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B - Paediatrics MANAGEMENT > Duchennes Muscular Dystrophy > Flashcards

Duchennes Muscular Dystrophy Flashcards

1
Q

What is Duchennes muscular dystrophy (DMD)?

A

A severe type of muscular dystrophy

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2
Q

What are muscular dystrophies?

A

A group of muscle diseases that result in increased weakening and breakdown of skeletal muscle over time

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3
Q

What is the incidence of DMD?

A

It affects 1 in 3000-6000 male infants

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4
Q

What is the life expectancy of patients with DMD?

A

Late 20’s

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5
Q

What is the cause of death in most causes of DMD?

A
  • Respiratory failure

- Associated cardiomyopathy

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6
Q

What is the inheritance pattern of DMD?

A

X-linked recessive, although about 1/3 have de novo mutations

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7
Q

What is the genetic abnormality in DMD?

A

Deletion of the gene for dystrophin

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8
Q

What is the role of dystrophin?

A

It connects the cytoskeleton of a muscle fibre to the surrounding extracellular matrix through the cell membrane

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9
Q

What happens when dystrophin is deficient?

A

There is an influx of calcium ions, a breakdown of the calcium calmodulin, and an excess of free radicals, ultimately leading to myofibre necrosis

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10
Q

What is the average age of diagnosis of DMD?

A

5 years old (but children often become symptomatic much earlier than this)

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11
Q

What are the clinical features of DMD?

A
  • Waddling gait
  • Language delay
  • Gowers sign
  • Pseudohypertrophy of calves
  • Slower and clumsier than peers
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12
Q

What is Gowers sign?

A

The need to turn prone to rise

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13
Q

What causes pseudohypertrophy of the calves in DMD?

A

Replacement of muscle fibres by fat and fibrous tissue

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14
Q

How does DMD progress?

A

Progressive muscular atrophy and weakness, so no longer ambulant by 10-14 years

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15
Q

How common are learning difficulties in DMD?

A

About 1/3 of affected children have learning difficulties

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16
Q

How can DMD be detected on neonatal screening?

A

Elevated CK

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17
Q

What is the initial investigation for suspected DMD?

A

CK

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18
Q

What is found on CK testing in DMD?

A

CK level 10-100x

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19
Q

Is CK high from birth in DMD?

A

Yes

20
Q

Does a normal CK at presentation exclude DMD?

A

Yes

21
Q

How is a precise diagnosis of DMD best achieved?

A

By a combination of;

  • Genetic analysis
  • Muscle biopsy, with assay for dystrophin protein
  • Clinical observation of muscle strength a function
22
Q

What are the differential diagnoses for DMD?

A
  • Other types of muscular dystrophy, particularly Becker’s muscular dystrophy
  • Other myopathies
  • Polymyositis
  • Neurological causes of muscle weakness
23
Q

Give an example of a neurological cause of muscle weakness

A

Spinal muscular atrophy

24
Q

What does the initial management of DMD include?

A
  • Information and support for family
  • Genetic diagnosis and counselling
  • Referral to specialist and MDT
25
Q

What does early-stage management when the child is walking include in DMD?

A
  • Physiotherapy
  • Knee-foot-ankle orthoses
  • Corticosteroids
26
Q

What is the purpose of physiotherapy in early-stage management of DMD?

A

To give advice on stretching to prevent contractures

27
Q

What is the purpose of knee-foot-ankle orthoses in early-stage management of DMD?

A

To prolong walking

28
Q

What is the purpose of corticosteroids in early-stage management of DMD?

A
  • Prolong ambulation by 6-12 months

- Help with respiratory function, cardiomyopathy, and scoliosis

29
Q

What is the usual steroid giving in DMD?

A

Prednisolone

30
Q

What is involved in management after walking is lost in DMD?

A
  • Help with mobility, usually with electric wheelchair
  • Cardiac and respiratory surveillance
  • Orthopaedic care
31
Q

What is involved in management in the later stages of DMD?

A
  • Support for increasing weakness and fatigue
  • Optimisation of respiratory and cardiac treatments
  • Nutritional advice
  • Palliative care
32
Q

What might be required to provide support for increasing weakness and fatigue in the later stages of DMD?

A

Wheelchair and other living adaptations

33
Q

What research is going into the treatment for DMD?

A

Into exon skipping drugs

34
Q

What do exon skipping drugs do in DMD?

A

May correct the open reading frame of the dystrophin gene

35
Q

Give an example of an exon skipping drug in DMD

A

Ataluren

36
Q

Who is ataluren used for in DMD?

A

Patients with a nonsense (skip) mutation

37
Q

What % of cases of DMD have a nonsense mutation?

A

10-15%

38
Q

What does ataluren do?

A

Allows bypass of the nonsense mutation and a production of a small amount of dystrophin

39
Q

What are the potential complications of DMD?

A
  • Scoliosis
  • Respiratory complications
  • Cardiac complications
  • Gastrointestinal symptoms
40
Q

What respiratory complications may arise from DMD?

A

Weakness of intercostal muscles

41
Q

What might weakness of intercostal muscles lead to?

A

Noctural hypoxia

42
Q

How does noctural hypoxia present?

A
  • Daytime headache
  • Irritability
  • Loss of appetite
43
Q

How can noctural hypoxia in DMD be managed to improve quality of life?

A

Overnight CPAP or non-invasive positive pressure ventilation

44
Q

What cardiac complications may arise from DMD?

A
  • Dilated cardiomyopathy

- Arrhythmias

45
Q

What causes gastrointestinal symptoms in DMD?

A

Smooth muscle being affected

46
Q

What gastrointestinal symptoms may result from DMD?

A
  • Gastric dilation

- Pseudo-obstruction

B - Paediatrics MANAGEMENT (106 decks)

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