Case history
Case history #1
A 48-year-old woman presents to hospital late at night with her family. She complains of anxiety, oral numbness, difficulty swallowing, progressive weakness, difficulty standing, and shortness of breath. She is afraid that she is "going to die". She celebrated a successful harvest of mussels with family members on a local beach and consumed a seafood stew prepared by family members on the beach. The family had collected mussels at low tide in the dark. She has a history of hypertension and hyperlipidaemia, but no history of pulmonary or neurological illness. Several other family members complained of oral numbness during the meal. One other family member reports weakness. On examination, she has weakness of her proximal muscles (3-4 out of 5) and cannot stand for gait testing. Her vital signs are normal except for hypertension (blood pressure 178/98 mmHg). The remainder of her examination is normal. Laboratory studies reveal no electrolyte abnormalities. Her peak expiratory flow rate is low at 140 L/minute (predicted 500 L/minute). She reports that her symptoms are worsening during the evaluation. The regional poison centre is contacted. The local health department closed the beach where the family had collected mussels due to elevated saxitoxin levels in shellfish sampled there. The family did not see the closure signs due to darkness. She is admitted for observation and monitoring. Two hours later, her oxygen saturation falls to 86% and her end-tidal CO₂ rises to 58 mmHg. She undergoes sedation, orotracheal intubation, and ventilation. She experiences progressive improvement of her weakness the next day. High blood pressure resolves. She requires ventilation for about 18 hours, and then has a successful spontaneous breathing trial and extubation. She is discharged 24 hours later with persisting, but improving, weakness.
Case history #2
A 27-year-old man returns from a diving expedition to the Solomon Islands with progressive weakness, incoordination, difficulty swallowing, and shortness of breath. He boarded a flight home shortly after completing a night dive collecting attractive shells. He remembers feeling a sting in his right hand and felt the onset of weakness about 30 minutes later. He had progressive weakness during the flight and difficulty walking. He was transported to the hospital by ambulance. On examination, he has a small puncture wound in the palm of the right hand without erythema or swelling. He has difficulty speaking, bilateral ptosis, and no gag reflex. All peripheral muscle groups are weak (3-4 out of 5) and he has difficulty with coordination tests, including gait and rapid alternating movements. His peak expiratory flow rate is 200 L/minute (predicted 600 L/minute). His vital signs and the remainder of the examination are normal. He reports that his symptoms are worsening during the evaluation. The regional poison centre is contacted. Images of concerning shells are reviewed and the cone snail shell Conus geographus is identified as similar to those he had collected.
Other presentations
Symptoms of tetrodotoxin poisoning, for example, following consumption of puffer fish or exposure to the blue-ringed octopus, can include anxiety, oral numbness, progressive weakness, and progressive paralysis leading to respiratory failure.
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