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  • Lou Gehrig’s disease
  • ALS
  • Motor neuron disease

  • 728.2 Muscular wasting and disuse atrophy, not elsewhere classified

  • M62.50 Muscle wasting and atrophy, not elsewhere classified, unspecified site


  • Quickly progressive, degenerative motor disorder caused by the loss of nerve cells in the anterior horn of the spinal cord and motor nuclei of the brain stem2
  • Loss of muscle strength and coordination

Essentials of Diagnosis

  • Rapid, progressive loss of motor function not attributable to internal or external injury
  • Diagnosis made by evidence of motor loss in multiple parts of the body, speed of degeneration, and ruling out other progressive neurologic disorders

General Considerations

  • Onset may be either in the extremities or in the bulbar region initially; eventually, all patients experience degeneration in both areas
  • Diagnosis requires evidence of denervation in at least three motor regions
  • Usually does not affect the senses


  • Male-to-female ratio: 2:13
  • Most patients aged > 45 years, but can be much younger3
  • 10% familial (tend to have onset at younger age)3

Signs and Symptoms

  • Both upper motor neuron and lower motor neuron signs and symptoms
  • Limb onset ALS
    • One side will be involved initially and spread to both sides within months
    • Patients usually report unexplained tripping while walking, or difficulty with buttons and small objects
    • Muscle fasciculation evident
    • Spasticity remains mild
  • Bulbar onset ALS
    • Difficulty with speech production; voice changes, hoarseness
    • Difficulty with swallowing; gagging, choking easily
    • Difficulty with saliva management, drooling
  • Sensation is spared, may experience transient paresthesias due to position or nerve compression
  • Bowel and bladder control usually maintained
  • Respiratory compromise evident with both bulbar and limb onset

Functional Implications

  • Loss of independence in mobility, self-care, eating, breathing
  • Dependence on others

Possible Contributing Causes

  • Primarily idiopathic
  • Family member who has a hereditary form

Differential Diagnosis

  • Progressive spinal muscular atrophy
  • Progressive bulbar palsy
  • Primary lateral sclerosis
  • Parkinson’s disease
  • Muscular dystrophy
  • Multiple sclerosis
  • Cervical spondylosis
  • Inflammatory myopathy
  • Myasthenia gravis
  • Inclusion body myositis

Laboratory Tests

  • Serum creatine kinase may be moderate elevated
  • Muscle biopsy
  • Genetic test for family history of ALS
  • Blood tests to rule out other conditions


Diagnostic Procedures

  • Electromyography (EMG): widespread fasciculation and fibrillation
  • Motor nerve conduction velocity test (NCV); if positive, demonstrates slight slowing with focal motor conduction block
  • ...

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