The Muscular Dystrophies Flashcards
Define muscular dystrophy
Group of inherited disorders with progressive muscle degeneration
What is Duchenne muscular dystrophy (DMD)?
- Most common muscular dystrophy
- Inherited x-linked recessive disorder
- Deletion of gene for dystrophin leading to infux of Ca2+, a breakdown of the calcium calmodulin complex and an excess of free radicals leading to myofibre necrosis
- CK markedly elevated
How does DMD present?
- Waddling lordotic gait
- Language delay
- Calf hypertrophy
- Weakness of limb girdles = Gower’s sign
- Sparing of facial, extraocular and bulbar muscles
- Clumsier and slower than peers
What is the prognosis for DMD?
- No longer ambulant by 10-14yrs
- Life expectancy =late 20s (resp failure or associated cardiomyopathy)
What are the investigations that should be done if muscular dystrophy is suspected?
- Plasma CK - markedly elevated
2. Genetic analysis - does not differentiate between milder Becker MD and DMD (need expert interpretation)
What are the key components of care in DMD?
- Assessment for power, joint ranges and contractures with appropriate input from physio and OT (e.g. splints for contractures)
- Access to speech therapy and dietary assessment
- Consideration on appropriate management of respiratory, cardiac and other systems’ complications
- Liaison with allied services, particularly educational/social services
- Genetic counselling for child and family members
- Psychological support for the child and family
*Managed by good local service with ongoing advice from a specialist centre
Are there any drugs that can be used for DMD?
- Corticosteroids - in ambulant children to preserve mobility and prevent scoliosis (exact mechanism of action unknown)
- Ataluren - for affected boys with nonsense mutation (10-15%); allows bypass of nonsense mutation and production of small amount of dystrophin
What is Becker muscular dystrophy (BMD)?
An inherited disorder of progressive muscle degeneration that is allelic with DMD but some functional dystrophin is produced
What is the prognosis of BMD?
- Feature clinically similar to DMD but slower progression
- Avg. age of onset 11yrs
- Loss of independent ambulation in late 20s
- Life expectancy well into middle/old age
What are the limb girdle muscular dystrophies?
- Present with proximal upper and lower limb weakness
- Associated with cardiomyopathy and difficulty breathing
- Different modes of inheritance
What are the congenital muscular dystrophies?
- Autosomal recessive inheritance
- Present at birth or in early infancy - weakness, hypotonia, contractures
- Feeding difficulties and breathing difficulties
- Muscle biopsy diagnostic
- May be linked to other CNS abnormalities
