Snakebites history and symptoms

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

History and Symptoms

• The bite site is usually painless. It may have classical paired fang marks, but this is not the most common picture. Often there are just a few lacerations or scratches, and sometimes these may be painless or go unnoticed. Bruising, bleeding, and local swelling may be present, but significant local tissue destruction is uncommon.
• Regional lymphadenopathy may be marked, even with non-venomous snake bites, and is not by itself an indication for the administration of antivenom. It may contribute to abdominal pain in children.
• The usual sequence of systemic symptom development:

  • (<1hr) Headache, irritability, photophobia, nausea, vomiting, diarrhea, confusion; coagulation abnormalities; occasionally sudden hypotension with loss of consciousness.
  • (1-3 hrs) Cranial nerve paralysis (ptosis, diplopia, dysphagia etc), abdominal pain, hemoglobinuria, hypertension, tachycardia, hemmorrhage.
  • (>3hrs) Limb and respiratory muscle paralysis leading to respiratory failure, peripheral circulatory failure with pallor and cyanosis, myoglobinuria, eventually death.

• This sequence of events is highly variable. Some bites, even apparently trivial ones, have been associated with acute deterioration over a five minute period leading to death. This may occur as soon as 30 minutes to an hour after the original bite. Acute, severe cardiac depression may be the mechanism for sudden death.
• Paralysis, when it occurs, usually commences with cranial nerves, then skeletal muscle, then the muscles of respiration. In small children or with highly venomous snake bites it may happen much more quickly.
• Major bleeding disturbances are rare although the development of coagulopathies and a DIC-like picture are relatively common. Thromboctopenia and hemolysis may occur. About 20% of patients who die after snake bite have cerebral hemmorrhages.
• Muscle destruction from myolytic toxins is not uncommon and may not be associated with muscle tenderness; it may lead to renal failure and should be specifically looked for, because early treatment with antivenom will reduce its severity.
• Snake bite should always be considered in any case of unexpected confusion or loss of consciousness following outdoor activities in snake country. Prognosis depends on the type of snake and the quantity of venom injected. An angry snake and multiple bites is associated with greater venom volumes.

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