Sensitivity and specificity of qualitative muscle ultrasound in assessment of suspected neuromuscular disease in childhood

Muscle ultrasound is considered a useful noninvasive technique for visualizing normal and pathological skeletal muscle. We determined the accuracy of qualitative muscle ultrasound in the discrimination of normal muscle from myopathic, neurogenic, and unspecifically abnormal tissue changes in the evaluation of suspected NMD in childhood. Sensitivity and specificity of muscle ultrasound were assessed by comparing sonographic classification of muscle tissue changes in 134 children with definitive diagnosis as provided by muscle histology or mutation analysis performed subsequently to the sonography. We found a sensitivity of 81% and a specificity of 96% for detection of any abnormal muscle tissue alteration by ultrasound. For detection of neurogenic changes, sensitivity was 77% with even higher specificity (98%). Accuracy was slightly lower for myopathic changes (79%) and clearly lower for unspecific abnormal tissue alterations (70%). Accuracy of ultrasound was lower in younger children. High reliability of muscle sonography justifies a more widespread use of this method in evaluation of suspected NMD in childhood.     

Quantitative ultrasonography of skeletal muscles in children: normal values

The purpose of this study was to establish normal values of muscle thickness, ratio of muscle thickness to subcutaneous fat thickness, and muscle echo intensity in children between 11 weeks and 16 years of age. Transverse scans of four muscles were made by standardized real-time ultrasound examination. The scans were digitized, and mean echo intensity was measured using gray-scale analysis. A multiple regression equation was used to study which independent parameter (age, height, weight, or sex) influenced the variables for each muscle. Muscle thickness depended on the child's weight. The other parameters did not significantly influence muscle thickness after correction for weight. The ratio of muscle thickness to subcutaneous fat thickness depended on age. Echo intensity showed no correlation with either of the variables. As a result, all normal values, including the equation to calculate them, are described. These normal data may help to determine the diagnostic value of muscle ultrasound in children with suspected neuromuscular disease.     

Quantitative skeletal muscle ultrasonography in children with suspected neuromuscular disease

We determined prospectively the diagnostic value of quantitative ultrasonography in detecting neuromuscular disorders in children. Ultrasonographic scans of four muscles were made in 36 children with symptoms or signs suggestive of neuromuscular disease, such as muscle weakness and hypotonia. The muscle thickness, ratio of muscle thickness to subcutaneous fat thickness, and echo intensity were determined in each muscle. The echo intensity was measured using computer-assisted gray-scale analysis. Thirteen of the 36 patients had a neuromuscular disorder (6 a myopathy and 7 a neuropathy). Differentiation between neuromuscular diseases and nonneuromuscular diseases could be made on the basis of echo intensities with a sensitivity of 92%, a specificity of 90%, a positive predictive value of 86%, and a negative predictive value of 95%. We conclude that computer-assisted quantitative analysis of muscle echo intensity is a reliable method to discriminate between neuromuscular and nonneuromuscular diseases in children.     

Ultrasound characterization of medial gastrocnemius tissue composition in children with spastic cerebral palsy

Introduction: In this study we aimed to characterize muscle composition of the medial gastrocnemius in children with spastic cerebral palsy (SCP) using quantitative ultrasound. Methods: Forty children with SCP, aged 4–14 years, participated in this study. Children were grouped according to the gross motor function classification system (GMFCS I–V) and compared with a cohort of age‐ and gender‐matched, typically developing children (TD; n = 12). Ultrasound scans were taken of the medial gastrocnemius. Images were then characterized using grayscale statistics to determine mean echo intensity (EI) and the size and number of spatially connected homogeneous regions (i.e., blobs). Results: Significant differences in skeletal muscle composition were found between children with SCP and their TD peers. Children classified as GMFCS III consistently exhibited the highest EI and blob area. Conclusions: This study demonstrates altered tissue composition in children with SCP visualized using ultrasound. Further work is required to determine the pathophysiology contributing to these alterations in SCP. Muscle Nerve 52:397–403, 2015     

Quantitative skeletal muscle ultrasound: diagnostic value in childhood neuromuscular disease

In this study we investigated the diagnostic value of quantitative skeletal muscle ultrasonography in 150 consecutively referred children with symptoms suspect for a neuromuscular disorder. Muscle thickness and quantitatively determined echo intensity of four muscles and the distribution of these variables within the body were examined. RESULTS: Patients with and without a neuromuscular disorder could be discriminated with a positive predictive value of 91% and a negative predictive value of 86%. Patients with a neurogenic disorder could be distinguished from myopathies and non-neuromuscular disorders with a positive predictive value of 86% and a negative predictive of 84%, using the pattern of distribution of pathology within the body. CONCLUSIONS: Skeletal muscle ultrasound is a good, practical and non-invasive aid in the diagnosis of neuromuscular disorders in children, that is able to discriminate between children with and without a neuromuscular disorder and between neurogenic disorders and myopathies with high predictive values.     

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. Muscle Nerve, 2010     

Muscle ultrasound in the assessment of suspected neuromuscular disease in childhood.

One hundred paediatric, muscle ultrasound examinations performed in the evaluation of suspected neuromuscular disease were reviewed. The results were related to the presence or absence of neuromuscular disease in each child assessed. The group comprised 66 males and 34 females, age range 2 months to 16 years (mean 5.3 years). Scans were graded I-IV, according to muscle echogenicity, using Heckmatt's criteria. Thirty-two children had a final diagnosis of neuromuscular disease. The sensitivity of ultrasound in detecting neuromuscular disease was 78% with 91% specificity. The test was more reliable in the sub-group of > 3 years with a sensitivity of 81% and specificity of 96%. There was a significant difference in disease status, (with and without neuromuscular disease), between children with a normal, grade I, scan and those with an abnormal, grade II, III, IV, image (chi-square, P < 0.001, 95% confidence limits 0.54-0.86). Muscle ultrasound is a specific and sensitive investigation for suspected neuromuscular disease in children.     

Muscle ultrasonography: a diagnostic tool for amyotrophic lateral sclerosis

ObjectiveIn 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.MethodsIn 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.ResultsUltrasonography 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.ConclusionsMuscle 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.SignificanceMuscle ultrasonography is a promising tool in the diagnostic work up of ALS.     

Ultrasound imaging of muscles in Duchenne muscular dystrophy

The ultrasound imaging of quadriceps, gastrocnemius and soleus muscles was performed in 30 patients with Duchenne muscular dystrophy (DMD) and 16 control subjects. In controls, the skeletal muscle itself was scarcely echogenic. However, bone surface and fascia were clearly echogenic. The transverse scan of muscle in all DMD patients showed an increased echogenicity, which made the echo from bone or fascia less intense. The abnormal muscle echo was graded according to Heckmatt et al. From the quantitative aspect, there was a significant correlation between disability scale of DMD patients and abnormal echogenicity of the quadriceps muscle. A similar correlation was also observed between results of manual muscle testing the ultrasound imaging. The soleus muscle was usually less abnormal than the gastrocnemius in the ultrasound imaging. Thus, the ultrasound imaging seemed to provide an important information for the clinical assessment of DMD patients.     

Calibrated quantitative ultrasound imaging of skeletal muscle using backscatter analysis

We evaluated the ability of an ultrasound method, which can characterize cardiac muscle pathology and has reliability across different imaging systems, to obtain calibrated quantitative estimates of backscatter of skeletal muscle. Our procedure utilized a tissue-mimicking phantom to establish a linear relationship between ultrasound grayscale and backscatter levels. We studied skeletal muscles of 82 adults: 45 controls and 37 patients with hereditary myopathies. We found that skeletal muscle ultrasound backscatter levels varied with probe orientation, age, and muscle contraction and pathology. Reliability was greater with the probe in longitudinal compared with transverse planes. Backscatter levels were higher in those >40 years of age, in muscle extension than flexion, and in myopathic patients than controls. Calibrated measurements of muscle backscatter have sensitivity and specificity in identifying and reliably measuring levels of skeletal muscle pathology.     

Skeletal muscle ultrasound

Muscle ultrasound is a convenient technique to visualize normal and pathological muscle tissue as it is non-invasive and real-time. Neuromuscular disorders give rise to structural muscle changes that can be visualized with ultrasound: atrophy can be objectified by measuring muscle thickness, while infiltration of fat and fibrous tissue increases muscle echo intensity, i.e. the muscles become whiter on the ultrasound image. Muscle echo intensity needs to be quantified to correct for age-related increase in echo intensity and differences between individual muscles. This can be done by gray scale analysis, a method that can be easily applied in daily clinical practice. Using this technique, it is possible to detect neuromuscular disorders with predictive values of 90%. Only in young children and metabolic myopathies the sensitivity is lower. Ultrasound is a dynamic technique and therefore capable of visualizing normal and pathological muscle movements. Fasciculations can easily be differentiated from other muscle movements. Ultrasound appeared to be even more sensitive in detecting fasciculations compared to Electromyography (EMG) and clinical observations, because it can visualize a large muscle area and deeper located muscles. With improving resolution and frame rate it has recently become clear that also smaller scale spontaneous muscle activity such as fibrillations can be detected by ultrasound. This opens the way to a broader use of muscle ultrasound in the diagnosis of peripheral nerve and muscle disorders.     

Real-time ultrasound imaging of muscles

A prospective study was done on 222 consecutive new patients referred to our pediatric muscle clinic to assess the diagnostic value of ultrasound imaging. Ultrasound scans were interpreted without knowledge of clinical presentation or results of other tests. Muscular dystrophy produced a brightly speckled pattern of increased echo from the muscle, whereas spinal muscular atrophy showed a moderate increase in muscle echo and associated muscle atrophy. Acute dermatomyositis produced a moderate increase in echo that varied markedly with the direction of the ultrasound beam in relation to the muscle fibres. The ultrasound scan was normal in children with hypotonia of cerebral origin, Prader Willi syndrome, ligamentous laxity, and other "nonneuromuscular" causes. In eight patients ultrasound scanning showed a striking degree of selective involvement of individual components of the quadriceps muscle, which provided considerable diagnostic help for selective needle biopsy. Ultrasound scanning in children has the major advantage of being a noninvasive and pleasant out-patient procedure, which can be readily done on multiple sites. It is a valuable screening test in the investigation of children with neuromuscular disorders.     

Hypokinesia and Rigidity as Clinical Manifestations of Mitochondrial Encephalomyopathy: Report of Three Cases

Three patients are reported with a neurological disorder in which hypokinesia and rigidity were the most prominent clinical signs. On CT scan and MRI, two were found to have bilateral lesions in the striatum, mainly in the putamen, and the third had bilateral lesions in the posterior limb of the internal capsule. Laboratory investigations suggested abnormal pyruvate metabolism in all three cases, which was confirmed to skeletal muscle in two cases. In the third the cause was a NADH dehydrogenase defect. The signs and symptoms, the bilateral striatal lesions in two of the patients, and the abnormal pyruvate metabolism justify a classification of mitochondrial encephalomyopathy, resembling Leigh syndrome. This diagnosis must be considered for infants and children presenting with Parkinsonian signs, and mitochondrial energy metabolism should be investigated.     

Skeletal muscle ultrasound

Abstract

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Muscle ultrasound is a convenient technique to visualize normal and pathological muscle tissue as it is non-invasive and real-time. Neuromuscular disorders give rise to structural muscle changes that can be visualized with ultrasound: atrophy can be objectified by measuring muscle thickness, while infiltration of fat and fibrous tissue increases muscle echo intensity, i.e. the muscles become whiter on the ultrasound image. Muscle echo intensity needs to be quantified to correct for age-related increase in echo intensity and differences between individual muscles. This can be done by gray scale analysis, a method that can be easily applied in daily clinical practice. Using this technique, it is possible to detect neuromuscular disorders with predictive values of 90%. Only in young children and metabolic myopathies the sensitivity is lower. Ultrasound is a dynamic technique and therefore capable of visualizing normal and pathological muscle movements. Fasciculations can easily be differentiated from other muscle movements. Ultrasound appeared to be even more sensitive in detecting fasciculations compared to Electromyography (EMG) and clinical observations, because it can visualize a large muscle area and deeper located muscles. With improving resolution and frame rate it has recently become clear that also smaller scale spontaneous muscle activity such as fibrillations can be detected by ultrasound. This opens the way to a broader use of muscle ultrasound in the diagnosis of peripheral nerve and muscle disorders.     

CONSEQUENCES OF MISDIAGNOSING MITOCHONDRIAL DISORDER

Diagnosing mitochondrial disorder remains a challenge. In a 75-year-old women, with short stature, muscle cramps, ptosis, fasciculations and progressive, proximal limb weakness and wasting, hyponatriemia, abnormal lactate-stress-test, and slightly abnormal electromyography, muscle biopsy suggested granulomatous myositis. Corticosteroids and azathioprin were ineffective. After a second work-up amyotrophic-lateral-sclerosis was diagnosed. Riluzole was started, without effect. She developed respiratory insufficiency, requiring mechanical ventilation. Apical ballooning was found. After switching to non-invasive positive pressure ventilation and physiotherapy, she markedly improved. After a third diagnostic work-up, mitochondrial disorder was suspected. Unfortunately, she died suddenly from a cardiac arrhythmia at home. Mitochondrial disorder may mimic motor neuron disease, muscle biopsy may mimic myositis, and may show only little evidence for respiratory chain disorder.     

Consequences of misdiagnosing mitochondrial disorder

Diagnosing mitochondrial disorder remains a challenge. In a 75-year-old women, with short stature, muscle cramps, ptosis, fasciculations and progressive, proximal limb weakness and wasting, hyponatriemia, abnormal lactate-stress-test, and slightly abnormal electromyography, muscle biopsy suggested granulomatous myositis. Corticosteroids and azathioprin were ineffective. After a second work-up amyotrophic-lateral-sclerosis was diagnosed. Riluzole was started, without effect. She developed respiratory insufficiency, requiring mechanical ventilation. Apical ballooning was found. After switching to non-invasive positive pressure ventilation and physiotherapy, she markedly improved. After a third diagnostic work-up, mitochondrial disorder was suspected. Unfortunately, she died suddenly from a cardiac arrhythmia at home. Mitochondrial disorder may mimic motor neuron disease, muscle biopsy may mimic myositis, and may show only little evidence for respiratory chain disorder.     

Contrast-enhanced Ultrasound in Dermatomyositis- and Polymyositis

Objective To evaluate prospectively contrast-enhanced ultrasound (CEUS) in patients suspected of having dermatomyositis or polymyositis. Methods In 35 patients (23 women, 12 men; mean age, 51 years ± 16 years) who were suspected of having dermatomyositis or polymyositis, perfusion in clinically affected skeletal muscles was quantified with contrast-enhanced intermittent power Doppler ultrasound. By applying a modified model that analyzed the replenishment kinetics of microbubbles, the perfusion-related parameters blood flow, local blood volume and blood flow velocity were measured. Findings were compared with muscle biopsy appearances and with the results of MRI that was performed with a 1.5-Tesla unit. Receiver operating characteristic analysis was performed and optimum thresholds for diagnosis of myositis were determined. Results Eleven patients had histologically confirmed dermatomyositis or polymyositis and showed significantly higher blood flow velocity (P = .01 for dermato- and P < .001 for polymyositis), blood flow (P < .001 for dermato- and polymyositis), and blood volume (P = .007 for dermato- and P < .001 for polymyositis) on contrast-enhanced ultrasound than those who did not have myositis. An increase in signal intensity on T2-weighted MR images was found in all patients with myositis. MRI had a sensitivity, specificity, positive (PPV), and negative predicting values (NPV) of 100%, 88%, 77%, and 100% for diagnosis of myositis, respectively. CEUS blood flow was the best ultrasound measure for diagnosis of dermato- or polymyositis with sensitivity, specificity, PPV, and NPV of 73%, 91%, 80%, and 88%, respectively. Conclusions Increased skeletal muscle perfusion measured by CEUS could serve as an additional measurer for the diagnosis of an inflammatory myopathy. Received in revised form: 6 June 2006 An erratum to this article is available at .     

Quantitative muscle ultrasound and quadriceps strength in patients with post‐polio syndrome

Introduction: We investigated whether muscle ultrasound can distinguish muscles affected by post‐polio syndrome (PPS) from healthy muscles and whether severity of ultrasound abnormalities is associated with muscle strength. Methods: Echo intensity, muscle thickness, and isometric strength of the quadriceps muscles were measured in 48 patients with PPS and 12 healthy controls. Results: Patients with PPS had significantly higher echo intensity and lower muscle thickness than healthy controls. In patients, both echo intensity and muscle thickness were associated independently with muscle strength. A combined measure of echo intensity and muscle thickness was more strongly related to muscle strength than either parameter alone. Conclusions: Quantitative ultrasound distinguishes healthy muscles from those affected by PPS, and measures of muscle quality and quantity are associated with muscle strength. Hence, ultrasound could be a useful tool for assessing disease severity and monitoring changes resulting from disease progression or clinical intervention in patients with PPS. Muscle Nerve 51 : 24–29, 2015     

Cylindrical spirals in a familial neuromuscular disorder

Cylindrical spirals are unique membranous structures that were detected in skeletal muscle of a mother and one of her two children; all three have percussion myotonia but no evidence of weak or wasted skeletal muscles. Muscle cramps, stiffness, posteffort muscle tightness, myotonic lid lag, and the cylinders appear or progress with age, but the disorder is asymptomatic in the children and only mildly incapacitating in the mother. The cylinders are 8 μ long and 1 μ wide, are composed of spiraling double-laminate membrane resembling myelin, and are derived from abnormal subsarcolemmal tubulovesicular structures that are interpreted as pathological T-tubes.     

Quantitative muscle ultrasound is a promising longitudinal follow-up tool in Duchenne muscular dystrophy

Responsive outcome measures are needed to follow the disease status of Duchenne muscular dystrophy (DMD) patients, as new therapeutic approaches become available for affected boys. Quantitative muscle ultrasound (QMUS) is potentially an attractive follow up tool for DMD because it reflects the severity of the dystrophic process without the need for invasive procedures, by quantifying echo intensity (i.e., mean grey level of muscle images) and muscle thickness. We performed a longitudinal follow-up of lower and upper extremity QMUS in 18 DMD patients and compared this with physical functioning in 11 of these patients. QMUS could be performed in every patient, and no patient was subjected to more than a total of 20min of ultrasound scanning time for this study. As expected we found a significant increase of echo intensity with age, reflecting increasing dystrophic muscle changes. This increase was related to ambulatory status, functional grading, muscle strength and motor ability. Our study establishes QMUS as a practical and child-friendly tool for the longitudinal follow up of DMD patients.