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- only 1 species of major medical importance in the U.S. - the bark scorpion (Centruroides exilicauda)
- found throughout Arizona and immediately surrounding regions of neighboring states
- 13 to 75 mm long, yellow-brown in color, variable striping on its dorsum
- differentiated from other U.S. scorpions by a small tubercle at the base of the stinger
- other scorpions of minimal significance found all across the southern U.S.
B.
Neurotoxic Scorpions (Centruroides exilicauda):
- its venom is complex; contains at least 5 distinct neurotoxins
- causes release of neurotransmitters from the autonomic nervous system and adrenal medulla, and
depolarizes neuromuscular junctions
- no major enzymatic components
1.
Clinical Manifestations:
- most stings are minor (most serious = children)
- sting is followed by the onset of intense pain at the site within several minutes (but, may be absent in
children under the age of ten)
- often there is hyperesthesia - intense pain with mild palpation or tapping over the site (the "tap test")
- pain or numbness may radiate up the extremity
- soft tissue swelling and ecchymosis are notably absent in stings by this species due to the lack of
major
venom
enzymes
- systemic symptoms reflect sympathetic, parasympathetic, and neuromuscular excitation
- early on: restlessness/anxiety, followed by hypersalivation, sensation of tongue thickening,
dysphagia, difficulty focusing or temporary blindness, roving eye movements, tachypnea and
respiratory distress, wheezing or stridor, bladder or bowel incontinence, muscle fasciculations and
spasm,
alternating
opisthotonus and emprosthotonus, and paralysis
- extreme neuromuscular hyperactivity may be mistaken for seizures
- supraventricular tachycardia and hypertension
- temperature may reach 40 deg C
- symptom duration is inversely proportional to age (up to 30 hr)
2.
Management:
a. Field Management:
- no specific first aid measures; ice application may reduce pain
b. Hospital Management:
- monitor vital signs closely
- routine admission labs (no tests of particular diagnostic benefit)
- local ice and mild analgesics
-
tetanus
status
should
be
updated
prn
- if more severe envenomation: oxygen, IV line, cardiac and pulse oximetry
- intubate if signs of respiratory failure or inability to handle secretions
-
anxiety,
restlessness,
muscular
hyperactivity
and moderate hypertension usually resolve with bed
rest & sedation (intravenous benzodiazepines) - respiratory status should be closely monitored
- adrenergic blocking agents have been recommended for hemodynamically significant SVT, but
efficacy has yet to be studied
-
antihypertensive
agents
if
severe blood pressure elevations occur
- Calcium gluconate: for severe spasms can be tried, though experience is purely anecdotal (10 ml of
a 10% solution given slowly intravenously; 0.1 ml/kg in children)
-
avoid
narcotics
-
have
a synergistic neurotoxic effect
- Antivenin:
-
goat-derived
C. exilicauda antivenin previously available in Arizona
-
was
only
produced
for
use
within that state (not FDA approved)
-
anecdotally
effective
in
severe
envenomations in small children (no controlled clinical trials)
- risked anaphylaxis and delayed serum sickness
