Muscle ultrasound in neuromuscular disorders

Abstract

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.

Diagnostic accuracy of common clinical tests for assessing abdominal muscle function after motor-complete spinal cord injury above T6

“…When considering the reliability of ultrasound as a measure of abdominal muscle function, our results with high ICC value of 0.957 in the control group are supported by previous work; 15,22 however, we observed less reliability in the SCI group. This finding may be because of difficulties in identifying fascial borders, as observed in the atrophied muscles of patients with Duchenne's muscular dystrophy or motor neuron disorders 23 and/or mislabelling of fascia borders owing to increased intramuscular fat, causing loss of contrast. 24 Compared with EMG, ultrasound measures of voluntary activity were highly specific (no false positive), but had poor sensitivity in detecting muscle activity when present.…”

Quantitative muscle ultrasound is useful for evaluating secondary axonal degeneration in chronic inflammatory demyelinating polyneuropathy

“…MUS findings including EI and MT in denervated hand muscles correlated with the severity of EMG abnormalities and facilitated the discrimination between moderate‐to‐severe muscle denervation and healthy hand muscles (Kim et al., 2016; Pillen et al., 2008; Simon et al., 2015). In this study, the quantitative MUS assessment on small hand muscles in patients with CIDP revealed that six out of 45 muscles with abnormally high EI and/or low MT suggested denervation following secondary axonal degeneration.…”

“…Pillen et al. insisted that MUS was equally or slightly less capable of detecting focal neuropathies than EMG, with a sensitivity estimated at 70% (Pillen et al., 2008). Simon et al.…”

“…The ICC (1, 1) was calculated from the three examinations. Stepwise multiple linear regression analysis was performed in the NC group to evaluate whether gender and age were independent predictors of EI and MT, as previously reported (Pillen et al., 2008). Based on the analysis, NCs were classified into several groups according to gender as well as age (40 years or less, 41–60 years, and 61 years or more).…”

Paediatric musculoskeletal US beyond the hip joint

“…In this heterogeneous class of disorders, US has proved effective for measuring the muscle bulk. Semiquantitative scales based on muscle echogenicity have been used to estimate dystrophic changes in terms of fatty degeneration and connective tissue replacement [58][59][60]. In this class of disorders, US allows dynamic scanning during muscle contraction and may reveal spontaneous muscle activity (e.g.…”