Antivenom-anticholinesterase Combination Reverses Cobra Snakebite Mimicking Brain Death

By Reuters Staff

August 03, 2020

NEW YORK (Reuters Health) - A combination of polyvalent snake antivenom (PSA) and anticholinesterase successfully reversed cobra snakebite mimicking brain death in a 57-year-old woman.

Around 5 million people have been victims of snakebite, whose complications have resulted in as many as 138,000 deaths worldwide. Snakebites are the second toxicology-relevant cause mimicking brain death. Arabian cobra venom competes with acetylcholine for postsynaptic nicotinic receptor and leads to curare-like neuromuscular paralysis.

Dr. Musa S. ALfaifi of King Khalid University, in Abha, Saudi Arabia, and colleagues report the case of a 57-year-old woman with a history of cobra snakebite who presented to a community emergency room with flaccid paralysis. Her breathing soon ceased and she became unresponsive, whereupon she was intubated and placed on mechanical ventilation.

She received five vials of PSA over the course of an hour, but her clinical status remained unchanged for six hours, at which point she was transferred to a tertiary-care center for further management.

At the tertiary-care center, she was unresponsive to external stimuli, her pupils were 4 mm and nonreactive to light, and she had absent reflexes. There was no spontaneous respiratory effort, and muscle power was zero in all four limbs. Respiratory, cardiovascular and abdominal examinations were otherwise normal, and her laboratory results were unremarkable.

She received an additional five vials of PSA over the first hour and, after transfer to the intensive-care unit, she received five vials of PSA every two hours.

After no clinical improvement following 30 vials of PSA, she was given a trial regimen of intravenous neostigmine along with an intravenous dose of atropine, immediately after which her pupils showed slight reaction to light.

PSA administration was extended for 24 hours, for a total dose of 50 vials (a "megadose," according to the authors), and she received three doses of neostigmine as well as pyridostigmine via nasogastric tube every six hours for 24 hours.

She recovered full neurological function within 48 hours. On day 3, she was weaned off mechanical ventilation and successfully extubated. She was discharged from ICU on day 4 and transferred to the general ward, from which she was eventually discharged home in normal condition, the authors report in the American Journal of Emergency Medicine.

"In the endemic area of cobra snakebite, we recommend excluding the neuroparalytic effect of snakebite before considering withdrawal of ventilatory support or organ donation, which would be catastrophic if missed," the authors write.

"The life-threatening presentation of cobra envenomation mandates the use of higher doses of PSA to reverse the neuroparalytic toxicity," they add. "We should consider the role of anticholinesterase as an adjunctive therapy to PSA in severe cobra envenomation."

Dr. ALfaifi did not respond to a request for comments.

SOURCE: American Journal of Emergency Medicine, online July 6, 2020.