Muscle Pathology Flashcards
1
Q
atrophy caused by
A
inactivity ischemia malnutrition aging chronic disease denervation corticosteroid induced myopathy
2
Q
necrosis
A
common response to muscle injury from primary muscle disease
3
Q
types of injury
A
external - toxin
internal - structural disturbance
4
Q
what 2 things happen during muscle necrosis?
A
- myophagocytosis
- satellite cells become myoblasts & repair the injury
5
Q
in chronic disorders what role does necrosis play with regeneration
A
muscle fiber necrosis wins out over regeneration = fibrosis
6
Q
Rhabdomyolysis
A
dissolution of skeletal muscle fibers that release myoglobin into the circulation
7
Q
Necrosis Rhabdomyolysis secondary to
A
Hypertension Viruses Mild Exercise Anesthesia EtOH
8
Q
Myositis
A
- inflammation of muscle
- autoimmune
- lymphocytes infiltrate the muscle and damage it
9
Q
Clinical Presentation of Myositis
A
malaise fever muscle swelling pain tenderness lethargy
10
Q
Fibrosis
A
- muscle cell loss
- limited capacity for regeneration
- fibrotic tissue lacks strength and distensibility
11
Q
Inflammatory Myopathies
A
non specific muscle weakness secondary to identifiable disease or condition
12
Q
what type of disorder is Inflammatory Myopathies
A
autoimmune origin
associated with other autoimmune and connective tissue disorders
13
Q
Morphology of Inflammatory Myopathies
A
- inflammatory cells are present
- necrosis and phagocytosis
- regeneration and atrophy
- fibrosis
14
Q
Inflammatory Myopathies symptoms
A
- symmetrical proximal muscle weakness
- insidious onset & gets worse
- includes neck muscles & larynx
- can have cardiac involvement & pulmonary muscle weakness
15
Q
Other causes of Inflammatory Myopathies
A
Bacterial infections (wound, trauma, spread from adjacent structures, sepsis)
Viral infection
Parasitic infection
16
Q
3 types of muscle diseases
A
- Neurogenic muscle atrophy
- Myopathy or primary muscle disease
- Disease of neuromuscular junction
17
Q
Neurogenic muscle atrophy
A
denervation
18
Q
Myopathy or primary muscle disease
A
destruction & loss of muscle mass
19
Q
Types of Myopathy or primary muscle disease
A
- dystrophies
- congenital myopathies
- inflammatory myopathies
- toxic or metabolic myopathies
20
Q
diseases of neuromuscular junction
A
Myasthenia gravis (MG)
Lambert-Eaton Myasthenic Syndrome (LEMS)
21
Q
Causes of Neurogenic Atrophy
A
Lower Motor Neuron Disease
PNS
22
Q
Denervation Atrophy of Neurogenic Atrophy
A
Atrophy is secondary to loss of myofibrils and myofilaments
- reinnervation attempts w/ every episode of denervation
- adjacent motor units help to try and “plug in”
-if not re-innervated = complete loss of fibrils and filaments
23
Q
Spinal Muscular Atrophy (SMA)
A
4 types - Type I - IV
- Degeneration of anterior horn cells
- 2nd most common lethal autosomal recessive disorder
24
Q
Type I: Werdnig-Hoffman (infantile SMA)
A
Progressive & severe weakness in early infancy
Absent survival motor neuron gene
Degeneration can begin in utero after motor units have been established
25
Type II: Intermediate form (SMA)
Progressive but stabilizes
Moderate to severe hypotonia
Shortened life span
Attain the ability to sit at some point
Reliance on power mobility
26
Type III: Kugelberg-Welander (Juvenile SMA)
Later onset & not necessarily progressive
Attain the ability to ambulate at some point - wheelchair dependent
"Limb-girdle muscular dystrophy"
27
Non-inherited Muscular Dystrophy
spontaneous mutation (30% of cases)
28
Inherited Muscular Dystrophy
Severe & Progressive X-linked degeneration of skeletal muscle
Mother is carrier
Affects boyd
Progressive wasting of pelvic and shoulder girdle
29
Duchenne MD Pathogenesis
Mutation of the gene that codes for dystrophin
Without it = muscle cells cannot regulate the influx of Ca2+ == causes disintegration & weakness
30
where is dystrophin located?
sarcolema
31
Duchenne MD Degeneration of muscle fibers
- Degeneration outpaces regeneration
- Progressive diseases in number of muscle fibers
- Progressive increase in fibrofatty connective tissue
32
Clinical Features of Duchenne MD
Elevated CK-MM
pelvic and shoulder girdle weakness
usually becomes evident at 2-4 years
Pseudohypertrophy of calf muscles (fibrofatty connective tissue)
33
Clinical Presentation of Duchenne MD
- Develop contracture
- Gower's sign
- In wheelchair by age 9-10
34
most common causes of death Duchenne MD
- Respiratory insufficiency
| - Cardiac Dysthymia
35
Fibrofatty connective tissue
end stage of neuromuscular disease
muscle was stained & replaced by fibrofatty connective tissue
36
Becker’s Muscular Dystrophy
dystrophin connects in the cytoskeleton of muscle fiber to the surrounding extracellular matrix through cell membrane
37
who is carrier in Becker’s Muscular Dystrophy
5 in 100,000 live male births
mother is carrier
38
Clinical Presentation Becker’s Muscular Dystrophy
Long life expectancy
Stay ambulatory for a long period of time (toe walkers = calf hypertrophy)
Involvement of proximal musculature first then distals
39
Contractures of Becker’s Muscular Dystrophy
- Elbow flexors
- Forearm pronators
- Wrist Flexors
- Plantar and Knee Flexors
- Hip Adduction
40
implications for PT during MD
maintain function in unaffected muscle groups for as long as possible
avoid eccentric exercises
contracture management
Glucocorticoid therapy
41
Facioscapulohumeral Dystrophy
Genetic defect
Autosomal dominant
42
Clinical Presentation of Facioscapulohumeral Dystrophy
mild form of MD
Starts with weakness and atrophy of facial muscles and shoulder girdle
Lower extremity weakness is delayed
43
do individuals develop contractures, skeletal deformities, or muscle hypertrophy in Facioscapulohumeral Dystrophy
NO
44
Myotonic Dystrophy
most common form of adult dystrophy
prolonged muscle spasm that cannot relax after contraction
45
what type of disorder is Myotonic Dystrophy
inherited autosomal dominant disorder
46
Type 1 Myotonic Dystrophy
slow twitch
fiber type atrophy
47
Type II Myotonic Dystrophy
fast twitch
Hypertrophy
48
Myotonic Dystrophy compared to Duchenne MD
far less necrosis and regeneration
49
Adult Clinical Presentation of Myotonic Dystrophy
20-30 y.o
progressive muscle weakness & stiffness of distal limbs
facial & jaw muscles are always effects
Personality deterioration
testicular atrophy
smooth muscle involvement
50
Congenital Clinical Presentation of Myotonic Dystrophy
seen only in offspring of women who have symptoms
infants born with severe muscular weakness
high incidence of mental defects
51
most common cause of toxic and metabolic myopathies
alcoholism
directly affects muscle cells = Rhabdomyolysis
Liver damage affects metabolism of lipids & carbohydrates
52
Toxic and Metabolic Myopathies drugs
Vitamin E overdose
Lead
Methotrexate
Penicillin
53
Metabolic Myopathies
```
DM
Cushing's
Addison's
Hyper/Hypo Thyroidism
Hormonal Imbalances
```
DM = secondary to vasculopathy
Cushing = too much cortisol = break down of tissue
Addison's = decreased glucocorticoid = decreased gluconeogenesis = decreased glycogen stores = weakness
Hyper/Hypo thyroidism = proximal weakness = pelvis>shoulders
54
Myasthenia Gravis
Disease of the Neuromuscular Junction
abnormal muscular fatigability
circulating antibodies to Ach receptors at the neuromuscular junction
55
What type of disorder is Myasthenia Gravis
acquired autoimmune disease
56
Incidence of Myasthenia Gravis
all races
twice as common in women
young adulthood
histologically - no muscular pathologic changes
57
Myasthenia Gravis effect on antibodies & Ach at the motor end plate
antibodies attach to Ach receptors = blocks the binding sites for Ach
- blocked receptor sites
- atrophic motor end plants
- decreased number of receptors
- widened synaptic space
58
Role of Thymus in Myasthenia Gravis
40% of patients have thymoma
75% have thymic hyperplasia
59
Clinical Features of Myasthenia Gravis
- fatigue and muscle weakness
- weakness of extraocular muscles
- dysphagia
- trunk weakness (respiratory insufficiency)
- arm weakness
60
Treatment of Myasthenia Gravis
Thymectomy, plasmapheresis & cholinesterase inhibitors
61
Lambert-Eaton Myasthenic Syndrome (LEMS)
muscle weakness
wasting
fatigability of proximal limbs and trunk
usually associated with small cell lung CA
62
How does Lambert-Eaton Myasthenic Syndrome (LEMS) defect Ach release ?
- Ca2+ channels are necessary for Ach release
| - Ca2+ channels are reduced on the presynaptic side
63
Two forms of Lambert-Eaton Myasthenic Syndrome (LEMS)
1 associated w/ SC lung CA
auto-immune
64
Torticollis
"Wry neck" - muscular fibrosis
65
Torticollis is contracture of what muscle
SCM
66
How does Torticollis occur
breach & forcep delivery - vacuum extraction & cesarean section
67
Spasmotic Torticollis
Cervical dystonia
3 in 10,000 adults
central disorder vs. muscle disorder
68
Arthrogryposis Multiplex Congenita
multiple congenital contractures present at birth
69
3 types of Arthrogryposis Multiplex Congenita
Amyoplasia
Distal
"everything else"
70
Arthrogryposis Multiplex Congenita other abnormalities
cleft palate, cardiac, urinary tract malformations
71
Clinical Manifestation of Arthrogryposis Multiplex Congenita
joint contracture
articular rigidity
muscle weakness
fibro-fatty tissue
72
Frog Posture Arthrogryposis Multiplex Congenita
slower to roll but quicker to sit and scoot
can hold standing once placed
73
In adulthood Arthrogryposis Multiplex Congenita
DJD secondary to overuse
May need powered mobility to project joints
