Topic 2 Pathology Tendons muscles nerves Flashcards
(112 cards)
1
Q
What are the two categories of muscle tear?
A
Direct trauma/crush injury
Indirect trauma/ Stretch injury
2
Q
What is the initial ultrasound appearance of a muscle tear?
A
o discontinuity in the muscle fibres and fibrous septa
o hypoechoic fluid filling the gap in torn muscle fibres.
o Echogenic debris may be present
3
Q
What is the ultrasound appearance of a muscle tear in the first 24-48 hrs?
A
o the tear will appear more heterogeneous as it fills with clotted blood.
4
Q
What is the ultrasound appearance of a muscle tear in the first 1-3 weeks?
A
o tear will again become hypo or anechoic as the haematoma begins to liquefy.
o Shaggy margins of the torn muscle will be evident.
5
Q
What must you determine when scanning a muscle tear?
A
o the site of the tear
o its extent and size
o location to a known landmark or joint
o percentage of muscle bulk involved in transverse orientation.
6
Q
What are some ultrasound appearances of a complete muscle tear?
A
o muscle is hyperechoic and retracted
o often with a smooth ‘bullnosed’ appearance to muscle ends
o it will be surrounded by a fluid haematoma.
o Contraction of the affected limb may help to visualise the ends of a tear.
o measure the distance between the retracted ends where possible.
7
Q
When does and indirect trauma/stretch injury occur to a muscle?
A
• occurs when the tension applied to the muscle is greater than the force they can withstand
8
Q
What is the most common site for a stretch injury?
A
- The myotendinous junctions are usually the weakest point
* therefore the more common site of muscle distraction injuries.
9
Q
What is the ultrasound appearance of a stretch/distraction injury?
A
- generally longitudinal or flame-shaped tears
- usually only partial and not complete ruptures
- tear will usually extend in the longitudinal plane
- may involve only a few bundles of muscle fibre, rather than the entire cross-section.
- Rarely a muscle may be torn from its site of origin or insertion
10
Q
What is the most common site for a muscle to be torn from it’s origin/insertion?
A
semitendinosus has avulsed from the ischial tuberosity
11
Q
What is the clinical presentation of a semitendinosus avulsion?
A
- tender proximal thigh
o and often a visible depression in the skin layer.
o Function may not be fully compromised, just weakened, as the other hamstring muscles maintain function
12
Q
Why can assessing a semitendinosus avulsion be difficult?
A
o Because the cavity fills rapidly with haematoma, a complete rupture can be difficult to assess for the size of the retraction gap
13
Q
What is myositis ossificans?
A
- Following an intramuscular haematoma, the affected region may calcify and then ossify.
- This is also known as heterotopic bone formation (HBF).
- HBF is a soft tissue inflammation followed by heterotopic bone ossification
14
Q
What are some causes of myositis ossificans?
A
- in 40 percent of cases there is no history of trauma
* it can develop through joint arthroplasty, central nervous injury, and direct soft tissue trauma.
15
Q
What does myositis ossificans look like on ultrasound initially?
A
o Initially will appear as a soft tissue mass
o with disorganised, heterogeneous internal architecture
o may be indistinguishable sonographically from a soft tissue neoplasm.
16
Q
How does myositis ossificans present clinically?
A
o Clinically it will present as a palpable firm mass.
17
Q
What does myositis ossificans look like on an ultrasound after 3 -4 weeks?
A
o calcifications will begin to appear
o may follow the ‘feathered’ pennate structure of the muscle fibres
o identifiable with sonography well before radiography will show them.
18
Q
What does myositis ossificans look like long term?
A
• calcific deposits will mature over five to six months within the muscle structure
19
Q
What is important when scanning myositis ossificans long term?
A
• it is important to try to show this ossification has occurred separate to bone, and does not represent bony periosteal pathology
20
Q
What is the most common site of myositis ossificans?
A
quadriceps muscles
21
Q
What percentage of quad muscle tears develop myositis ossificans?
A
50 percent of quads contusions develop HBF
22
Q
How can muscle healing appear on ultrasound?
A
- decreased size and echogenicity of haematoma followed by a complete resolution
- increased echogenicity and thickness of the margins of the tear
- reorganisation of the muscle architecture to normal appearance, with fibro-adipose septa re-appearing
23
Q
What are some complications of muscle healing?
A
- formation of linear, stellate or nodular scar tissue and increased risk of re-rupture
- formation of a muscle cyst, which may contain septae
- myositis ossificans (HBF)
- muscular atrophy
- compartment syndrome
24
Q
What should you do when scanning a intramuscular mass?
A
o detecting and defining the mass, that is, position, size, margins
o characterising the mass, that is, echotexture, calcification
o whether it has increased vascularity (in comparison to the surrounding muscle)
o compressibility
o evidence of local and regional extension
25
What is the most common malignant muscle tumour?
malignant fibrous histiocytoma
| it is rare
26
What is the typical appearance of a malignant fibrous histiocytoma?
hypoechoic, uniloculated, and have an increased vascularity with a low resistance flow.
27
Name some malignant muscle tumours?
lymphoma, metastasis, liposarcoma and synovial sarcoma.
28
What are some examples of intramuscular fluid collections?
```
o post-traumatic hematomas
o abscesses
o ganglia
o cysts
o necrotic tumors
```
29
How can you differentiate between intermuscular and intramuscular fluid collections on ultrasound?
* The intramuscular collections are usually round
| * intermuscular collection are fusiform.
30
What do muscle cysts look like on US?
* rare
* should conform to the standard ultrasound criteria for a cyst
* They may be difficult to distinguish from some muscle tears
* in general, a muscle cyst is more difficult to compress than a muscle tear
31
What is a muscle angioma?
soft tissue neoplasms consisting of different types of vascular channels including lymphatic vessels within the muscle often associated with variable amounts of adipose tissue
32
How do muscle angiomas present?
slow-growing mass in association with chronic pain especially after exercise. They are often tender to palpation and compressible
33
How do muscle angiomas appear on US?
* may be hypo or hyperechoic
* uni or multiloculated
* may change shape in response to muscle contraction or exercise
34
Where to muscle aponeurosis injuries occur?
* occur where muscles adjoin each other
| * such as the aponeurosis between the medial head of gastrocnemius and the soleus
35
What sort of force can cause a muscle aponeurosis rupture?
• sudden shearing force between muscles acting in differing degrees of contracture will result in a linear anechoic fluid collection of blood between the two muscles at the site of maximal tenderness.
36
where can muscle hernia occur?
• Any region where there is a fascial defect or weakness can allow the underlying muscle to herniate through
37
What is the most common cause of muscle hernia?
previous trauma or surgery
38
What is compartment syndrome characterized by?
• characterised by the raised intramuscular pressure within a muscle group
39
What does compartment syndrome commonly cause?
muscle ischaemia and necrosis
40
How does compartment syndrome appear on ultrasound?
o the relevant muscle group will appear enlarged and hyperechoic compared to the unaffected limb.
o If there is resultant muscle ischaemia then regions of diffuse heterogeneity and even small cyst formations may be seen.
o If you are suspicious of compartment syndrome, consider the muscle carefully for relevant asymmetric muscle density.
41
what is Rhabdomyolysis?
• general term denoting skeletal muscle necrosis
42
How is rhabdomyolysis usually conformed?
clinically by the presence of muscle proteins in the urine (myoglobinuria
43
When is US useful in the setting of ?rhabdomyolysis?
may be used to distinguish between this condition and deep vein thrombosis, as the patient will present with a painful, swollen calf or thigh.
44
What are the US features of Rhabdomyolyisis?
* increase in size of muscle
* mixed echogenicity of muscle
* fluid collections throughout the region
45
What is myositis?
Muscle infection/inflammation
46
What can cause myositis?
trauma, bacterial, viral, fungal or parasitic infections, or due to systemic disease
47
How does myositis appear on ultrasound?
* opposite of normal muscle.
* The fibroadipose septa are distended with inflammatory exudate and appear relatively hypoechoic.
* The muscle fibres become relatively hyperechoic.
* Comparison with the contralateral side is essential.
* Over time, an abscess will evolve with central necrosis and a collection of purulent material.
48
Why is the clinical picture important in myositis?
• Because the sonographic features of an abscess can be similar to a muscle haematoma, the clinical picture of fever, chills, leukocytosis and elevated erythrocyte sedimentation rate (ESR) will ensure diagnosis
49
Why is ultrasound used in the context of neuromuscular disease?
can be used to assess muscular dystrophies, and to help differentiate these from central nervous system muscular dystrophies
50
What does muscular dystrophy look like on ultrasound?
* Muscular dystrophy involves the progressive replacement of normal muscle tissue with adipose tissue.
* These muscles appear more hyperechoic
* as the sound is more rapidly attenuated, the underlying structures become difficult to see.
51
What does CNS muscular dystrophy look like on US?
* muscle architecture remains normal to ultrasound
| * but there is an overall decrease in the thickness of the muscle when compared with a normal subject.
52
What is tendinopathy?
* Broad range of disorders involving tendons
| * Can be traumatic, metabolic and systemic conditions, to the chronic overuse condition known as tendinosis.
53
What is tendinosis?
The result of degenerative tendon disease of any cause
chronic overuse is the most common mechanism.
Clinically it can manifest as pain, decreased exercise tolerance of the tendon and a reduction in function.
54
Should the term tendinitis still be used?
No
suggests inflammation of the tendon
most chronic overuse conditions have no inflammatory response
anti-inflammatory pharmacotherapy does not provide significant long-term benefit in tendinopathy
can wrongfully guide treatment.
55
What are the stages of tendinosis according to the continuum model?
Reactive tendinopathy
Tendon dysrepair
degenerative tendinopathy
56
What does reactive tendinopathy look like on ultrasound?
o Fusiform or diffuse swelling
| o Hypoechogenicity
57
What does tendon dysrepair look like on ultrasound?
o tendons are thick with more localised changes in one area of the tendon
o Small focal areas of hypoechogenicity
o Some discontinuity of the collagen fascicle
o Increased vascularity on power or colour Doppler
o linear defects within the abnormal tissue
o "insubstance degenerative partial tears or splits".
58
What does degenerative tendinopathy look like on ultrasound?
o Marked heterogeneity of the matrix
o Changes are mostly focal
o Islands of degenerative pathology seen between other stages of tendinosis and normal tendon
o mucoid degeneration appears as a fluid filled cystic mass.
o Numerous large vessels may be seen on colour or power Doppler
59
What risk does degenerative tendinopathy pose?
• Chronic tendinosis can result in partial or complete rupture when even minor physical activity is applied
60
What is the enthesis?
Tendon bone interface
| aka tendon insertion or osteotendinous junction
61
What is enthesopathy?
Disease of the enthesis
| can be related to overuse or genetic pre disposition to insertional inflammation
62
How does enthesopathy appear on ultrasound?
o disruption and irregularity to the cortical bone layer
o loss of continuity of the associated tendon fibrils
o eventually the formation of bone spurs
o may be quite tender on palpation
o Tendon may be thickened and hypoechoic
o Hyperaemia may be seen on colour Doppler
63
What can cause tenosynovitis?
• may occur as an overuse phenomenon or as a result of an inflammatory condition, such as rheumatoid arthritis
64
What is tenosynovitis?
• inflammatory state which involves the tendon and its associated synovial sheath
65
How does tenosynovitis appear on ultrasound?
* increased fluid around the tendon in the sheath due to acute inflammation is detected as an anechoic halo around the tendon on transverse images
* longitudinal images the tendon is bounded by anechoic lines
* Fluid in a tendon sheath is not always anechoic; debris may be present.
* tendon may be slightly increased in volume, showing a region of fusiform enlargement and decreased echogenicity of the tendon.
* The tendon sheath itself can thicken and demonstrate hypervascularity on Doppler evaluation
66
When should septic tenosynovitis be suspected?
• a history of penetrating injury or foreign body, septic tenosynovitis should be considered
67
What is the progression of calcific tendinosis?
o accumulative stage - presence of the calcification is often asymptomatic.
o Cause - due to persistent hypoxia some of the tendon is transformed into fibrocartilage in which chondrocytes mediate the deposition of calcium salts.
o Phagocytes accumulate around the calcific foci, with accompanying vascular proliferation.
o The vascular pathways aid in resorption of the calcific deposits, and aid the perfusion of the tendon.
o With resorption calcific deposits become less chalky and gritty and are more 'toothpaste-like' in texture.
o On ultrasound, the calcium may lose its characteristic posterior shadowing and is usually quite tender to palpation.
68
What are the most common sites of tendon subluxation?
long head of biceps brachii at the bicipital groove, and the peroneal tendons at the lateral malleolus.
69
When does subluxation occur?
• Where the support mechanism has been disrupted
70
How can a subluxed or dislocated tendon appear on ultrasound?
• when undergoing abnormal frictional forces, will become swollen and hypoechoic with changes associated with tendinosis
, the tendon may sublux in and out of its normal floor during certain movements, or remain dislocated out of its usual position despite dynamic manipulations.
71
What is Pigmented villonodular synovitis (PVNS)?
• a metaplasia of the synovial membrane of unknown aetiology.
72
How does PVNS appear on ultrasound?
* thickened shaggy synovium
* numerous hypoechoic nodules in synovium
* joint effusion
* articular erosion
73
What is the most commonly affected part of the achilles by tendinosis?
• most commonly affects the midportion of the tendon, or “watershed,” where there is overlapping blood supply.
74
What is the second most common area of the achilles affected by tendinosis?
* Tendon degeneration can also occur at the bone-tendon interface or enthesis
* seen in the Achilles as insertional tendinosis at the calcaneus.
75
What can achilles tendinitis appear as?
* When the peritenon becomes inflamed, either in conjunction with a tendinitis or without, the ultrasound findings are fairly specific.
* Most commonly involved is the peritenon around the Achilles tendon
* The peritenon appears thickened and hypoechoic at the site of pain
* in transverse images shows a 'crescenteric' shaped thickened protrusion at the lateral or medial margins of the tendon.
* In a longitudinal image the thickened sheath may be involved over one to two centimetres, and protrudes into the deeper tissues of Kager's fat pad.
76
How can achilles tendinosis appear?
fusiform, hypoechoic swelling of the tendon
If the enthesis is involved the insertion on the calcaneus is thickened and hypoechoic with loss of the normal fibrillar pattern
May be hyperemia on color Doppler imaging
may be dorsal calcaneal enthesophytes.
77
How does elbow tendinosis appear on ultrasound?
* Tendinosis at the tendon-bone interface is the most common pattern of degeneration seen in the common flexor and extensor origins
* Similar to tendinosis elsewhere, insertional tendinosis or enthesopathy is characterized by tendon expansion and hypoechogenicity
* In insertional tendinosis neovascularization may be a more prominent feature and bony erosion may also be present
78
How can tendon tears appear on ultrasound?
1. Discontinuity of fibers (partial or complete) with hypoechoic or anechoic gap
2. Focal thinning of the tendon
3. Hematoma (usually small)
4. Bone fragment (in cases of avulsion)
5. Nonvisualization of retracted tendon (in complete tear)
79
What do partial tendon tears look like on ultrasound?
* occur either in the transverse orientation or in the longitudinal direction parallel to the tendon fibers (longitudinal splits, fissurations).
* In transverse tears, US shows both the intact and the retracted ruptured portions of tendon in association with a hypoechoic blood collection
80
What do complete tendon tears look like on US?
* Lack of tendon retraction indicates a partial rather than complete tear
* It is the most important feature in distinguishing a partial from complete rupture
81
What are the most common places for a ganglion?
Dorsum of the hand and foot.
| can arise from a joint or tendon sheath or nerve sheath
82
How does a tendon ganglion appear on us?
* rounded or lobulated homogeneous anechoic cysts with acoustic enhancement
* internal low level echoes may be encountered in longstanding or inflamed lesions
* Occasionally, ganglia expands within the tendon substance, weaken the tendon structure, and predispose it to rupture.
83
How does a tendon giant cell tumour present?
painless soft tissue swelling affecting the volar aspect of digits with lateral and circumferential extension.
84
How does a tendon giant cell tumour appear on ultrasound?
* nonspecific solid hypoechoic mass adjacent to a normally appearing tendon
* Cortical bone erosions of the phalanges, secondary to pressure from the overlying lesion, and displacement of the digital arteries, can also be appreciated.
85
What causes entrapment neuropathy?
* Damage to a peripheral nerve by extrinsic pressure results in a compression neuropathy.
* The nerve will be trapped at narrow osteofibrous canals and bony ridges by abnormal bands of muscle or connective tissue that tether the nerve.
86
What may nerve entrapment lead to?
o muscle weakness or loss of function
o pain or tingling in the affected limb
o loss of bulk at the affected muscle.
87
How is nerve entrapment mostly diagnosed?
relies primarily on clinical features and electrophysiological testing, but these studies only indicate the level of the lesion.
88
How can ultrasound be helpful when investigating nerve entrapment?
* can enhance the diagnosis by direct visualisation of the nerve and assessment of the surrounding structures that may be causing the nerve compression
* may be able to show a nerve subluxing in and out of its normal position during dynamic manipulation
89
What should one look for when assessing a nerve?
o look for enlargement
o decreased echogenicity when compared to the normal side.
o Remember that some patients may have bilateral neuropathies occurring, so you are looking for focal changes along the course of the nerve.
o You may also note changes in the muscle that is along the distal pathway of the nerve.
o The atrophied muscle will have a loss of bulk, it will lack that pennate bundle structure and will probably appear more diffusely echogenic due to the fatty replacement.
90
In a patient with a nerve tumour what should ultrasound address?
* whether the mass originates from the nerve or compresses it extrinsically
* definition of the echotexture for histological correlation
* detection of signs of malignancy, that is, sudden increase in size, indistinct tumour margins, and adhesions between the mass and surrounding tissues
* assistance with needle biopsy
91
What ultrasound feature indicates a nerve tumour?
If the proximal and distal ends of the mass are connected to the ends of a nerve, then you are likely to have a mass originating from the nerve, such as neurofibroma (neuroma), or Schwannoma (neurinoma or neurilemmoma).
92
What is the ultrasound appearance if the mass is extrinsic to the nerve?
If the mass is extrinsic to the nerve (that is, ganglion, lipoma) you may be able to follow the nerve as it alters its course around the mass
93
What are the three main nerve tumour categories?
o Schwannoma
o Neurofibroma
o Malignant peripheral nerve sheath tumour
• All are associated with type-1 (von Recklinghausen) neurofibromatosis
94
How do nerve tumours appear on ultrasound?
* fusiform shape
* oriented longitudinally in the nerve axis
* revealing tapered ends that are in continuity with the nerve of origin
* Most lesions appear as hypoechoic masses and have well-defined margin
* Associated findings are the “split fat” and the “target” sign
* In many cases neurofibromas and schwannomas cannot be differentiated on US
* Neurofibromas develop as centrally located masses
* schwannomas tend to grow eccentrically to the nerve
95
What are the main signs of malignancy in a nerve tumour?
• US is not able to give a confident differentiation between benign and malignant neurogenic masses
• main signs of malignancy are:
o large tumor size (>5 cm);
o illdefined margins suggesting edema and infiltration of adjacent tissues;
o calcifications;
o and heterogeneous structure with central necrosis
o however, it must be noted that benign lesions can also share these features.
96
What is neurofibrolipoma?
* a disorder of unknown origin
* causes infiltration of the perineurium and epineurium with fibrofatty tissue.
* More than 80% of cases involve the median nerve
* When associated with unilateral macrodactyly, it is termed “macrodystrophia lipomatosa” and tends to affect the second or third digit of the hand or foot.
* There is extensive fatty infiltration of the nerve and the whole digit, with accompanying osseous overgrowth.
97
How does neurofibrolipoma appear on US?
thickened alternating hyperechoic and hypoechoic bands, reflecting the fibrofatty infiltrate
98
What causes traumatic neuromas?
Direct trauma
amputation
• Terminal (amputation) neuromas result from partial or complete transection of the nerve and arise at the proximal nerve end
• most common site of occurrence is in the lower limbs after surgical amputation
99
How do traumatic neuromas generally present?
* proliferative masses that represent a disorganized attempt at nerve regeneration
* often clinically palpable as small, firm, tender masses
100
How do traumatic neuromas appear on ultrasound?
- Because of their fibrous capsule, traumatic neuromas are usually well defined and hypoechoic with attenuation characteristics similar to muscle
101
What is a mortons neuroma?
• “Morton’s neuroma” is a misnomer that describes a benign mass of perineural fibrosis involving a plantar digital nerve lying between two metatarsal heads
102
Where does a mortons neuroma most commonly occur?
between the heads of the third and fourth metatarsals
103
What is the most likely cause of a mortons neuroma?
friction of the nerve against the transverse intermetatarsal ligament.
104
How does mortons neuroma appear on sonography?
ovoid hypoechoic compressible mass is visible in the intermetatarsal space Fluid within the intermetatarsal bursae is a common associated finding affecting the first three web spaces.
105
What is an intraneural perineuroma?
* a rare focal neural lesion
| * causes a slowly progressive painless mononeuropathy.
106
How does an intraneural perineuoma appear on US?
• Sonography shows the lesion to be hypoechoic, with mildly elongated fusiform enlargement of the involved nerve
107
What is the most common site for a nerve sheath ganglia?
* most frequently involve the large nerves about the knee
* especially the peroneal nerve at the level of fibular head
* may be extension of ganglia related to the proximal tibiofibular joint that typically infold in the space between the epineurium and the nerve fascicles or may arise primarily in the nerve sheath
108
How does a nerve sheath ganglia present clinically?
palpable mass and neuroogic symptoms resulting from nerve compression.
109
How do nerve sheath ganglia present clinically?
appear as spindle-shaped cysts in the nerve and may contain septations
110
What is carpal tunnel syndrome?
• compression and flattening of the nerve occurs within the carpal tunnel, at the palmar aspect of the wrist causing neurologic symptoms
111
How does carpal tunnel syndrome appear on US?
* The sonographic diagnosis of carpal tunnel syndrome is made by measuring the cross-sectional area of the median nerve at the level of the pronator quadratus and comparing this to the cross-sectional area of the median nerve in the carpal tunnel at the level of the pisiform.
* A difference of more than 2 mm2 between the two measurements is highly associated with carpal tunnel syndrome
* Bowing and thickening of the overlying flexor retinaculum can also be observed
112
What can cause ulnar nerve neuropathy?
Compression subluxation or dislocation of the ulnar nerve at the cubital tunnel
