TREATMENT

Treatment is symptomatic and supportive, with no known antidote. In severe intoxication, basic support measures should be initiated, with monitoring of fluid and electrolytes, cardiac function, and blood gases with the awareness that severe bradycardia and respiratory paralysis can occur. Mechanical ventilatory support and oxygen may be needed in the event of respiratory failure, and rarely, transvenous cardiac pacing may be required in the presence of refractory bradycardia or heart block. If vomiting has not occurred within 6 to 8 hours after ingestion, emetics or gastric lavage may be used to promote gastric emptying and elimination of any remaining fish products. Activated charcoal combined with a nonmagnesium-containing cathartic in a slush can be administered to promote elimination of the toxin.

Intravenous mannitol is the first drug of choice for acute situations, especially within the first 24 hours. After the first 24 hours, treatment with mannitol has reportedly had less dramatic results, but the infusion can be used repeatedly if symptoms persist.⁹

Atropine (0.01 to 0.02 mg/kg intravenously every 10 minutes) for symptomatic heart rate less than 50 per minute has been useful, as well as dopamine infusion (5 mg/kg per minute to 20 mg/kg per minute) for severe and prolonged hypotensive episodes or when cardiovascular symptoms predominate. In severe poisoning, intravenous calcium gluconate in doses of 15 g/kg over 15 minutes, followed by a continuous infusion of 45 to 70 mg/kg until serum calcium is in midnormal range, has been recommended. This is used to act as a substrate against competitive inhibition of calcium by ciguatoxin.

Certain medications appear to be more selectively effective for individual symptoms. Indomethacin has been helpful for the dysesthesia, myalgia, arthralgia, and itching; ketorolac and other nonsteroidal anti-inflammatory agents appear to have similar actions. Acetaminophen has been reported to be more effective than other analgesics for the associated headache. Corticosteroids are said to be useful for late recurring arthralgias that are not responsive to other anti-inflammatory compounds. It is not surprising that the anticonvulsant gabapentin is helpful in those patients with shooting pains, pruritus, and dysesthesias.¹⁰ Cyproheptadine, an antihistamine with antiserotonergic and anticholinergic effects, has also been reported to be effective in relieving the itching and sensory reversal phenomena.⁶ Amitriptyline has been reported to be helpful in improving some ciguatera symptoms.¹¹ Fluoxetine has recently been reported to have similar effects, especially on the symptom of chronic fatigue.¹²

A diet eliminating fish or fish products, shellfish or shellfish products, nuts, coconuts, nut products, seeds, seed products (including oils), alcoholic beverages or ethanol-containing products, mayonnaise, chocolate, and mushrooms has been recommended. This serotonin-sparing diet is important while a patient remains intoxicated and has been advocated for 3 to 6 months after symptoms resolve.⁶

Finally, ciguatoxin exposure can be largely prevented by not eating fish. Reputable local suppliers are the best source of fish in suspected areas. In general, small fish are less toxic than larger fish. The viscera and roe of tropical fish should never be ingested in an area known to be potentially ciguatoxic. Certain fish that are high in the carnivorous food chain (barracuda, hogfish, and eels, among others) should never be eaten in endemic areas, where the sale is often prohibited by law.