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Musculoskeletal Physiopathology > Other Myopathies > Flashcards

Other Myopathies Flashcards

1
Q

Myasthenia gravis typically affects females at age ___
It typically affects males at age ___

A

Females: 20-30
Males: >50

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2
Q

What is the etiology of myasthenia gravis?

A

Acquired autoimmune disease

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3
Q

With myasthenia gravis, patients develop antibodies to…

A

acetylcholine receptors (at the neuromuscular junction)

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4
Q

myasthenia gravis

What is the result of destruction of acetylcholine receptors at the neuromuscular junction?

A

Decreased surface area, increased gap between nerve ending and muscle

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5
Q

A 25-year-old female patient presents with acute abnormal muscular fatigability and weakness. You notice that she has ptosis as well.
Which myopathy is likely?

A

Myasthenia gravis

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6
Q

A 58-year-old male patient presents with abnormal muscular fatigability and weakness. You notice that he has diplopia and a mask-like expression with a snarl. In his medical history, it is revealed that he has a thymoma.
What is the likely myopathy?

A

Myasthenia gravis

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7
Q

How are extraocular muscles frequently affected by myasthenia gravis?

A
  • Ptosis
  • Diplopia
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8
Q

If a patient has a mask-like facial expression or snarl and you suspect myasthenia gravis, what should you rule out?

A

Stroke (with MRI/CT)

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9
Q

How does thymoma affect 15% of patients with myasthenia gravis?

A

Residual thymus is a benign tumor but increases T cells

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10
Q

What is the mortality of myasthenia gravis?
What will likely cause mortality in someone with myasthenia gravis?

A

Mortality is about 10%, usually due to respiratory insufficiency

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11
Q

Myasthenia gravis may be comorbid with ___

A

other autoimmune conditions

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12
Q

Approximately 15% of patients with myasthenia gravis have a ___

A

thymoma (benign tumor, residual thymus)

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13
Q

What are some treatments for myasthenia gravis?

A
  • Thymectomy
  • Corticosteroids
  • Methotrexate
  • Anticholinesterase drugs
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14
Q

What is myositis ossificans?

A

Metaplasia of soft tissue to bone following trauma/contusion (usually crushing injury)

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15
Q

Myositis ossificans can occur in tendons, ligaments, fat, fascia, joint capsule etc.
Where does it most often occur?

A

Muscle

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16
Q

What are the three primary stages of myositis ossificans?

A
  1. Pseudosarcoma
  2. Differentiation
  3. Maturation
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17
Q

myositis ossificans

Pseudosarcoma begins with ___

A

trauma, often blunt trauma (crushed or torn) (forming hematoma)

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18
Q

myositis ossificans

After trauma, there is extensive damage and cell death during pseudosarcoma
How is the sarcolemma affected?

A

Holes appear in sarcolemma sheath and fluid accumulates

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19
Q

myositis ossificans

During pseudosarcoma, holes appear in sarcolemma sheath and fluid accumulates
What makes these holes larger?

A

Phagocytes invade

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20
Q

myositis ossificans

Where in the pseudosarcoma is the greatest damage?

A

The center of injury

21
Q

myositis ossificans

During pseudosarcoma, damaged tissue is liquefied and replaced by ___

A

sheets of non-specific cells

22
Q

myositis ossificans

The process of pseudosarcoma can be aggravated by…

A
  • trauma
  • massage
  • stretching
  • surgery
  • excess activity
  • ultrasound
23
Q

myositis ossificans

After 15 days of pseudosarcoma, there is extensive proliferation of ___

A

mesenchymal tissue
(and minimal osteoid formation)

24
Q

myositis ossificans

Pseudosarcoma often looks like neoplasia histologically
Radiographically it can look like ___

A

periosteal reaction (hazy ossification in soft tissue)

25
Q

myositis ossificans

Pseudosarcoma can easily be confused with an ___

A

osteosarcoma
Look for a history of trauma

26
Q

myositis ossificans

When does differentiation occur?

A

2-3 months post surgery

27
Q

myositis ossificans

During differentiation, mesenchymal cells become…

A

fibroblasts, chondroblasts, and osteoblasts (metaplasia)

28
Q

myositis ossificans

Which cells remove debris during differentiation?

A

Giant cells

29
Q

myositis ossificans

How does the periphery of the injury behave during differentiation?
How does the center of the injury behave?

A

Periphery begins to mineralize
Ceneter may remain as a fluid filled cyst or filled with undifferentiated cells

30
Q

myositis ossificans

What is the zonal phenomenon that occurs during differentiation?

A
  • Mature bone develops around periphery
  • Oppositive of neoplastic process (osteosarcoma ossifies from the inside out)
31
Q

myositis ossificans

During maturation, a ___ is developed that separates the injury from surrounding tissues

A

periosteum (mature trabecular and cortical bone)

32
Q

myositis ossificans

Once a periosteum has developed during maturation, separating the injury from surrounding tissues, what are some ways it may progress?

A
  • May remain indefinitely
  • May shrink and disappear (not problematic)
  • May be surgically removed (once matured, too early and it will return)
33
Q

What are some clinical manifestations of myositis ossificans?

A
  • Pain in the muscle
  • Decreased ROM
  • Hard palpable lump may be found deep in the muscle
  • Can be associated with neurological disease
34
Q

Fibrodysplasia ossificans progressiva is also known as ___

A

progressive myositis ossificans

35
Q

How common is progressive myositis ossificans?

A

Rare

36
Q

What is the etiology of progressive myositis ossificans?

A

Some cases are inherited; no history of trauma

37
Q

Progressive myositis ossificans usually involves which muscles?

A

Postural muscles: back and major joints

38
Q

With progressive myositis ossificans, muscles become progressively…

A

ossified (sheet-like)

39
Q

When do progressive myositis ossificans symptoms begin in life?

A

Childhood (as early as age 2)

40
Q

Progressive myositis ossificans is generally fatal due to ___

A

loss of pulmonary function

41
Q

Denervation affects which muscle fibers?

A

Both type I and II fibers

42
Q

Denervation includes multiple disease processes that cause progressive…

A

muscle weakness and atrophy

43
Q

denervation

Nerve root avulsion and compressive neuropathies both affect which neurons?

A

Lower motor neurons

44
Q

Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophies are both examples of ___

A

denervation

45
Q

Skeletal muscle fibers are separated from lower motor neurons and the cells have atrophied. They appear angular and dark histologically.
What is the diagnosis?

A

Denervation

46
Q

denervation

If reinnervation does not occur, what happens?

A

Atrophy progresses and muscle fibers are replaced by adipose tissue

47
Q

How do denervated fibers initially present?
How do they present as the disease progresses?

A

Initially scattered irregularly, but cluster as disease progresses

48
Q

denervation

What is fiber-type grouping?

A

As one motor neuron takes over a given field of fibers, fiber types group together

Musculoskeletal Physiopathology (31 decks)

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