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Scorpion envenomation causing neuromuscular toxicity (United States, Mexico, Central America, and Southern Africa)

Frank LoVecchio, DO, MPH, FACEP
Section Editors
Daniel F Danzl, MD
Stephen J Traub, MD
Michele M Burns, MD, MPH
Deputy Editor
James F Wiley, II, MD, MPH


This topic will discuss the clinical manifestations, diagnosis, and management of envenomation by scorpions whose stings cause neuromuscular toxicity (eg, Centruroides species [indigenous to the southwestern United States, Mexico, and Central America] and Parabuthus species [inhabiting Western and Southern Africa]).

The clinical manifestations, diagnosis, and treatment of scorpion envenomations in other parts of the world that cause autonomic storm, myocardial depression, and pulmonary edema are discussed separately.


Scorpions, which are grouped in the phylum Arthropoda, have a lobster-like body shape with seven sets of paired appendages: the chelicerae, the pedipalps (claws), four sets of legs, and the pectines (a pair of comb-like structures on the ventral surface) (figure 1). The segmented tail curves upward dorsally, ending in a terminal bulbous segment called the telson, which contains paired venom glands and the stinger. In the United States, a subaculear tooth on a small, slender scorpion is specific to Centruroides exilicauda (sculpturatus), also known as the bark scorpion (picture 1 and picture 2 and picture 3) [1,2].

Envenomation occurs through stinging, not biting. Scorpions clutch prey in their pedipalps (claws) and thrust the tail overhead to sting. Although envenomations are sometimes reported as bites, true scorpion bites have not been documented and would be inconsequential if they did occur. Scorpions can sting multiple times, although the first sting depletes or nearly depletes the telson of venom.

A characteristic physical property of scorpions is that they fluoresce when illuminated by ultraviolet light, as from a black light or a medical Wood's lamp (picture 4) [3]. This property is used in collecting scorpions for breeding or venom harvesting and in providing pest control. The fluorescent pigment in scorpion cuticle is most likely riboflavin.

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Literature review current through: Nov 2017. | This topic last updated: Mar 01, 2017.
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