Myopathies

Question 1

What is the pathology the results from damage to an anterior (ventral) horn neuron?

Answer 1

Denervation atrophy

Question 2

What is the most common form of spinal muscular atrophy?

Answer 2

Werdnig-hoffmann disease

Question 3

Whatis the cause, signs and symptoms of Werdnig-Hoffman disease?

Answer 3

-degeneration of the cells in the anterior horn of the spinal cord and the motor buclei in the brainstem

–> lower motor neuron disease, leads to flaccid paralysis, especially of the trunk and limbs

–>floppy babies, lack of suckling and respiratory failure

Question 4

What is the course of Werdnig-Hoffman disease?

Answer 4

• onset from birth to 4months
• death within 3 years
• type 1 spinal muscular atrophy

Question 5

What is the inheritance pattern of Werdnig-Hoffman disease?

Answer 5

Autosomal recessive

Question 6

What is the appearnece of Werdnig-Hoffman disease histologically?

Answer 6

grouped atrophy

Question 7

What does an immuno peroxidase stain in BMD look like?

Answer 7

Question 8

What is it called in DMD when the calves appear to enlarge before atrophy? What is really going on?

Answer 8

Pseudohypertrophy

-deposition of fat and connective tissue inbetween the muscle cells

Question 9

What is the resulting action of type I and type II fibers in mytonic muscular dystrophy (DM)

Answer 9

• atrphy of Type I
• hypertrophy of Type II

Question 10

What is the classic motion affected with DM?

Answer 10

-unable to relax from handshakes

Question 11

What is a sign of DM in infants?

Answer 11

-Tenting of the upper lip

Question 12

What is the histologic appearence of DM?

Answer 12

• central nuclei in cross section along with variation in fiber size
• fibrosis as well long strings of nuclei in longitudinal section

Question 13

Central nuclei in DM

Answer 13

Question 14

What is the cause of thyrotoxic myopathy?

Answer 14

-hypothyroidism

Question 15

What are the signs and symptoms of thyrotoxic myopathy?

Answer 15

-proxmal muscle weakness

–>may precede exophthalmos

Question 16

What is the cause of ethanol myopathy?

Answer 16

-Binge drinking

Question 17

What is the pathophysiology of ethanol myopathy?

Answer 17

-acute myopathy

–>rhabdomyolysis leading to myoglobinuria

–>may lead to renal failure

Question 18

What are the signs of steroid drug-induced myopathy?

Answer 18

• proximal muscle weakness
• muscle atrophy of type 2 fibers

Question 19

What is another treatment that could result in drug induced myopathy?

Answer 19

-chloroquin (antimalarial)

Question 20

What is the cause of Myasthenia Gravis?

Answer 20

-loss of ACh receptors due to biding of ACh antibodies

Question 21

What are the first clinical signs of MG?

Answer 21

• weakness of extraocular muscles: ptosis and diplopia
• generalized weakness

Question 22

What was the major cause of death in patients with MG?

Answer 22

-Respiratory compromise

Question 23

What is the treatment of generalized weakness from MG?

Answer 23

-AChE inhibitors, prednisone. plasmapheresis

Question 24

What is the pathophysiology of Lambert-Eaton syndrome?

Answer 24

• Content and binding of ACh vesicles is normal but antibodies to the Ca channels cause a reduction in response to stimulation.
• Repetitive stimulation leads to and increase in nerve conduction

Question 25

What does Lambert-eaton normally develop from?

Answer 25

paraneoplastic process commonlt associated with small-cell carcinomas of the lung

Question 26

Does patients with eaton-lambert respond to AchE agents?

Answer 26

No