Black widow spider bite: Difference between revisions
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==Background== | ==Background== | ||
*Identification: red hourglass on otherwise black spider | |||
*Genus: ''Latrodectus'' | |||
[[File:Western Black Widow (Latrodectus hesperus).jpg|thumb|Black widow spider]] | [[File:Western Black Widow (Latrodectus hesperus).jpg|thumb|Black widow spider]] | ||
===Mechanism=== | ===Mechanism=== | ||
*α-Latrotoxin envenomation causes massive release of neurotransmitters (norepinephrine, dopamine, acetylcholine, glutamate and GABA) from the nerve terminals → muscle cramps, tachycardia, hypertension | |||
*This clinical envenomation syndrome is known as latrodectism | |||
==Clinical Features== | ==Clinical Features== | ||
===Local=== | ===Local=== | ||
*Pinprick sensation; then increasing local pain that may spread to entire extremity | *Pinprick sensation; then increasing local pain that may spread to entire extremity | ||
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*[[Headache]], [[nausea/vomiting]], diaphoresis, [[photophobia]], [[dyspnea]] | *[[Headache]], [[nausea/vomiting]], diaphoresis, [[photophobia]], [[dyspnea]] | ||
*[[A-fib]], [[myocarditis]], [[priapism]], and death are rare | *[[A-fib]], [[myocarditis]], [[priapism]], and death are rare | ||
===Grading System=== | |||
*Grade 1: Range from no symptoms to local pain at the envenomation site with normal vital signs | |||
*Grade 2: Involve muscular pain at the envenomation site to migration to the trunk, diaphoresis at bite site and normal vital signs | |||
*Grade 3: Include grade 2 with abnormal vital signs; diaphoresis distant to envenomation site, generalized myalgias to back, chest and abdomen, nausea vomiting and headaches. | |||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
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==Diagnosis== | ==Diagnosis== | ||
* | *Generally clinical diagnosis | ||
==Management== | ==Management== | ||
*Local wound care and tetanus prophylaxis are | *Local wound care, analgesia and tetanus prophylaxis are mainstays of treatment | ||
**Grade 1: Cold packs and NSAIDs | |||
**Grade 2/3: IV Opioids and Benzodiazepines | |||
**Grade 1: Cold packs and | *Antivenin - indicated for systemic illness only | ||
**Grade 2/3: IV Opioids and | **Dosage: Usual dose is one to two vials diluted in 50 to 100 mL 5% dextrose or 0.9% sodium chloride, then infused over 1 hour | ||
* | **Use is controversial - ''Morbidity'' (pain, cramping and autonomic disturbances) are high, but ''mortality'' is low. Antivenin is horse serum derived, and can lead to anaphylaxis and serum sickness | ||
**Consider for: Pediatric patients, pregnant women, elderly | |||
*Routine antibiotic use is not indicated | |||
** | |||
* | |||
==Disposition== | ==Disposition== | ||
*Generally may be discharged | |||
*Consider admission for: | *Consider admission for: | ||
**Symptoms of moderate envenomation | **Symptoms of moderate or severe envenomation | ||
**Pregnant women | **Pregnant women | ||
**Children | **Children | ||
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==External Links== | ==External Links== | ||
==References== | ==References== | ||
Revision as of 03:11, 4 April 2016
Background
- Identification: red hourglass on otherwise black spider
- Genus: Latrodectus
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Mechanism
- α-Latrotoxin envenomation causes massive release of neurotransmitters (norepinephrine, dopamine, acetylcholine, glutamate and GABA) from the nerve terminals → muscle cramps, tachycardia, hypertension
- This clinical envenomation syndrome is known as latrodectism
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
- Headache, nausea/vomiting, diaphoresis, photophobia, dyspnea
- A-fib, myocarditis, priapism, and death are rare
Grading System
- Grade 1: Range from no symptoms to local pain at the envenomation site with normal vital signs
- Grade 2: Involve muscular pain at the envenomation site to migration to the trunk, diaphoresis at bite site and normal vital signs
- Grade 3: Include grade 2 with abnormal vital signs; diaphoresis distant to envenomation site, generalized myalgias to back, chest and abdomen, nausea vomiting and headaches.
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
Diagnosis
- Generally clinical diagnosis
Management
- Local wound care, analgesia and tetanus prophylaxis are mainstays of treatment
- Grade 1: Cold packs and NSAIDs
- Grade 2/3: IV Opioids and Benzodiazepines
- Antivenin - indicated for systemic illness only
- Dosage: Usual dose is one to two vials diluted in 50 to 100 mL 5% dextrose or 0.9% sodium chloride, then infused over 1 hour
- Use is controversial - Morbidity (pain, cramping and autonomic disturbances) are high, but mortality is low. Antivenin is horse serum derived, and can lead to anaphylaxis and serum sickness
- Consider for: Pediatric patients, pregnant women, elderly
- Routine antibiotic use is not indicated
Disposition
- Generally may be discharged
- Consider admission for:
- Symptoms of moderate or severe envenomation
- Pregnant women
- Children
- Preexisting cardiovascular disease or HTN