View source for Funnel-web spider bite

==Background==
[[File:Funnel Web Spider.png|200px|thumb|right|Female Blue Mountains Funnel-web Spider, (Hadronyche versuta) Image: Mike Gray]]
*Identification: Glossy black cephalothorax and velvety black abdomen, often with reddish hairs.<ref>Leslie V. Boyer, Greta J. Binford, Janice A. Degan. Spider Bites. Paul S. Auerbach. In: Auerbach’s Wilderness Medicine. 7th Ed. 2017: 1002-1003.</ref> 
**Females grow up to 4cm in length, whereas males are smaller and more delicate.
**Females dig a funnel shaped burrow under rocks, logs or building foundation and rarely stray, whereas males wander after reaching maturity and may enter buildings
**Aggressive behavior, 4-5mm fangs which can penetrate a chicken skull, and potent venom make these among the deadliest spiders in the world. 
*Genus: ''Atrax'' and ''Hadronyche''<ref>Leslie V. Boyer, Greta J. Binford, Janice A. Degan. Spider Bites. Paul S. Auerbach. In: Auerbach’s Wilderness Medicine. 7th Ed. 2017: 1002-1003.</ref>
*The most clinically relevant species are restricted to Eastern Australia near Sydney and the central coast region of New South Wales and adjacent Blue Mountains.<ref>Leslie V. Boyer, Greta J. Binford, Janice A. Degan. Spider Bites. Paul S. Auerbach. In: Auerbach’s Wilderness Medicine. 7th Ed. 2017: 1002-1003.</ref>

===Venom===
*Components of the venom include Atraxotoxin and Robustoxin which appear to induce widespread neurotransmitter release, resulting in neuromuscular and autonomic stimulation.

==Clinical Features==
*90% of bites will not involve significant envenomation. 
*Local Symptoms:
**Intense pain, wheal with erythema at injection site, localized sweating with piloerection, 
**Lasts for 30min
**Is not thought to produce skin necrosis
*Systemic Symptoms
**Earliest: Perioral tingling, diaphoresis, nausea/vomiting, salivation, and lacrimation.
**Severe: 
***Pulmonary edema with dyspnea
***Peripheral neuromuscular syndrome including fasciculations, tremors, and spasms 
***Impaired consciousness
***Death due to pulmonary edema, hypotension, or cardiac arrest

==Differential Diagnosis==
{{Bites and stings DDX}}

==Evaluation==
*Generally a clinical diagnosis

==Management==
*[[Pressure Immobilization Dressing]]
**Wrap the length of the bitten extremity with an elastic bandage
**Splint the extremity in neutral position to immobilize
**Immobilize victim and transport to medical care
**''If a patient presents with a tourniquet or pressure immobilization dressing, obtain IV access for potential resuscitation before removing.''
*Supportive Care
**O2, mechanical ventilation if needed
**Gentle IV fluids
**[[Atropine]] for sialorrhea bronchorrhea
*Antivenom
**Specific IgG antivenom has been developed by Commonwealth Serum Laboratories
**Empiric treatment with 2 amps (100mg/amp) of IgG in the setting of systemic signs/symptoms
**2amps repeated Q15 min until symptom resolution occurs
**2-8amps total dose reported
**No difference in dosing between adults and peds. 
**No adverse effects reported in 40 patients over 10 years

==Disposition==
*May discharge those without systemic signs after period of ED observation
*Admit those with systemic signs or requiring antivenom

==See Also==
*[[Spider bites]]

==External Links==


==References==
<references/>

[[Category:Environmental]]
[[Category:Dermatology]]