The most significant morbidity and mortality from scorpion stings is from the Buthidae family, characterized by a triangular central sternal plate. This family includes the venomous Androctonus genus in northern Africa, Leiurus in the Middle East, Tityus in South America, and Centruroides in North America.
Centruroides are found primarily in the southwestern United States and northern Mexico and are characterized by a variable subaculear tooth beneath the stinger. They may be striped and are yellow to brown in color. These scorpions tend to hide in crevices, woodpiles, bedding, clothing, and shoes. Envenomation produces a mild local reaction of pain, swelling, burning, and ecchymosis.
Buthidae Sternal Plate. The Buthidae family is associated with the most significant envenomations and is characterized by triangular sternal plates (left). Members of the other scorpion families have pentagonal sternal plates (right).
Buthidae Sternal Plate. The triangular appearance of the sternal plate is well seen in this scorpion, a member of the Buthidae family. (Photo contributor: Sean P. Bush, MD.)
Centruroides exilicauda (the bark scorpion) envenomation can lead to progressive symptoms and, very rarely, death. The venom of C exilicauda initially produces local paresthesias and pain (grade 1), which may be accentuated by tapping the involved area. More severe envenomations may produce remote paresthesias (grade II) and either somatic or autonomic nervous system dysfunction (grade III). Systemic symptoms may include tachycardia, nausea, wandering eye movements, blurred vision, difficulty breathing, trouble swallowing, restlessness, and involuntary shaking. Both somatic and autonomic dysfunction may be present (grade IV). Systemic reactions tend to be more severe in younger patients and may result in death, usually from respiratory arrest.
Centruroides exilicauda. Members of this species are yellow to brown and usually less than 5 cm long. Below the stinger is the telson, within which are two glands containing venom. (Photo contributor: Sean P. Bush, MD.)
Subaculear Tooth. The barb noted at the base of the stinger is variably present in Centruroides (left) and absent in other species (right).
Centruroides limbatus. Subaculear tooth. A variable subaculear tooth is characteristic of Centruroides. This is an example of a large subaculear tooth on the telson from C limbatus. Centruroides exilicauda typically has a smaller, sometimes subtle “tooth.” (Photo contributor: Sean P. Bush, MD.)
Management and Disposition
Treatment depends on the severity of envenomation. Grade I or II envenomations are treated with supportive care (ice, oral analgesia) and tetanus prophylaxis. Envenomations that progress to ...