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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Related Studies

Ontology: Saxitoxin (C0036248)

Definition (MSH) A compound that contains a reduced purine ring system but is not biosynthetically related to the purine alkaloids. It is a poison found in certain edible mollusks at certain times; elaborated by GONYAULAX and consumed by mollusks, fishes, etc. without ill effects. It is neurotoxic and causes RESPIRATORY PARALYSIS and other effects in MAMMALS, known as paralytic SHELLFISH poisoning.
Definition (CSP) powerful heat stable neurotoxin synthesized and secreted by certain dinoflagellates, which accumulates in the tissues of bivalve mollusks feeding on the dinoflagellates, and can cause a severe toxic reaction in animals consuming these shellfish.
Concepts Biologically Active Substance (T123) , Hazardous or Poisonous Substance (T131) , Organic Chemical (T109)
MSH D012530
SnomedCT 23317009
English Gonyaulax Toxin, Mitilotoxin, Saxitonin, Toxin, Gonyaulax, 1H,10H-Pyrrolo(1,2-c)purine-10,10-diol, 2,6-diamino-4-(((aminocarbonyl)oxy)methyl)-3a,4,8,9-tetrahydro-, (3aS-(3aalpha,4alpha,10aR*))-, Saxitoxin, STX, Saxitoxin [Chemical/Ingredient], saxitoxins, stx, saxitoxin, Saxitoxin (substance)
Swedish Saxitoxin
Czech saxitoxin
Finnish Saksitoksiini
French Toxine de Gonyaulax, Mytilotoxine, Saxitoxine
Italian Gonyautossina, Sassitossina, Mitilotossina, Saxitonina, Gonyaulax-tossina, Saxitossina
Polish Saksytoksyna
Japanese Gonyaulax属毒素, サキシトキシン
Spanish saxitoxina (sustancia), saxitoxina, Saxitoxina, Toxina Gonyaulaxa
German Gonyaulaxtoxin, Saxitoxin
Portuguese Saxitoxina, Toxina de Gonyaulax

Ontology: Paralytic Shellfish Poisoning (C0275144)

Definition (MSH) A condition caused by ingestion of shellfish contaminated with SAXITOXIN from dinoflagellate species in the genus Alexandrium.
Concepts Injury or Poisoning (T037)
MSH D057096
SnomedCT 230681000, 241776009, 77889005
English Parlytc shellfsh caus tox efft, PSP-Paralytic shellfish poison, Paralytic Shellfish Poisoning, Paralytic Shellfish Poisonings, Poisonings, Paralytic Shellfish, Shellfish Poisoning, Paralytic, Shellfish Poisonings, Paralytic, Poisoning, Paralytic Shellfish, Paralytic shellfish causing toxic effect (disorder), Paralytic shellfish poisoning, Poisoning due to red tide of dinoflagellates, Saxitoxin poisoning, Paralytic shellfish causing toxic effect, PSP - Paralytic shellfish poisoning, Paralytic shellfish poisoning (disorder), Paralytic shellfish causing toxic effect [Ambiguous]
French IPC (Intoxication Paralysante par Coquillages), Intoxication paralysante par coquillages, Intoxication paralysante par fruits de mer, Intoxication paralytique par fruits de mer, Intoxication paralytique par coquillages, IPFM
German Paralytische Schalentiervergiftung
Czech měkkýši, korýši - paralytická otrava
Italian Intossicazione da molluschi paralizzanti
Norwegian Paralytisk skalldyrforgiftning
Spanish intoxicación paralítica por moluscos, intoxicación por marea roja (trastorno), intoxicación por marea roja, intoxicación secundaria a marea roja de dinoflagelados