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Brown Recluse Spider Bites

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					Brown Recluse Spider Bites
The Spider
The brown recluse spider
(Loxosceles reclusa) has the
potential to inflict injury.
It is seen predominantly in the
South Central United States.
Adult spiders are soft-bodied and
yellowish-tan to dark brown.
They are about 1/4 to 1/2 inch
long, and their leg span is about the
size of a half dollar.
A distinguishing characteristic is
the violin-shaped marking on the
dorsal cephalothorax (see Slide 2).




                                        Image courtesy of US
                                        Centers for Disease
                                        Control and Prevention.
The Spider
Incidents involving the brown
recluse spider usually occur in
summer months.
The spider prefers dark, dry, and
undisturbed locations, such as
woodpiles, the underside of rocks,
and storage areas in garages, attics,
basements, and linen closets.
Bites are rare, however, even in
houses that are heavily infested
with spiders. For this reason, a
diagnosis of a recluse bite is
unlikely in areas that lack
significant populations of
Loxosceles spiders.



                                        Image courtesy of US
                                        Centers for Disease Control
                                        and Prevention.
The Bite
It is estimated that less than 10% of
envenomations result in severe skin
necrosis.
Wounds destined for necrosis
usually show signs of progression,
such as bullae formation, cyanosis,
and hyperesthesia, within 6-12
hours.
Central blistering surrounded by a
ring of blanched skin that is itself
surrounded by a large area of
asymmetric erythema leads to the
typical "red, white, and blue" sign
of a recluse bite.
In this patient, the bite area turned
blue and dark red by the evening of
the first day.

                                        Image courtesy of Dale Losher.
The Wound
In cutaneous necrosis, a bulla
develops at the center of the
affected area and becomes necrotic,
involving both superficial and deep
tissues.

Areas with increased adipose
tissue, such as the thighs, buttocks,
and abdomen, are more likely to
undergo severe necrosis than bites
occurring at other sites.

Systemic loxoscelism, although
unusual, may include fever,
nausea, hematologic disorders, and
renal failure.

This image shows the wound on
the third day after the bite.           Image courtesy of Dale Losher.
The Wound
Brown recluse spider venom is
protein-based and includes
sphingomyelinase D2, which acts
directly on red blood cells to cause
lysis.

At the stage shown, these bites may
be associated with significant pain
related to incipient necrosis of skin
and subcutaneous tissues.

The resultant eschar and ulceration
may take months to resolve.

Patients should be advised to avoid
both strenuous exercise and local
heat to help limit spread of the
venom.
                                        Image courtesy of Dale Losher.
Severe Wound
Almost all recluse bites heal nicely
in 2-3 months without medical
treatment.

When treatment is deemed
appropriate, a conservative
approach is best, using cold
compresses, simple analgesics,
elevation of an affected extremity,
and cleansing of the bite site.

In this severe case, the patient
withstood 8 days of having an open
wound to drain the spider's toxins
and needed intravenous antibiotics
and pain medication almost 24
hours a day.

                                       Image courtesy of Dale Losher.
Severe Wound
Excision of a necrotic skin site may
be advisable (especially for the rare
large lesion) but only after an
eschar has formed, adjacent tissues
seem to have recovered, and
normal healing is possible, which
can take up to 6-8 weeks. In this
patient, a 5-inch-wide area of dead
tissue was excised 11 days after the
bite.

The extensive size of the wound
necessitated skin grafting. Image




                                        Photo courtesy of Dale Losher.
Skin Grafting
Inpatient care is not indicated for
cutaneous symptoms from a
recluse bite.

In systemic symptoms, a hemolytic
episode is seen that is usually self-
limited and requires no special
treatment.

Systemic steroids with intravenous
hydration and monitoring of renal
function may be needed in some
cases.

38 days after the bite, this patient
waits to see the results of the skin
grafting.

                                        Image courtesy of Dale Losher.
Skin Graft
The prognosis for recluse bites is
good, and most patients show an
excellent outcome. In most cases,
pain subsides within 1 week, and a
striking reduction in the size of the
necrosis is evident.

Healing may be slow, but all
recluse wounds heal, usually with a
minimum of scar tissue.

In this severe case, the skin graft
was healing well 38 days after the
bite.




                                        Image courtesy of Dale Losher.
Healed Wound & Skin
Graft
To prevent recluse bites,
individuals (particularly those who
live in endemic areas) should learn
to recognize the brown recluse
spider and become familiar with its
environment.

Patient awareness is the primary
factor in making the correct
diagnosis and forming the
appropriate treatment plan for the
recluse bite.

This patient's large wound is fully
healed approximately 10 months
after the bite.



                                      Image courtesy of Dale Losher.
Eschar Formation
Dapsone has been shown to limit
tissue destruction in some
experimental models, but the
results have been mixed and
largely disappointing.

A latency period of even a few
hours before dapsone is started
may negate any beneficial effects.

Dapsone can cause hemolysis,
especially in the setting of G6PD
deficiency.

This image shows a brown recluse
bite 1 week after early use (within
72 hours) of dapsone.
Healing
After 1 month of treatment with
dapsone and topical antibiotic, the
lesion showed good delineation of
margins and granulation tissue at
its edges and base.
At this stage, this eschar was
debrided and healed well with
topical antibiotics and daily
dressing changes.

Because dapsone can cause
hemolysis, complete blood counts
should be performed weekly for
the first month and then monthly
for 6 months.

Treatment should be discontinued
if a significant reduction in
platelets, leukocytes, or
hematopoiesis is noted.

				
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