II. Pathophysiology

  1. Ingestion of seafood (esp. clams and mussels) contaminated with the Neurotoxin Saxitoxin
    1. Saxitoxin is not destroyed by cooking
    2. Saxitoxin contamination is not detected by food taste or smell
  2. Saxitoxin (Mitilotoxin) original sources (Gonyaulax species)
    1. Marine dinoflagellates (Alexandrium, Gymnodium)
    2. Freshwater blue green algae (cyanobacteria)
  3. Saxitoxin concentrates in filter feeders (clams, mollusks)
  4. Saxitoxin mechanism of action (similar to Tetradotoxin)
    1. Blocks voltage gated Sodium channels
    2. Prevents Action Potentials from propogating down nerve axon

III. Symptoms

  1. Onset: 30-60 minutes after ingestion
    1. Onset may be delayed 120 minutes (or even 24 hours after ingestion)
  2. Nonspecific symptoms
    1. Headache
    2. Nausea or Vomiting
  3. Progressive neurologic symptoms
    1. Numbness or parasthesias of the face, lips and extremities
    2. Dizziness or Ataxia
    3. Dysphagia
    4. Muscle Weakness to paralysis
    5. Respiratory Failure

IV. Exam

  1. Complete Neurologic Exam (including respiratory effort on deep breathing)

V. Labs

  1. No immediate lab testing identifies Paralytic Shellfish
  2. Health departments can run serum, urine and gastrointestinal secretions for Saxitoxin
    1. May be indicated in outbreaks, but not immediately useful medically

VI. Management

  1. Supportive Management with Mechanical Ventilation as needed
  2. Observe suspected ingestions for 4-6 hours
    1. May discharge home if no progression and patient reliable
    2. Caution regarding delayed onset up to 24 hours

VII. References

  1. Tomaszewski (2020) Crit Dec Emerg Med 34(8):24
  2. Hurley (2014) West J Emerg Med 15(4):378-81 +PMID: 25035737 [PubMed]

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