Pathology- Myopathies

Question 1

What is a denervation atrophy?

Answer 1

any process that affects the anterior horn cells or axon in the PNS

Question 2

What is the most common form of denervation atrophy?

Answer 2

Wednig-Hoffman disease

Question 3

What is the onset and mortality rate of Werdnig-Hoffman disease?

Answer 3

onset from birth-4 mo, death within 3 years, it has type 1 spinal muscular atrophy

Question 4

What is the inheritance of Werdnig-Hoffman disease?

Answer 4

autosomal recessive

Question 5

What are the clinical features of Werdnig-Hoffman disease?

Answer 5

absence of stretch reflexes, flaccid paralysis, floppy babies, lack sucking ability, respiratory failure

Question 6

What are the 2 most common X-linked dystrophies?

Answer 6

Duchenne and Becker

Question 7

Is DMD or BMD more severe?

Answer 7

DMD

Question 8

What is mutated in DMD?

Answer 8

dystrophin gene on Xp21

Question 9

What are the clinical features of DMD?

Answer 9

muscle fiber size variations, increase in internalized nuclei, degeneration necrosis and phagocytosis of msucle, increase in connective tissue, regeneration os muscle fibers.

Question 10

What stain can you use for a muscle to see dystrophin and thus be able to Dx DMD?

Answer 10

immunoperoxidase stain, which should stain dystrophin at the periphery of the normal muscle fibers

Question 11

Where in the body does DMD affect?

Answer 11

begins in the pelvic girdle and extends to the shoulder girdle.

Question 12

What type of tissue increases in the calf of DMD pt’s?

Answer 12

adipose tissue

Question 13

What is the clinical presentation of DMD?

Answer 13

cardiac failure, mental retardation, CK increases during 1st decade and decreases muscle mass decreaases, death from respiratory or cardiac failure or infection

Question 14

What is myotonic dystrophy?

Answer 14

impared muscle relaxation

Question 15

What is the msot common form of adult dystrophy?

Answer 15

myotonic dystrophy

Question 16

What is the inheritance of myotonic dystrophy?

Answer 16

autosomal dominant

Question 17

What is the clinical presentation of myotonic dystrophy?

Answer 17

atrophy of type I fibers and hypertrophy of type II fibers, stiffness, cataracts, CNS problems, facial and jaw muscles affected

Question 18

What muscle can you percuss on the pt to Dx myotonic dystrophy?

Answer 18

thenar muscles, where the thumb moves sharply into opposition and adduction and slowly returns to an initial position

Question 19

What is the clinical presentation of thyrotoxic myopathies?

Answer 19

proximal muscle weakness, exophthalamos

Question 20

What causes thyrotoxic myopathies?

Answer 20

decreased thyroid fxn –> muscle crtamps, movement and reflexes slowed

Question 21

Who is affected more by thyrotoxic myopathies, males or females?

Answer 21

Males 4:1

Question 22

What is ethanol myopathy?

Answer 22

binge drinking –> acute myopathy –> rhabomyolysis –> myoglobinuria –> possible renal failure

Question 23

What is drug-induced myopathy?

Answer 23

steroids can cause proximal muscle weakness and muscle atrophy

Question 24

What happens in myasthenia gravis?

Answer 24

loss of Ach receptors from an increas ein Ach Ab’s

Question 25

What are the causes of myasthenia gravis?

Answer 25

thymic hyperplasia (65%) or thymomas (15%)

Question 26

What are the Sx of myasthenia gravis?

Answer 26

extraocular muscle ptosis and diplopia, generalized weakness, respiratory ocompromise (major cause of death), decrease nerve conduction with repetitive stimualtion

Question 27

What is affected in Lambert-Eaton syndrome?

Answer 27

the NMJ

Question 28

What does Lambert-Eaton syndrome develop as?

Answer 28

a paraneoplasic process that causes small cell CA in 60% of pts

Question 29

What are the clinical features of Lambert-Eaton syndrome?

Answer 29

proximal muscle weakness, increase in nerve conduction with repetitive stimulation

Question 30

Is there a benefit with AchE blocking in Lambert-Eaton syndrome?

Answer 30

No

Question 31

What causes Lambert-Eaton syndrome?

Answer 31

autoimmunity to Ca++