Muscular Dystrophy and Spinal Muscular Atrophy

Question 1

What is muscular dystrophy?

Answer 1

Hereditary progressive disorder, characterised by muscle weakness from birth to late adulthood.

Question 2

What are the five different forms of muscular dystrophy?

Answer 2

1. Duchenne
2. Becker
3. Congenital
4. Fascio-scapulo-humeral
5. Myotonic

Question 3

What can occur to the muscle when dystrophin is absent?

Answer 3

In the absence of dystrophin muscle cells are susceptible to damage induced by torsional forces during muscle contraction

Question 4

Besides a lack of dystrophin and increased CPK levels, what other pathologies contribute to muscular dystrophy?

Answer 4

1. The absence of nitric oxide (NO) synthase

2. Autoimmune responses to protease activation damages muscle

Question 5

What is the most common form of muscular dystrophy?

Answer 5

Duchenne

Question 6

What is the life expectancy for Duchenne type?

Answer 6

Variable - late teens to 30s

Question 7

What is the primary impairment of DMD?

Answer 7

Progressive weakness secondary to loss of myofibrils

Question 8

What is the gold standard treatment in the medical management of DMD?

Answer 8

Corticosteroids

Question 9

What are the benefits of steroid therapy?

Answer 9

• Preservation of muscle strength and motor function with ambulation
• Improvement in and prolonged stabilisation of pulmonary function
• Preservation of cardiac function
• Delay in or prevention of need for scoliosis surgery
• Retention of UL strength

Question 10

What are the side effects of steroid therapy?

Answer 10

• Excessive weight gain
• Osteoporosis
• Slowing of growth
• Delayed puberty
• Behaviour changes
• Immune suppression

Question 11

What are the three primary approaches to orthopaedic surgery in the management of DMD?

Answer 11

• Minimalist approach: limited to relief of symptoms
• Rehabilitative approach: tendon lengthening transfers aimed at prolonging ambulation in calipers or orthotics
• Prophylactic tendon releases

Question 12

What are the main characteristics of early stage DMD?

Answer 12

• No significant functional impairment
• Cognitive and language delays
• Toe walking may be evident
• Reduced head control
• Lordotic with winging scapula
• Positive Gowers sign
• No limitations in ROM before 5 years of age
• Pseudo hypertrophy of calves

Question 13

What interventions are implemented for early stage DMD?

Answer 13

• Social activities e.g. swimming, bike riding, ball play
• Activities to promote respiratory function e.g. hydrotherapy
• Family coping responses and goals
• Manual stretches