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Sting, Scorpion, Emergency Medicine

Basics

Description

- Scorpion venom is neurotoxic: - Sodium channels opening - Prolonged firing of neurons

- Onset within minutes, progressing to maximum severity in ’ Ό1 " 2 hr but may persist ≤48 " 72 hr. - Scorpion species determines symptomatology (Centruroides sculpturatus, aka Centruroides exilicauda or bark scorpion, is the only species in US causing symptoms). - Local tissue effects: - No erythema - Pain - Hyperesthesia

- Parasympathetic effects: - Hypotension - Bradycardia - Hypersalivation

- Somatic effects: - Involuntary muscle contractions - Restlessness

- Grades I and II envenomations: - Grades III and IV envenomations: - BUN, creatinine - Electrolytes - UA - CBC

- Severely agitated patients: - Creatine kinase - Urine myoglobin

  • Scorpion venom is neurotoxic:Sodium channels openingProlonged firing of neurons
  • Autonomic, somatic, and cranial nerve excitation occurs.
  • Symptoms begin within minutes of bite.
  • Symptoms persist 1 " 72 hr.

Etiology

  • Centruroides species found in Southern US, Mexico, Central America, and Caribbean
  • Many other species in Asia, Africa, Israel, South America, and Middle East
  • Can be misdiagnosed as seizures, amphetamine poisoning, or meningitis
  • Higher mortality and severity of illness

Diagnosis

Signs and Symptoms

  • Onset within minutes, progressing to maximum severity in ’ Ό1 " 2 hr but may persist ≤48 " 72 hr.
  • Scorpion species determines symptomatology (Centruroides sculpturatus, aka Centruroides exilicauda or bark scorpion, is the only species in US causing symptoms).
  • Local tissue effects:No erythemaPainHyperesthesia
  • Autonomic effects:Sympathetic symptoms:TachycardiaHypertensionHyperthermiaPulmonary edemaAgitationPerspirationParasympathetic effects:HypotensionBradycardiaHypersalivation
  • Somatic effects:Involuntary muscle contractionsRestlessness
  • Cranial nerve effects:Roving eye movementsBlurred visionNystagmusTongue fasciculationsLoss of pharyngeal muscle control

Essential Workup

  • Identification of scorpion species not needed if scorpion is native to US (see above).
  • Maintain high clinical suspicion in endemic areas
  • Assess envenomation grade severity:Grade I: Local pain and/or paresthesias at siteGrade II: Local pain and/or paresthesias at a remote siteGrade III: Either cranial/autonomic or somatic skeletal neuromuscular dysfunctionGrade IV: Both cranial/autonomic and somatic skeletal muscle dysfunction

Diagnosis Tests & Interpretation

Lab

  • Grades I and II envenomations:
  • Grades III and IV envenomations:BUN, creatinineElectrolytesUACBC
  • Severely agitated patients:Creatine kinaseUrine myoglobin
  • Severe respiratory distress:
  • ABGs

Imaging

  • Chest radiograph for respiratory symptoms
  • ECG for tachycardia

Differential Diagnosis

  • Snake, spider, insect envenomation
  • Tetanus
  • Diphtheria
  • Botulism
  • Overdose/dystonic reaction
  • Seizures
  • Infections

Treatment

Pre-Hospital

Initial Stabilization/Therapy

  • ABCs
  • Endotracheal intubation if necessary
  • IV
  • O2
  • Monitor

Ed Treatment/Procedures

  • Mild envenomations " grades I and II:Oral analgesicsTetanus prophylaxis
  • Severe envenomations " grades III and IV:Antivenom (Anascorp), expensive therapyTetanus prophylaxisHypertensive urgencies/emergencies (rare):Standard therapy such as labetalolHypotension:IV fluid resuscitation and pressor therapy with dopamineSevere agitation:Treatment for rhabdomyolysis if present

Medication

  • Antivenom: Centruroides (scorpion) (Rx: Anascorp infuse 3 vials IV over 10 min); monitor for up to 60 min after completing infusion to determine if symptoms are resolved. Additional doses may be used if needed; infuse 1 vial at a time at 30 " 60 min intervals.
  • Dopamine: 2 " 5 Όg/kg/min IV; increase in 5 " 10 Όg/kg/min as needed
  • Midazolam: 1 " 2 mg (peds: 0.01 " 0.05 mg/kg) IV
  • Labetalol: 20 mg (peds: 0.3 " 1 mg/kg/dose) q10min
  • Fentanyl: 50 " 150 Όg (peds: 1 " 3 Όg/kg) IV
  • Tetanus toxoid: 0.5 mL IM (peds: Same dose)

Antivenom doses are the same in children because dosage is based on venom burden.

Follow-Up

Disposition

Admission Criteria

  • Grades III and IV envenomations require admission to ICU.
  • If antivenom is given with resolution of symptoms, observe for 1 " 2 hr if asymptomatic.

Discharge Criteria

  • Grades I and II envenomations after a short observation period (3 " 4 hr after sting occurred) for progression of symptoms
  • Grades III and IV envenomations given antivenom with resolution of symptoms can be discharged.
  • If patient received antivenom, discuss signs and symptoms of delayed serum sickness.
  • Discuss possibility of persistence of pain and paresthesias at site.
  • Encourage patient to return for progression of symptoms.

Toddlers are more likely to have early airway involvement.

Followup Recommendations

Primary care follow-up if antivenin given.

Pearls and Pitfalls

  • Maintain high index of suspicion for scorpion stings in endemic areas when patients present with typical symptoms.

Additional Reading

  • Boyer LV, Theodorou AA, Berg RA, et al. Antivenom for critically ill children with neurotoxicity from scorpion stings. N Engl J Med. 2009;360(20):2090 " 2098.
  • LoVecchio F, McBride C. Scorpion envenomations in young children in central Arizona. J Toxicol Clin Toxicol. 2003;41(7):937 " 940.
  • O 'Connor A, Ruha AM. Clinical course of bark scorpion envenomation managed without antivenom. J Med Toxicol. 2012;8(3):258 " 262.
  • Quan D. North American poisonous bites and stings Crit Care Clin. 2012;28(4):633 " 659.

See Also (Topic, Algorithm, Electronic Media Element)

  • Botulism
  • Rhabdomyolysis
  • Seizures
  • Spider Bite, Black Widow
  • Tetanus

Codes

ICD9

989.5 Toxic effect of venom

ICD10

T63.2X1A Toxic effect of venom of scorpion, accidental, init

SNOMED

  • 217670007 poisoning due to scorpion venom (disorder)