North American Envenomation Syndromes

A case report of mis-snaken identity: When misdiagnosis really bites

When patients present with an unknown puncture wound, emergency physicians need to consider regional hazards, in addition to standard mechanical injury etiologies. In the Southwestern United States, one such hazard is the rattlesnake. In this report, we present a case in which a rattlesnake envenomation was not considered as a possible cause for a puncture wound of unknown origin, which resulted in an envenomation left untreated for 7 days. A full dry bite observation period of 12 h with serial physical exams and laboratory analysis with guidance from the region poison control center might have led to earlier recognition of an envenomation and antivenom administration. A male patient in his late 70's felt a painon his right ankle while in his backyard in southern Arizona. He did not see the cause and assumed he had sustained an insect bite. He went to the ED that day with minor pain and swelling and was discharged home. One week later, he re-presented severely anemic with edema and ecchymosis to the entire right lower extremity that developed over several days after his first ED visit. He was admitted for antivenom and blood transfusion and discharged on hospital day three. For as long as humans continue to interact with the natural world, venomous creature encounters are going to continue to happen. Rattlesnake envenomation should be included in a physician's differential diagnosis even if one is not witnessed, especially in regions with high rattlesnake activity. In addition to assessing for other potential causes of undifferentiated puncture wounds, serial physical examinations and laboratory testing (with guidance of the regional poison center) are necessary to rule out rattlesnake envenomation.

Neurotoxicity Associated With the Southern Pacific Rattlesnake (Crotalushelleri)

The Southern Pacific rattlesnake (Crotalus helleri) is commonly encountered throughout Southern California. Typical toxicity includes tissue injury and hematologic toxicity. However, neurotoxicity is not commonly reported with rattlesnake envenomations, other than infrequently with select species, including the Mojave rattlesnake (Crotalus scutulatus scutulatus). Importantly, clinical neurotoxicity has not been well described with the Southern Pacific rattlesnake, the only rattlesnake in the city of Los Angeles, along with the Southern and coastal regions of Los Angeles County. In this case series, 7 patients envenomated by the Southern Pacific rattlesnake with significant neurotoxicity, including dysarthria, ataxia, and myokymia, are presented. Clinicians practicing in this region should be aware of evolving patterns of toxicity associated with the Southern Pacific rattlesnake.