Amyotrophic Lateral Sclerosis

Snapshot

• A 61-year-old male presents with left-sided hand weakness and trouble with walking. He is not sure why these symptoms occur. On physical exam, tongue fasciculations are appreciated. He has slow speech. The left upper extremity shows forearm atrophy and depressed reflexes. The right lower extremity is hypertonic, with 3+ reflexes and positive Babinski sign.  

Introduction

• A progressive neurodegenerative disease affecting both upper and lower motor neurons
  • there are sporadic (~90% of cases) and familial causes
  • sensation is intact
  • bowel and bladder are spared
• Certain cases may be due to superoxide dismutase type 1 (SOD-1) mutations
  • results in the generation of free radicals, eventually leading to cell death
• Epidemiology
  • age of onset:
    • ~60 years of age in sporadic cases
• ~50 years of age in familial cases

Presentation

• Symptoms
  • progressive weakness affecting any segment of the body
    • asymmetric limb weakness (most common)
    • upper and lower motor neuron signs 
      • upper motor neuron (UMN) signs
        • spasticity or stiffness
        • hyperreflexia
        • dysarthria
        • dysphagia
      • lower motor neuron (LMN) signs
        • atrophy
        • fasciculations
        • hyporeflexia
• weakness

Evaluation

• LMN signs determined by physical exam, electrophysiologic, or neuropathologic studies
• UMN signs determined by physical exam
• Symptom progression spread or signs
• No other disease process can explain the patient’s findings

Differential

• Benign fasciculations
• Spinal muscular atrophy
• Poliomyelitis
• Multiple sclerosis
• Syringomyelia

Treatment

• Riluzole 
  • only medication to slow disease progression
  • may decrease excitotoxic damage to neurons
• Supportive treatment

Prognosis, Prevention, and Complications

• Prognosis
  • main cause of death is respiratory failure
• Complications
  • weight loss
  • respiratory failure
  • sialorrhea
  • depression