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Condition/Disorder Synonyms

  • Lou Gehrig disease

  • Amyotrophic lateral sclerosis (ALS)

  • Motor neuron disease

ICD-9-CM Code

  • 728.2 Muscular wasting and disuse atrophy, not elsewhere classified

ICD-10-CM Code

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

Preferred Practice Pattern

Key Features


  • 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 is 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 greater than 45 but can be much younger3

  • About 10% familial (tend to have onset at younger age)3

Clinical Findings

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.

  • Bulbaronset 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

Means of Confirmation or Diagnosis

Laboratory Tests

  • Serum creatine kinase may be moderately elevated

  • Muscle biopsy

  • Genetic test for family history of ALS

  • Blood tests to rule out other conditions


  • Magnetic ...

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