Electrodiagnosis in puffer fish poisoning--a case report.

Purpose: To report the electrodiagnostic features in a patient with severe intoxication caused by ingesting puffer fish.

Method: case report.

Results: Our patient was among 6 people in a family affected by puffer fish poisoning, 5 of whom suffered acute flaccid paralysis and respiratory failure. Four of them died several hours after ingestion. One of the two surviving patients was admitted to our hospital with intubation and mechanical ventilation. Clinical examination showed a deep comatose-like state. One day after poisoning, no compound muscle action potentials (CMAPs) or sensory nerve action potentials (SNAPs) were noted The insertional activity was normal but no motor unit action potentials (MUAPs) were found EEG showed posterior dominant alpha waves which were replaced transiently by beta activities with light stimulation. The patient was treated in an intensive care unit, taken off the respirator 3 days later, then completely recovered without any sequelae. The patient assured caregivers that he had been conscious during the first day, when EEG and EMG were performed. Electrodiagnostic examination 5 days after the poisoning showed nearly normal amplitudes of CMAPs and SNAPs with nearly normal motor and sensory velocities. The lack of abnormal needle EMG signs suggested axonal sparing.

Conclusions: Our study results suggest that in severe puffer fish poisoning the toxin (tetrodotoxin) has a complete conduction block effect on myelinated nerve fibers and spares axons, and it appears that the toxin has no effect on the CNS. The toxin effects were rapidly and completely reversed over the course of intensive care.