Scorpion Envenomation

Kyle Avery, MS, MS-3
University of Arizona College of Medicine - Phoenix
EMRA MSC Legislative Coordinator

Scorpion envenomation, although rare, may be a presenting injury seen in the emergency department. Scorpion stings are more common in endemic areas such as Arizona, Utah, New Mexico, Texas, and others. Most individuals stung by scorpion’s experience only localized pain, but some may develop paresthesias, neuromuscular symptoms, autonomic disturbances, and cranial nerve dysfunction.²  Each year 1.2 million people are stung by scorpions, of those 3,250 cases result in death. It is more common for workers and adults to be stung by scorpions, but more severe symptoms can be present in the elderly or young.⁶

The Arizona bark scorpion (Centruroides sculpturatus) is of particular concern when considering scorpion stings because it is the only scorpion in the United States with venom potent enough to cause significant medical issues.¹ Although well-adapted for desert living, this species prefers cool, moist areas such as crevices and the underside of rocks. It is native to the Southwestern United States, particularly the Sonoran Desert, and is nocturnal in nature. Of the compounds characterized in its venom, known toxins include a variety of heat-stable neurotoxins, a platelet-aggregation inhibitor, and an ACE inhibitor.

Grading of Scorpion Envenomation

GRADE 1: Localized pain and/or paresthesias at the site of envenomation.

GRADE 2: Pain and/or paresthesias, remote from site of envenomation.

GRADE 3: Either cranial nerve dysfunction: Tongue fasciculations, hypersalivation,

slurred speech or opsoclonus. Or neuromuscular dysfunction: Involuntary shaking and jerking of extremities.

GRADE 4: Both cranial nerve and neuromuscular dysfunction.⁵

Treatment

Ice packs to the site of injury can be applied. Pain medication can also be given depending on the amount of pain the patient is experiencing. If muscle spasms occur or the patient is anxious benzodiazepines can be given as well. In grade 3 and 4 envenomation the FDA approved Anascorp can be administered. The FDA recommends an initial dose of 3 vials.⁵

However, each vial can cost up to $8,000-10,000 or more and it has become common practice to give one vial and reassess before giving additional vials. Keep in mind Anascorp can carry the risk of anaphylaxis or other allergic reactions. Anascorp may not be stocked in all emergency rooms around the country and may only be in locations where scorpions are endemic. However always keep in mind these creatures can catch a ride in luggage or clothing so although rare, they can present in travelers from these areas.

References:

1. Klotz SA, Yates S, Smith SL, Dudley S Jr, Schmidt JO, Shirazi FM. Scorpion Stings and Antivenom Use in Arizona. Am J Med. 2021;134(8):1034-1038. doi:10.1016/j.amjmed.2021.01.025
2. Boyer LV, Theodorou AA, Berg RA, et al. Antivenom for critically ill children with neurotoxicity from scorpion stings. N Engl J Med. 2009;360(20):2090-2098. doi:10.1056/NEJMoa0808455
3. U.S. Food and Drug Administration. (2012). Drug labeling resources. U.S. Department of Health and Human Services. https://www.fda.gov/media/81093/download
4. Anascorp. Tucson, AZ: Rare Disease Therapeutics, Inc.; 2011. https://www.anascorp-us.com/resources/Brochure.pdf. Accessed June 8, 2024
5. Boyer LV, Theodorou AA, Berg RA, Arizona Envenomation investigators, et al. Antivenom for critically ill children with neurotoxicity from scorpion stings. N Engl J Med. 2009;360(20):2090-8. Available at: https://wikem.org/wiki/Scorpion_envenomation#cite_ref-Boyer_1-1. Accessed June 8, 2024
6. Kumar R. (2022). An update on epidemiology and management practices of Scorpion envenomation in India. Journal of family medicine and primary care, 11(9), 4932–4935. https://doi.org/10.4103/jfmpc.jfmpc_2300_21