Amyotrophic Lateral Sclerosis

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Block C5 - Aging and Elderly


Stephen Hawking has ALS.

Also known as: Lou Gehrig's Disease.

Epidemiology[edit]

  • Can be familial.
    • Mutation on chromosome 21.
      • Defective Cu/Zn superoxide dismutase 1 (aka SOD1 enzyme).
      • Produces superoxide free radical injury of neurons.

Pathophysiology[edit]

  • Degeneration of upper and lower motor neurons.
    • Upper: corticospinal tract degeneration.
    • Lower: anterior horn cell degeneration.
  • Cell body dies.
  • Unknown cause.

Symptoms[edit]

  • Only the motor neurons are effected.
  • Only disease which causes upper and lower dysfunction.
  • Asymmetric progressive weakness in face and limbs.
  • Normal sensation; no sensory problems.
  • No bowel/bladder dysfunction.
  • Upper motor neuron (inhibitory) dysfunction:
    • Weakness.
    • Increased reflexes.
    • Positive babinski.
    • Dysarthria.
    • Dysphagia.
    • Spasticity.
      • Treatment:
        • GABA agonist:
          • Baclofen.
          • Diazepam.
        • Central alpha 2 adrenergic agonist:
          • Tizanidine.
  • Lower motor neuron (excitatory) dysfunction:
    • Muscle weakness.
    • Wasting.
    • Atrophy.
    • Flaccid paralysis.
    • Decreased reflexes.
    • Negative babinski.
    • Fasciculations.
    • Respiratory paralysis.
    • Cognitive defects.

Course[edit]

  • Average survival: 3-5 years from time of diagnosis.
  • Death from ALS occurs due to:
    • Respiratory failure.
    • Lose airway protection because poor motor function and aspirate. This leads to lung infections.

Diagnosis[edit]

  • Requires LMN signs in 2 or more extremities and UMN signs in 1 or more extremities.
  • Nerve conduction studies.
  • Electromyography (EMG):
    • Muscular denervation.
    • Motor blockade.

Treatment[edit]

  • Supportive treatments.
  • Glutamate antagonist:
    • Riluzole.
      • Decreases glutamate induced excitotoxicity.
      • Slows the destruction of the motor neurons.
      • Slows disease progression.

Links[edit]