Duchenne's Muscular Dystrophy

Question 1

What protein is absent in Duchenne’s muscular dystrophy?

Answer 1

Dystrophin

Question 2

What is the inheritance pattern of Duchenne’s muscular dystrophy?

Answer 2

X-linked recessive; age of onset is 2-6yo in young males only

Question 3

What are conditions a/w Duchenne’s muscular dystrophy?

Answer 3

1) Scoliosis
2) Equinovarus foot
3) Calf pseudohypertrophy

Question 4

How does Becker’s Muscular Dystrophy differ from Duchenne’s?

Answer 4

1) Becker’s has decreased not absent dystrophin
2) Age of onset later, slower progression, increased life expectancy
3) More prone to cardiomyopathy

Question 5

What is the typical cause of death for Duchenne’s?

Answer 5

cardiorespiratory issues around age 20

Question 6

What physical exam finding can differentiate between SMA and Duchenne’s?

Answer 6

1) Duchenne’s will have intact deep tendon reflexes;
2) Duchenne’s has characteristic Gower’s sign (rises from ground by walking hands up legs);
3) SMA will have normal CPK

Question 7

What is the initial management of Duchenne’s?

Answer 7

1) Corticosteroids 0.75mg/kg/day; significantly slows progression and maintains ambulation
2) PT for ROM
3) Pulmonary night care
4) bracing for scoliosis is contraindicated

Question 8

Prior to surgical management of scoliosis in Duchenne’s, what labs/tests are indicated?

Answer 8

Cardiac and pulmonary function studies; may be too high risk of surgery due to cardiopulmonary compromise

Question 9

What anesthesia complication is common in Duchenne’s?

Answer 9

Malignant hyperthermia; pretreat with dantrolene

Question 10

What foot deformity is common with Duchenne’s and what is the treatment?

Answer 10

equinovarus foot; treat with nighttime AFOs, possible TAL and PTT transfer

Question 11

What are the indications for PSF in Duchenne’s?

Answer 11

1) Curve progression to 30°
2) Curve >20° in nonambulatory pt
3) FVC below 35%