Muscle ultrasound detects fasciculations and facilitates diagnosis in ALS

Open-label pilot study of ranolazine for cramps in amyotrophic lateral sclerosis

INTRODUCTION/AIMS

Neuronal hyperexcitability (manifested by cramps) plays a pathological role in amyotrophic lateral sclerosis (ALS), and drugs affecting it may help symptomatic management and slow disease progression. We aimed to determine safety and tolerability of two doses of ranolazine in patients with ALS and evaluate for preliminary evidence of drug-target engagement by assessing muscle cramp characteristics.

METHODS

We performed an open-label dose-ascending study of ranolazine in 14 individuals with ALS in two sequential cohorts: 500 mg (cohort 1) and 1000 mg (cohort 2) orally twice daily. Each had a 2-week run-in period, 4-week drug administration, and 6-week safety follow-up. Primary outcome was safety and tolerability. Exploratory measures included cramp frequency and severity, fasciculation frequency, cramp potential duration, ALS Functional Rating Scale---Revised score, and forced vital capacity.

RESULTS

Six and eight participants were enrolled in cohorts 1 and 2, respectively. There were no serious adverse events. Two subjects in cohort 2 discontinued the drug due to constipation. The most frequent drug-related adverse event was gastrointestinal (40%). Cramp frequency decreased by 54.8% (95% confidence interval [CI], 39%-70.8%) and severity decreased by 46.3% (95% CI, 29.5-63.3%), which appeared to be dose-dependent, with decreased awakening due to cramps. Other outcomes showed no change.

DISCUSSION

Ranolazine was well tolerated in ALS up to 2000 mg/day, with gastrointestinal side effects being the most frequent. Ranolazine reduced cramp frequency and severity, supporting its investigation for muscle cramps in a future placebo-controlled trial.

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.

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.

Volumetric assessment of spontaneous mechanical activities by simultaneous multi-slice MRI techniques with correlation to muscle fiber orientation

The purpose of this work was assessment of volumetric characteristics of spontaneous mechanical activities in musculature (SMAMs) by diffusion-weighted simultaneous multi-slice (DW-SMS) imaging and spatial correlation to anatomical structure, as revealed by fusion to fiber tractographic information derived from diffusion-tensor imaging (DTI). The feasibility of using DW-SMS to image spontaneous events in human musculature was assessed by phantom measurements. Series of DW-SMS images and DTI datasets were recorded from the resting calf of three human subjects. Simultaneously recorded SMAMs in multiple slices were analyzed regarding spatial extension by the Kolmogorov-Smirnov test. Direct correlation of spatial distribution of SMAMs and fiber orientation was investigated by mapping of muscle fibers to multi-slice SMAM datasets. The DW-SMS strategy allows simultaneous assessment of SMAMs in several slices of resting skeletal musculature, since 73.9% of SMAM-affected volumes have shown SMAMs in multiple DW-SMS slices. Spatial extension of SMAMs was highly correlated over different simultaneously recorded DW-SMS slices, and affected areas followed the orientation of muscle fibers with a connectivity ratio up to 57.18 ± 14.80% based on event count and connectivity count maps. In 89.2% of all SMAM-affected datasets muscle fiber connectivity was shown in at least two adjacent slices. Direct correlation between SMAMs in human lower leg musculature and underlying anatomical structure was revealed by high muscle fiber connectivity (89.2%). SMAMs have shown a wide distribution along the longitudinal muscle direction (73.9% in multiple DW-SMS slices) with direct involvement of muscle fibers. Correlation between SMAMs in multiple DW-SMS slices and crossing muscular fiber tracts provides evidence that SMAMs result from physiological processes in musculature. Fusion of DW-SMS with DTI facilitates non-invasive studies of muscle fiber involvement in SMAMs in resting muscle.

Surface electromyogram and muscle ultrasonography for detection of muscle fasciculations in pediatric peripheral neuropathy

A 12-year-old girl presented with talipes equinus of both legs, attenuation of upper and lower limb tendon reflexes, thermal hyperalgesia, and reduction of vibratory sensation. On clinical examination, muscle twitches of fingers of both hands, as well as the abductor halluces and the dorsal interossei muscles of the right foot were observed. Nerve conduction velocity was significantly declined in the upper and lower extremities. Needle electromyography (EMG) was not performed; however, ultrasonography revealed repetitive, semi-regular muscle twitches lasting 0.2-0.4s, concomitant with muscle discharges on surface EMG in the right foot muscles. These findings were compatible with contraction fasciculation in muscles under chronic reinnervation. Nerve and muscle biopsies were suggestive of chronic motor, sensory, and autonomic neuropathy. This is the first case of pediatric peripheral neuropathy where muscle fasciculation was noninvasively identified by simultaneous surface EMG and ultrasonography.

ACM. Dementia in motor neuron disease: reviewing the role of MRI in diagnosis

The superimposed clinical features of motor neuron disease (MND) and frontotemporal dementia (FTD) comprise a distinct, yet not fully understood, neurological overlap syndrome whose clinicopathological basis has recently been reviewed. Here, we present a review of the clinical, pathological and genetic basis of MND-FTD and the role of MRI in its diagnosis. In doing so, we discuss current techniques that depict the involvement of the selective corticospinal tract (CST) and temporal lobe in MND-FTD.

Ultrasound-Based Detection of Fasciculations in Healthy and Diseased Muscles

Involuntary muscle activations are diagnostic indicators of neurodegenerative pathologies. Currently detected by invasive intramuscular electromyography, these muscle twitches are found to be visible in ultrasound images. We present an automated computational approach for the detection of muscle twitches, and apply this to two muscles in healthy and motor neuron disease-affected populations. The technique relies on motion tracking within ultrasound sequences, extracting local movement information from muscle. A statistical analysis is applied to classify the movement, either as noise or as more coherent movement indicative of a muscle twitch. The technique is compared to operator identified twitches, which are also assessed to ensure operator agreement. We find that, when two independent operators manually identified twitches, higher interoperator agreement (Cohen's κ) occurs when more twitches are present (κ = 0.94), compared to a lower number (κ = 0.49). Finally, we demonstrate, via analysis of receiver operating characteristics, that our computational technique detects muscle twitches across the entire dataset with a high degree of accuracy (0.83 < accuracy < 0.96).

Neuromuscular ultrasonography: quantifying muscle and nerve measurements

Neuromuscular ultrasonography can be used both descriptively and quantitatively in the evaluation of patients with neuromuscular disorders. This article reviews the quantitative use of this technology, particularly measurements of the size and echogenicity of nerve and muscle, as a tool for assessing the severity, progression, and response of these tissues to therapeutic interventions. Neuromuscular ultrasonography has several features, including portability and noninvasiveness, that make it an attractive research tool for advancing the diagnosis and treatment of neuromuscular disorders.