Questions 1.
burns makes thermal injury and caustic exposure unlikely. The absence of vomiting casts doubts on toxic ingestion. 2. The sudden onset of severe pain associated with localized redness, swelling, muscle spasms, and physical exam findings consistent with a sympathetic toxidrome are suggestive of a widow spider envenomation. 3. Management consists of good supportive care, including analgesia. Parenteral opioids are generally required. Antivenom should be considered for symptoms that are refractory to standard therapy. Tetanus immunization should be updated as needed. Prophylactic antibiotics are unnecessary.
What is the differential diagnosis?
2. What is likely responsible for this child’s symptoms? 3. How should he be treated? Discussion 1. The differential diagnosis of sudden pain, particularly isolated to a single extremity, includes toxicological (e.g., envenomation, caustic exposure) and nontoxicological causes (e.g., trauma, muscle spasm). The absence of bruising decreases the likelihood of trauma. The absence of
SCORPION ENVENOMATIONS
There are approximately 90 scorpion species native to the U.S. 70 Most cause little to no harm to humans. Approximately two dozen produce more consequential pain, and one species, the Arizona bark scorpion ( Centruroides sculpturatus ), can cause potentially life-threatening envenomations. Centruroides sculpturatus is native to Arizona and adjacent areas of California, Nevada, and New Mexico. It is a slender, yellow-tan animal typically growing no longer than 70 mm. Several other Centruroides have been implicated in significant envenomation. The striped bark scorpion, C. vittatus , is the most widely distributed scorpion in the U.S., from New Mexico to the East coast, and as far north as Nebraska and Missouri. It resembles the Arizona bark scorpion but has two distinctive longitudinal stripes on its dorsum. Other medically significant scorpions include the Florida bark scorpion ( C. hentzi ), giant hairy scorpions (genus Hadrurus ), Vaejovid scorpions (family Vaejovidae), and the California swollen stinger scorpion ( Anuroctonus pococki ). Scorpion stings are commonly reported to U.S. poison centers. Between 2015 and 2017, there were 41,971 exposures, an average of 13,390 annually. 1-3 Children younger than age six accounted for 4,462 (10.6%) of these cases. A total of 12,306 (29.3%) reported scorpion envenomations were in victims younger than age 20. Scorpion venom is stored in a bulb at the tail, and it is through the tip of the tail that the venom is injected in defense or to incapacitate prey. Native scorpion venom contains primarily polypeptide neurotoxins that exert their effects on ion channels. Manifestations of native scorpion stings are neurotoxic. 71,90 There are no local tissue effects or hematologic toxicity. Contrary to many certifying and licensing examination preparatory course materials, pancreatitis is not a clinical feature of U.S. scorpion
envenomings. There is a grading system used to describe the clinical features of Arizona bark scorpion envenomation. ● Grade I: Pain and/or paresthesias at/near the injection site ● Grade II: Pain and/or paresthesias at a location remote from the injection site in addition to local effects ● Grade III: Either cranial nerve or somatic skeletal neuromuscular dysfunction, for example, opsoclonus, hypersalivation, dysphagia, or involuntary shaking ● Grade IV: Both cranial nerve and somatic skeletal neuromuscular dysfunction Out-of-hospital management of scorpion envenomation is supportive. Some victims develop sialorrhea, tongue fasciculations, and/or laryngospasm, so airway patency should be reassessed repeatedly. Suction is often required. Airway adjuncts, including endotracheal intubation, may be necessary. Patients with significant diaphoresis and/or vomiting may need aggressive fluid resuscitation. Pain is frequently severe, and parenteral opioids are typically necessary. Benzodiazepines may be used for anxiolysis and sedation. Dexmedetomidine has been used successfully in scorpion envenomation. As with other terrestrial envenomations, there is no role for any tourniquets, constrictive bandages, venom extraction devices, incision of the envenomation site, prophylactic antibiotics, or electrical therapy. In-hospital management is similar to prehospital treatment, with one additional therapeutic option. There is an FDA-approved antivenom for Arizona bark scorpion envenomations. Anascorp is an equine-derived F(ab’) 2 antivenom that has demonstrated safety and efficacy in treating these envenomations. 91 Unfortunately, availability and financial constraints may preclude its routine use.
HYMENOPTERA STINGS
Hymenoptera are an order of insects that includes wasps, bees, and ants. There are more than 150,000 species worldwide, including more than 15,000 bee species, greater than 20,000 ant species, and at least 100,000 wasp species. Multiple species are found in every U.S. state. Figure 20. Eastern Yellowjacket (Vespula Maculifrons)
The Apidae family includes honeybees and bumblebees. An important distinction between the two is that honeybees have a barbed stinger that embeds in the victim. Honeybees die after they sting. Bumblebees are larger and hairier than honeybees. Their stingers lack barbs; they are able to induce multiple stings. Hybridized honeybees (HHBs), also referred to as Africanized bees or killer bees, are descendants of southern African bees imported in 1956 by Brazilian scientists attempting to breed a honeybee better adapted to the South American tropics. Some of these bees escaped quarantine in 1957 and began breeding with local Brazilian honeybees. The resultant bees multiplied quickly and extended their range throughout South and Central America at a rate greater than 200 miles per year. HHBs entered the U.S. via Hidalgo, Texas, in 1990, and hives have since spread throughout the southern half of the country. Hybridized honeybees acquired the name killer bees because they will viciously attack people and animals that stray into their territory. Only a minimal disturbance is necessary to precipitate an HHB attack. Although all honeybees respond to threats to their colonies, HHBs respond more quickly and in much greater numbers than do European honeybees.
Source: Jason Pike
Page 26
Book Code: RPTTX2024
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