Posted by Mark Sternfeld on January 8, 2011, 10:48 am, in reply to "scorpion"
Scorpion bites are rarely life threatening except in the elderly and pediatric population. Here is an excerpt from Adam's Emergency Medicine text: |
The scorpion is easily recognized by a tail-like abdominal segment that forms into a venom-filled bulb (telson). In the United States, scorpions are commonly encountered hazards mainly in the southwest, where Centruroides exilicauda (formerly C. sculpturatus), or the bark scorpion, is endemic. They commonly hide in dark spaces such as closets and shoes; the exoskeleton's ability to fluoresce under ultraviolet light is sometimes helpful in localizing these creatures. Worldwide, species that represent significant hazards to human health include Tityus spp. in Trinidad and Brazil, and Buthus and Parabuthus spp. in India, Africa, and the Middle East. Most scorpion stings occur when the creature feels threatened or alarmed.
The venom of C. exilicauda is complex and targets excitable membranes. The result is abnormal prolonged opening of sodium channels at the neuromuscular junction and at both sympathetic and parasympathetic nerve endings. Dangerous varieties of scorpions from other countries can cause a massive release of catecholamines from nerve terminals, particularly norepinephrine and acetylcholine, leading to diverse effects.
Local effects of erythema and tingling may be present, but these may be quite subtle initially. Tapping the site of discomfort gently accentuates the reported symptoms, even in the absence of visible skin lesions. Systemic symptoms, which are more dramatic than local effects, peak around 5 hours after the sting; these commonly include hypertension, tachycardia, convulsions, cranial neuropathies, roving opthalmoplegia (also known as “oculogyric crisis”), ataxia, abdominal cramps, and respiratory failure from neuromuscular dysfunction.
The stings of other scorpion genera may produce unique syndromes. Tityus scorpions in Trinidad and South America can cause pancreatitis, and in India and Africa, the Buthus and Parabissesuthus varieties can cause pulmonary hemorrhage, gastrointestinal bleeding, and disseminated intravascular coagulation, presumably because of the presence of phospholipase in the venom.
Testing of serum electrolytes, creatinine phosphokinase (CPK), and cardiac isozymes, as well as chest radiography and electrocardiography should be considered in patients at high risk of cardiac ischemia. Neurologic testing such as computed tomography of the head and lumbar puncture may be required in cases in which other neurologic disease processes are suspected.
The majority of patients respond to supportive care and aggressive pain management with analgesics and muscle relaxants. Continuous infusion of benzodiazepines may be considered in well-monitored patients to decrease agitation and abnormal motor activity. Short-acting antihypertensives such as esmolol or nitroprusside are also appropriate in the setting of severe hypertension and tachycardia.
Respiratory failure or fatigue warrant aggressive airway management and possibly intubation; this complication is especially concerning in the pediatric and elderly populations, which are most vulnerable to mortality from scorpion stings. Rarely, pancreatitis and coagulopathy require intensive supportive care with meticulous fluid management and transfusion of blood products.
Scorpion antivenom is not presently available in the United States.
Patients with severe signs and symptoms require admission, and intensive care may be necessary for pediatric and elderly patients. Patients who are comfortable and have normal vital signs and diagnostic testing results can safely be discharged. Wounds from scorpion stings do not usually require specific therapy for infection.
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