Amyotrophic Lateral Sclerosis (ALS)

Background

• 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

Clinical Features

• Acute respiratory failure
  • Predicted by forced VC <25 mL/kg or 50% decrease from normal
• Aspiration pneumonia
• Trauma related to extremity weakness

Differential Diagnosis

Weakness

• Neuromuscular weakness
  • UMN:
    • CVA
    • Hemorrhagic stroke
    • Multiple sclerosis
    • Amyotrophic Lateral Sclerosis (ALS) (UMN & LMN)
  • Spinal cord disease:
    • Infection (Epidural abscess)
    • Infarction/ischemia
    • Trauma (Spinal Cord Syndromes)
    • Inflammation (Transverse Myelitis)
    • Degenerative (Spinal muscular atrophy)
    • Tumor
  • Peripheral nerve disease:
    • Guillain-Barre syndrome
    • Toxins (Ciguatera)
    • Tick paralysis
    • DM neuropathy (non-emergent)
  • NMJ disease:
    • Myasthenia gravis crisis
    • Botulism
    • Organophosphate toxicity
    • Lambert-Eaton myasthenic syndrome
  • Muscle disease:
    • Rhabdomyolysis
    • Dermatomyositis
    • Polymyositis
    • Alcoholic myopathy
• Non-neuromuscular weakness
  • Can't miss diagnoses:
    • ACS
    • Arrhythmia/Syncope
    • severe infection/Sepsis
    • Hypoglycemia
    • Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
      • Hypokalemic periodic paralysis
      • Thyrotoxic periodic paralysis
    • Respiratory failure
  • Emergent Diagnoses:
    • Symptomatic Anemia
    • Severe dehydration
    • Hypothyroidism
    • Polypharmacy
    • Malignancy
  • Other causes of weakness and paralysis
    • Acute intermittent porphyria (ascending weakness)

Management

1. Nebulized medications
2. Steroids
3. Antibiotics
4. Assisted ventilation / intubation

See Also

• Weakness
• Intubation

References

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

Authors

Ross Donaldson