The Crotalus (South American Rattlesnake) lives mainly in dry regions in South America. They cause less than 10% of snakebites in Brazil.
The site of the snakebite may be normal or show mild edema with hyperemia. Pain at the site of the bite may be absent or minor. Paresthesias may follow the bite and last for several weeks.
Neurotoxic facies associated with Crotalus envenomation:
(1) unilateral or bilateral ptosis and paralysis of facial muscles (during first 6 hours)
(2) ophthalmoplegia
(3) mydriasis (dilation of the pupil)
(4) blindness
(5) diplopia
(6) involvement of cranial nerves may result in associated difficulty in swallowing and changes in taste or smell.
Clinical Finding
Moderate Severity
Severe
neurotoxic facies
mild to moderate
moderate to severe
myalgia
none or mild
moderate or severe
urine color
normal to light pink
dark urine from rhabdomyolysis
urine production
present
oliguria or anuria, with renal failure
blood coagulation
clottable
unclottable
respiratory function
normal
respiratory failure may be occur
Laboratory findings:
(1) myoglobinuria
(2) elevated serum CK
(3) hypofibrinogenemia
Dosing antivenom based on severity of disease (as available in Brazil during 1987):
(1) moderate envenomation: 10 ampules
(2) severe envenomation: 20 or more ampules
To read more or access our algorithms and calculators, please log in or register.
