Tetrodotoxin

Background

• Neurotoxin found in several marine animals (pufferfish, certain angelfish, blue-ringed octopus)
  • Heat-stable toxin not destroyed by washing, freezing or cooking
• Blocks neuronal action potential by blocking voltage-gated sodium channels
• Consumption of improperly prepared pufferfish responsible for vast majority of human toxicity (e.g. fugu restaurants)

Mechanism of Injury

• Tetrodotoxin binds to and blocks fast-gated sodium channels, blocking conduction of nerve signals.

Clinical Features

Onset of symptoms usually within 30 min to 4 hours after eating pufferfish

• Paresthesias, body numbness
• Dysarthria, dysphagia
• Headache
• Vomiting, diarrhea, abdominal pain
• Ascending paralysis
• Respiratory failure
• Death

Differential Diagnosis

Marine toxins, envenomations, and bites

• Toxins
  • Ciguatera
  • Scombroid
  • Tetrodotoxin (e.g. pufferfish)
  • Shellfish poisoning
    • Amnesic shellfish poisoning
    • Diarrheal shellfish poisoning
    • Neurotoxic shellfish poisoning
    • Paralytic shellfish poisoning
• Stingers
  • Stingray injury
• Venomous fish
  • Cone shell
  • Lionfish
  • Sea urchins
  • Crown-of-Thorns Starfish
  • Stonefish
  • Other: Catfish, zebrafish, scorpion fish
• Nematocysts
  • Coral reef
  • Fire coral
  • Jellyfish (Cnidaria)
    • Box jellyfish
      • Irukandji syndrome
    • Sea wasp
  • Portuguese man-of-war
  • Sea anemones
  • Seabather's eruption
• Phylum porifera (sponges)
• Bites
  • Alligator and crocodile attacks
  • Octopus bite
  • Shark bite
• Infections
  • Vibrio species in saltwater
  • Aeromonas species in freshwater

Evaluation

• Pufferfish can be tested for the toxin, but decision to treat should be based on clinical picture
• Evaluate for other treatable causes of symptoms

Management

• Supportive care is mainstay of treatment
• May require intubation if concern for progressive paralysis
• Acetylcholinesterase inhibitors (e.g. neostigmine)

Disposition

• Admit (may need ICU)

See Also

• Marine toxins and envenomations