SFGH am report pearls: ALS

Takeaway pearl: Think ALS with upper and lower motor neuron signs, although given the poor prognosis, make sure to rule out mimics including cervical radiculomyelopathy, thyroid disorders, multifocal motor neuropathy, and paraneoplastic syndromes

ALS (amyotrophic lateral sclerosis)

  • progressive, incurable, neurodegenerative disorder that causes muscle weakness and usually death within 3-5 years (although 10-20% survive >10 years)
  • El Escorial diagnostic criteria
    • evidence of lower motor neuron degeneration by clinical, EP, or neuropathological exam (muscle atrophy, weakness, fasciculations)
    • evidence of upper motor neuron degeneration by clinical exam (increased reflexes, clonus, babinski signs)
    • progressive spread of symptoms or signs within a region or to other regions
  • 5-10% related to a genetic mutation
  • Differential diagnosis:
    • Multifocal motor neuropathy – LMN pattern – antibodies against GM1 ganglioside and responde to IVIG
    • Cervical radiculomyelopathy (LMN signs at the level of lesion with UMN signs below it)
    • Inflammatory myopathy
    • Thyrotoxicosis (UMN signs with pyramidal tract dysfunction and LMN signs from peripheral neuropathy)
    • Malignancy with intraspinal lesions or paraneoplastic symptoms
  • Therapy:
    • mostly symptom based management
      • noninvasive positive pressure ventilation – prolongs life and improves symptoms of dyspnea
      • discuss GOC related to long-term mechanical ventilation
      • PEG placement for symptomatic dysphagia
      • glycopyrrolate for secretions
    • Riluzole: mechanism unknown, but thought to reduce glutamate-induced excitotoxicity
      • prolongs survival by ~2 months

 

Brooks BR. El Escorial World Federation of Neurology criteria for the diagnosis of amyotrophic lateral sclerosis. Subcommittee on Motor Neuron Diseases/Amyotrophic Lateral Sclerosis of the World Federation of Neurology Research Group on Neuromuscular Diseases and the El Escorial “Clinical limits of amyotrophic lateral sclerosis” workshop contributors. J Neurol Sci 1994; 124 Suppl:96.

 

Rowland LP and Shneider NA. Amyotrophic Lateral Sclerosis.  NEJM 2001; 344: 1688-1700.

 

Shefner JM. Amyotrophic lateral sclerosis. In: Office Practice of Neurology, 2nd ed, Samuels, MA, Feske, SK (Eds), Churchill Livingstone, Philadelphia 2003. p.548.

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