Rosen & Barkin's 5-Minute Emergency Medicine Consult (661 page)

• Pediatric, elderly, pregnant, or symptomatic patients
  
• Significant cardiovascular symptoms and signs, or severe HTN, particularly in presence of premorbid cardiac disease or chronic HTN
  
• Respiratory distress or pulmonary edema
  
• Persistent symptoms not responding to aggressive management and specific antivenin
  

• Asymptomatic patients with no positive identification of a black widow spider can be released after observation for 1–2 hr
  
• Asymptomatic patients with no comorbid illness with a positive identification of the black widow spider should be observed for a minimum of 4–6 hr and discharged if their condition does not change
  
• All discharged patients must be instructed to watch for the following symptoms and to seek appropriate follow-up:
  
  • Hematuria
    
  • Rash
    
  • Joint pain
    
  • Lymphadenopathy
    
  • Shortness of breath
    
  • Signs of infection
    
• Discharged patients who received antivenin should be instructed to watch for signs of serum sickness:
  
  • Type III delayed hypersensitivity
    
  • Uncommon
    
  • Occurs 5 days–3 wk post treatment
    
  • Treat with antihistamines and steroids
    

Toxicology consult for patients requiring admission or antivenin administration

• In most untreated patients, symptoms peak after 2–3 hr and then begin to resolve, occasionally recurring episodically over the following few days
  
• In otherwise healthy adults, complete resolution of symptoms occurs within 2–3 days
  
• Neurology follow-up if persistent neurologic symptoms last weeks to months including:
  
  • Fatigue
    
  • Generalized weakness or myalgias
    
  • Paresthesias
    
  • Headache
    
  • Insomnia
    
  • Impotence
    
  • Polyneuritis
    

• Widow bites in infants may present as intractable crying
  
• A high fever and WBC count should prompt consideration of alternatives to spider bites (e.g., infection)
  

• Boyer LV, Binford GJ, McNally JT. Spider bites. In: Auerbach, ed.
  Wilderness Medicine.
  5th ed. Philadelphia, PA: Mosby; 2007.
  
• Clark RF, Wethern-Kestner S, Vance MV, et al. Clinical presentation and treatment of black widow spider envenomation: A review of 163 cases.
  Ann Emerg Med
  . 1992;21(7):782–787.
  
• Otten EJ. Venomous animal injuries. In: Marx JA, Hockenberger RS, Walls RM, et al., eds.
  Rosen’s Emergency Medicine.
  7th ed. Philadelphia, PA: Mosby; 2009.
  
• Weinstein S, Dart R, Staples A, et al. Envenomations: An overview of clinical toxinology for the primary care physician.
  Am Fam Physician
  . 2009;80(8):793–802.
  

See Also (Topic, Algorithm, Electronic Media Element)

Spider Bite, Brown Recluse

CODES

989.5 Toxic effect of venom

BASICS

Local or systemic illness caused by brown recluse spider bite envenomation

• Brown recluse spider (also known as the fiddleback spider) features:
  
  • Appearance:
    
    • Delicate body and legs spanning 10–25 mm
      
    • Tan- to dark-brown with darker violin-shaped marking visible on the upper aspect of the head
      
    • 3 pairs of eyes
      
  • Found widely throughout the south-central part of US
    
  • Habitat: Typically warm and dry locations, indoors or outdoors such as wood piles, bundles of rags, cellars, under rocks, or in attics
    
  • Bites are typically defensive
    
• Mechanism of toxicity:
  
  • Venom is a complex cocktail of enzymes and peptides that:
    
    • Binds to RBC and causes hemolysis
      
    • Causes prostaglandin release and activates complement cascade
      
    • Causes lipolysis and tissue necrosis
      
    • Triggers platelet aggregation and thrombosis
      
    • Triggers allergic response to venom antigenic properties
      
    • May lead to shock and DIC in rare cases
      
  • Toxicity proportional to:
    
    • The amount of venom relative to the size of patient
      
    • Location of envenomation on the body
      

• Children are more vulnerable to a given amount of venom than healthy adults
  
• Fatality more common in children due to severe intravascular hemolysis
  

DIAGNOSIS

Diagnosis is based not only on the clinical presentation but also on a reliable history of a spider bite.

• An isolated cutaneous lesion is the most common presentation
  
• Bite sites are usually located in areas under clothing where spider gets trapped between clothing and skin
  
• Local wound symptom onset:
  
  • Bite onset is usually asymptomatic, but some may report burning or stinging sensation
    
  • 1–24 hr later, patients may report aching or pruritis locally
    
• Systemic features:
  
  • Rare complication
    
  • More common in children than adults
    
  • Develop during the 1st 1–3 days postenvenomation.
    
  • Patient may report:
    
    • Fever, chills
      
    • Weakness, malaise
      
    • Nausea, vomiting, diarrhea
      
    • Dyspnea
      
    • Myalgias, muscle cramps, arthralgias
      
    • Jaundice
      
    • Petechial or urticarial rash
      
    • Generalized pruritic rash
      
    • Hematuria or dark urine
      

• Bite wound:
  
  • Usually no visible injury if examined within the 1st 1–3 days
    
  • There may be a pinprick lesion, local blanching and induration, or erythema.
    
  • Tissue injury may develop at bite site:
    
    • Initially, bite mark may be surrounded by edema
      
    • Next, an erythematous border will develop around a purple center with a thin ring of ischemia between the 2
      
    • Serous or hemorrhagic bullae may form in the center after 24–72 hr
      
    • Blister may gradually enlarge and darken with the development of and eschar of skin and subcutaneous fat necrosis over 3–4 days
      
    • Eschar sloughs off 2–5 wk later leaving an ulcer in its place
      
    • Necrosis develops most extensively where subcutaneous fat is greatest
      
    • Lower-extremity blisters may spread distally under the influence of gravity
      
    • Local response is not dependent on the extent of envenomation and cannot be used to predict the likelihood or severity of subsequent systemic illness
      
• Skin:
  
  • Jaundice
    
  • Petechia
    
  • Urticaria
    
  • Generalized maculopapular rash
    

• Careful inquiry required to elicit the spider bite history
  
• Routine lab testing not necessary unless systemic toxicity present.
  

• Spider venom can be detected in skin lesions, but widespread clinical testing is not available yet
  
• CBC:
  
  • Hemolytic anemia
    
  • Thrombocytopenia, particularly with DIC
    
  • Leukocytosis
    
• Electrolytes:
  
  • Hyperkalemia or acidosis in renal failure
    
• BUN, creatinine
  
• Creatine kinase may be elevated in rhabdomyolysis
  
• Prothrombin time/partial thromboplastin test may be prolonged in DIC
  
• d
  -dimer and fibrin degradation products may be elevated in DIC
  
• Fibrinogen may be decreased in DIC
  
• Urinalysis:
  
  • Hemoglobinuria
    
  • Proteinuria
    

• CXR in systemic toxicity
  
• Soft tissue radiograph of bite site
  

• Angioedema
  
• Bacterial soft tissue infection; MRSA
  
• Burn
  
• Cutaneous anthrax
  
• Diabetic ulcer
  
• Decubitus ulcer
  
• Erythema nodosum
  
• Fungal infection
  
• Gonococcal hemorrhagic lesion
  
• Herpes simplex
  
• IV drug use or “skin popping”
  
• Vascular insufficiency with secondary ulcer
  
• Lyme disease
  
• Neoplastic lesion
  
• Other arachnid envenomation
  
• Poison ivy or oak
  
• Pyoderma gangrenosum
  
• Sporotrichosis
  
• Stevens–Johnson syndrome
  
• Thrombosis
  
• Vasculitis
  
• Warfarin use