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Image from Simone Y, van der Meijden A. J Venom Anim Toxins Incl Trop Dis. 2021;27:e20210002. PMID: 34527038; PMCID: PMC8425188. [Creative Commons Attribution 4.0 International License (CC by 4.0).]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Scorpions are found in every continent but Antarctica. They are members of the phylum Arthropoda and arachnids, with a total of eight appendages, including a pair of pedipalps or claws, as well as a segmented tail (the metasoma) that ends with the telson, a bulbous organ containing venom glands and a stinger.[1] Scorpion bites are not described in the literature. Scorpion stings and their resulting envenomation are known as scorpionism.[1]

Less than 1% of all scorpion species are life threatening to humans; most serious and fatal cases of envenomation occur in the very young or the very old, or in patients with significant medical comorbidities. Similar to snakebites, care is complicated in many areas where emergency and critical care resources are limited (India, Iran, Turkey, Africa, the Middle East, Mexico, tropical and subtropical areas of the Western Hemisphere).[1-4]

Image from Godoy DA, Badenes R, Seifi S, Salehi S, Seifi A. Cureus. 2021;13(4):e14715. PMID: 34055554; PMCID: PMC8158070. [CC by 4.0.]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Scorpions are more active at night, and stings are more frequent in the summer months or after rainfall when scorpions may have more encounters with humans. Scorpion stings generally produce one of the following toxidromes, although overlap may exist, even among geographically and genetically diverse species, and more than one toxidrome may be present concurrently[2-4]:

  • Tissue necrosis, hemolysis, and cytolysis: Disseminated intravascular coagulation (DIC), hemolytic uremic syndrome (HUS), and acute renal toxicity may result.
  • Autonomic storm and cardiotoxicity: Symptoms of either sympathetic or parasympathetic overload may manifest.
  • Neuromuscular toxicity: Loss of bulbar or skeletal muscle control may ensue.

Scorpion venom may also cause pancreatitis or severe allergic reactions, including anaphylaxis.[4]

Image from Galih Surya Alam | Shutterstock.

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Tissue Necrosis, Hemolysis, and Cytolysis

Hemiscorpius lepturus is a scorpion species native to the Middle East and Iran. Its venom is similar in composition and morphology to brown recluse spider venom, causing tissue necrosis, cytolysis, and hemolysis; DIC and HUS can result.[2,3,5,6] Other complications of H lepturus envenomation (eg, rhabdomyolysis, acute renal failure) may also lead to significant morbidity and mortality, particularly among children.[3-5] Neurologic or autonomic symptoms are less common (pediatric > adult patients).[3,5]

Envenomation from H lepturus is typically painless and occurs at night, while victims are asleep. Thus, many stings go unnoticed, and the diagnosis of envenomation results after examination reveals the characteristic skin changes associated around the sting site. Within 1-2 days of envenomation, local evidence of lymphangitis, edema, and erythema may progress to purpuric bullae, which eventually become necrotic. Eventually, if DIC develops, generalized hemorrhage, petechiae, and purpura may be noted. The systemic inflammation that results from tissue damage and hemolysis can produce myalgias, fatigue, and fever; death, although rare, results from complications of HUS and renal failure.[7]

Image of pulmonary edema in cardiogenic shock from Hellerhoff | Wikimedia Commons. [CC by-ShareAlike (SA) 4.0 International.]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Autonomic Storm

The venom of scorpions of the genera Tityus, Androctonus, Buthus, Leiurus, and Hottentotta contain alpha-toxins that bind and activate sodium channels in the pre- and postsynaptic membranes of sympathetic and parasympathetic neurons, resulting in sustained action potentials and depolarization.[8] Excessive and unregulated release of neurotransmitters develops (eg, acetylcholine, norepinephrine, epinephrine), which can lead to autonomic storm and be marked by a dominance of either sympathetic or parasympathetic effects, depending on the venom.[8]

Cholinergic excess may elicit excessive salivation, bronchorrhea, lacrimation, vomiting, diarrhea, and bradycardia. The "killer Bs"— bronchoconstriction, bronchorrhea, and bradycardia—may trigger death. Tachycardia, arrhythmias, hypertension, and agitation may arise from sympathetic overstimulation. Severe envenomation may cause cardiac toxicity (possibly due to cardiac stunning from excessive catecholamine release), which may manifest as arrhythmias or left heart failure, with resultant pulmonary edema and/or cardiogenic shock.[8]

Scorpion venom may also stimulate the exocrine pancreas to release proteolytic enzymes, resulting in pancreatitis.[8]

Left image from Andrew Meeds. [CC by 4.0 International.] Right image from Ryan van Huyssteen. [CC by-SA 4.0 International.] Both images via iNaturalist.

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Neuromuscular Toxidrome

Envenomation by Centruroides and Parabuthus scorpion species can produce significant neuromuscular toxicity.[3,9] A main venom component is alpha-toxins, similar to those of Tityus, Androctonus, Buthus, Leiurus, and Hottentotta venoms. However, in contrast to the venoms of those latter species, which largely activate the autonomic nervous system, the venoms of Centruroides and Parabuthus act principally at the neuromuscular junction, causing sustained release of neurotransmitters at the neuromuscular synapses and the neuromuscular junction, as well as hyperactive and dysregulated activation of the muscular system.[3,9]

Severe Centruroides and Parabuthus envenomation may manifest with cranial nerve dysfunction, including dysphagia, tongue fasciculations, increased oral secretions, and rotatory nystagmus. Skeletal muscle activation may present as restlessness, myoclonic jerking, alternating opisthotonos, and tremor, which may be mistaken for seizure activity, although the patient is generally completely alert. Excessive motor activation may result in hyperthermia in severe cases. Some autonomic activation may also accompany muscular activation in Centruroides and Parabuthus envenomations.[9]

Image of a urine sample from a patient with rhabdomyolysis from James Heilman, MD | Wikimedia Commons. [CC by-SA 3.0 Unported.]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Workup

Target the diagnostic workup in scorpion envenomation toward the main toxidromes and to rule out other differential diagnostic considerations. For example, in regions where H lepturus stings are possible, investigate the development of rhabdomyolysis, DIC, and HUS. Thus, consider the following studies[2]:

  • Serum electrolyte levels, including potassium and calcium
  • Complete blood count with peripheral blood smear
  • Coagulation studies, including fibrinogen and d-dimer levels
  • Creatine kinase levels
  • Blood glucose levels
  • Serum lactate levels
  • Liver and pancreatic enzyme levels
  • Blood urea nitrogen level and creatinine/glomerular filtration rate
  • Urinalysis
Image of a scorpion sting by Palmira Cupo. From Cupo P. Rev Soc Bras Med Trop. 2015 Nov-Dec;48(6):642-9. PMID: 26676487. [CC by 4.0 International.]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Management

Mild stings

Treatment of mild H lepturus stings is largely supportive, including pain management and tetanus prophylaxis.[2-4] Antibiotics are not routinely indicated and should be reserved for cases of suspected bacterial superinfection of the sting site.

Administer intravenous (IV) Razi polyvalent scorpion antivenom within 2 hours of the sting. Although some benefit in improving outcomes may still exist with delayed administration, data are lacking.

Closely monitor patients for postantivenom development of allergic reactions, including anaphylaxis or angioedema, although these are less common with newer antivenom formulations.[2-4] Provide standard supportive care for DIC, HUS, and acute renal failure, including fluid and blood product administration, as indicated.[2,8]

Image courtesy of Joseph U Becker, MD.

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Autonomic and/or neuromuscular symptoms

The medical care of scorpion stings producing autonomic or neuromuscular findings and symptoms depends largely on grading of the envenomation severity (shown).[2,4] Note that autonomic and neuromuscular symptoms may occur simultaneously. In addition to the diagnostics studies discussed earlier (see slide 6), consider obtaining electrocardiography and levels of cardiac biomarkers and brain natriuretic peptide, as well as a chest x-ray and cardiopulmonary ultrasound to evaluate left ventricular function and the presence of pulmonary edema.

Grade I and II stings: Pain control with anti-inflammatories and tetanus prophylaxis is often all that is required.[2,8,9] A 12-24–hour observation period to surveil for the development of autonomic symptoms is reasonable.

Grade II or higher severity: Consider intensive care unit (ICU) monitoring. Consult with a medical toxicologist with experience in treating scorpion envenomations. In the setting of severe autonomic toxicity resulting in adrenergic stimulation, consider giving prazosin, an alpha-1 adrenergic receptor blocker that has demonstrated reduction in the effects of sympathetic overload in patients with scorpion venom–induced autonomic storm.[2,8,9]

Image of a scorpion sting site 56 hours after the sting from Fuentes-Silva D, Santos AP Jr, Oliveira JS. J Venom Anim Toxins Incl Trop Dis. 2014;20:52. PMID: 25873941; PMCID: PMC4395898. [CC by 4.0 International.]

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Limited support exists in the literature for use of antivenom for scorpion stings resulting in autonomic storm, and evidence is limited and varies by species on the use of scorpion-specific antivenom. For example, limited effect is suspected for stings by Leiurus, Tityus, and Hottentotta species, but an argument could be made to use antivenom with severe cases involving these species, particularly if a positive identification is not possible.[2,8,9]

Image courtesy of Joseph U Becker, MD.

Scorpion Stings: From Mild Local Effects to Death

Joseph U Becker, MD | September 6, 2022 | Contributor Information

Neuromuscular symptoms

Scorpion envenomation by Centruroides and Parabuthus species also has a grading system (shown).[2,8,9]

Grade I or II envenomations: Most do not require significant medical intervention.

Grades III and IV envenomations: In general, promptly consult with a medical toxicologist, and treat patients in an ICU setting. In addition to the standard diagnostic and supportive care described earlier (see slide 6), in cases of grade III or IV Centruroides envenomation, administer IV Anascorp scorpion antivenom[2,8,9]; in cases of grade III or IV Parabuthus envenomation in southern Africa, administer IV SAIMR (South African Institute for Medical Research) scorpion-specific antivenom.[8,9]

As with the administration of other antivenoms, closely monitor and prepare for the development of severe allergic reactions (eg, anaphylaxis, angioedema) to scorpion antivenom. Respiratory support, including endotracheal intubation and mechanical ventilation, may be required. Serum sickness may also be a delayed complication of antivenom administration (several days to a week).[2,8,9]

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References