Scorpion Sting Neurotoxicity
Yes, scorpion stings cause neurotoxicity through venom neurotoxins that trigger massive autonomic nervous system discharge, predominantly sympathetic, with children being particularly vulnerable to severe systemic envenomation and life-threatening complications. 1
Mechanism of Neurotoxicity
Scorpion venom contains neurotoxins that cause sudden release of neurotransmitters from the autonomic nervous system, creating a cascade of sympathetic and parasympathetic effects 1. This neurotoxic mechanism directly affects multiple vital systems including cardiovascular, respiratory, and neuromuscular function 1.
Clinical Manifestations of Neurotoxicity
Local symptoms alone occur in most North American stings, but systemic neurotoxicity develops in approximately one-third of cases and can be fatal 2, 1:
Neurological Signs
- Extreme and perpetual restlessness (most common in young children) 3
- Roving eye movements 3
- Muscle rigidity 2
- Confusion and altered mental status 2
- Convulsions 4
- Encephalopathy 5
Autonomic Dysfunction
- Hypertension (constant at the beginning of systemic envenomation) 1
- Cardiac dysrhythmias 6
- Respiratory compromise including acute pulmonary edema 4, 5
- Cardiovascular failure 4, 6
Vulnerable Populations
Children under 10 years of age represent 80% of scorpion envenomation cases and are particularly sensitive to neurotoxic effects 3, 4. The severity and mortality risk are significantly higher in pediatric patients, with systemic envenomation being potentially lethal 4, 1.
Elderly patients are also at higher risk for severe systemic symptoms requiring antivenom administration 2.
Critical Time Factor
Patients with severe neurotoxicity arrive at hospitals after significantly longer delays than those with mild symptoms, and delayed presentation correlates with worse outcomes and higher mortality 4. Time to treatment is a critical determinant of survival 4.
Management of Neurotoxicity
Immediate Recognition and Activation
Emergency services must be called immediately if systemic symptoms develop, including difficulty breathing, muscle rigidity, dizziness, or confusion 2.
Antivenom Therapy
Antivenom should be administered for severe systemic envenomation, particularly in pediatric patients with cardiovascular or respiratory compromise 2. This is the only etiological treatment and, when administered early, prevents many complications and improves outcomes 1.
- Minimum dose: 5 ampoules (5 ml) diluted in 20-50 ml saline, injected slowly intravenously 6
- New antivenoms are highly purified immunoglobulin fragments with excellent efficacy and safety 1
- Adverse reactions are now very rare and usually mild 1, 6
Intensive Care Monitoring
All patients with severe systemic envenomation require close surveillance in an intensive care unit with continuous cardiac monitoring 4. This enables early detection and treatment of life-threatening complications including cardiac failure, respiratory failure, convulsions, and hypertension 4.
Adjunctive Pharmacotherapy
Protocol-guided therapy with prazosin (30 mcg/kg/dose every 6 hours until recovery) and dobutamine for acute pulmonary edema has demonstrated significant mortality reduction 5. However, prazosin is not mentioned in current American Heart Association guidelines as standard first-line therapy 2.
Common Pitfalls
Do not use phenobarbital as routine treatment—there is no evidence it decreases morbidity or mortality, and massive doses have been associated with respiratory arrests 3.
Do not assume antibiotics are needed for swelling, as this is caused by mediator release from neurotoxin effects, not infection 2.
Do not apply suction to the sting site 2.
Do not delay antivenom administration in patients with systemic symptoms—early treatment is critical for preventing complications and death 4, 1.
Prognosis
Most patients with local symptoms only recover completely within 24-48 hours 2. However, mortality from neurotoxic envenomation occurs primarily from myocarditis, acute pulmonary edema, and encephalopathy 5. Deaths are concentrated in children who receive delayed treatment (>4 hours after sting) 5.