Scorpion

Aka: Scorpion, Centruroides sculpturatus, Arizona Bark Scorpion, Scorpion Sting

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II. Background

  1. Scorpions are Arachnids with venomous Stingers in their tails
  2. Scorpions tend to hide in crevices, shoes

III. Mechanism: Toxicity

  1. Envenomation is via the tip of the Scorpion tail
  2. Most Scorpions cause only self-limited, local reactions
  3. Centruroides Scorpion Stings may result in severe Envenomation (5% of cases)
    1. Arizona Bark Scorpion (Centruroides sculpturatus) venom is a Neurotoxin
    2. Striped Bark Scorpion (Centruroides vittatus) is also a Neurotoxin, but less harmful than sculpturatus

IV. Types: Centruroides

  1. Arizona Bark Scorpion (Centruroides sculpturatus)
    1. Yellow to brown Scorpions
    2. Subnuclear tooth at the base of the Stinger
    3. Much more potentially dangerous than the Striped Bark Scorpion
  2. Striped Bark Scorpion (Centruroides vittatus)
    1. Black stripes on thorax

V. Symptoms

  1. Immediate burning pain at site of sting (typically on an extremity)
  2. Local or regional hyperesthesia for varying period

VI. Signs

  1. Local reaction (Scorpion other than C. sculpturatus)
    1. Erythema
    2. Edema
    3. Ecchymosis
  2. Tap test (Suggests C. sculpturatus sting)
    1. Administer sharp tap at wound site
    2. Positive
      1. Patient experiences significant pain
      2. Abruptly withdraws wound site
  3. Centruroides sculpturatus reaction
    1. Muscle spasm
    2. Excessive Salivation
    3. Fever
    4. Tachycardia
    5. Nystagmus
    6. Blurred Vision
    7. Slurred speech
    8. Respiratory distress or Wheezing
    9. Cranial Nerve dysfunction (e.g. roving eye movement)
    10. CNS hyperstimulation
    11. Seizures
    12. Cardiogenic Shock
    13. Pulmonary Edema

VII. Exam

  1. Sting site evaluation
  2. Thorough Neurologic Exam including Cranial Nerve exam

VIII. Grading: Envenomation

  1. Grade 1
    1. Pain and Paresthesias at localized site of sting
  2. Grade 2
    1. Pain and Paresthesias at remote site from bite (as well as meeting Grade 1 Criteria)
  3. Grade 3
    1. Meets criteria for Grade 2 sting AND
    2. ONE of the following neurologic criteria
      1. Cranial Nerve Involvement (e.g. Nystagmus, Dysarthria, Dysphagia, Drooling)
      2. Skeletal neuromuscular involvement (e.g. writhing, Fasciculations, jerking, Tetany)
      3. Autonomic signs (Salivation, Vomiting, bronchospasm, diaphoresis, Tachycardia)
  4. Grade 4
    1. All findings of Grade 3 Envenomation are present

IX. Labs: Grade 3 and 4 Envenomations

  1. Complete Blood Count
  2. Comprehensive Metabolic Panel
  3. Creatine Kinase
  4. Urinalysis

X. Course: Centruroides sculpturatus

  1. Infants <1 years: Fatal reactions are not uncommon
  2. Child <5 years: Potentially life threatening reactions
  3. Adults: Variable reactions but rarely fatal (elderly may be at higher risk)

XI. Management: General

  1. First aid and general measures
    1. Clean bite site with soap and water
    2. Ice or cool compress to wound site
    3. Elevation of affected part
    4. Tourniquets are not recommended for the affected, stung limb
    5. Avoid home remedies (e.g. Garlic)
  2. General Medical Approach
    1. Immediate medical attention for children
    2. Try to identify the Scorpion type that caused the bite
    3. Consult poison control
    4. Tetanus Vaccine as needed
  3. Symptomatic therapy
    1. Antihistamines
    2. Corticosteroids
    3. Consider Regoinal Anesthesia
    4. Analgesics
      1. NSAIDs
      2. Acetaminophen
      3. Opioids are often needed
        1. Avoid Morphine if antivenom planned (increases Histamine release with risk of Anaphylaxis)
  4. Disposition
    1. Observe Grade 1 cases for at least 4 hours
    2. Observe Grade 2 cases at least 4 hours and until symptoms are controlled or improving
    3. Admit Grade 3 and 4 Envenomations to ICU (see below)

XII. Management: Severe Envenomation (Grade 3 and 4 Envenomation)

  1. Admit to Intensive Care Unit
  2. Arizona Bark Scorpion (Centruroides sculpturatus) Antivenom
    1. Indicated for Grade 3 or Grade 4 Envenomations
    2. Reduces length of severity of symptoms
    3. Antivenom is a risk for Anaphylaxis
  3. Observe closely
    1. ABC Management
      1. Respiratory depression
      2. Adequate ventilation
    2. CNS Hyperstimulation
    3. Seizures
    4. Severe Hypertension
      1. Consider Prazosin or vasodilator
    5. Manage Cardiogenic Shock
    6. ParenteralAnalgesics
    7. Parenteral Benzodiazepines

XIII. Complications: Severe Envenomation

  1. Airway compromise or respiratory arrest
  2. Pulmonary Edema or Cardiogenic Shock
  3. Myocardial Infarction
  4. Cardiac Dysrhythmia
  5. Pancreatitis
  6. Takotsubo Cardiomyopathy

XIV. References

  1. (2021) Presc Lett 28(7): 40
  2. Cowling and Ferreri (2019) Crit Dec Emerg Med 33(2): 17-25
  3. Herness (2022) Am Fam Physician 106(2): 137-47 [PubMed]

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