Myopathies

Question 1

MUSCULAR DYSTROPHIES

Question 2

What are muscular dystrophies characterized by?

Answer 2

Progressive muscle weakness and wasting

Question 3

What serum level is oftentimes elevated in muscular dystrophies?

Answer 3

creatine kinase

Question 4

A genetic defect on the short arm of the X chromosome has been identified in _____ dystrophy

Answer 4

Duchenne

Question 5

This genetic defect found in Duchenne’s cdes for what protein? What is the affect?

Answer 5

dystrophin

Levels are markedly reduced or absent in the muscle of these patients

Question 6

Are dystrophin levels affected in the Becker variety of muscular dystrophies?

Answer 6

No

Question 7

What medication improves muscle strength and function in boys with Duchenne dystrophy?

Answer 7

Prednisone

Question 8

What things must be avoided and what things are encouraged in these patients?

Answer 8

Bed rest is associated with a worsening of the disease

PT and orthopedic procedures may help counteract deformities or contractures

Question 9

MYOTONIC DYSTROPHY

Question 10

Myotonic dystrophy is a slow, progressive, inherited disorder that manifests in the __ or __ decade of life

Answer 10

3rd or 4th

Question 11

How many types of myotonic dystrophies have been determined?

Answer 11

2

Question 12

What are 3 muscular symptoms of myotonia?

Answer 12

• muscle stiffness
• marked delay in muscle relaxation following contraction
• weakness and wasting of the facial, SCM, and distal limb muscles

Question 13

What are 6 clinical features of myotonia?

Answer 13

• cataracts
• frontal baldness
• testicular atrophy
• diabetes mellitus
• cardiac abnormalities
• intellectual changes

Question 14

What drug may be helpful when myotonia is disabling?

Answer 14

Sodium channel blockers such as…

• phenytoin
• procainamide
• mexiletine

Question 15

True or False

Associated weakness and the course of myopathy are influenced by treatment

Answer 15

False

Question 16

MYOTONIA CONGENITA

Question 17

Myotonia congenita is commonly inherited as a _____ trait

Answer 17

dominant

Question 18

The responsible gene on chromosome 7 is responsible for what?

Answer 18

encoding a voltage-gated chloride channel

Question 19

When do symptoms of myotonia congenita develop?

Answer 19

early childhood

Question 20

What are the 2 signs and symptoms of myotonia?

Answer 20

• muscle stiffness that is enhanced by cold and inactivity

- muscle hypertrophy

Question 21

What relieves muscle stiffness?

Answer 21

exercise

Question 22

What durgs are used to treat myotonia congenita?

Answer 22

• procainaminde
• tocainide
• mexiletine
• phenytoin

Question 23

INCLUSION BODY MYOSITIS

Question 24

Inclusion body myositis begins _____, usually after middle age

Answer 24

insidiously

Question 25

What is the main characteristic of inclusion body myositis?

Answer 25

progressive proximal weakness of first the LEs and then the UEs

Question 26

Where does muscle weakness often begin in inclusion body myositis? (LE and UE)

Answer 26

- the quadriceps femoris | - forearm flexors

Question 27

What confirms the diagnosis of inclusion body myositis?

Answer 27

muscle biopsy

Question 28

What drug therapy has been found to have a mild benefit on inclusion body myositis?

Answer 28

Intravenous immunoglobin (IVIG) therapy

Question 29

MITOCHONDRIAL MYOPATHIES

Answer 29

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Question 30

What can be seen on pathologic examination of skeletal muscle with the modified Gomori stain in patients with mitochondrial myopathies?

Answer 30

characteristic "ragged red fibers" containing accumulations of abnormal mitochondria

Question 31

What 2 signs do patients with mitochondrial myopathies present with?

Answer 31

- progressive external ophthalmoplegia | - limb weakness that is exacerbated or induced by activity

Question 32

Some patients with mitochondrial myopathies present with what type of dysfunction?

Answer 32

CNS (epilepsy, ragged red fiber syndrome, or MERRF)

Question 33

What does the acronym MELAS stand for?

Answer 33

Myopathy Encephalopathy Lactic Acidosis Stroke-like episodes

Question 34

What type of patients do mitochondrial myopathies develop?

Answer 34

- AIDS patients receiving zidovudine | - HIV1 patients receiving HAART

Question 35

ASSOCIATED MYOPATHIES

Answer 35

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Question 36

What are some associated disorders myopathy may occur with?

Answer 36

- chronic hypokalemia | - endocrinopathy

Question 37

Myopathy may develop in patients taking what drugs?

Answer 37

- corticosteroids - chloroquine - colchinice - clofibrate - emetine - aminocaproic acid - statin drugs - bretylium tosylate

Question 38

Weakness due to myopathy is mainly _____.

Answer 38

proximal

Question 39

Preexisitng myotonia may be exacterbsated or unmasked by what drugs?

Answer 39

- depolarizing muscle relaxants - beta-blockers - fenoterol - ritodrine - diuretics