Muscular Dystrophy Flashcards

1
Q

how does muscular dystrophy occur?

A

inherited (x-linked recessive) gene

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2
Q

how is muscular dystrophy characterized?

A

progressive

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3
Q

what is the pathogenesis of muscular dystrophy?

A

absent dystrophin cannot protect complex
loss of complex = degrades muscle fibers

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4
Q

which muscular dystrophy subtype is associated with the most severe clinical symptoms?

A

duchenne muscular dystrophy (DMD)

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5
Q

which muscular dystrophy subtype is associated with a later onset and a milder clinical course?

A

becker muscular dystrophy (BMD)

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6
Q

which muscular dystrophy subtype is associated damage to the heart and skeletal muscle is spared?

A

DMD-associated dilated cardiomyopathy

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7
Q

what occurs to dystrophin in Duchenne muscular dystrophy (DMD)?

A

dystrophin levels are reduced or absent

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8
Q

what occurs to dystrophin in Becker muscular dystrophy (BMD)?

A

dystrophin protein is altered

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9
Q

what is the primary symptom in muscular dystrophy?

A

weakness

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10
Q

which is affected first: proximal or distal limb muscles? upper or lower extremities?

A

proximal
lower

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11
Q

using hands to push into an upright position when getting up from the floor

A

gower’s sign

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12
Q

what presents in patients with Duchenne muscular dystrophy associated with dilated cardiomyopathy? (2)

A

conduction abnormalities
arrhythmias

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13
Q

what 2 fracture locations are common?

A

arm and leg fractures

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14
Q

what develops in nearly all patients with DMD? what can it lead to?

A

progressive scoliosis + weakness
acute respiratory failure

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15
Q

what may be diminished or gone in DMD?

A

reflexes

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16
Q

what is essential when muscular dystrophy is diagnosed?

A

genetic counseling for family

17
Q

what percentage of symptomatic female carries of a mutated dystrophin gene have an elevated serum CK?

A

70%

18
Q

how does elevated serum CK present in DMD?

A

10-20x the upper limit of normal

19
Q

how does elevated serum CK present in BMD/female carriers?

A

2-3x normal

20
Q

how early can molecular genetic testing be done?

A

12 weeks gestation

21
Q

what will be seen in a muscle biopsy to diagnose MD? (3)

A

degeneration
isolated opaque hypertrophic fibers
replacement of muscle by fat and connective tissue

22
Q

what is the clinical course of DMD? (2)

A

wheelchair bound by 12 yo
die in late teens from resp or cardio

23
Q

what is the clinical course of BMD? (2)

A

ambulatory into adult life
survive beyond 30 yo

24
Q

what is the mean age of death of a patient with BMD? what is the most common cause of death?

A

mid 40s
dilated cardiomyopathy

25
Q

what is the treatment for MD?

A

prednisone
rehab w/ PT, OT, SLP
vit D + calcium is needed

26
Q

what 2 diagnostics can be done to monitor MD?

A

echo or cardiac MRI

27
Q

what treatment should be started if evidence of ventricular dysfunction on cardiac imaging?

A

ACE inhibitor

28
Q

what treatment should be started if overt heart failure is present? (3)

A

diuretics
digoxin
+/- heart transplant

29
Q

what referral can be done if patient is in a wheelchair?

A

pulmonology