Muscular Dystrophies Flashcards
Muscular Dystrophies - Definition
Genetic disorders characterized by progressive muscle degeneration and weakness
How do MDs differ?
- age of onset
- distribution of weakness
- Rate progression
- +/- calf hypertrophy on CK levels
- patterns of inheritence (male disease, females as carriers)
Duchene Muscular Dystrophy:
- pattern of inheritence
- age of onset
- pathogenesis
- life expectancy
- X-linked recessive gene mutation
- 3-5 yrs
- lack of dystrophin protein: leads to muscle fragility
- in the 30s (som into 40 and 50s)
- fastest progressing MD
DMD: first muscles affected, later muscles affected
muscles of the hip, pelvic area, thighs, and shoulder
later: skeletal muscles in the arms, legs, and trunk
by early teens: muscles of heart and respiration
DMD: unique signs/symptoms
- gower’s sign
- calf hypertrophy (via fatty depositions)
3 loss of ambulation by 9-12yrs
Becker Muscular Dystrophy
- age of onset
- progression
less severe DMD
age of onset = >10yrs
slower progression than DMD, less predictable
Facioscapulohumeral Muscular Dystrophy (FSH, FSHD)
- pattern of inheritence
- definition
- age of onset
- life expectance
- CPK levels
- genetic: shorter segment of DNA on chromosome 4
- progressive muscular degeneration (slow) with increasing weakness and atrophy
- adult onset (20s) or infantile
- normal life expectancy
- normal CPK levels
Facioscapulohumeral Muscular Dystrophy (FSH, FSHD)
- muscles affected, early and late
Early: eyes and mouth, shoulder blades and upper arms
Later: abdominals, sometimes the hip muscles
*does NOT affect muscles of respiration
Myotonic Muscular Dystrophy: Characteristics
- weakness of voluntary muscles (varies by type of MMD and age)
- myotonia: inability to relax muscles at will (difficult to let go after shaking hands)
- Progression affects: heart, lungs, GI tract, genital system
Type 1 MMD
abnormally expanded section of gene on chromosome 19 (DMPK) - most common type
Type 2 MMD
Abnormally expanded section of gene on chromosome 3 (ZNF9)
- symptoms often mild and slow progressing
- rarely occurs in childhood
Types of Type 1 MMD based on age of onset
- Adult onset: begins with weakness in muscles of face, neck, fingers, and ankles; slowly progressive for these and other muscles
- Congenital-onset: requires ventilation, do not make it out of first year
- Juvenile-Onset: can be very different from adult onset
* earlier onset = worse prognosis!
Diagnosis of MD
- DNA analysis (genetic testing)
- EMG (no neuro issues, # of recruited muscles low)
- Muscle biopsy (degeneration and fatty deposition- if beckers no fatty deposition)
Treatment of MD
- Corticosteroids (only for DMD)
- Supportive managements- respiratory care
- Orthopedic- scoliosis
- rehab
Strengthening strategies with MD
prevent muscle damage! will be using the same muscles over and over to increase force and rate.
trying to maintain function
use low load
No eccentrics! (don’t want to encourage muscle breakdown)
strengthen 3 or higher, brace when lower
NO SORENESS
never to exhaustion- only 60% HRmax
