2. Introduction
• Muscle ultrasound is a useful tool in the diagnosis of
neuromuscular disorders
• Disorders result in muscle atrophy and intramuscular
fibrosis and fatty infiltration, which can be visualized with
ultrasound.
3. • Neuromuscular ultrasound is an emerging diagnostic
subspecialty field.
• Neuromuscular ultrasound focuses on primary diseases
of nerve and muscle.
4. • Distinct from musculoskeletal ultrasound, which focuses
on traumatic and degenerative changes of tendons and
synovial joints.
• High resolution ultrasound allows to study peripheral
nerves to evaluate neuromuscular diseases.
5. Evolution of Neuromuscular
Ultrasound
• First report of the utility of neuromuscular ultrasound was
in 1980 with the elucidation of distinct imaging
characteristics of muscular dystrophy.
6. Clinical Indications for Neuromuscular
Ultrasound
• High resolution/high frequency ultrasound transducers
made it possible to routinely study peripheral nerves.
• Anatomic changes are frequently associated with
inflammatory and compressive neuropathies and that
these changes are of diagnostic significance.
7. • Possible to image fasciculations of muscle, most recently,
fibrillations.
• Atrophy and hypertrophy are readily measured as are
changes in quantitative muscle echo intensity
8. • Interventional applications of neuromuscular ultrasound-
• Neuromuscular ultrasound is now routinely used to guide
local anesthetic administration for proximal nerve and
brachial plexus blocks.
9. Ultrasound decreases the risk of inadvertent intraneural or
intravascular injection and enhances nerve localization
which lowers drug doses needed and improves safety
margins.
10. Used to guide therapeutic injections of botulinum toxin in
muscle and salivary glands
Steroids into the carpal tunnel
Biopsies of nerve and muscle
Ultrasound guided EMG needle placement can also be
used to more safely study high risk muscles such as the
diaphragm,
Assist with direct needle stimulation of deep nerves at
sites inaccessible to percutaneous stimulation
11. BASIS OF ULTRASOUND IMAGING
• PRINICIPAL:
• Ultrasound image is created based on returning echoes
and their temporal and acoustic properties.
• Amount of returning echoes per area determines the gray
value of the image, that is, the echo intensity
12. What happened in diseased muscle?
• In diseased muscles, replacement by fat and fibrous
tissue occurs.
• Fat and fibrous tissue have a different acoustical
impedance, thereby increasing the number of reflecting
interfaces in the muscle, which gives the muscle a whiter
appearance
13.
14. • Diagnostic frequencies lie in the range of 2–20 MHz, with
corresponding wavelengths of 0.8 – 0.08 mm.
15. • To achieve the best resolution, transducers with a high
frequency are preferable.
• Depth of penetration is correlated inversely with
frequency.
• Generally, 5 or 7.5-MHz probes are used in muscle
ultrasound studies, to ensure sufficient depth penetration.
16. • Nowadays, possible to use broadband transducers ( 5–17
MHz),
• Combining the advantage of high frequencies to image
superficial structures with high resolution and lower
frequencies to reach deeper structures.
• Ultrasound techniques have further improved, resulting in
display of muscle tissue with resolutions up to 0.1 mm
17. NORMAL MUSCLE IN USG
• Normal muscle tissue appears as a structure with low
echo intensity (i.e., it is black in appearance).
• Muscle tissue is divided by echogenic sheets of
perimysial connective tissue.
19. • Gives the muscle a speckled appearance in the
transverse plane
• In the longitudinal plane, hyperechoic lines are visible,
forming a linear or pennate structure
20.
21. ECHOGENESITY OF MUSCLE?
• Sonographic appearance of muscle is fairly distinct and
can easily be differentiate from surrounding structures
such as subcutaneous fat, bone, nerves and blood
vessels.
• Boundaries of the muscle are clearly visible, as the
epimysium surrounding the muscle is a highly reflective
(echogenic) structure.
25. Ultrasound in Neuromuscular
disorders
• Neuromuscular disorders usually lead to changes in
muscle morphology that can be visualized with
ultrasound.
• Both atrophy and changes in muscle architecture can be
assessed.
26. Screening tool
• Currently, muscle ultrasound used as a screening tool
• in initial diagnostic phase of patients with suspected
neuromuscular disorders.
• An abnormal ultrasound, and especially increased muscle
echo intensity, is indicative of such a disorder.
27. • EMG and muscle biopsy, are necessary to determine the
type of neuromuscular disorder
• Specific muscle ultrasound findings can give additional
clues that may help in directing the differential diagnosis
28. USG-as a screening tool
• Prospective studies in children shown that-
• Visual evaluation of muscle echo intensity, the presence
of a neuromuscular disorder can be detected with a
sensitivity of 67%–81% and a specificity of 84%–92%.
• Brockmann K, Becker P, Schreiber G, Neubert K, Brunner E, Bonnemann C. Sensitivity
and specificity of qualitative muscle ultrasound in assessment of suspected
neuromuscular disease in childhood. Neuromuscul Disord 2007;17:517–523.
29. • Quantification of muscle echo intensity improved the
sensitivity to 87%– 92%.
• High sensitivity, muscle ultrasound is very suitable for
screening purposes.
30. Dynamic Muscle Ultrasound
• Muscle ultrasound is not confined to static images but can
also be used for dynamic imaging, such as in contracting
muscles.
• Provides quantitative data about changes in muscle
configuration during movement.
• This feature has been used in patients with myositis, who
were shown to have less thickening of the muscles during
contractions than healthy controls.
31. • Fasciculations can also be visualized dynamically as local
thickening and twisting in axial sections of relaxed muscle
• Easily be distinguished from other movements
• Like-
Arterial pulsations-unifocal, rhythmic movements
voluntary muscle contractions-involving the entire muscle
32. • Ultrasound actually appears to be more sensitive in
detecting fasciculations than EMG, probably because
larger areas of muscle are sampled than with an EMG
needle.
33. • Possible to see fasciculations during voluntary muscle
contraction, which is impossible with EMG because of the
summation of voluntary electrical potentials recorded by
the needle electrodes.
34. Muscle Ultrasound for Discriminating
Neurogenic Disorders and Myopathies
• Main ultrasound feature of both myopathies and
neurogenic disorders is an increased muscle echo
intensity
• Their appearance is different on muscle ultrasound.
35.
36. • In a study of 40 floppy infants, ultrasound showed a
92% concordance with EMG findings in differentiating
between myopathies and neuropathies
• Aydinli N, Baslo B, Caliskan M, Ertas M, Ozmen M. Muscle ultrasonography
and electromyography correlation for evaluation of floppy infants. Brain Dev
2003;25:22–24.
37. • Neurogenic disorders usually show an inhomogeneous
increase of echo intensity with atrophy
38.
39. • Myopathies generally result in a homogeneous increase
of muscle echo intensity, often accompanied by a
preserved muscle bulk, as in DMD
40.
41. • Patients with myopathies showed a more equal
distribution of muscle thickness and echo intensity
throughout their body.
• These features appeared to be very specific and made it
possible to differentiate between neuropathies and
myopathies with a positive predictive values of 86% and a
negative predictive value of 84%.
Pillen S, Verrips A, van Alfen N, Arts IM, Sie LT, Zwarts MJ.Quantitative skeletal muscle
ultrasound: diagnostic value in childhood neuromuscular disease. Neuromuscul Disord
2007;17:509 –516.
42. Muscle Ultrasound in Specific
Neuromuscular Disorders
• Value of ultrasound in the detection of specific
neuromuscular disorders and differentiation from other
neuromuscular disorders has never been investigated
prospectively.
• Most studies are confined to descriptions of ultrasound
appearances
43. Muscular Dystrophies
• Muscle ultrasound changes in neuromuscular disorders
were first described in patients with DMD
• In preclinical cases, muscle ultrasound can be normal, but
when the first clinical signs become apparent, muscle
ultrasound is abnormal in almost every patient, showing
normal muscle thickness with increased muscle echo
intensity
44. • Within the muscle, the echo intensity has homogeneous
(fine granular) distribution
• Proximal muscles have the highest echo intensities
become so high in advanced cases that the bone echo is
diminished or absent.
• Similar findings were reported in children with Becker and
limb girdle muscular dystrophies
45. • Congenital muscular dystrophies (CMDs)
• Muscle echo intensity is severely increased in almost all
instances
• CMD is associated with extensive histopathological
muscle changes with an extensive replacement of muscle
by fat and connective tissue
46. • Bethlem myopathy:
• Muscle ultrasound has a peculiar echo density in the
anterior middle of the rectus femoris muscle
• “central shadow sign,” centered around the central
fascia that is normally seen in this muscle
47. Congenital Myopathies.
• Only a few reports of ultrasound findings of these patients
are available, and in most the ultrasound examination was
abnormal, but with highly heterogeneous findings
• Patients with nemaline myopathy can show marked
selective muscle involvement
48.
49. Inflammatory Myopathies.
• Muscle echo intensity is increased with focal alterations
within the muscle, which makes it possible to differentiate
them from other myopathies
50.
51. • In polymyositis, muscle atrophy and increase muscle
echo intensities are usually more pronounced in the lower
extremities
• whereas in dermatomyositis the upper and lower
extremities are involved equally
52. • Inclusion-body myositis shows more atrophy compared
to other inflammatory myopathies and a strongly
increased muscle echo intensity
• Findings can be focal and are often asymmetrical
• Most pronounced in the distal muscles
53.
54. Metabolic and Mitochondrial
Myopathies
• Metabolic and mitochondrial disorders usually have
normal or only slightly elevated muscle echo intensity.
• Sensitivities of 25%–45% have been reported in children
with mitochondrial myopathies
• Muscle thickness is often decreased.
55. Motor Neuron Disorders
• Spinal Muscular Atrophy :
• Spinal muscular atrophy (SMA) causes severe muscle
atrophy accompanied by increased echo intensity,
although early in the course of the disease the ultrasound
scan can be normal.
56. • Distribution of ultrasound abnormalities is distinct in SMA,
lower limbs, and especially the quadriceps muscle, show
most abnormalities, whereas the biceps brachii muscle is
relatively spared.
• Muscle echo intensity has an inhomogeneous, moth-
eaten pattern corresponding to areas with atrophic fibers
(bright areas) and groups of hypertrophic fiber (black
areas)
57.
58. • ALS:
• Muscle ultrasonography in patients with amyotrophic
lateral sclerosis (ALS) shows a combination of increased
echo intensity, decreased muscle thickness, and
extensive fasciculations, even in the early stages of the
disease.
59. Peripheral Nerve Disorders
• EDS is the investigation choice in detecting peripheral
neuropathies, with high diagnostic accuracy
• Ultrasound of nerves can detect common nerve
entrapments like CTS.
Ultrasound is increasingly used in the diagnosis of CTS
60. ULTRASOUND IN CTS
Assess “Thickening of the median nerve”
Expressed as an increase in the cross-sectional area of
the median nerve at the carpal tunnel inlet more than 13
mm ( normal <10–13 mm),
Flattening of the nerve at the level of the hamate
Best diagnostic criteria (Tai et al., 2012).
ULTRASONOGRAPHY FOR DIAGNOSING CARPAL TUNNEL SYNDROME: A META-ANALYSIS
OF DIAGNOSTIC TEST ACCURACY;tai et al: Ultrasound in Med. & Biol., Vol. 38, No. 7, pp.
1121–1128, 2012.
61.
62.
63. • Muscle ultrasound can detect the consequences of
nerve damage by showing atrophy and increased echo
intensity in muscles innervated by the affected nerve
Useful in –
Nerve root injury
Brachial plexus injury
CIDP
64. • Polyneuropathies result in muscle ultrasound changes,
with involvement being more severe distally than
proximally
65. • Muscle ultrasound appeared to be slightly less capable of
detecting focal neuropathies than EMG, with a sensitivity
estimated at 70%.
• Increased echo intensity was the most distinctive feature
on ultrasound.
Bargfrede M, Schwennicke A, Tumani H, Reimers CD. Quantitative ultrasonography in focal
neuropathies as compared toclinical and EMG findings. Eur J Ultrasound 1999;10:21–29.
66. • Muscle echo intensity was strongly correlated with the
presence of spontaneous activity on EMG.
• Earliest ultrasound abnormalities appear 10–14 days after
nerve injury, which is when spontaneous activity appears
on EMG.
67. USG V/S MRI,CT SCAN
MRI/CT
• MRI is capable of detecting
neuromuscular disorders,
but no prospective studies
have yet been performed
• Advantage of both MRI and
CT, their ability to visualize
deeper muscles, especially
when overlying muscles are
severely affected with
inflammatory myopathies
• MRI/CT- cost
USG
• USG can detect changes
in early or
presymptomatic disease,
and in metabolic or
mitochondria Myopathies.
• Less cost
• Ease of availibility
68. USG V/S MRI,CT SCAN
MRI/CT
• Necessity of sedation in
young children.
• CT detects fatty infiltration
caused by neuromuscular
disorders ,superior to MRI
in detecting calcifications
in inflammatory
myopathies
• Disadvantage of ionizing
radiation
USG
• No sedation
• No radiation expousure
69. USG V/S EMG
EMG
• Sensitivity of EMG In
detecting neurogenic
disorders was very high in
every age group (88%–
100%)
• Invasive
• Less usefull in pediatric
age group
USG
• Low sensitivity &
specificity
• Noninvasive screening
tool
• Easily used in pediatric
age group
70. CONCLUSION
Non-invasiveness of ultrasound as a screening tool in
suspected neuromuscular disorders in sharp contrast to
another frequently used tool
EMG is a measurement of function, and ultrasound is
concerned with structure, the use of both techniques is
complementary
Application of dynamic muscle ultrasound can provide a
bridge between the study of muscle structure and
function.
71. References
• Muscle ultrasound in neuromuscular diseases;pillen et
al:Muscle Nerve 37: 679–693, 2008
• Position statement, American association of
neuromuscular and electrodiagnostic medicine;walker et
al: Dec 2014
• Muscle ultrasound; Jahannaz Dastgir;national institute of
neurological diseases and stroke
• Uptodate.com
• Sonography in carpel tunnel syndrome;Hunderfund et al:
Muscle Nerve 44: 485–491, 2011
• Bradley”s Neurology 7th edition
