II. Background
III. Mechanism: Toxicity
- Envenomation is via the tip of the Scorpion tail
- Most Scorpions cause only self-limited, local reactions
- Centruroides Scorpion Stings may result in severe Envenomation (5% of cases)
- Arizona Bark Scorpion (Centruroides sculpturatus) venom is a Neurotoxin
- Striped Bark Scorpion (Centruroides vittatus) is also a Neurotoxin, but less harmful than sculpturatus
IV. Types: Centruroides
- Arizona Bark Scorpion (Centruroides sculpturatus)
- Yellow to brown Scorpions
- Subnuclear tooth at the base of the Stinger
- Much more potentially dangerous than the Striped Bark Scorpion
- Striped Bark Scorpion (Centruroides vittatus)
- Black stripes on thorax
V. Symptoms
- Immediate burning pain at site of sting (typically on an extremity)
- Local or regional hyperesthesia for varying period
VI. Signs
- Local reaction (Scorpion other than C. sculpturatus)
- Erythema
- Edema
- Ecchymosis
- Tap test (Suggests C. sculpturatus sting)
- Administer sharp tap at wound site
- Positive
- Patient experiences significant pain
- Abruptly withdraws wound site
- Centruroides sculpturatus reaction
- Muscle spasm
- Excessive Salivation
- Fever
- Tachycardia
- Nystagmus
- Blurred Vision
- Slurred speech
- Respiratory distress or Wheezing
- Cranial Nerve dysfunction (e.g. roving eye movement)
- CNS hyperstimulation
- Seizures
- Cardiogenic Shock
- Pulmonary Edema
VII. Exam
- Sting site evaluation
- Thorough Neurologic Exam including Cranial Nerve exam
VIII. Grading: Envenomation
- Grade 1
- Pain and Paresthesias at localized site of sting
- Grade 2
- Pain and Paresthesias at remote site from bite (as well as meeting Grade 1 Criteria)
- Grade 3
- Meets criteria for Grade 2 sting AND
- ONE of the following neurologic criteria
- Cranial Nerve Involvement (e.g. Nystagmus, Dysarthria, Dysphagia, Drooling)
- Skeletal neuromuscular involvement (e.g. writhing, Fasciculations, jerking, Tetany)
- Autonomic signs (Salivation, Vomiting, bronchospasm, diaphoresis, Tachycardia)
- Grade 4
- All findings of Grade 3 Envenomation are present
IX. Labs: Grade 3 and 4 Envenomations
- Complete Blood Count
- Comprehensive Metabolic Panel
- Creatine Kinase
- Urinalysis
X. Course: Centruroides sculpturatus
- Infants <1 years: Fatal reactions are not uncommon
- Child <5 years: Potentially life threatening reactions
- Adults: Variable reactions but rarely fatal (elderly may be at higher risk)
XI. Management: General
- First aid and general measures
- Clean bite site with soap and water
- Ice or cool compress to wound site
- Elevation of affected part
- Tourniquets are not recommended for the affected, stung limb
- Avoid home remedies (e.g. Garlic)
-
General Medical Approach
- Immediate medical attention for children
- Try to identify the Scorpion type that caused the bite
- Consult poison control
- Tetanus Vaccine as needed
- Symptomatic therapy
- Antihistamines
- Corticosteroids
- Consider Regoinal Anesthesia
- Analgesics
- NSAIDs
- Acetaminophen
- Opioids are often needed
- Avoid Morphine if antivenom planned (increases Histamine release with risk of Anaphylaxis)
- Disposition
- Observe Grade 1 cases for at least 4 hours
- Observe Grade 2 cases at least 4 hours and until symptoms are controlled or improving
- Admit Grade 3 and 4 Envenomations to ICU (see below)
XII. Management: Severe Envenomation (Grade 3 and 4 Envenomation)
- Admit to Intensive Care Unit
- Arizona Bark Scorpion (Centruroides sculpturatus) Antivenom
- Indicated for Grade 3 or Grade 4 Envenomations
- Reduces length of severity of symptoms
- Antivenom is a risk for Anaphylaxis
- Observe closely
- ABC Management
- Respiratory depression
- Adequate ventilation
- CNS Hyperstimulation
- Seizures
- Severe Hypertension
- Consider Prazosin or vasodilator
- Manage Cardiogenic Shock
- ParenteralAnalgesics
- Parenteral Benzodiazepines
- ABC Management
XIII. Complications: Severe Envenomation
- Airway compromise or respiratory arrest
- Pulmonary Edema or Cardiogenic Shock
- Myocardial Infarction
- Cardiac Dysrhythmia
- Pancreatitis
- Takotsubo Cardiomyopathy
XIV. References
- (2021) Presc Lett 28(7): 40
- Cowling and Ferreri (2019) Crit Dec Emerg Med 33(2): 17-25
- Herness (2022) Am Fam Physician 106(2): 137-47 [PubMed]