II. Pathophysiology
- Ingestion of seafood (esp. clams and mussels) contaminated with the Neurotoxin Saxitoxin
- Saxitoxin is not destroyed by cooking
- Saxitoxin contamination is not detected by food taste or smell
- Saxitoxin (Mitilotoxin) original sources (Gonyaulax species)
- Marine dinoflagellates (Alexandrium, Gymnodium)
- Freshwater blue green algae (cyanobacteria)
- Saxitoxin concentrates in filter feeders (clams, mollusks)
- Saxitoxin mechanism of action (similar to Tetradotoxin)
- Blocks voltage gated Sodium channels
- Prevents Action Potentials from propogating down nerve axon
III. Symptoms
- Onset: 30-60 minutes after ingestion
- Onset may be delayed 120 minutes (or even 24 hours after ingestion)
- Nonspecific symptoms
- Progressive neurologic symptoms
- Numbness or parasthesias of the face, lips and extremities
- Dizziness or Ataxia
- Dysphagia
- Muscle Weakness to paralysis
- Respiratory Failure
IV. Exam
- Complete Neurologic Exam (including respiratory effort on deep breathing)
V. Labs
- No immediate lab testing identifies Paralytic Shellfish
- Health departments can run serum, urine and gastrointestinal secretions for Saxitoxin
- May be indicated in outbreaks, but not immediately useful medically
VI. Management
- Supportive Management with Mechanical Ventilation as needed
- Observe suspected ingestions for 4-6 hours
- May discharge home if no progression and patient reliable
- Caution regarding delayed onset up to 24 hours
VII. References
- Tomaszewski (2020) Crit Dec Emerg Med 34(8):24
- Hurley (2014) West J Emerg Med 15(4):378-81 +PMID: 25035737 [PubMed]