Revision - Musclar Dystrophy Flashcards
Inheritance of DMD?
X-linked recessive
Presenting complaint in DMD?
Progressive proximal weakness in children
What gene is affected in Duchenne’s?
The gene encoding DYSTROPHIN on the X chromosome
Clinical features of Duchenne’s?
1) proximal muscle weakness
2) delayed motor milestones
3) calf pseudohypertrophy
4) Gower’s sign
5) 30% of patients have intellectual impairment
What investigation serves as a good screening test for Duchenne’s?
CK - nearly always raised
What is used to confirm the diagnosis of Duchenne’s?
Genetic testing
What medication is used in the management of Duchenne’s?
Oral prednisolone –> improve muscle function
Life expectancy of Duchenne’s?
25-35 years with good management of the cardiac and respiratory complications.
What investigation is used to assess for dilated cardiomyopathy in Duchenne’s?
Annual echo
What is the key respiratory complication of Duchenne’s?
Respiratory failure 2ary to muscle weakness
What are some complications seen 2ary to longterm corticosteroid use in Duchenne’s?
1) osteoporosis
2) avascular necrosis of femoral head
3) obesity
4) Addisonian crisis triggered by suddenly stopping steroids or intercurrent illness
5) impaired glucose tolerance
What is a ‘less severe’ version of DMD?
Becker’s muscular dystrophy
What is the hallmark feature of myotonic dystrophy?
Delayed muscle relaxation following voluntary contraction or percussion (myotonia).
I.e. prolonged muscle contraction
This may present in exams with a patient that is unable to let go after shaking someones hand, or unable to release their grip on a doorknob after opening a door.
What is the role of dystrophin?
Stabilises the muscle cell membrane
What causes calf pseudohypertrophy in DMD?
Calves are enlarged from fat and fibrosis NOT muscle bulk increase
