Muscle ultrasonography: a diagnostic tool for amyotrophic lateral sclerosis.

OBJECTIVE: In a prospective study we tested whether muscle ultrasonography can differentiate between amyotrophic lateral sclerosis (ALS) and mimics. Furthermore, we assessed the ability of ultrasonography to identify subclinical lower motor neuron involvement. METHODS: In 59 patients, suspected for adult onset motor neuron disease, ultrasound scans were made of 12 different muscle groups. Echo intensity was determined and each muscle was screened for fasciculations. Ultrasonography was considered diagnostic for ALS when echo intensity was 1.5 SD above normal in at least two muscles and fasciculations were present in at least four muscles. RESULTS: Ultrasonography differentiated between ALS and mimics with 96% sensitivity and 84% specificity. In the 27 ALS patients, ultrasonography detected 15 regions with lower motor neuron involvement that were negative using either clinical examination or needle EMG. CONCLUSIONS: Muscle ultrasound can differentiate between amyotrophic lateral sclerosis and mimics with high sensitivity and specificity, and is a sensitive tool to screen for regional lower motor neuron involvement. SIGNIFICANCE: Muscle ultrasonography is a promising tool in the diagnostic work up of ALS.

Fasciculations and their F-response revisited: high-density surface EMG in ALS and benign fasciculations.

OBJECTIVE: To compare the prevalence of fasciculation potentials (FPs) with F-responses between patients with amyotrophic lateral sclerosis (ALS) and patients with benign fasciculations. METHODS: In seven patients with ALS and seven patients with benign fasciculations, high-density surface EMG was recorded for 15 min from the gastrocnemius muscle. Template matching was used to search for pairs of FPs with a repetition within 10-110 ms. RESULTS: Interspike interval (ISI) histograms were constructed from 282 pairs of benign fasciculations and from 337 FP pairs in ALS. Peaks attributable to F-waves were found at latencies of 32 ms (benign) and 35 ms (ALS). Five patients with benign fasciculations and four patients with ALS had FPs with F-waves. CONCLUSIONS: F-waves of FPs occur in both conditions - therefore they are not diagnostically helpful. SIGNIFICANCE: F-waves confirm the distal origin of FPs for an individual axon. The occurrence of these FPs in a benign condition suggests that the generation of ectopic discharges in the distal axons is not specific to progressive neurodegeneration.

Muscle changes in amyotrophic lateral sclerosis: a longitudinal ultrasonography study.

OBJECTIVE: We performed a longitudinal study to assess structural muscle changes in amyotrophic lateral sclerosis (ALS) using ultrasonography. METHODS: During a follow-up of 6 months, ultrasonography parameters (muscle thickness, echo intensity and fasciculations) were obtained from 6 muscle groups in 31 ALS patients, together with strength and scores on the revised ALS functional rating scale (ALSFRS-r). RESULTS: At baseline, we found an increased echo intensity and decreased thickness, and these parameters correlated with lower strength. Moreover, ultrasound abnormalities were also detected in muscles with preserved strength. Longitudinal changes in echo intensity, muscle thickness and fasciculations showed large variations between patients. Rates of change in ultrasound parameters did not correlate with changes in ALSFRS-r or strength. CONCLUSION: In patients with ALS ultrasound abnormalities can be found in muscles with preserved strength. The pattern of ultrasonographic muscle changes in ALS is highly variable and shows no evident correlation with functional measures. SIGNIFICANCE: Ultrasonography is not suitable to monitor disease progression in ALS.

Muscle ultrasonography to predict survival in amyotrophic lateral sclerosis.

The authors assessed the prognostic value of muscle ultrasonography in 31 patients with amyotrophic lateral sclerosis (ALS) and compared it with accepted prognostic variables like functional capacity (measured with the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS)) and muscle strength. Each patient was examined once. The following ultrasonography parameters were determined: muscle thickness, echo intensity (EI) and the presence of fasciculations. Correlations between baseline measurements, preslope values and survival were calculated. EI, disease duration, muscle strength preslope and ALSFRS-R preslope correlated with survival. Using a stepwise multivariate analysis, the combination of EI preslope and ALSFRS-R preslope was shown to have the best predictive value for survival.

Normal values for quantitative muscle ultrasonography in adults.

Ultrasonography can detect structural muscle changes caused by neuromuscular disease. Quantitative analysis is the preferred method to determine if ultrasound findings are within normal limits, but normative data are incomplete. The purpose of this study was to provide normative muscle ultrasonography data for muscle thickness and echo intensity for five different muscle groups in adults. Bilateral scans of the sternocleidomastoid, biceps brachii/brachialis, forearm flexor group, quadriceps femoris, and tibialis anterior were made in 95 volunteers, aged 17-90 years. Both muscle thickness and echo intensity showed gender differences and a muscle-specific non-linear correlation with age. The muscles of the upper extremities showed right-left differences. These data demonstrate the effect of age on muscle characteristics and provide normative values that can be used in clinical practice.

Prevalence and distribution of fasciculations in healthy adults: Effect of age, caffeine consumption and exercise.

Our objective was to determine the prevalence and distribution of fasciculations in healthy adults and to assess the effect of age, caffeine and exercise. Fasciculations were studied with ultrasonography in 58 healthy adults in various age categories. Questionnaires were used to determine effect of caffeine and regular exercise on the presence of fasciculations. Finally, we tested the effect of strenuous exercise on fasciculations in 10 healthy adults. Twenty-five subjects (43%) showed fasciculations on ultrasonography, mostly in the abductor hallucis longus muscle. Fasciculations were only sporadically encountered in muscle groups above the knee. Subjects with fasciculations were significantly older than those without. Caffeine and regular physical exercise did not influence the prevalence of fasciculations. However, strenuous physical exercise caused a temporary increase in fasciculations, but only in lower leg muscles. Fasciculations above the knee should raise suspicion and may warrant further investigation.

Muscles alive: ultrasound detects fibrillations.

OBJECTIVE: Muscle ultrasound is capable of visualizing muscle movements. Recent improvements in ultrasound technology have raised the question whether it is also possible to detect small-scale spontaneous muscle activity such as denervation. In this study we investigated the ability of dynamic muscle ultrasound to detect fibrillations. METHODS: Eight patients with fibrillations were measured simultaneously by ultrasound and EMG to verify which movements on ultrasound examination corresponded to fibrillation potentials on EMG. The temperature dependency of ultrasound detected fibrillations and the observer agreement was assessed in five healthy subjects with focal denervation induced by botulinum toxin. RESULTS: Fibrillations appeared on ultrasound examination as small, irregularly oscillating movements within the muscle while the overall shape of the muscle remains undisturbed. Visibility of fibrillations with ultrasound decreased with lower temperatures, with a 32% decrease at 30 degrees C compared to 39 degrees C. The interobserver agreement was substantial with a kappa of 0.65 for experienced observers. CONCLUSION: Fibrillations could be visualized with ultrasound. Consistent results could be obtained from trained observers. Care has to be taken to ensure an optimal muscle temperature to avoid false negative results, especially in distal muscles. SIGNIFICANCE: Visualization of fibrillations by muscle ultrasound opens the way for a new diagnostic application of this technique.

Skeletal muscle ultrasound: correlation between fibrous tissue and echo intensity.

In this study, we examined the correlation between muscle ultrasound and muscle structure. Echo intensity (EI) of 14 muscles of two golden retriever muscular dystrophy dogs was correlated to the percentage interstitial fibrous tissue and fat in muscle biopsy. A significant correlation between interstitial fibrous tissue and EI was found (r = 0.87; p < 0.001). The separate influence of interstitial fat on muscle EI could not be established as only little fat was present. We conclude that fibrous tissue causes increased muscle EI. The high correlation between interstitial fibrous tissue and EI makes ultrasound a reliable method to determine severity of structural muscle changes.

Muscle ultrasound in neuromuscular disorders.

Muscle ultrasound is a useful tool in the diagnosis of neuromuscular disorders, as these disorders result in muscle atrophy and intramuscular fibrosis and fatty infiltration, which can be visualized with ultrasound. Several prospective studies have reported high sensitivities and specificities in the detection of neuromuscular disorders. Although not investigated in large series of patients, different neuromuscular disorders tend to show specific changes on muscle ultrasound, which can be helpful in differential diagnosis. For example, Duchenne muscular dystrophy results in a severe, homogeneous increase of muscle echo intensity with normal muscle thickness, whereas spinal muscular atrophy shows an inhomogeneous increase of echo intensity with severe atrophy. A major advantage of muscle ultrasound, compared to other imaging techniques, is its ability to visualize muscle movements, such as muscle contractions and fasciculations. This study reviews the possibilities and limitations of ultrasound in muscle imaging and its value as a diagnostic tool in neuromuscular disorders.

Quantitative muscle ultrasonography in amyotrophic lateral sclerosis.

In this study, we examined whether quantitative muscle ultrasonography can detect structural muscle changes in early-stage amyotrophic lateral sclerosis (ALS). Bilateral transverse scans were made of five muscles or muscle groups (sternocleidomastoid, biceps brachii/brachialis, forearm flexor group, quadriceps femoris and anterior tibialis muscles) in 48 patients with ALS. Twenty-five patients were also screened for fasciculations. Quantitative analysis revealed a significant increase in echo intensity in all muscles and a decrease in muscle thickness of the biceps brachii, forearm flexors and quadriceps femoris on both sides. Fasciculations were easy to detect in multiple muscles of all screened patients except one. We conclude that quantitative ultrasonography can be used to detect muscle changes caused by ALS in an early phase of the disease. (E-mail: m.zwarts@neuro.umcn.nl).

Effects of visual center of pressure feedback on postural control in young and elderly healthy adults and in stroke patients.

The goal of this study was to compare young and elderly healthy individuals and elderly stroke patients in their capacity to use visual CP feedback (VF) in controlling both quiet standing and weight shifting and to assess their sensory re-weighing when this VF is withdrawn. A total of 40 participants were involved in this study. Participants were asked to either quietly stand on a force platform for a period of 45 s with eyes open (EO), using visual feedback (VF) or without visual feedback (No VF) or to perform a dynamic weight shifting task while using VF or No VF. During the quiet standing trials with VF, only the young (YO) were able to decrease the amplitude and increase the frequency of their sway in either plane. Removal of the VF resulted in a 'destabilizing' effect in both healthy elderly (EL) and stroke patients (ST) in the sagittal plane. With regard to the dynamic task, both the YO and EL were generally more successful at weight shifting in terms of speed and control when compared to the ST. Yet, when VF was removed, only the YO were able to largely maintain speed and precision of control. Hence, providing or removing visual CP feedback during quiet standing or removing VF during visually controlled weight shifting can discriminate healthy young participants from healthy elderly, but does not clearly discriminate healthy elderly from stroke patients in the same age group. Results revealed that sagittal plane imbalance in healthy elderly and stroke patients may be largely due to the effects of aging, whereas frontal plane imbalance is much more specific for the postural problems associated with stroke.