Amyotrophic lateral sclerosis


  • Progressive muscle atrophy/weakness due to degeneration of upper and lower motor neurons
  • Patients will rarely present to the ED undiagnosed
  • Likely related to mutated superoxide dismutase (SOD1) gene
  • Involvement of the anterior horn cells

Clinical Features

A man with ALS using a head-mounted laser pointer to comunicate. Note asymetic motor weakness.
A man with amyotrophic lateral sclerosis (ALS). (A) He needs assistance to stand. (B) Advanced atrophy of the tongue. (C) There is upper limb and truncal muscle atrophy with a positive Babinski sign. (D) Advanced thenar muscle atrophy.
  • Acute respiratory failure
    • Predicted by forced VC <25 mL/kg or 50% decrease from normal
  • Aspiration pneumonia
  • Trauma related to extremity weakness
  • Asymmetric weakness without sensory findings with mixed upper and lower motor nerve findings

Differential Diagnosis



MRI (axial FLAIR) demonstrates increased T2 signal within the posterior part of the internal capsule, consistent with the diagnosis of ALS.

Evaluate for complications of ALS or other treatable causes of progressive weakness


  • CBC
    • Evaluate for anemia/infection
  • CPK
    • Elevation associated with myopathy
  • BMP
    • Electrolyte abnormalities (hypercalcemia, hypokalemia, etc.) can cause weakness
  • UA
    • Evaluate for source of infection
  • ABG
    • Helps identify respiratory failure


  • CXR
    • May identify aspiration, pneumonia, or other comorbid conditions


  • FVC
    • Sensitive indicator of respiratory muscle weakness
    • FVC <50% typically requires ventilatory support



  • Admission
    • Admit if patient requires respiratory support or has other complications requiring admission
    • Evaluate patient's ability to be cared for at home; admit if needed
  • Discharge
    • If stable, and new onset ALS is suspected, discharge with a referral for outpatient evaluation by neurologist
    • If stable, and ALS has previously been diagnosed, discharge if outpatient treatment remains available for patient

See Also

External Links


  • Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e (2010), Chapter 167. Chronic Neurologic Disorders