Muscle wasting

Muscle wasting is the loss of muscle bulk due to:

• reduced neuronal stimulation of the muscle
• primary muscle disease:
  • muscular dystrophy
  • myopathy
  • myositis

Reduced neuronal stimulation of the muscle may be due to:

• a lesion of the peripheral nerve or the neuromuscular junction:
  • often referred to as a "lower motor neurone" lesion
  • when there is a progressive lesion of a motor nerve, wasting only occurs when collateral sprouting from surviving neurones is not sufficient to preserve muscle function
  • EMG will detect a motor unit potential abnormality
• disuse atrophy:
  • often occurs around a painful joint
  • EMG is usually normal
• parietal atrophy:
  • due to stroke
  • EMG is usually normal