Muscular dystrophy

Question 1

what is muscular dystrophy

Answer 1

-progressive degeneration of skeletal muscle

(d/t atrophy, necrosis & pseudohypertrophy)

Question 2

there are different types of muscular dystrophy what is the most common

Answer 2

• Duchenne MD is most common

- 1 in 3500 live births (predominantly in male)

Question 3

how do you determine what type of muscular dystrophy it is?

Answer 3

1. MOT- mode of transmission ex. Autosomal, recessive, sex linked
2. Muscles ex. (distal) (muscle groups affected)
3. rate of progression (months, years, decades)
4. age of onset

Question 4

what is the etiology of muscular dystrophy

Answer 4

-genetic -monogenic
-recessive, x-linked (sex linked)
x-linked recessive mother is carrier to son

Question 5

what is pseudohypertrophy in muscular dystrophy

Answer 5

fibrofatty connective tissue replaces muscle fibers (something replaces muscle)

Question 6

what does recessive mean

Answer 6

2 alleles need to be defective

Question 7

patho of muscular dystrophy

Answer 7

• gene is on short arm of x chromosome:
  - codes for dystrophin (membrane protein)
  - attachment of contractile filaments(this is normal function of the protein)
• mutation causing altered dystrophin which then causes poor contractile protein attachemnt which then causes fiber necrosis with use of muscle and then there is poor repair & regeneration which causes more necrosis
• calcium influx (ca ions move from outside cell to inside cell) & enzyme release (eg. CK-creatinine kinase-subset for skeletal muscle, serum marker which is an indicator of muscle damage)

Question 8

what are the manifestations of muscular dystrophy?

Answer 8

• asymptomatic until approx 2-3 (muscles less used, injury occurs when muscles used)
• when muscles damaged presentation is muscle weakness
• progressive muscle weakness (all skeletal muscles affected)
• major problem when respiratory muscles & cardiac muscle affected which may occur even though cardiac muscle is not skeletal muscle
• death from resp & cardiac complications

Question 9

diagnosing muscular dystrophy

Answer 9

• hx, px (movement)
• biopsy of muscle for fibrofatty connective tissue (confirms diagnosis)
• serum Creatinine Kinase (indicates damage to muscles does not confirm diagnosis)
• genetic testing:
  - prenatal approx 12 wks
  - carrier status (test mother)

Question 10

treatment of muscular dystrophy

Answer 10

• supportive & symptomatic
• increase comfort & function (assistance with mobility) (breathing exercises, even though injury is inflicted when muscles used, but when muscles not used cause atrophy, cautiously respiratory therapist does breathing exercise)
• individual will likely die from respiratory & cardiac problems