Spider bites: Difference between revisions
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===Background=== | ===Background=== | ||
*Red hourglass on otherwise black spider | *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 === | === Clinical Features === | ||
#Local | #Local |
Revision as of 23:58, 4 November 2013
Brown Recluse
Background
- White "violin" shape
Clinical Features
- Bite is initially painless
- Mild reaction
- Most common
- Mild erythematous lesion that later becomes firm and heals without scar
- Severe reaction
- Begins w/ mild-severe pain several hrs after bite accompanied by erythema and swelling
- Hemorrhagic blister then forms surrounded by vasoconstriction-induced blanched skin
- By day 3 or 4 hemorrhagic area may become ecchymotic
- Leads to "red, white, and blue" sign (erythema, blanching, ecchymosis)
- By end of first week ecchymotic area may become necrotic w/ eschar formation
- Systemic effects
- Rare
- Occur predominantly in children 24-72hr after the bite
- Include nausea/vomiting, fever, arthralgias, thrombocytopenia, rhabdo, renal failure
Treatment
- Local wound care
- Abx are indicated only if signs of infection exist; secondary infections are uncommon
Black Widow
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
- 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
Treatment
- 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
Tarantula
Clinical Features
- Abdominal hairs may be flicked a short distance when threatened
- Rarely penetrate human skin but can imbed deeply into conjunctiva and cornea
- Bites can be painful but systemic symptoms other than fever are unusual
Management
- Red eye and pain after handling a tarantula necessitates an ocular exam
- Hairs may be difficult to detect on slit lamp
- Treatment is surgical removal of hairs and topical steroids
See Also
Source
- Tintinalli
- Rosen's