Ver el código de «Scorpion envenomation»

==Background==
*Most scorpion stings in North America result only in local pain. 
*Arizona Bark Scorpion (''Centruroides sculpturatus''), found in AZ, NV, NM, TX, and CA, is the only neurotoxic species found in North America and can cause systemic toxicity.<ref name="Boyer" />

[[File:Bbasgen-bark-scorpion.jpg|thumb|Arizona Bark Scorpion, (''Centruroides sculpturatus'')]]

===Pathophysiology===
*Four neurotoxins (toxins I to IV) have been isolated from ''C. exilicauda''
*Toxins target excitable membranes, especially at the neuromuscular junction, by opening sodium channels → repetitive depolarization of nerves in both sympathetic and parasympathetic nervous systems → catecholamine and acetylcholine release.<ref>Nelson, Lewis, and Lewis R. Goldfrank. Goldfrank's Toxicologic Emergencies. New York: McGraw-Hill Medical Division, 2014. Print.</ref>

==Clinical Features==
[[File:PMC4395898 40409 2014 85 Fig2 HTML.png|thumb|Local scorpion sting (''Rhopalurus amazonicus Lourenço'', Brazil).]]

===Local reaction===
*Pain and [[paresthesias]] near envenomation site.
**"Tap" test: severe local tenderness when affected area is lightly tapped

===Systemic reaction===
*Uncommon but can be severe, particularly in children
*[[Cranial nerve palsies]] and [[weakness|somatic motor dysfunction]] can develop:
**Abnormal roving eye movements, blurred vision, pharyngeal muscle incoordination
**Tongue fasciculations and uncoordinated motor agitation (flailing or jerking extremities)
*Hypersalivation, noncardiac [[pulmonary edema]]
**can → [[respiratory distress]]/failure
*[[Tachycardia]], other dysautonomias, and severe agitation can also be present
*Without antivenom, symptoms typically last 24-48 hrs

===Grades of ''Centruroides'' envenomation===
*Grade 1 - Local pain and/or paresthesias at site of envenomation
*Grade 2 - Pain and/or paresthesias remote from the site of the sting, in addition to local findings
*Grade 3 - Either cranial nerve/autonomic dysfunction '''or''' somatic skeletal neuromuscular dysfunction
**Cranial nerve dysfunction - Blurred vision, roving eye movements, hypersalivation, tongue fasciculations, dysphagia, dysphonia, problems with upper airway
**Somatic skeletal neuromuscular dysfunction - Restlessness, severe involuntary shaking or jerking of the extremities that may be mistaken for a seizure
*Grade 4 - Combined cranial nerve/autonomic dysfunction '''and''' somatic skeletal neuromuscular dysfunction

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

==Evaluation==
*Generally clinical diagnosis
**Be aware that a discrete scorpion sting mark may not be clinically apparent.

==Management==
*Supportive care
**Cold compress to area of sting
**[[analgesia|Analgesic]] and anti-inflammatory medications
**[[Benzodiazepines]] may help with agitation and muscle spasm
**Intubation for pulmonary symptoms is rare, but may be necessary
*[[Atropine]]
**May be given for hypersalivation and respiratory distress caused
**Contraindicated for scorpion stings not indigenous to US (may exacerbate adrenergic effects)
**Alternatively, can administer [[glycopyrrolate]]
*Anascorp antivenom (Centruroides immune Fab) - Only stocked by certain hospitals in Arizona, Nevada, and Utah<ref>http://www.anascorp-us.com/hospital/ Accessed 08/03/15</ref>
**Resolves clinical syndrome within 4hr<ref>http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm266515.htm</ref><ref name="Boyer">Boyer LV, Theodorou AA, Berg RA, Arizona Envenomation investigators, et al. Antivenom for critically ill children with neurotoxicity from scorpion stings. N Engl J Med. 2009 May 14;360(20):2090-8.</ref>
**Common side effects: vomiting, pyrexia, rash, nausea, and pruritus
**Serious side effects: anaphylaxis
**Costs approximately $8000 per vial, and requires 3-4 vials for treatment<ref>http://www.azcentral.com/news/articles/2011/11/10/20111110scorpion-drug-cost.html</ref>

==Disposition==
*Grade I or II envenomation may generally be discharged after 6 hours of observation in the ED without progression of symptoms.
*Grade III or IV envenomation likely requires antivenom administration and/or admission.

==See Also==
*[[Envenomations, bites and stings]]

==References==
<references/>

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