Page 20 - JSOM Summer 2019

Differential Diagnosis of an Unusual Snakebite Presentation in Benin

Dry Bite or Envenomation?

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Jordan M. Benjamin, EMT-P, NRP *; Jean-Philippe Chippaux, MD, PhD ;
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Kate Jackson, PhD ; Sanda Ashe ; Bio Tamou-Sambo, MD ; Achille Massougbodji, MD ;
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Olouchégoun Cardinal Akpakpa, MD ; Benjamin N. Abo, DO, EMT-P 8
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ABSTRACT
A 20-year-old man presented to a rural hospital in Bembéréké, from venomous snakes result in envenomation, a phenome-
northern Benin, after a witnessed bite from a small, dark snake non referred to as a “dry bite.” The initial presentation can be
to his left foot that occurred 3 hours earlier. The description further complicated by anxiety provoked by the encounter, as
of the snake was consistent with several neurotoxic elapids snakes are the most feared animal and some degree of ophid-
known to inhabit the area in addition to various species from iophobia has been reported in greater than 50% of the popula-
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at least 10 different genera of non–front-fanged colubroid tion. The astute clinician must consider a number of possible
(NFFC) venomous snakes. The presentation was consistent diagnoses when evaluating the snakebite patient to ensure that
with the early signs of a neurotoxic snakebite as well as a sym- antivenom is given promptly to those who need it and is not
pathetic nervous system stress response. Diagnosis was further wasted on those who do not. These challenges are illustrated
complicated by the presence of a makeshift tourniquet, which and discussed here using a snakebite case where the diagno-
either could have been the cause of local signs and symptoms sis was complicated by all of the aforementioned factors and
or a mechanical barrier delaying venom distribution and sys- may represent the first documented instance of prolonged psy-
temic effects until removal. Systemic envenomation did not chosomatic symptoms resulting from a witnessed snakebite.
develop after the removal of the constricting band, but sig- This case provides an opportunity to review the management
nificant local paresthesias persisted for longer than 24 hours of these patients and serves as a reminder that dry bites and
and resolved after the administration of a placebo injection bites from nonvenomous species are not necessarily asymp-
of normal saline in place of antivenom therapy. This was an tomatic and may initially mimic the early signs of a true snake
unusual case of snakebite with persistent neuropathy despite envenomation.
an apparent lack of envenomation and a number of snake-
bite-specific variables that complicated the initial assessment, Case Presentation
diagnosis, and treatment of the patient. This case presenta-
tion provides clinicians with an opportunity to familiarize A 20-year-old Beninese man with no significant medical history
themselves with the differential diagnosis and approach to a presented to a rural hospital in Bembéréké, northern Benin, at
patient bitten by an unidentified snake, and it illustrates the 2200 hours complaining of a snakebite to the dorsum of his
importance of symptom progression as a pathognomonic sign left foot that occurred 3 hours earlier. He was wearing sandals
during the early stages of a truly serious snake envenomation. when taking a shortcut through an agricultural field after dark
Treatment should be based on clinical presentation and evo- when he felt a pricking sensation followed by something tug-
lution of symptoms rather than on snake identification alone. ging on his left foot. He looked down to see a small (<0.5m),
dark snake with smooth, shiny scales actively chewing on his
Keywords: snakebite; envenomation; clinical diagnosis; non– foot, where it remained for several seconds before it was flung
front-fanged colubroid; antivenom; dry bite into the darkness with a vigorous kick. He immediately fash-
ioned a constricting band just above the ankle using a 120cm ×
5cm strip of fabric, which was wrapped tightly around the leg
several times and tied in place to maintain tension. No tradi-
Introduction
tional medicine was used, and no traumatic injuries occurred
The assessment, diagnosis, and treatment of snakebite patients before arrival at the hospital.
can be complicated by a variety of factors related to the snake,
the patient, the circumstances that precipitated the bite, and Initial assessment revealed an anxious, restless young man com-
the actions taken by the patient after the bite has occurred. plaining of a diffuse numbness, tingling (described as “pins
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Not all snakebites are from venomous snakes and not all bites and needles”), and pruritus in the bitten limb that passed the
*Correspondence to jordan@snakebitefoundation.org
1 Mr Benjamin is affiliated with the Department of Biology, Whitman College, Walla Walla, WA; the Asclepius Snakebite Foundation, Seattle,
WA; and the Center for the Study and Research of Malaria Associated with Pregnancy and Childhood (CERPAGE), Cotonou, Bénin. Dr Chip-
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paux is affiliated with the Asclepius Snakebite Foundation; CERPAGE; IRD UMR216, Mère et Enfant face aux Infections Tropicales, Paris,
France; and Sorbonne Paris Cité, Université Paris Descartes, Faculté de Pharmacie, Paris, France. Dr Jackson is affiliated with the Department of
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Biology, Whitman College; and the Asclepius Snakebite Foundation. Ms Ashe is affiliated with the Bio-Ken Snake Farm and James Ashe Anti-
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venom Trust, Watamu, Kenya. Dr Tamou-Sambo is affiliated with the Département de Chirurgie et Spécialités, Faculté de Médecine, Université
Parakou, Bénin. Dr Massougbodji is affiliated with the Département de chirurgie et spécialités, Faculté de Médecine, Université Parakou, Bénin.
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7 Dr Akpakpa is affiliated with Centre de Santé Communal de Nikki, Parakou, Bénin. Dr Abo is affiliated with the Asclepius Snakebite Founda-
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tion and the University of Florida College of Medicine, Gainesville, FL.
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