Presentation and course
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• Ciguatera affects multiple organ systems and may have gastrointestinal, neurologic, cardiovascular, dermatological, genitourinary, and emotional components.
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• Neurologic manifestations affect more than 75% of cases.
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• Neurologic manifestations usually follow the development of gastrointestinal symptoms.
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• Neurologic symptoms can be protracted, sometimes lasting many months.
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• Neurologic symptoms can include various sensory complaints, including numbness and dysesthesias of the extremities; pruritus; temperature reversal; cold allodynia; toothache; circumoral paresthesia; and burning mouth syndrome.
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• Headaches, dizziness/vertigo, malaise/profound fatigue, circumoral tingling, dysgeusia (eg, metallic taste), dry mouth, pain or tingling in the extremities, and a "loose," sensation of the teeth are common complaints.
Ciguatera affects multiple organ systems and may have gastrointestinal, neurologic, cardiovascular, dermatological, genitourinary, and emotional components (39; 20). Onset of symptoms is usually within 15 minutes to 72 hours (most within 12 hours) of the ingestion of contaminated fish (07). Acute illness can be prolonged and the resulting neurologic symptoms can last months, with variable asymptomatic and symptomatic periods (28; 32; 33; 39; 30).
Gastrointestinal. Gastrointestinal symptoms are often the most frequent and earliest manifestations, affecting more than 90% of cases (20). Gastrointestinal symptoms include hypersalivation, abdominal cramps and pain, nausea, intense vomiting, and watery diarrhea. The symptoms generally resolve within one to two days (33).
Neurologic. Neurologic manifestations affect more than 75% of cases (20). Neurologic manifestations usually follow the development of gastrointestinal symptoms, suggesting that the neurologic manifestations may be due to a different physiologic process, such as neuronal or Schwann cell swelling through prolonged activation of sodium channels (02). Neurologic symptoms can be protracted, sometimes lasting many months (33).
Neurologic symptoms can include various sensory complaints, including numbness and dysesthesias (eg, prickling and burning sensations) of the extremities; pruritus (either generalized or affecting preferentially the palms and soles); temperature reversal (eg, where cold objects feel hot, or occasionally vice versa: "hot-cold inversion," "temperature reversal," "sensory inversion"); cold allodynia (ie, pain from mildly cold skin temperatures that would not generally be considered painful); toothache; circumoral paresthesia; and burning mouth syndrome (66; 07; 152; 11; 50; 20). The inverted sensory phenomenon is considered by some to be pathognomonic of involvement with marine toxins (09), although it has also been reported rarely in diabetic and uremic polyneuropathies (151). The Lhermitte phenomenon can occur with ciguatera poisoning (74), and hyperintense signal on T2-weighted sequences in the cervical cord has been reported with ciguatera poisoning (144).
Headaches, dizziness/vertigo, malaise/profound fatigue, circumoral tingling, dysgeusia (eg, metallic taste), dry mouth, pain or tingling in the extremities, and a "loose," sensation of the teeth are common complaints. Cranial nerve abnormalities may also include ptosis, miosis, trismus, various oculomotor and lower cranial nerve palsies, spontaneous downbeat and perverted head-shaking nystagmus, impaired smooth pursuit, visual fixation suppression failure during the bithermal caloric test, and aphonia (100). Other central nervous system manifestations may include opisthotonus, meningismus (ie, signs of meningeal irritation without meningitis), ataxia, and rarely intractable seizures (46). Neuromuscular abnormalities may include hyporeflexia/areflexia, stocking-glove hypesthesia or numbness, carpopedal spasm, myalgias, low back pain, muscle stiffness or spasm, fasciculations, and elevated CPK levels (144). Rarely, the patient may proceed to develop peripheral flaccid paralysis, respiratory muscle paralysis with respiratory failure, generalized seizures, stupor, and death.
Cardiovascular. Cardiovascular manifestations are noted in approximately 40% of cases (20). Cardiovascular manifestations most often involve bradycardia or hypotension but can include hypotension, hypertension, bradycardia, tachycardia, other arrhythmias, heart block, pulmonary edema, and congestive heart failure (07; 34; 32; 03; 20). In a study of 124 cases of ciguatera intoxication from French Polynesia, cardiovascular symptoms were the primary criteria of severity, with bradycardia and hypotension documented in 75% and 43%, respectively (58).
Dermatologic. The patient may develop a rash, which if present is usually diffuse, nonraised, confluent, and erythematous. Loss of hair and nails has been reported.
Genitourinary. Genitourinary signs include the following: painful urination; pain in the perineum, penis, or vagina; and pain in the penis during erection, which may be intensified during ejaculation (129). Cases have been reported of dyspareunia in unaffected women following ejaculation by their male partners, suggesting the possibility of sexual transfer of the toxin, although this has not been proven (82; 80; 27). The toxin can cross the placental barrier causing hypoactivity or shivering movements of the fetus that can be detected by sonography, and also similarly causing transient hypoactivity of the newborn. Ciguatoxin can be secreted in the breast milk causing hypersensitivity of the nipples that interferes with breast feeding, as well as diarrhea in the infant (Blythe and deSylva 1990).
Emotional. The patient may be emotionally depressed, hyperexcitable, anxious, nervous, giddy, apprehensive, restless, and agitated. Hysteria, delirium, hallucinations, and irrational behavior may occur (55). The varied and often inexplicable symptoms of ciguatera have been postulated in some cases to be related to somatization (145) but this is unlikely to explain many cases, even with unusual complaints, given the consistency of many of the reports of the affected individuals in different times and locales.
Hypothermia. A high frequency (approximately 60%) of hypothermia (ie, body temperature lower than 36.5 °C) was reported in one study (20).
Prognosis and complications
The prognosis of ciguatera poisoning is generally good, with symptoms typically subsiding within three to six weeks. However, the outcome apparently depends on the dose of toxin or toxins initially ingested, individual susceptibility, and whether sensitization has occurred. Once intoxication has occurred, the consumption of fish and alcohol may aggravate the condition, and should be eliminated from the diet, at least initially.
Ciguatera-related mortality is rare (less than 0.1% of reported cases) (37).
Chronic ciguatera. Chronic ciguatera is marked by disproportionate disability and nonspecific refractory symptoms such as fatigue, cognitive deficits, and pain, and has many similarities to chronic Lyme disease. After the acute phase of ciguatera, many bothersome symptoms may linger for months to years, including pruritus after alcohol consumption, dysesthesias, myalgias, arthralgias, sensitivity to cold, marked fatigue, malaise, and depression (09; 95; 64; 131; 110; 49; 89; 35). Ciguatera is a consideration in the differential diagnosis of chronic fatigue syndrome (112).
The disease is vastly underdiagnosed; diagnosis is made almost entirely by history, and usually in retrospect. There are few physical findings, none of which are diagnostic.
Any combination of gastrointestinal, neurologic, cardiovascular, dermatological, genitourinary, and emotional symptoms should arouse the clinical suspicion to inquire whether fish has been ingested. The initial gastrointestinal phase may be the only manifestation, and similarly isolated neurologic involvement may occur. Occasionally, a patient may present with only the inverted sensory phenomenon or with pruritus after alcohol and have no other symptoms. Reexposure may cause a significant worsening of symptoms (60).
An 18-year-old man suddenly developed painful dysesthesias while living in Hong Kong. He recalled no prior illnesses, other than some gastrointestinal distress and abdominal pain. The dysesthesias in his hands and feet waxed and waned, but were exacerbated by eating certain foods (eg, chicken, fish, and bouillabaisse) and drinking alcohol. He had no weakness. The patient’s neurologic exam was normal, except for some minimal sensory loss to vibration in his feet.
Nerve conduction velocity studies demonstrated a polyneuropathy involving both the hands and feet. The F waves were mildly delayed in his lower extremities, and his distal sensory and motor latencies were mildly delayed with relatively intact amplitudes. EMG showed some chronic denervation, suggesting some prior axonal involvement.
The patient's syndrome was compatible with a CTX-induced neuropathy. The ingestion of fish and alcohol is well known to exacerbate CTX neuropathy.