged in amyotrophic lateral sclerosis

OBJECTIVE

In amyotrophic lateral sclerosis (ALS), motor neurons become hyperexcitable and spontaneously discharge electrical impulses causing fasciculations. These can be detected by two noninvasive methods: high-density surface electromyography (HDSEMG) and muscle ultrasonography (MUS). We combined these methods simultaneously to explore the electromechanical properties of fasciculations, seeking a novel biomarker of disease.

METHODS

Twelve ALS patients and thirteen healthy participants each provided up to 24 minutes of recordings from the right biceps brachii (BB) and gastrocnemius medialis (GM). Two automated algorithms (Surface Potential Quantification Engine and a Gaussian mixture model) were applied to HDSEMG and MUS data to identify correlated electromechanical fasciculation events.

RESULTS

We identified 4,197 correlated electromechanical fasciculation events. HDSEMG reliably detected electromechanical events up to 30 mm below the skin surface with an inverse correlation between amplitude and depth in ALS muscles. Compared to Healthy-GM muscles (mean = 79.8 ms), electromechanical latency was prolonged in ALS-GM (mean = 108.8 ms; p = 0.0458) and ALS-BB (mean = 112.0 ms; p = 0.0128) muscles. Electromechanical latency did not correlate with disease duration, symptom burden, sum muscle power score or fasciculation frequency.

CONCLUSIONS

Prolonged fasciculation electromechanical latency indicates impairment of the excitation-contraction coupling mechanism, warranting further exploration as a potential novel biomarker of disease in ALS.

SIGNIFICANCE

This study points to an electromechanical defect within the muscles of ALS patients.

Amyotrophic Lateral Sclerosis Risk Genes and Suppressor

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to death by progressive paralysis and respiratory failure within 2-4 years of onset. About 90-95% of ALS cases are sporadic (sALS), and 5-10% are inherited through family (fALS). Though the mechanisms of the disease are still poorly understood, so far, approximately 40 genes have been reported as ALS causative genes. The mutations in some crucial genes, like SOD1, C9ORF72, FUS, and TDP-43, are majorly associated with ALS, resulting in ROS-associated oxidative stress, excitotoxicity, protein aggregation, altered RNA processing, axonal and vesicular trafficking dysregulation, and mitochondrial dysfunction. Recent studies show that dysfunctional cellular pathways get restored as a result of the repair of a single pathway in ALS. In this review article, our aim is to identify putative targets for therapeutic development and the importance of a single suppressor to reduce multiple symptoms by focusing on important mutations and the phenotypic suppressors of dysfunctional cellular pathways in crucial genes as reported by other studies.

Autoimmune neuromyotonia

PURPOSE OF REVIEW

Autoimmune neuromyotonia encompasses a group of rare immune-mediated neurological disorders frequently associated with anti-contactin-associated protein-like 2 (CASPR2) antibodies and featuring clinical and electrical signs of peripheral nerve hyperexcitability (PNH). We aim to summarize the current knowledge on immune-mediated neuromyotonia, focusing on clinical presentations, pathophysiology, and management.

RECENT FINDINGS

Neuromyotonia is a major feature of several autoimmune neurological syndromes characterized by PNH with or without central neurological system involvement. Experimental and clinical evidence suggest that anti-CASPR2 antibodies are directly pathogenic in autoimmune neuromyotonia patients.

SUMMARY

Neuromyotonia, a form of PNH, is a major feature in several syndromes associated with anti-CASPR2 antibodies, including cramp-fasciculation syndrome, Isaacs syndrome, Morvan syndrome, and autoimmune limbic encephalitis. Diagnosis relies on the identification of motor, sensory, and autonomic signs of PNH along with other neurological symptoms, anti-CASPR2 antibody-positivity, and of characteristic electroneuromyographic abnormalities. Paraneoplastic associations with thymoma are possible, especially in Morvan syndrome. Patients usually respond to immune-active treatments, including steroids, intravenous immunoglobulins, plasma exchanges, and rituximab.

Recent advances in the diagnosis and prognosis of amyotrophic lateral sclerosis

The diagnosis of amyotrophic lateral sclerosis can be challenging due to its heterogeneity in clinical presentation and overlap with other neurological disorders. Diagnosis early in the disease course can improve outcomes as timely interventions can slow disease progression. An evolving awareness of disease genotypes and phenotypes and new diagnostic criteria, such as the recent Gold Coast criteria, could expedite diagnosis. Improved prognosis, such as that achieved with the survival model from the European Network for the Cure of ALS, could inform the patient and their family about disease course and improve end-of-life planning. Novel staging and scoring systems can help monitor disease progression and might potentially serve as clinical trial outcomes. Lastly, new tools, such as fluid biomarkers, imaging modalities, and neuromuscular electrophysiological measurements, might increase diagnostic and prognostic accuracy.

Neuronal Hyperexcitability and Free Radical Toxicity in Amyotrophic Lateral Sclerosis: Established and Future Targets

Amyotrophic lateral sclerosis (ALS) is a devastating disease with evidence of degeneration involving upper and lower motor neuron compartments of the nervous system. Presently, two drugs, riluzole and edaravone, have been established as being useful in slowing disease progression in ALS. Riluzole possesses anti-glutamatergic properties, while edaravone eliminates free radicals (FRs). Glutamate is the excitatory neurotransmitter in the brain and spinal cord and binds to several inotropic receptors. Excessive activation of these receptors generates FRs, inducing neurodegeneration via damage to intracellular organelles and upregulation of proinflammatory mediators. FRs bind to intracellular structures, leading to cellular impairment that contributes to neurodegeneration. As such, excitotoxicity and FR toxicities have been considered as key pathophysiological mechanisms that contribute to the cascade of degeneration that envelopes neurons in ALS. Recent advanced technologies, including neurophysiological, imaging, pathological and biochemical techniques, have concurrently identified evidence of increased excitability in ALS. This review focuses on the relationship between FRs and excitotoxicity in motor neuronal degeneration in ALS and introduces concepts linked to increased excitability across both compartments of the human nervous system. Within this cellular framework, future strategies to promote therapeutic development in ALS, from the perspective of neuronal excitability and function, will be critically appraised.

Fasciculation intensity and limb dominance in amyotrophic lateral sclerosis: a muscle ultrasonographic study

Background and purpose

Muscle ultrasonography has been increasingly recognized as a useful tool for detection of fasciculations. Separately, concordance between dominant hand and onset side has been reported in amyotrophic lateral sclerosis (ALS). The aim of this study was to reveal the distribution of fasciculations in the whole body, focusing on handedness.

Methods

In 106 consecutive patients with ALS, muscle ultrasonography was systematically performed in 11 muscles (the tongue, and bilateral biceps brachii, 1st dorsal interosseous [FDI], T10-paraspinalis, vastus lateralis and tibialis anterior muscles). The fasciculation intensity was scored from 0 to 3 for each muscle.

Results

Fasciculations were more frequently found in the limb muscles than the tongue and paraspinalis. Side and handedness analyses revealed that fasciculation intensity in FDI was significantly more prominent on the right (median [inter-quartile range] 2 [0 - 3]) than left (1.5 [0 - 3]; p = 0.016), and in the dominant hand (2 [1 - 3]) than non-dominant side (1.5 [0 - 3]; p = 0.025). The differences were greater in patients with upper limb onset. There were no side differences in the lower limb muscles. Multivariate analyses showed that male patients had more frequent fasciculations in the dominant FDI (β = 0.22, p < 0.05).

Conclusion

More intensive fasciculations are present in the FDI in the dominant hand and gender might be associated with fasciculation intensities. This distribution pattern of fasciculations might be associated with pathogenesis of ALS.

Benign Fasciculation Syndrome and Migraine Aura without Headache: Possible Rare Side Effects of the BNT162b2 mRNA Vaccine? A Case Report and a Potential Hypothesis

The BNT162b2 (Pfizer BioNTech) mRNA vaccine is an effective vaccine against COVID-19 infection. Here, we report an adverse event following immunization (AEFI) in a 48-year-old female patient who presented with fasciculations, migraine auras without headaches and in an increased discomfort of previously present palpitations, as well as excitation and insomnia. Her fasciculations were intermittently present until the time this paper was written, starting from the 6th day post-vaccination; they changed localization and frequency, but most commonly they were generalized, affecting almost all muscle groups. The patient also suffered from two incidents of migraine auras with visual kaleidoscope-like phenomena without headaches a few months after the vaccination. These symptoms were considered to be AEFI and no causal relation with the vaccine could be proven.

Ultra-early amplitude decrement after repetitive nerve stimulation supports early neuromuscular junction injury in amyotrophic lateral sclerosis: a prospective cross-sectional study

The dying-back hypothesis holds that the damage to neuromuscular junctions and distal axons in amyotrophic lateral sclerosis occurs at the earliest stage of the disease. Previous basic studies have confirmed early damage to neuromuscular junctions, but it is difficult to obtain such evidence directly in clinical practice. In this prospective cross-sectional study, we recruited 22 patients with early amyotrophic lateral sclerosis with disease duration < 12 months and with clinical symptoms limited to the upper limbs. We also recruited 32 healthy controls. Repetitive nerve stimulation was performed, and patients were followed for 12 months. We found a significant change in the response to repetitive nerve stimulation in amyotrophic lateral sclerosis patients without spontaneous electromyographic activity. Patients that were prone to denervation had an increased decrement response of target muscles after repetitive nerve stimulation. These results suggest that changes in response to repetitive nerve stimulation may occur before denervation in amyotrophic lateral sclerosis patients. The damage to lower motor neurons is more obvious in patients with a higher percentage of repetitive never stimulation-related amplitude decrements. This study was approved by the Institutional Ethics Committee of Peking University Third Hospital (approval No. M2017198) on August 24, 2017.

Fasciculations in Children

Fasciculations are the most common form of spontaneous muscle contraction. They frequently occur in healthy individuals. However, there are a minority of situations that fasciculations are observed in association with specific neurologic disorders. Publications concerning the evaluation of pediatric patients experiencing fasciculations are limited. These children may undergo invasive or expensive diagnostic investigations that are unnecessary. Moreover, without careful consideration of differential diagnoses, rare neuromuscular disorders that present with fasciculations in the pediatric age group can be under-recognized by pediatric neurologists. This review examines the most important pediatric disorders presenting with fasciculations and other spontaneous muscle contractions to guide pediatric neurologists in evaluating these children.

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.

Benign fasciculations: A follow-up study with electrophysiological studies

INTRODUCTION/AIMS

Fasciculations can be symptomatic, yet not progress to amyotrophic lateral sclerosis (ALS), a condition categorized as benign fasciculation syndrome (BFS). We aimed to assess electrodiagnostic changes and clinical course over time in patients with BFS.

METHODS

This was a retrospective review of medical records of patients who were referred because of a suspicion of ALS or who had directly asked for a consultation because of a personal concern regarding ALS. All clinical and electromyography (EMG) investigations were performed by the same neurologist, following an established protocol. In addition, laboratory testing and imaging studies were performed as determined to be clinically necessary.

RESULTS

We included 37 subjects (mean age 46 ± 14.7 y, 29 male, 7 healthcare professionals). Most patients had experienced fasciculations in both upper and lower limb muscles (62.2%); the remaining patients had fasciculations only in their lower limbs. EMG in seven subjects showed chronic neurogenic potentials in addition to fasciculation potentials; all of these were older men. Follow-up data were available in 24 patients (median 4.7 y), 21 with repeat EMGs, including all those with neurogenic EMG changes at baseline (median 6.5 y). Two-thirds of patients reported symptomatic improvement: 57.1% of those with abnormal EMG and 61.1% with normal EMG. The EMG changes were stable.

DISCUSSION

Prognosis of BFS is favorable, regardless of minor EMG abnormalities. The latter do not necessarily imply progression to ALS.

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.

Characterization of Fasciculation Potentials (FPs) in Amyotrophic Lateral Sclerosis (ALS) and Peripheral Nerve Hyperexcitability Syndromes (PNH)

This study is aimed at investigating the features of fasciculation potentials (FPs) in amyotrophic lateral sclerosis (ALS) and peripheral nerve hyperexcitability syndromes (PNH). Needle electrophysiologic examination (EMG) was performed for 5-15 muscles in the ALS and PNH patients. The spontaneous activity of fasciculations and fibrillations/sharp-waves (fibs-sw) was recorded. The distribution, firing frequency, and waveform parameters of FPs in muscles were calculated and compared. In total, 361 muscles in ALS patients and 124 muscles in PNH patients were examined, with the FP detection rates of 45.1% and 53.2%. Moreover, the ALS patients with the upper limb onset had the highest FP detection rate. Fasciculations occurred more frequently in the upper limbs than in the lower limbs in ALS and PNH. The detection rate of fibs-sw in the bulbar muscle was relatively low, which could be elevated when combining fibs-sw and FPs. Benign FPs in PNH were of smaller amplitude, shorter duration, and fewer phases/turns, compared with malignant FPs in ALS. The FP area in PNH was significantly smaller than that in ALS. The incidence of polyphasic FPs in ALS was distinctly greater than that in PNH. The firing frequency of FPs in PNH was higher than that in ALS. There was no significant difference in the amplitude, duration, phases and turns, and area of FPs between groups with and without fibs-sw in the muscles of normal strength in ALS. Conclusively, it is necessary to detect the FPs in the thoracic and bulbar muscles of patients suspected having ALS. FP parameters in ALS are significantly different from PNH.

Upper and Lower Motor Neuron Degenerations Are Somatotopically Related and Temporally Ordered in the Sod1 Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating and fatal neurodegenerative disease arising from the combined degeneration of upper motor neurons (UMN) in the motor cortex, and lower motor neurons (LMN) in the brainstem and spinal cord. This dual impairment raises two major questions: (i) are the degenerations of these two neuronal populations somatotopically related? and if yes (ii), where does neurodegeneration start? If studies carried out on ALS patients clearly demonstrated the somatotopic relationship between UMN and LMN degenerations, their temporal relationship remained an unanswered question. In the present study, we took advantage of the well-described Sod1^G86R model of ALS to interrogate the somatotopic and temporal relationships between UMN and LMN degenerations in ALS. Using retrograde labelling from the cervical or lumbar spinal cord of Sod1^G86R mice and controls to identify UMN, along with electrophysiology and histology to assess LMN degeneration, we applied rigorous sampling, counting, and statistical analyses, and show that UMN and LMN degenerations are somatotopically related and that UMN depletion precedes LMN degeneration. Together, the data indicate that UMN degeneration is a particularly early and thus relevant event in ALS, in accordance with a possible cortical origin of the disease, and emphasize the need to further elucidate the molecular mechanisms behind UMN degeneration, towards new therapeutic avenues.

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.

Improving clinical trial outcomes in amyotrophic lateral sclerosis

Individuals who are diagnosed with amyotrophic lateral sclerosis (ALS) today face the same historically intransigent problem that has existed since the initial description of the disease in the 1860s - a lack of effective therapies. In part, the development of new treatments has been hampered by an imperfect understanding of the biological processes that trigger ALS and promote disease progression. Advances in our understanding of these biological processes, including the causative genetic mutations, and of the influence of environmental factors have deepened our appreciation of disease pathophysiology. The consequent identification of pathogenic targets means that the introduction of effective therapies is becoming a realistic prospect. Progress in precision medicine, including genetically targeted therapies, will undoubtedly change the natural history of ALS. The evolution of clinical trial designs combined with improved methods for patient stratification will facilitate the translation of novel therapies into the clinic. In addition, the refinement of emerging biomarkers of therapeutic benefits is critical to the streamlining of care for individuals. In this Review, we synthesize these developments in ALS and discuss the further developments and refinements needed to accelerate the introduction of effective therapeutic approaches.

Fasciculation frequency at the biceps brachii and brachialis muscles is associated with amyotrophic lateral sclerosis disease burden and activity

INTRODUCTION

Fasciculations are most commonly seen in the biceps brachii muscle in amyotrophic lateral sclerosis (ALS). In this study we have explored the association between fasciculation frequency in a single location-biceps brachii and brachialis muscles (BB), and disease burden and activity.

METHODS

Sonographic muscle studies were performed in 90 ALS patients, 47 of whom were seen in subsequent follow-up. The association between fasciculations frequency at the BB and ALS Functional Rating Scale-Revised (ALSFRS-R) and manual muscle testing (MMT) scores was determined.

RESULTS

High fasciculation frequency at the BB, where detection rate was the highest, was associated with shorter disease duration, greater muscle thickness, higher MMT scores, and faster rate of decline in ALSFRS-R initially, and MMT subsequently.

DISCUSSION

High fasciculation frequency at the BB as determined by sonography, is associated with less impairment at time of examination, and a more active disease with a more rapid progression.

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.

Fasciculations demonstrate daytime consistency in amyotrophic lateral sclerosis

INTRODUCTION

Fasciculations represent early neuronal hyperexcitability in amyotrophic lateral sclerosis (ALS). To aid calibration as a disease biomarker, we set out to characterize the daytime variability of fasciculation firing.

METHODS

Fasciculation awareness scores were compiled from 19 ALS patients. In addition, 10 ALS patients prospectively underwent high-density surface electromyographic (HDSEMG) recordings from biceps and gastrocnemius at three time-points during a single day.

RESULTS

Daytime fasciculation awareness scores were low (mean: 0.28 muscle groups), demonstrating significant variability (coefficient of variation: 303%). Biceps HDSEMG recordings were highly consistent for fasciculation potential frequency (intraclass correlation coefficient [ICC] = 95%, n = 19) and the interquartile range of fasciculation potential amplitude (ICC = 95%, n = 19). These parameters exhibited robustness to observed fluctuations in data quality parameters. Gastrocnemius demonstrated more modest levels of consistency overall (44% to 62%, n = 20).

DISCUSSION

There was remarkable daytime consistency of fasciculation firing in the biceps of ALS patients, despite sparse and intermittent awareness among patients' accounts.

Cerebellar degeneration in adult spinal muscular atrophy patients

BACKGROUND

Spinal muscular atrophy (SMA) is a genetic motor neuron disease related to deletions in the SMN1 gene. There is mounting evidence that the disease is not restricted to motor neurons. In this neuroimaging study, we aimed to investigate the presence of in-vivo cerebellar damage in adult SMA patients not treated with disease-modifying treatment.

METHODS

Twenty-five molecularly confirmed patients with SMA type III or IV and 25 healthy controls underwent MRI with cerebellar focused structural analysis by the CERES automated pipeline. Volumetry (total and gray matter-GM) as well as cortical thickness of the cerebellar lobules were compared in both groups. Full clinical and demographic data were then assessed for correlations with cerebellar imaging findings.

RESULTS

Volumes of cerebellar lobules VIIIB (right), IX and X were significantly smaller in patients with SMA. Lobule IX also had GM atrophy in comparison to controls. We found no significant correlation between clinical findings and cerebellar damage.

CONCLUSIONS

Neuroimaging detects cerebellar structural changes in adult SMA patients, suggesting that neurodegeneration is not confined to the lower motor neurons in the disease.

The rise and fall of fasciculations in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a devastating neurodegenerative disease with a median survival of 3 years from symptom onset. Accessible and reliable biomarkers of motor neuron decline are urgently needed to quicken the pace of drug discovery. Fasciculations represent an early pathophysiological hallmark of amyotrophic lateral sclerosis and can be reliably detected by high-density surface electromyography. We set out to quantify fasciculation potentials prospectively over 14 months, seeking comparisons with established markers of disease progression. Twenty patients with amyotrophic lateral sclerosis and five patients with benign fasciculation syndrome underwent up to seven assessments each. At each assessment, we performed the amyotrophic lateral sclerosis-functional rating scale, sum power score, slow vital capacity, 30-min high-density surface electromyography recordings from biceps and gastrocnemius and the motor unit number index. We employed the Surface Potential Quantification Engine, which is an automated analytical tool to detect and characterize fasciculations. Linear mixed-effect models were employed to account for the pseudoreplication of serial measurements. The amyotrophic lateral sclerosis-functional rating scale declined by 0.65 points per month (P < 0.0001), 35% slower than average. A total of 526 recordings were analysed. Compared with benign fasciculation syndrome, biceps fasciculation frequency in amyotrophic lateral sclerosis was 10 times greater in strong muscles and 40 times greater in weak muscles. This was coupled with a decline in fasciculation frequency among weak muscles of -7.6/min per month (P = 0.003), demonstrating the rise and fall of fasciculation frequency in biceps muscles. Gastrocnemius behaved differently, whereby strong muscles in amyotrophic lateral sclerosis had fasciculation frequencies five times greater than patients with benign fasciculation syndrome while weak muscles were increased by only 1.5 times. Gastrocnemius demonstrated a significant decline in fasciculation frequency in strong muscles (2.4/min per month, P < 0.0001), which levelled off in weak muscles. Fasciculation amplitude, an easily quantifiable surrogate of the reinnervation process, was highest in the biceps muscles that transitioned from strong to weak during the study. Pooled analysis of >900 000 fasciculations revealed inter-fasciculation intervals <100 ms in the biceps of patients with amyotrophic lateral sclerosis, particularly in strong muscles, consistent with the occurrence of doublets. We hereby present the most comprehensive longitudinal quantification of fasciculation parameters in amyotrophic lateral sclerosis, proposing a unifying model of the interactions between motor unit loss, muscle power and fasciculation frequency. The latter showed promise as a disease biomarker with linear rates of decline in strong gastrocnemius and weak biceps muscles, reflecting the motor unit loss that drives clinical progression.

Longitudinal transcriptomic analysis of altered pathways in a CHMP2Bintron5-based model of ALS-FTD

Amyotrophic lateral sclerosis and frontotemporal dementia are two neurodegenerative diseases with currently no cure. These two diseases share a clinical continuum with overlapping genetic causes. Mutations in the CHMP2B gene are found in patients with ALS, FTD and ALS-FTD. To highlight deregulated mechanisms occurring in ALS-FTD linked to the CHMP2B gene, we performed a whole transcriptomic study on lumbar spinal cord from CHMP2B^intron5 mice, a model that develops progressive motor alterations associated with dementia symptoms reminiscent of both ALS and FTD. To gain insight into the transcriptomic changes taking place during disease progression this study was performed at three stages: asymptomatic, symptomatic and end stage. We showed that before appearance of motor symptoms, the major disrupted mechanisms were linked with the immune system/inflammatory response and lipid metabolism. These processes were progressively replaced by alterations of neuronal electric activity as motor symptoms appeared, alterations that could lead to motor neuron dysfunction. To investigate overlapping alterations in gene expression between two ALS-causing genes, we then compared the transcriptome of symptomatic CHMP2B^intron5 mice with the one of symptomatic SOD1^G86R mice and found the same families deregulated providing further insights into common underlying dysfunction of biological pathways, disrupted or disturbed in ALS. Altogether, this study provides a database to explore potential new candidate genes involved in the CHMP2B^intron5-based pathogenesis of ALS, and provides molecular clues to further understand the functional consequences that diseased neurons expressing CHMP2B mutant may have on their neighbor cells.

ALS Genetics, Mechanisms, and Therapeutics: Where Are We Now?

The scientific landscape surrounding amyotrophic lateral sclerosis (ALS) continues to shift as the number of genes associated with the disease risk and pathogenesis, and the cellular processes involved, continues to grow. Despite decades of intense research and over 50 potentially causative or disease-modifying genes identified, etiology remains unexplained and treatment options remain limited for the majority of ALS patients. Various factors have contributed to the slow progress in understanding and developing therapeutics for this disease. Here, we review the genetic basis of ALS, highlighting factors that have contributed to the elusiveness of genetic heritability. The most commonly mutated ALS-linked genes are reviewed with an emphasis on disease-causing mechanisms. The cellular processes involved in ALS pathogenesis are discussed, with evidence implicating their involvement in ALS summarized. Past and present therapeutic strategies and the benefits and limitations of the model systems available to ALS researchers are discussed with future directions for research that may lead to effective treatment strategies outlined.

Preprocessing surface EMG data removes voluntary muscle activity and enhances SPiQE fasciculation analysis

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A novel preprocessing step removes the need for manual selection of relaxed surface EMG data.

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SPiQE provides reliable fasciculation analysis from raw thirty-minute recordings in ALS.

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This paves the way for clinical calibration of a potential novel biomarker of disease progression.

Objectives

Fasciculations are a clinical hallmark of amyotrophic lateral sclerosis (ALS). The Surface Potential Quantification Engine (SPiQE) is a novel analytical tool to identify fasciculation potentials from high-density surface electromyography (HDSEMG). This method was accurate on relaxed recordings amidst fluctuating noise levels. To avoid time-consuming manual exclusion of voluntary muscle activity, we developed a method capable of rapidly excluding voluntary potentials and integrating with the established SPiQE pipeline.

Methods

Six ALS patients, one patient with benign fasciculation syndrome and one patient with multifocal motor neuropathy underwent monthly thirty-minute HDSEMG from biceps and gastrocnemius. In MATLAB, we developed and compared the performance of four Active Voluntary IDentification (AVID) strategies, producing a decision aid for optimal selection.

Results

Assessment of 601 one-minute recordings permitted the development of sensitive, specific and screening strategies to exclude voluntary potentials. Exclusion times (0.2–13.1 minutes), processing times (10.7–49.5 seconds) and fasciculation frequencies (27.4–71.1 per minute) for 165 thirty-minute recordings were compared. The overall median fasciculation frequency was 40.5 per minute (10.6–79.4 IQR).

Conclusion

We hereby introduce AVID as a flexible, targeted approach to exclude voluntary muscle activity from HDSEMG recordings.

Significance

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

Count of Fasciculation in Ultrasound Can Predict the Prognosis of Amyotrophic Lateral Sclerosis

Background:

Although muscle ultrasound (MUS) is known to facilitate the diagnosis and evaluation of the severity of amyotrophic lateral sclerosis (ALS), the number of fasciculation has been scarcely examined as a predictive marker of the prognosis in ALS.

Objective:

The objective of this study was to examine the predictive value of fasciculation number for the prognosis of ALS.

Materials and Methods:

We examined fasciculation count (FasC), defined as the number of fasciculation per unit of time and area in MUS, of 11 patients with clinically probable or definite ALS. Thereafter, they were observed for maximally 2 years, unless they reached the endpoint of decease or receiving tracheostomy.

Results:

Six patients, who thereafter reached the endpoint within 2 years, had significantly higher FasC (223 [49.3] vs. 34 [13], P = 0.0043) and shorter disease duration (7 [2.3] vs. 33 [17], P = 0.0022) at MUS than the remaining five patients without reaching the endpoint.

Discussion and Conclusion:

Our study suggested that high FasC in MUS can predict rapid progression in ALS. Due to the limitations such as small sample size, suboptimal length of the observational period, and confounding factor of disease duration, further investigations are required.