Treatment of ciguatera may include intravenous (IV) mannitol infusion. Other treatments, such as amitriptyline, gabapentin, pregabalin, and tocainide, have been used, but there is limited supporting evidence and they appear variably effective.7
Mannitol reverses the effects of ciguatoxin, with suppression of spontaneous action potentials and reversal of neuronal edema.8,9 It is reasonable to offer mannitol for acute or persistent symptoms of ciguatera fish poisoning even after a delay of several weeks.
A recent systematic review found that mannitol has the largest body of evidence supporting its use, although that evidence is generally of low quality (case reports and large case series).7 While these reports10-13 describe beneficial effects of mannitol, a single randomized trial suggested that mannitol is no more effective than normal saline.14 However, this study was underpowered and had inadequate treatment concealment; twice as many saline control patients as mannitol-treated patients requested a rescue dose of mannitol.14
Mannitol may be most effective when given early in the course of ciguatera but has shown some success when given later.5,12,13 In 1 large case series, the longest interval from symptom onset to successful treatment was 70 days, although most patients with satisfactory results received mannitol in the first few days.5
Our patient was administered an IV infusion of 100 g of 20% mannitol over 1 hour. She received the infusion 140 days after the onset of her symptoms and experienced rapid symptom relief.
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