Muscular Dystrophies Flashcards Preview

Foundations II-Neurology > Muscular Dystrophies > Flashcards

Flashcards in Muscular Dystrophies Deck (20)
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1
Q

What is muscular dystrophy?

A

inherited group of myopathic disorders

genetic defects impair normal muscle func.
-characterized by progressive muscle weakness and wasting

2
Q

Besides muscle weakness and wasting, what else can be seen in muscular dystrophy?

A

muscle contractures

impairment of respiratory func.

skeletal deformities

cardiac involvement

3
Q

What are the most common types of muscular dystrophies?

A

Duchenne Muscle Dystrophy

Becker muscular dystrophy

4
Q

Etiology of DMD?

A

2/3 inherited mutation on X chromosome

1/3 spontaneous mutation

5
Q

Etiology of BMD?

A

almost all inherited from mom carrying genetic mutation on X chromosome

6
Q

Epidemiology of muscular dystrophy?

A

very rare for females to develop DMD or BMD

7
Q

Pathophys of DMD and BMD

A

both have genetic mutation on X chromosome Xp21 position

DMD: LOSS of func. expression, affected gene codes for the protein dystrophin > dystrophin levels reduced or absent

BMD: REDUCED func. expression, affected gene codes for dystrophin > dystrophin levels are generally normal but the protein is altered

8
Q

What occurs as a result of the genetic mutation?

A

ongoing degeneration and regeneration of muscle fibers

progressive breakdown of affected skeletal muscle
-can have muscle pseudohypertrophy and later atrophy

9
Q

Clinical manifestations of DMD?

A

growth delay in first yr of life

cognitive impairment

muscle involvement
-weakness begins at 2-3 y/o

10
Q

What muscles are typically affected first in DMD?

A

proximal before distal

LE before UE

11
Q

Gait in pt with DMD?

A

waddling gait develops btwn 12-15

Gower’s sign: may use hand support when arising from ground

12
Q

pulmonary abn in DMD?

A

impaired res func > need ventilator support by ~25

Scoliosis > decreased CW compliance

Gradual weakening of res muscles

13
Q

What cardiac abn. may occur with DMD?

A

primary dilated cardiomyopathy

conduction abnormalities

usually around teenage yrs

14
Q

What sxs can occur late in DMD disease progression?

A

urinary and bowel incontinence

15
Q

Clinical manifestation of BMD?

A

Muscle involvement onset 5-15 yrs, milder and slower progression, need for ambulatory support occurs much later and wheelchair dependence is rare

CARDIAC involvement is often the predominant feature

growth delay and cognitive impairment UNCOMMON

16
Q

When should you suspect muscular dystrophy?

A

any evidence of delayed motor milestones in young child with +fam hx

child not walking by 16-18 mos or presence of Gower’s sign, toe walking or calf hypertrophy

unexplained elevated transaminase levels

17
Q

Why would transaminase levels be elevated in muscular dystrophy?

A

due to muscle inflammation and breakdown which must be metabolized by the body > puts extra stress on liver

18
Q

Dx studies?

A

CK

Genetic testing for Xp21 gene mutation

EMG

Muscle biopsy

Dilated cardiomyopathy work up: Echo, ECG

Spirometry: res func

19
Q

What would be positive findings on muscle biopsy?

A

DMD: absence of dystrophin

BMD: diminished quantity or quality of dystrophin

20
Q

Tx for muscular dystrophy?

A

Prednisone 0.75mg daily or every other day
-can delay wheelchair dependence by 3 yrs

PT

psychological support

surg for muscle contractures & scoliosis

Ambulatory support

Cardioprotective meds

Ventilatory support > almost all DMD will need