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Toxicology – Paralytic Shellfish Poisoning (PSP)
Source
PSP is caused by saxitoxin, a heat-stable toxin that accumulates in shellfish such as mussels, clams, oysters, and scallops. The toxin originates from dinoflagellates (marine algae), especially during algal blooms known as “red tides,” and becomes concentrated in shellfish consumed by humans
.
Typical Presentation
Symptoms usually begin quickly—within 10 to 30 minutes—after eating contaminated shellfish. Cases are often linked to harvesting shellfish during red tide events.
Clinical Features
Early signs include tingling or numbness around the mouth and in the extremities, often accompanied by a sensation of lightness or floating. As toxicity progresses, patients may develop nausea, vomiting, abdominal pain, dizziness, and poor coordination. Severe cases can lead to muscle weakness, paralysis, cranial nerve dysfunction, temporary vision loss, and respiratory failure requiring ventilatory support.
Mechanism of Action
Saxitoxin blocks voltage-gated sodium channels in nerve cells, preventing normal nerve conduction and leading to paralysis.
Management
There is no specific antidote. Treatment is supportive, with particular attention to airway protection and respiratory support if paralysis develops.
Key Points
Source
PSP is caused by saxitoxin, a heat-stable toxin that accumulates in shellfish such as mussels, clams, oysters, and scallops. The toxin originates from dinoflagellates (marine algae), especially during algal blooms known as “red tides,” and becomes concentrated in shellfish consumed by humans
.
Typical Presentation
Symptoms usually begin quickly—within 10 to 30 minutes—after eating contaminated shellfish. Cases are often linked to harvesting shellfish during red tide events.
Clinical Features
Early signs include tingling or numbness around the mouth and in the extremities, often accompanied by a sensation of lightness or floating. As toxicity progresses, patients may develop nausea, vomiting, abdominal pain, dizziness, and poor coordination. Severe cases can lead to muscle weakness, paralysis, cranial nerve dysfunction, temporary vision loss, and respiratory failure requiring ventilatory support.
Mechanism of Action
Saxitoxin blocks voltage-gated sodium channels in nerve cells, preventing normal nerve conduction and leading to paralysis.
Management
There is no specific antidote. Treatment is supportive, with particular attention to airway protection and respiratory support if paralysis develops.
Key Points
- Rapid onset of neurological symptoms after shellfish ingestion is characteristic.
- Cooking does not destroy the toxin.
- Red tide exposure can also cause symptoms through inhalation of aerosolized toxins.
- Part of a broader group of shellfish poisonings (PSP, ASP, DSP, NSP).
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