November 7, 2024

32 year-old man presents with a spider bite

By Med-Challenger · 1 minute read

A 32-year-old man presents 3 to 4 hours after a spider bite in rural Kansas. He states that he saw the spider (see Figure 1) but did not have any initial sensation of the bite.

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Figure 1.

The area where the bite occurred now has a stinging sensation and there is some evidence of developing blisters (see Figure 2).

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Figure 2.

Which of the following is the most appropriate therapy for this patient?

wound care, immobilization, tetanus prophylaxis, analgesics, and antipyretics
administration of dapsone 100 mg twice daily for 2 weeks
early excision or intralesional injection of corticosteroids
hyperbaric oxygen therapy

The correct answer is:

Wound care, immobilization, tetanus prophylaxis, analgesics, and antipyretics

Key Point:

Optimal therapy for brown recluse spider bites is extremely controversial.

Explanation:

Many therapies have been proposed; however, few--with the exception of local wound care--have proven to be beneficial. Some may even be harmful. At this time, the only therapy that is clearly beneficial is local wound care and symptom control.

Early excision and intralesional injection of corticosteroids are not advised. These lesions undergo considerable transformation over days to weeks following envenomation. Excising the local wound at this time does not preclude expansion of the wound or the associated and considerable morbidity. Intralesional steroids may actually promote wound expansion by spreading the venom. When administered early, dapsone may inhibit local infiltration of the wound by leukocytes and, therefore, decrease size; however, numerous studies have not demonstrated any clear benefit to dapsone compared with other therapies. Dapsone is also associated with the development of hepatitis, hemolysis, and methemoglobinemia. Animal studies have mixed results about the benefits of hyperbaric oxygen therapy for reducing the final size of the wound.

Reference:

Otten EJ. Venomous animal injuries (chapter 55). In: Walls R, et al. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed., 2018:698-714.

This question appears in Med-Challenger Emergency Medicine Review with CME

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