Spider bites

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Background

  • Red hourglass on otherwise black spider

Mechanism

Envenomation causes release of acetylcholine and norepinephrine from the nerve terminals causing muscle cramps, tachycardia and hypertension

Clinical Features

  1. Local
    1. Pinprick sensation; then increasing local pain that may spread to entire extremity
    2. Erythema appears 20-60 min after the bite
    3. Pain begins to abate after several hours and disappears by 2-3d
  2. Systemic
    1. Muscle cramp-like spasms in large muscle groups (although exam rarely reveals rigidity)
    2. Pain becomes generalized
      1. Severe abdominal wall musculature pain and cramping
    3. HA, n/v, diaphoresis, photophobia, dyspnea
    4. A-fib, myocarditis, priapism, and death are rare

Treatment

  1. Pain and muscle spasms
    1. Opiods and benzos
  2. Systemic illness
    1. Antivenin
      1. Consider for:
        1. Children
        2. Pregnant women
        3. Elderly

Disposition

  1. Consider admission for:
    1. Symptoms of moderate envenomation
    2. Pregnant women
    3. Children
    4. Pts w/ preexisting cardiovascular disease or HTN

Tarantula

Clinical Features

  1. Abdominal hairs may be flicked a short distance when threatened
    1. Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
  2. Bites can be painful but systemic symptoms other than fever are unusual

Management

  1. Red eye and pain after handling a tarantula necessitates an ocular exam
    1. Hairs may be difficult to detect on slit lamp
  2. Treatment is surgical removal of hairs and topical steroids

Review Questions

Environmental emergencies question – Regarding black widow and brown recluse spider envenomations, which of the following is FALSE?

Black widow spiders (BWS) are found in the temperate regions of six continents and are widespread through North America, including the western United States (California included).
Signs and symptoms associated with BWS (e.g. diffuse pain, muscle cramps, tachycardia, and hypertension) usually develop begin within 30 to 120 minutes of the envenomation.
After antivenom for BWS is administered, symptoms typically resolve within 30 minutes, with complete relief within 2 hours.
Brown recluse spider (BRS) envenomation is most common in west coast states, such as California.
Most bites from BRS have a benign clinical course, but necrosis with induration and eschar formation may occur, and systemic effects, such as fever, chills, headache, malaise, arthralgia, and myalgias progress after more than 24 to 48 hours and resolve by 72 to 96 hours post bite.


See Also

Sources

  • Tintinalli
  • Rosen's