Black widow spider bite: Difference between revisions
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Revision as of 23:30, 11 March 2015
Background
- Identification: 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
- Local
- Pinprick sensation; then increasing local pain that may spread to entire extremity
- Erythema appears 20-60 min after the bite
- Pain begins to abate after several hours and disappears by 2-3d
- Systemic
- Muscle cramp-like spasms in large muscle groups (although exam rarely reveals rigidity)
- Pain becomes generalized
- Severe abdominal wall musculature pain and cramping
- HA, n/v, diaphoresis, photophobia, dyspnea
- A-fib, myocarditis, priapism, and death are rare
Differential Diagnosis
Envenomations, bites and stings
- Hymenoptera stings (bees, wasps, ants)
- Mammalian bites
- Closed fist infection (Fight bite)
- Dog bite
- Marine toxins and envenomations
- Toxins (ciguatera, neurotoxic shellfish poisoning, paralytic shellfish poisoning, scombroid, tetrodotoxin
- Stingers (stingray injury)
- Venomous fish (catfish, zebrafish, scorpion fish, stonefish, cone shells, lionfish, sea urchins)
- Nematocysts (coral reef, fire coral, box jellyfish, sea wasp, portuguese man-of-war, sea anemones)
- Phylum porifera (sponges)
- Bites (alligator/crocodile, octopus, shark)
- Scorpion envenomation
- Reptile envenomation
- Spider bites
Workup
Management
- Pain and muscle spasms
- Opiods and benzos
- Systemic illness
- Antivenin
- Consider for:
- Children
- Pregnant women
- Elderly
- Consider for:
- Antivenin
Disposition
- Consider admission for:
- Symptoms of moderate envenomation
- Pregnant women
- Children
- Pts w/ preexisting cardiovascular disease or HTN