Selected topic: Toxicology
Suspected Brown Recluse Envenomation: A Case Report and Review of Different Treatment Modalities

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Abstract

Background: The Loxosceles reclusa, commonly known as the brown recluse spider, is responsible for virtually all cases of spider bites leading to a significant necrosis. Case Report: We report the case of a 72-year-old man who presented to the Emergency Department complaining of back pain, weakness, and diarrhea. The patient stated that he sustained a bug bite 1 week before presenting to the hospital. His wound was necrotizing in nature and after an exhaustive work-up, the most likely etiology was found to be envenomation by a brown recluse spider, Loxosceles reclusa. Conclusion: This is an endemic cause of a necrotizing wound bite in areas of the Midwestern and Southern United States, but it is rarely reported in the Northeast.

Introduction

There are several species of Loxosceles spiders in the United States; the most common and dangerous being Loxosceles reclusa, commonly known as the brown recluse spider (BRS). BRS bites are responsible for virtually all cases of spider bites leading to a significant necrosis, however, some authors suggest that the only way to definitively diagnosis a BRS bite is to identify the spider itself, which is often not available (1). BRS bites occur most often in the Midwest from Nebraska to Ohio, and the South from Georgia to Texas (2). Although all spiders are poisonous, most species do not have large enough fangs to penetrate human skin. Most bites tend to heal without medical treatment, whereas some lead to necrotic lesions and, rarely, bites may lead to a systematic illness known as Loxoscelism. Loxoscelism is not a reportable illness, making nationwide tracking difficult. In endemic areas where the BRS population is dense, envenomation is infrequent, leading many to believe that the occurrence of bites in non-endemic areas is even less likely (3, 4). Many lesions attributed to the BRS actually result from other causes, making these bites appear more common than their actual incidence (3, 5, 6) (Table 1).

A typical bite exhibits a characteristic pattern that includes pruritis, pain, and erythema within 6 h, and an irregular, erythematous ring that demarcates the bite by 24 h. In more severe cases, necrosis can be seen within 48–72 h. Early signs of necrosis are hyperesthesia, bullae, and cyanosis, leading to an ulcer that is red-blue in color, painful, and covered by an eschar. The severity of the lesion does not correlate to developing systematic Loxoscelism (Table 2). Rare but dangerous complications of BRS bites include pyoderma gangrenosum, intravascular hemolysis, renal failure, pulmonary edema, and systemic toxicity. Wendell states that only 10–15% of bites lead to “major problems” that were defined as unacceptable scarring, hospitalization, or chronic lesions (3).

Identifying the spider itself is considered to be the only conclusive way to diagnose a BRS bite. The BRS is commonly described as having a violin-shaped or fiddle-like brown marking on its dorsal surface (Figure 1) (7). This marking, however, is not unique to the BRS species. A more distinguishing feature is the number of eyes. Whereas most spiders have eight, L. reclusa has six eyes arranged in a distinctive pattern of three pairs, known as dyads, with one pair in the front and the other two pairs on the side of the cephalothorax (Figure 2) (8). They are nocturnal and are considered to be house spiders, as their habitat includes attics, basements, boxes, sheds, and woodpiles. The spiders are not known to migrate out of their native areas, but may be moved from place to place by humans, leading to reports of bites in non-endemic areas (3, 5, 9).

In this review, we performed a literature search for current trends in the treatment of BRS bites. We hope to provide clarification of possible treatment methods for the clinician who is presented with a suspected BRS bite.

Section snippets

Case Report

A 72-year-old man was brought to the emergency department (ED) complaining of back pain, weakness, and diarrhea. The patient was noted to have a wound on the right side of his upper back, which he stated occurred from a “bug bite” 1 week before his hospital visit. The wound progressed during the week and was the size of an egg when he presented to the ED. The wound was extremely painful to touch, pruritic, and not relieved with any medications. He denied any fever or chills, night sweats,

Discussion

Most BRS bites heal without aggressive medical treatment. Bites may be cleaned and treated with “RICE” (rest-ice-compression-elevation). Mild bites may be treated symptomatically with aspirin and antihistamines. Tetanus status should be updated as with any penetrating wound. It has been suggested that bites with tissue breakdown should be treated prophylactically with antibiotics such as a cephalosporin. Systemic Loxoscelism can be treated supportively with hydration, and monitored with serial

Conclusion

Most Loxosceles lesions will heal without treatment. Many conditions can mimic the symptoms of BRS bites, and most treatments are controversial and have side effects. The studies we have reviewed have not conclusively shown that the treatments used significantly alter the natural outcome of the bites (22). We cannot at this time recommend dapsone, hyperbaric oxygen, nitroglycerin, electric shock therapy, or surgical excision as treatment options. It is certainly possible that well-controlled

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