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Genetic testing

The genetic basis of the primary myopathies means that genetic testing can be essential to the specific diagnosis.Management

This depends on the diagnosis as well as the severity and extent of disease.

Emergency manangement

Myopathy can, rarely, present acutely or with acute complications. Examples include:

• Respiratory difficulties:
  • Respiratory failure can occur in a number of the myopathies
  • Aspiration pneumonia may be associated with this
  • Cardiac complications may be associated including cardiomyopathy and conduction defects.
• Some metabolic myopathies:
  • Hypokalaemia:
    • Oral supplements
    • Cautious use of IV potassium
    • Prophylactic drugs (spironolactone and acetazolamide).
  • Hyperkalaemia:
    • Carbohydrate loading (for example early in attacks with hyperkalaemic periodic paralysis)
    • Glucose and insulin.
  :
• Rhabdomyolysis:
  • Causes life threatening renal complications and associated metabolic problems (hyperkalaemia)
  • Usually requires intensive care management.
• Polymyalgia rheumatica:
  • Treatment with corticosteroids
  • Be aware of associatedtemporal arteritis.

Long term care

• Myopathy associated with respiratory failure:
  • Monitor pulmonary function (early restrictive pattern may occur before onset of symptoms)
  • Beware of symptoms of nocturnal hypoxia (poor sleep, nightmares, headaches)
  • Physiotherapy
  • May require tracheostomy and permanent ventilation.
• Specific medication may be useful in particular situations for particular myopathies
• Genetic counselling
• Surgery:
  • Tendon release surgery for example to prolong ability to walk.
• Physical aids:
  • Walking aids
  • Wheelchairs
  • Adaptive devices.
• Family support
• Dietary advice
  • General- for example to prevent obesity
  • Specific.

• Respiratory failure
• Aspirartion pneumonia
• Musculoskeletal problems:
  • Many associated deformities can occur
  • Joint contractures
  • Chest deformities
  • Spinal deformities including scoliosis.
• Malignant hyperthermia can occur with central core disease.

This depends on the specific diagnosis. The primary disorders are incurable conditions with varied prognosis. Secondary myopathy may be corrected by treating the underlying cause.Prevention

Genetic counselling is, in some of the most common myopathies such as DMD, the only intervention that can prevent disease. In general:

• Give genetic counseling early
• Test early for carrier status where appropriate
• Consider prenatal diagnostic testing where appropriate
• Advances in molecular genetics may help in the future.   PLEASE PROCEED TO NEXT PAGE